Pub Date : 2024-09-12DOI: 10.1101/2024.09.07.611817
Dominic Kuang, Shanna Romand, Anna S Zvereva, Bianca MO Marchesano, Stefano Buratti, Ke Zheng, Evelien Mylle, Cornelia Spetea Wiklund, Daniel Van Damme, Bernhard Wurzinger, Markus Schwarzlander, Markus Teige, Alex Costa, Simon Stael
Plants require water and light for photosynthesis, but light, when focused by water droplets on leaves, can create high light intensity spots that are harmful to plants. As excessive light intensity can reduce growth or even induce cell death, it is vital for plants to detect and react to changes in light exposure and acclimate to high light stress. Ca2+ signaling was previously implicated in high light acclimation. However, the dynamics of free Ca2+ concentration in the chloroplast, the primary site of photosynthesis, or in the nucleus and in the cytoplasm, where transcription and translation for long term acclimation occurs, remain unknown. Here we studied the dynamics and mechanism of the Ca2+ response to high light exposure. Focusing light through a glass bead to mimic water droplets triggered an increase of the free Ca2+ concentration in the chloroplast stroma of Arabidopsis thaliana. This finding was corroborated using established and newly developed genetically encoded calcium indicators, which revealed a biphasic increase in the stromal free Ca2+ concentration when exposed to varying intensities and qualities of light. Among photosynthetic by products, reactive oxygen and lipophilic species in particular, have been implicated in high light stress acclimation. A H2O2 signature was induced, albeit with different dynamics than the Ca2+ response, while chemical inhibition of the photosynthetic electron transport points towards singlet oxygen as a potential culprit of the high light-induced increase in stromal free Ca2+ concentration. The observed dynamics differed from those of a heat shock induced Ca2+ signature, although temperature had a positive effect on the Ca2+ response. Based on Ca2+ inhibitor treatments and the free Ca2+ concentration dynamics, we suggest that the high light induced stromal Ca2+ is derived from the endoplasmic reticulum rather than from the cytoplasm. In conclusion, inspired by the burning glass effect of water droplets on leaves, we uncovered a Ca2+ response that implicates a novel mechanism for plants to acclimate to high light stress, a process that will become increasingly relevant in a changing climate.
{"title":"Burning glass effect of water droplets triggers an ER-derived calcium response in the chloroplast stroma of Arabidopsis thaliana leaves","authors":"Dominic Kuang, Shanna Romand, Anna S Zvereva, Bianca MO Marchesano, Stefano Buratti, Ke Zheng, Evelien Mylle, Cornelia Spetea Wiklund, Daniel Van Damme, Bernhard Wurzinger, Markus Schwarzlander, Markus Teige, Alex Costa, Simon Stael","doi":"10.1101/2024.09.07.611817","DOIUrl":"https://doi.org/10.1101/2024.09.07.611817","url":null,"abstract":"Plants require water and light for photosynthesis, but light, when focused by water droplets on leaves, can create high light intensity spots that are harmful to plants. As excessive light intensity can reduce growth or even induce cell death, it is vital for plants to detect and react to changes in light exposure and acclimate to high light stress. Ca2+ signaling was previously implicated in high light acclimation. However, the dynamics of free Ca2+ concentration in the chloroplast, the primary site of photosynthesis, or in the nucleus and in the cytoplasm, where transcription and translation for long term acclimation occurs, remain unknown. Here we studied the dynamics and mechanism of the Ca2+ response to high light exposure. Focusing light through a glass bead to mimic water droplets triggered an increase of the free Ca2+ concentration in the chloroplast stroma of Arabidopsis thaliana. This finding was corroborated using established and newly developed genetically encoded calcium indicators, which revealed a biphasic increase in the stromal free Ca2+ concentration when exposed to varying intensities and qualities of light. Among photosynthetic by products, reactive oxygen and lipophilic species in particular, have been implicated in high light stress acclimation. A H2O2 signature was induced, albeit with different dynamics than the Ca2+ response, while chemical inhibition of the photosynthetic electron transport points towards singlet oxygen as a potential culprit of the high light-induced increase in stromal free Ca2+ concentration. The observed dynamics differed from those of a heat shock induced Ca2+ signature, although temperature had a positive effect on the Ca2+ response. Based on Ca2+ inhibitor treatments and the free Ca2+ concentration dynamics, we suggest that the high light induced stromal Ca2+ is derived from the endoplasmic reticulum rather than from the cytoplasm. In conclusion, inspired by the burning glass effect of water droplets on leaves, we uncovered a Ca2+ response that implicates a novel mechanism for plants to acclimate to high light stress, a process that will become increasingly relevant in a changing climate.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"131 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-12DOI: 10.1101/2024.09.01.610688
Christian Ary Vasquez-Castro, Elodie Morel, Bernardo Garcia-Simpson, Mario Vallejo-Marin
Study premise: Pollen transfer efficiency (PTE) and pollen deposition patterns on a pollinator's body significantly influence plant reproductive success. However, studies on pollen fates (i.e., the destination of pollen grains after being released) in animal-pollinated species, particularly those offering pollen as the sole reward, are limited. Here, we investigated pollen fates in two nectarless, buzz-pollinated Solanum species with contrasting floral morphology. Methods: We conducted experimental trials involving one pollen donor and four recipient flowers of Solanum rostratum and S. dulcamara, using captive Bombus terrestris as pollinator. After each trial, we assessed the amount of pollen remaining in the anthers, deposited on stigmas, placed on the pollinator, and falling to the ground. We then estimated pollen fates and PTE, and modelled their pollen deposition curves. Key results: We found that S. rostratum produced more pollen but had a more restricted pollen dispensing schedule compared to S. dulcamara. Although PTE was similar between species (0.72% vs. 1.07%, for S. rostratum and S. dulcamara, respectively), pollen loss mainly occurred due to falling to the ground in S. rostratum and bee grooming in S. dulcamara, potentially explained by their different floral architectures. Both species exhibited a typical exponential decay pattern in pollen deposition, with the first visited flowers receiving the most outcross pollen. Conclusions: Our results suggest that PTE in pollen-rewarding, buzz-pollinated species is quantitatively similar to that in nectar-rewarding flowers with single pollen units (PTE = 1-2%), and that different buzz-pollinated flower architectures achieve similar PTE although through different pollen-loss pathways.
研究前提：花粉传递效率（PTE）和花粉在授粉者身体上的沉积模式对植物的繁殖成功率有很大影响。然而，有关动物授粉物种花粉命运（即花粉粒释放后的去向）的研究非常有限，尤其是那些以花粉作为唯一回报的物种。在此，我们研究了两种无花蜜、嗡嗡授粉且花朵形态截然不同的茄科植物的花粉命运。研究方法我们使用人工饲养的土蜂作为授粉昆虫，对茄科植物茄属（Solanum rostratum）和茄属（S. dulcamara）的一朵授粉花和四朵受粉花进行了实验。每次试验后，我们都会评估花粉在花药中的剩余量、柱头上的沉积量、授粉器上的花粉量以及掉落地面的花粉量。然后，我们估算了花粉的命运和PTE，并模拟了它们的花粉沉积曲线。主要结果我们发现，与杜鹃花相比，萝藦科植物产生的花粉更多，但花粉散布时间更有限。虽然两种植物的 PTE 相似（S. rostratum 和 S. dulcamara 的 PTE 分别为 0.72% 和 1.07%），但花粉损失主要发生在 S. rostratum 落到地面和 S. dulcamara 被蜜蜂梳理的过程中，这可能是它们不同的花卉结构造成的。两个物种的花粉沉积都呈现出典型的指数衰减模式，最先到访的花朵获得的外交花粉最多。结论我们的研究结果表明，花粉奖励型嗡嗡授粉物种的PTE与花蜜奖励型单花粉单位花卉的PTE（PTE = 1-2%）在数量上相似，不同的嗡嗡授粉花卉结构虽然通过不同的花粉损失途径实现相似的PTE。
{"title":"The fate of pollen in two morphologically contrasting buzz-pollinated Solanum flowers","authors":"Christian Ary Vasquez-Castro, Elodie Morel, Bernardo Garcia-Simpson, Mario Vallejo-Marin","doi":"10.1101/2024.09.01.610688","DOIUrl":"https://doi.org/10.1101/2024.09.01.610688","url":null,"abstract":"Study premise: Pollen transfer efficiency (PTE) and pollen deposition patterns on a pollinator's body significantly influence plant reproductive success. However, studies on pollen fates (i.e., the destination of pollen grains after being released) in animal-pollinated species, particularly those offering pollen as the sole reward, are limited. Here, we investigated pollen fates in two nectarless, buzz-pollinated Solanum species with contrasting floral morphology. Methods: We conducted experimental trials involving one pollen donor and four recipient flowers of Solanum rostratum and S. dulcamara, using captive Bombus terrestris as pollinator. After each trial, we assessed the amount of pollen remaining in the anthers, deposited on stigmas, placed on the pollinator, and falling to the ground. We then estimated pollen fates and PTE, and modelled their pollen deposition curves. Key results: We found that S. rostratum produced more pollen but had a more restricted pollen dispensing schedule compared to S. dulcamara. Although PTE was similar between species (0.72% vs. 1.07%, for S. rostratum and S. dulcamara, respectively), pollen loss mainly occurred due to falling to the ground in S. rostratum and bee grooming in S. dulcamara, potentially explained by their different floral architectures. Both species exhibited a typical exponential decay pattern in pollen deposition, with the first visited flowers receiving the most outcross pollen. Conclusions: Our results suggest that PTE in pollen-rewarding, buzz-pollinated species is quantitatively similar to that in nectar-rewarding flowers with single pollen units (PTE = 1-2%), and that different buzz-pollinated flower architectures achieve similar PTE although through different pollen-loss pathways.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-10DOI: 10.1101/2024.09.09.611939
Ka Kit Chung, Ziwei Zhao, Kai Ching Law, Juncai Ma, Cheuk Him Jack Chiang, Kwan Ho Leung, Ruben Shrestha, Yixin Wu, Chaorui Li, Lei Feng, Xibao Li, Ka-Ming Lee, Kam-Bo Wong, Shou-Ling Xu, Caiji Gao, Xiaohong Zhuang
Macroautophagy (hereafter autophagy) is essential for cells to respond to nutrient stress by delivering cytosolic contents to vacuoles for degradation via the formation of a multi-layer vesicle named autophagosome. A set of autophagy-related (ATG) regulators are recruited to the phagophore assembly site for the initiation of phagophore, as well as its expansion and closure and subsequent delivery into the vacuole. However, it remains elusive that how the phagophore assembly is regulated under different stress conditions. Here, we described an unknown Arabidopsis (Arabidopsis thaliana) cytosolic ATG8-interaction protein family (ERC1/2), that binds ATG8 and NBR1 to promote autophagy. ERC1 proteins translocate to the phagophore membrane and develop into classical ring-like autophagosomes upon autophagic induction. However, ERC1 proteins form large droplets together with ATG8e proteins when in the absence of ATG8 lipidation activity. We described the property of these structures as phase-separated membraneless condensates by solving the in vivo organization with spatial and temporal resolution. Moreover, ERC1 condensates elicits a strong recruitment of the autophagic receptor NBR1. Loss of ERC1 suppressed NBR1 turnover and attenuated plant tolerance to heat stress condition. This work provides novel insights into the mechanical principle of phagophore initiation via an unreported ERC1-mediated biomolecular condensation for heat tolerance in Arabidopsis.
{"title":"Biomolecular condensation of ERC1 recruits ATG8 and NBR1 to drive autophagosome formation for plant heat tolerance","authors":"Ka Kit Chung, Ziwei Zhao, Kai Ching Law, Juncai Ma, Cheuk Him Jack Chiang, Kwan Ho Leung, Ruben Shrestha, Yixin Wu, Chaorui Li, Lei Feng, Xibao Li, Ka-Ming Lee, Kam-Bo Wong, Shou-Ling Xu, Caiji Gao, Xiaohong Zhuang","doi":"10.1101/2024.09.09.611939","DOIUrl":"https://doi.org/10.1101/2024.09.09.611939","url":null,"abstract":"Macroautophagy (hereafter autophagy) is essential for cells to respond to nutrient stress by delivering cytosolic contents to vacuoles for degradation via the formation of a multi-layer vesicle named autophagosome. A set of autophagy-related (ATG) regulators are recruited to the phagophore assembly site for the initiation of phagophore, as well as its expansion and closure and subsequent delivery into the vacuole. However, it remains elusive that how the phagophore assembly is regulated under different stress conditions. Here, we described an unknown Arabidopsis (Arabidopsis thaliana) cytosolic ATG8-interaction protein family (ERC1/2), that binds ATG8 and NBR1 to promote autophagy. ERC1 proteins translocate to the phagophore membrane and develop into classical ring-like autophagosomes upon autophagic induction. However, ERC1 proteins form large droplets together with ATG8e proteins when in the absence of ATG8 lipidation activity. We described the property of these structures as phase-separated membraneless condensates by solving the in vivo organization with spatial and temporal resolution. Moreover, ERC1 condensates elicits a strong recruitment of the autophagic receptor NBR1. Loss of ERC1 suppressed NBR1 turnover and attenuated plant tolerance to heat stress condition. This work provides novel insights into the mechanical principle of phagophore initiation via an unreported ERC1-mediated biomolecular condensation for heat tolerance in Arabidopsis.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"151 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1101/2024.09.07.611788
Alexandra Siffert, Joelle Schlaepfer Sasse
Sugars are critical for plant growth, development, and environmental interactions. They have multiple roles as nutrients for plants, associated beneficial and pathogenic microbes, and as signaling compounds for immunity. We characterize the interconnectedness of these functions by analyzing sugar metabolism and transporter mutant lines. We find that in these lines, root-derived compounds, exudates, are significantly altered in comparison with wild-type not only for carbohydrates, but also for lipids, organic acids, and defense compounds. Quantification of sugar exudation reveals more carbon release during the day than at night, altered sugar exudation in mutant lines, and an opposite exudation pattern with elevated exudation at night for pgm1, a line deficient in starch synthesis. Sugar levels in exudates and tissues did not correlate, suggesting a controlled mode of exudation for sugars. Altered sugar levels have functional consequences: mutant lines exhibit increased resistance against the pathogen Pseudomonas syringae and harbor altered numbers of microbes on roots. Day- and nighttime exudates of mutant lines impact the growth of single microbes such as an inability to grow for Bacillus subtilis. Exogenous sugar alters the production of reactive oxygen species in a plant development-dependent manner with opposite effects at 9 days and 14 days. An RNAseq experiment reveals candidate genes potentially involved in this regulation. Our data highlight that sugar metabolism is intricately linked with other metabolite pathways. Alteration of single genes in central carbon metabolism profoundly alters plant immune responses and plant-microbe interactions.
{"title":"Altered Arabidopsis thaliana sugar metabolism affects exudation, immune responses, and plant-microbe interactions","authors":"Alexandra Siffert, Joelle Schlaepfer Sasse","doi":"10.1101/2024.09.07.611788","DOIUrl":"https://doi.org/10.1101/2024.09.07.611788","url":null,"abstract":"Sugars are critical for plant growth, development, and environmental interactions. They have multiple roles as nutrients for plants, associated beneficial and pathogenic microbes, and as signaling compounds for immunity. We characterize the interconnectedness of these functions by analyzing sugar metabolism and transporter mutant lines. We find that in these lines, root-derived compounds, exudates, are significantly altered in comparison with wild-type not only for carbohydrates, but also for lipids, organic acids, and defense compounds. Quantification of sugar exudation reveals more carbon release during the day than at night, altered sugar exudation in mutant lines, and an opposite exudation pattern with elevated exudation at night for\t<em>pgm1</em>, a line deficient in starch synthesis. Sugar levels in exudates and tissues did not correlate, suggesting a controlled mode of exudation for sugars. Altered sugar levels have functional consequences: mutant lines exhibit increased resistance against the pathogen <em>Pseudomonas syringae\t</em> and harbor altered numbers of microbes on roots. Day- and nighttime exudates of mutant lines impact the growth of single microbes such as an inability to grow for <em>Bacillus subtilis</em>. Exogenous sugar alters the production of reactive oxygen species in a plant development-dependent manner with opposite effects at 9 days and 14 days. An RNAseq experiment reveals candidate genes potentially involved in this regulation. Our data highlight that sugar metabolism is intricately linked with other metabolite pathways. Alteration of single genes in central carbon metabolism profoundly alters plant immune responses and plant-microbe interactions.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1101/2024.09.06.611645
Jonas Mueller, Yvonne Koenig, Sabrina Kaiser, Christian Loefke, Melanie Krebs, David Scheuring
The phytohormone salicylic acid (SA) is a key factor to balance plant defence as well as growth and development. While its role in plant defence has been investigated for decades, regulation of plant growth and development has only come into focus recently. It has been demonstrated that SA application inhibits growth independently of the established Non-expressor of Pathogenesis Related (NPR) receptors. However, the underlying mechanism of this growth inhibition on the cellular level remains largely elusive. Here we show that SA restricts cell elongation and induces changes of vacuolar morphology and pH. Rapidly upon SA application we observe homotypic vacuole fusion and a significant increase in vacuolar pH. These changes seem to be independent of the phytohormone auxin which has been reported to crosstalk with SA. By increasing vacuolar pH, SA directly impacts basic cellular functions such as vesicle trafficking or nutrient storage, leading eventually to cell size restriction and limited growth. Our results demonstrate an NPR-independent mechanism to attenuate growth, potentially allowing free resources to be relocated to withstand environmental stresses.
植物激素水杨酸（SA）是平衡植物防御和生长发育的关键因素。几十年来，人们一直在研究水杨酸在植物防御中的作用，但它对植物生长和发育的调控作用直到最近才受到关注。研究表明，施用 SA 可抑制生长，而不依赖于已建立的非致病基因表达相关受体（NPR）。然而，这种生长抑制作用在细胞水平上的潜在机制在很大程度上仍然难以捉摸。在这里，我们发现 SA 限制了细胞的伸长，并诱导液泡形态和 pH 值的变化。施用 SA 后，我们迅速观察到同型液泡融合和液泡 pH 值显著升高。这些变化似乎与植物激素辅助素无关，据报道，植物激素辅助素与 SA 有相互影响的作用。通过增加液泡 pH 值，SA 会直接影响细胞的基本功能，如囊泡贩运或营养储存，最终导致细胞大小受限和生长受限。我们的研究结果证明了一种不依赖 NPR 的生长衰减机制，它有可能使自由资源被转移以抵御环境压力。
{"title":"Salicylic Acid restricts cell elongation and induces changes of vacuolar morphology and pH","authors":"Jonas Mueller, Yvonne Koenig, Sabrina Kaiser, Christian Loefke, Melanie Krebs, David Scheuring","doi":"10.1101/2024.09.06.611645","DOIUrl":"https://doi.org/10.1101/2024.09.06.611645","url":null,"abstract":"The phytohormone salicylic acid (SA) is a key factor to balance plant defence as well as growth and development. While its role in plant defence has been investigated for decades, regulation of plant growth and development has only come into focus recently. It has been demonstrated that SA application inhibits growth independently of the established Non-expressor of Pathogenesis Related (NPR) receptors. However, the underlying mechanism of this growth inhibition on the cellular level remains largely elusive. Here we show that SA restricts cell elongation and induces changes of vacuolar morphology and pH. Rapidly upon SA application we observe homotypic vacuole fusion and a significant increase in vacuolar pH. These changes seem to be independent of the phytohormone auxin which has been reported to crosstalk with SA. By increasing vacuolar pH, SA directly impacts basic cellular functions such as vesicle trafficking or nutrient storage, leading eventually to cell size restriction and limited growth. Our results demonstrate an NPR-independent mechanism to attenuate growth, potentially allowing free resources to be relocated to withstand environmental stresses.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"173 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1101/2024.09.06.611148
Ya-wen Hsu, Chine-Ta Juan, Cian-Ling Guo, Huei-Jing Wang, Guang-Yuh Jauh
Cytokinesis marks the culmination of cell division when the cytoplasm undergoes division to yield two daughter cells. This intricate process encompasses various biological phenomena, including the organization of the cytoskeleton and the dynamics of vesicles. The development of the cell plate aligns with alterations in the cytoskeleton structure and vesicles derived from the trans–Golgi, ultimately resulting in the formation of the planar cell plate. Nevertheless, the coordination of these processes in plants remains to be determined. Here, we introduce HYCCIN–CONTAINING2 (HYC2) as a pivotal cytoskeleton cross–linking protein that accumulates at phragmoplasts and plays a crucial role in cell plate formation. A genetic study involving the depletion of HYC2 post–anaphase in Arabidopsis revealed HYC2′s function in cell plate formation. HYC2 interacted with dynamin–related protein 1A (DRP1A) and SH3 domain–containing protein 2 (SH3P2), essential for membrane tubulation during cell plate formation. The recruitment of SH3P2 and DRP1A to the cell plate and phragmoplast organization was compromised in homozygous hyc2–2 mutant globular embryos. Our results shed light on the cytoskeletal function of HYC2 in assembling the cell plate, potentially by guiding vesicles containing SH3P2–DRP1A to the planar cell plate.
{"title":"Recruitment of SH3P2–DRP1A by HYCCIN2 Drives Membrane Tubulation in Arabidopsis Embryonic Cell Plate Formation","authors":"Ya-wen Hsu, Chine-Ta Juan, Cian-Ling Guo, Huei-Jing Wang, Guang-Yuh Jauh","doi":"10.1101/2024.09.06.611148","DOIUrl":"https://doi.org/10.1101/2024.09.06.611148","url":null,"abstract":"Cytokinesis marks the culmination of cell division when the cytoplasm undergoes division to yield two daughter cells. This intricate process encompasses various biological phenomena, including the organization of the cytoskeleton and the dynamics of vesicles. The development of the cell plate aligns with alterations in the cytoskeleton structure and vesicles derived from the <em>trans</em>–Golgi, ultimately resulting in the formation of the planar cell plate. Nevertheless, the coordination of these processes in plants remains to be determined. Here, we introduce HYCCIN–CONTAINING2 (HYC2) as a pivotal cytoskeleton cross–linking protein that accumulates at phragmoplasts and plays a crucial role in cell plate formation. A genetic study involving the depletion of HYC2 post–anaphase in Arabidopsis revealed HYC2′s function in cell plate formation. HYC2 interacted with dynamin–related protein 1A (DRP1A) and SH3 domain–containing protein 2 (SH3P2), essential for membrane tubulation during cell plate formation. The recruitment of SH3P2 and DRP1A to the cell plate and phragmoplast organization was compromised in homozygous <em>hyc2–2</em> mutant globular embryos. Our results shed light on the cytoskeletal function of HYC2 in assembling the cell plate, potentially by guiding vesicles containing SH3P2–DRP1A to the planar cell plate.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1101/2024.09.09.612020
Leander Rohr, Luiselotte Rausch, Klaus Harter, Sven zur Oven-Krockhaus
Traditional models such as the fluid mosaic model or the lipid raft hypothesis have shaped our understanding of plasma membrane (PM) organization. However, recent discoveries have extended these paradigms by pointing to the existence of micro- and nanodomains. Here, we investigated the role of the cytoskeleton in general and whether the picket fence model, established in animal cells, is transferable to the plant cell system. By using single-particle tracking photoactivated localization microscopy (sptPALM) in combination with genetically encoded enzymatic tools for the targeted disruption of the cytoskeleton, we studied the dynamics and nanoscale organization of a selection of PM receptor-like kinases (RLKs) and receptor-like proteins (RLPs). Our findings show that the disintegration of actin filaments leads to decreased diffusion, more restrictive motion patterns, and enlarged clusters, whereas the disintegration of microtubules results in increased diffusion, more unconstrained diffusive behavior, and decreased cluster sizes of the tested RLKs and RLPs. These results underscore the potential unique regulatory functions of cytoskeleton components in plants and suggest an altered mechanism compared to the picket fence model of the animal cell system. Our qualitative data can serve as the foundation for further investigations aimed at developing a comprehensive and refined model of protein dynamics and organization in plant cells.
{"title":"Contrasting Effects of Cytoskeleton Disruption on Plasma Membrane Receptor Dynamics: Insights from Single-Molecule Analyses","authors":"Leander Rohr, Luiselotte Rausch, Klaus Harter, Sven zur Oven-Krockhaus","doi":"10.1101/2024.09.09.612020","DOIUrl":"https://doi.org/10.1101/2024.09.09.612020","url":null,"abstract":"Traditional models such as the fluid mosaic model or the lipid raft hypothesis have shaped our understanding of plasma membrane (PM) organization. However, recent discoveries have extended these paradigms by pointing to the existence of micro- and nanodomains. Here, we investigated the role of the cytoskeleton in general and whether the picket fence model, established in animal cells, is transferable to the plant cell system. By using single-particle tracking photoactivated localization microscopy (sptPALM) in combination with genetically encoded enzymatic tools for the targeted disruption of the cytoskeleton, we studied the dynamics and nanoscale organization of a selection of PM receptor-like kinases (RLKs) and receptor-like proteins (RLPs). Our findings show that the disintegration of actin filaments leads to decreased diffusion, more restrictive motion patterns, and enlarged clusters, whereas the disintegration of microtubules results in increased diffusion, more unconstrained diffusive behavior, and decreased cluster sizes of the tested RLKs and RLPs. These results underscore the potential unique regulatory functions of cytoskeleton components in plants and suggest an altered mechanism compared to the picket fence model of the animal cell system. Our qualitative data can serve as the foundation for further investigations aimed at developing a comprehensive and refined model of protein dynamics and organization in plant cells.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"125 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1101/2024.09.07.611822
Tim Y.Y. Tian, Geoffrey O Wasteneys, Colin B Macdonald, Eric N Cytrynbaum
The self-organization of cortical microtubules within plant cells is an emergent phenomenon with important consequences for the synthesis of the cell wall, cell shape, and subsequently the structure of plants. Mathematical modelling and experiments have elucidated the underlying processes involved. There has been recent interest in the influence of geometric cues on array orientation, be it direct (cell shape) or indirect (tension in the membrane). However, the mechanical influence of membrane curvature on these elastic filaments has largely been ignored. A previous model was proposed to describe how the anchoring process may control the shape of individual microtubules seeking to minimize bending on a cylindrical cell. We implement this process into a model of interacting microtubules and find the cell curvature influence should be significant: the array favours orientations parallel to the direction of elongation rather than the expected transverse direction. Even without elasticity, the geometry of large cells hinders robust microtubule organization. These results suggest the necessity of additional processes to overcome these factors. We propose a simple model of orientation-dependent catastrophe in the context of cellulose microfibrils impeding microtubule polymerization and find a moderate impedance to be sufficient to generate transverse arrays despite the geometric influences.
{"title":"Cell geometry, microtubule anchoring and anisotropic dynamic instability: challenges and solutions to transverse cortical array organization","authors":"Tim Y.Y. Tian, Geoffrey O Wasteneys, Colin B Macdonald, Eric N Cytrynbaum","doi":"10.1101/2024.09.07.611822","DOIUrl":"https://doi.org/10.1101/2024.09.07.611822","url":null,"abstract":"The self-organization of cortical microtubules within plant cells is an emergent phenomenon with important consequences for the synthesis of the cell wall, cell shape, and subsequently the structure of plants. Mathematical modelling and experiments have elucidated the underlying processes involved. There has been recent interest in the influence of geometric cues on array orientation, be it direct (cell shape) or indirect (tension in the membrane). However, the mechanical influence of membrane curvature on these elastic filaments has largely been ignored. A previous model was proposed to describe how the anchoring process may control the shape of individual microtubules seeking to minimize bending on a cylindrical cell. We implement this process into a model of interacting microtubules and find the cell curvature influence should be significant: the array favours orientations parallel to the direction of elongation rather than the expected transverse direction. Even without elasticity, the geometry of large cells hinders robust microtubule organization. These results suggest the necessity of additional processes to overcome these factors. We propose a simple model of orientation-dependent catastrophe in the context of cellulose microfibrils impeding microtubule polymerization and find a moderate impedance to be sufficient to generate transverse arrays despite the geometric influences.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1101/2024.09.08.611708
Victor Sanchez de Medina Hernandez, Marintia Mayola Nava Garcia, Marion Clavel, Ranjith K. Papareddy, Veselin I. Andreev, Peng Gao, Juan Carlos De la Concepcion, Varsha Mathur, Lorenzo Picchianti, Nenad Grujic, Rokoslana Kobylinska, Alibek Abdrakhmanov, Heloise Duverge, Gaurav Anand, Nils Leibrock, Anita Bianchi, Tim Crawford, Luca Argiro, Azadeh Mohseni, Marta Garcia Leon, Mateusz Matuszkiewickz, Margot Raffeiner, Cheuk-Ling Wun, Jakob V. Kanne, Anton Meinhart, Elisabeth Roitinger, Isabel Baurle, Byun-Ho Kang, Morten Petersen, Suayib Ustun, Yogesh Kulathu, Tim Clausen, Silvia Ramundo, Yasin Dagdas
Selective autophagy is a fundamental protein quality control pathway that safeguards proteostasis by degrading damaged or surplus cellular components, particularly under stress. This process is orchestrated by selective autophagy receptors (SARs) that direct specific cargo for degradation. While significant strides have been made in understanding the molecular framework of selective autophagy, the diversity of SAR repertoires across species remain largely unexplored. Through a comparative interactome analysis across five model organisms, we identified a suite of conserved and lineage-specific SAR candidates. Among these, we validated CESAR as a conserved SAR critical for proteostasis under proteotoxic stress. CESAR specifically facilitates the degradation of hydrophobic, ubiquitinated protein aggregates and is indispensable for heat stress tolerance. Our study offers a rich resource for SAR discovery and positions CESAR as a pivotal regulator of proteostasis, with broad implications for improving stress resilience in plants.
选择性自噬是一种基本的蛋白质质量控制途径，它通过降解受损或过剩的细胞成分（尤其是在应激状态下）来保障蛋白稳态。这一过程由选择性自噬受体（SARs）协调，SARs 引导特定货物降解。虽然人们在了解选择性自噬的分子框架方面取得了长足进步，但不同物种的 SAR 受体的多样性在很大程度上仍未得到探索。通过对五种模式生物的相互作用组进行比较分析，我们发现了一系列保守的和特定品系的 SAR 候选物。其中，我们验证了 CESAR 是一种保守的 SAR，对蛋白毒性胁迫下的蛋白稳态至关重要。CESAR 专门促进疏水性泛素化蛋白质聚集体的降解，对于热应激耐受性是不可或缺的。我们的研究为发现 SAR 提供了丰富的资源，并将 CESAR 定位为蛋白稳态的关键调控因子，对提高植物的胁迫恢复能力具有广泛的意义。
{"title":"Cross-species interactome analysis uncovers a conserved selective autophagy mechanism for protein quality control in plants","authors":"Victor Sanchez de Medina Hernandez, Marintia Mayola Nava Garcia, Marion Clavel, Ranjith K. Papareddy, Veselin I. Andreev, Peng Gao, Juan Carlos De la Concepcion, Varsha Mathur, Lorenzo Picchianti, Nenad Grujic, Rokoslana Kobylinska, Alibek Abdrakhmanov, Heloise Duverge, Gaurav Anand, Nils Leibrock, Anita Bianchi, Tim Crawford, Luca Argiro, Azadeh Mohseni, Marta Garcia Leon, Mateusz Matuszkiewickz, Margot Raffeiner, Cheuk-Ling Wun, Jakob V. Kanne, Anton Meinhart, Elisabeth Roitinger, Isabel Baurle, Byun-Ho Kang, Morten Petersen, Suayib Ustun, Yogesh Kulathu, Tim Clausen, Silvia Ramundo, Yasin Dagdas","doi":"10.1101/2024.09.08.611708","DOIUrl":"https://doi.org/10.1101/2024.09.08.611708","url":null,"abstract":"Selective autophagy is a fundamental protein quality control pathway that safeguards proteostasis by degrading damaged or surplus cellular components, particularly under stress. This process is orchestrated by selective autophagy receptors (SARs) that direct specific cargo for degradation. While significant strides have been made in understanding the molecular framework of selective autophagy, the diversity of SAR repertoires across species remain largely unexplored. Through a comparative interactome analysis across five model organisms, we identified a suite of conserved and lineage-specific SAR candidates. Among these, we validated CESAR as a conserved SAR critical for proteostasis under proteotoxic stress. CESAR specifically facilitates the degradation of hydrophobic, ubiquitinated protein aggregates and is indispensable for heat stress tolerance. Our study offers a rich resource for SAR discovery and positions CESAR as a pivotal regulator of proteostasis, with broad implications for improving stress resilience in plants.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1101/2024.09.05.611346
VIRGINIA WAINAINA, Tina Rathjen, Trijntje Hughes, Annelie Marquardt, Natalie Fletcher, Hayley Casarotto, Meredith McNeil, Kerensa McElroy, Ling-Ling Gao
Lupin (Lupinus spp.) seeds are valued for their high protein content (35-40%) for both human and animal consumption. Seed development in crop plants is a critical factor influencing both seed fate and yield, hence, understanding the molecular mechanisms of seed development is essential. This study conducted a transcriptome analysis of Narrow Leaf Lupin (NLL) during seed development stages (3, 6, 9, 12, 15, 18, and 21 days after flowering) to investigate transcriptional dynamics and identify key candidate genes that control seed development. Approximately 357 million sequencing reads were generated from nine samples from leave, flower and seed tissues, enabling the identification of 34,769 expressed genes. The analysis revealed dynamic gene expression, with early stages marked by high metabolic activity and later stages focusing on storage protein synthesis and nutrient reservoir formation. The differential expression patterns of seed storage protein genes, including cupin groups (α, β, γ, and δ conglutins), were notable. The expression of α and β conglutins increased at later stages (15-21 days after flowering), supporting their role in grain filling and nutrient storage. Genes related to quinolizidine alkaloid biosynthesis, such as lysine/ornithine decarboxylase and purine permease transporter 1, showed late expression patterns suggesting alkaloid synthesis and transport during later stages. Many of the well-established transcription factors (TFs) known for their roles in seed development (bHLH, AP2, MYB, ERF, C2H2, NAC, WRKY, and C3H zinc finger families) showed differential expression, thus reinforcing the validity of our findings. These findings lay the groundwork for understanding the genetic and molecular mechanisms of seed development in lupin, contributing to enhanced crop management and breeding programs.
{"title":"Deciphering transcriptional programming during lupin (Lupinus angustifolius) seed development using RNA-seq","authors":"VIRGINIA WAINAINA, Tina Rathjen, Trijntje Hughes, Annelie Marquardt, Natalie Fletcher, Hayley Casarotto, Meredith McNeil, Kerensa McElroy, Ling-Ling Gao","doi":"10.1101/2024.09.05.611346","DOIUrl":"https://doi.org/10.1101/2024.09.05.611346","url":null,"abstract":"Lupin (Lupinus spp.) seeds are valued for their high protein content (35-40%) for both human and animal consumption. Seed development in crop plants is a critical factor influencing both seed fate and yield, hence, understanding the molecular mechanisms of seed development is essential. This study conducted a transcriptome analysis of Narrow Leaf Lupin (NLL) during seed development stages (3, 6, 9, 12, 15, 18, and 21 days after flowering) to investigate transcriptional dynamics and identify key candidate genes that control seed development. Approximately 357 million sequencing reads were generated from nine samples from leave, flower and seed tissues, enabling the identification of 34,769 expressed genes. The analysis revealed dynamic gene expression, with early stages marked by high metabolic activity and later stages focusing on storage protein synthesis and nutrient reservoir formation. The differential expression patterns of seed storage protein genes, including cupin groups (α, β, γ, and δ conglutins), were notable. The expression of α and β conglutins increased at later stages (15-21 days after flowering), supporting their role in grain filling and nutrient storage. Genes related to quinolizidine alkaloid biosynthesis, such as lysine/ornithine decarboxylase and purine permease transporter 1, showed late expression patterns suggesting alkaloid synthesis and transport during later stages. Many of the well-established transcription factors (TFs) known for their roles in seed development (bHLH, AP2, MYB, ERF, C2H2, NAC, WRKY, and C3H zinc finger families) showed differential expression, thus reinforcing the validity of our findings. These findings lay the groundwork for understanding the genetic and molecular mechanisms of seed development in lupin, contributing to enhanced crop management and breeding programs.","PeriodicalId":501341,"journal":{"name":"bioRxiv - Plant Biology","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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