Environmental and Experimental Botany最新文献

This study investigates how the absence of trichomes and variations in stomatal properties affect the quantum efficiency of photosynthesis in Arabidopsis thaliana during drought stress. We analyzed three genotypes: Col-8 (with trichomes and lower stomatal density), epf1epf2 (with higher stomatal density), and tmm-1 (lacking trichomes and altered stomatal characteristics) to determine the influence of these anatomical traits on photosynthetic performance. Under well-watered conditions, epf1epf2 and tmm-1 exhibited higher photosynthetic efficiency (Fv´/Fm´) compared to Col-8. During drought stress, Col-8 maintained stable Fv´/Fm´, while epf1epf2 and tmm-1 experienced significant reductions. Our findings indicate that the presence of trichomes and higher stomatal density positively impacts photosynthetic efficiency under optimal watering while the presence of trichomes becomes less crucial under drought stress. Efficient adjustment of stomatal density and size under drought conditions plays a more significant role. These insights emphasize the importance of considering anatomical traits in breeding programs to enhance drought resistance and photosynthetic performance in plants.

Rapeseed (Brassica napus L.) is a globally significant overwintering oilseed crop. Polyamine oxidase (PAO), an evolutionarily conserved family of FAD-binding proteins, plays crucial roles in plant growth, development, and response to abiotic stress. However, there is a scarcity of systematic identification and functional analysis of the PAO gene family in rapeseed. In this study, we identified 8, 7, 9, 16, 14 and 13 PAO genes in the genomes of B. rapa, B. nigra, B. oleracea, B. napus, B. juncea and B. carinata, respectively, which can be categorized into three subgroups: PAO1, PAO2/3/4, and PAO5. Molecular evolutionary analyses revealed a high conservation of PAO genes in Brassicaceae plants. RNA-seq and RT-qPCR analyses demonstrated the different expression patterns of different subgroups of BnaPAO genes in various tissues and under different treatments in rapeseed. Remarkably, among those PAO genes, only BnaPAO1 genes (BnaA.PAO1.a and BnaC.PAO1.a) were strongly induced by freezing stress. Further analysis confirmed that overexpression of BnaC.PAO1.a significantly improved the freezing tolerance of rapeseed by scavenging ROS. These findings provide a foundation for understanding the biological functions of PAO genes in response to freezing stress in rapeseed.

Banana (Musa spp.) is a vital tropical fruit crop cultivated worldwide and is known for its nutritional value. The cultivation of bananas is often challenged by environmental stresses such as cold and drought, which can adversely affect plant productivity. In response to these challenges, plants deploy adaptive mechanisms to mitigate the impacts of environmental stresses. Calcium (Ca²⁺), recognized as a universal second messenger, is pivotal in cellular responses to hormones, pathogens, and stress factors. This study explores the potential of exogenous calcium supplementation as a cost-effective and promising solution, influencing metabolic activities and signal transductions in plants. To investigate the defensive role of Ca²⁺ supplementation in banana plants subjected to drought (200 mM Mannitol) and cold (14 °C) stress, comprehensive analyses were conducted to elucidate the mechanism underlying Ca²⁺-mediated stress tolerance. The plants were treated with mannitol, cold or Hoagland, and then supplemented with CaCl₂ (15 mM). Exogenous Ca²⁺ treatment significantly increased the proline content and maintained water balance and cellular stability. Additionally, it enhanced the production of protective secondary metabolites and activated key antioxidant enzymes, countering oxidative stress. Molecular analysis revealed an upregulation of calcium-binding proteins involved in stress response, while Ca²⁺ treatment reduced lipid peroxidation, as indicated by lower malondialdehyde (MDA) levels, signifying improved membrane integrity and reduced oxidative damage. These findings underscore the protective impact of exogenously supplied calcium, offering insights for sustainable strategies to enhance banana resilience in the face of environmental challenges and climate change.

Invasive plants commonly compete with native plants in the introduced range; however, how leaf litter and rhizosphere soil microbes influence the competition between invasive and native plants with varying microbial sources and seedling densities remains to be characterized. In this study, the invasive plant Ageratina adenophora (Asteraceae) and two cooccurring native plant species, Senecio scandens (Asteraceae) and Achyranthes bidentata (Amaranthaceae), were used as experimental plants to test their impacts in a greenhouse. We observed that leaf litter and rhizosphere soil microbes negatively or neutrally impacted invasive or native plant growth when competing. However, microbes enhanced the competitive dominance of A. adenophora over S. scandens but weakened its competitiveness over A. bidentata. Leaf litter microbes were more beneficial for A. adenophora growth and thus made it more competitive than rhizosphere soil microbes when competing with S. scandens. Regardless of the presence or absence of microbes, conspecific inoculation was better for A. adenophora growth and thus enhanced competition dominance more than heterospecific inoculation when competing with A. bidentata. A high seedling density was more beneficial for A. adenophora competition dominance than a low density was when A. adenophora was competing with S. scandens. Nonetheless, the relative competitiveness of A. adenophora was greater than that of the two native species; in particular, A. adenophora had stronger competitive dominance over A. bidentata than over S. scandens. Our data confirmed that the important role of leaf litter microbes in the competition between invasive and native plants cannot be ignored.

Spring cold stress poses a great threat to wheat reproductive growth, leading to compromised spike development and grain yield. There are two types of cold stress i.e. chilling stress (CS, above zero) and freezing stress (FS, below zero). However, it is unclear whether there is a difference in the mechanism of CS and FS in regulating spikelet development. This study aimed to unravel the underlying regulation in determining the difference for wheat spikelet exposed to CS at 2 °C and FS at −2°C by integrative analyses of transcriptome, metabolome, and physiology. Delayed floret development and shrunken cellular morphology in both CS and FS were observed, even malformation and degradation of anther cells occurred in FS. Kyoto Encyclopedia of gene and genomes (KEGG) analyses revealed that the most abundantly enriched pathways are phytohormone biosynthesis, starch and sucrose metabolism, and phenylpropanoid biosynthesis. Further physiological assays related to the identified pathways were performed. Compared to CS, the signal of abscisic acid (ABA), salicylic acid (SA) and jasmonic acid (JA) was more pronounced, and the signal of auxin (IAA) and gibberellin (GA) was inhibited further in FS. In addition, the contents of glucose, fructose and trehalose were elevated in CS, owing to greater activities of cell wall invertase and sucrose synthase, while the hexose content was decreased owing to lower activities of such enzymes in FS, concomitantly, flavonoid barely changed in CS, but it dramatically amounted in FS. Taken together, the glucose and trehalose pathway, along with induced ABA and SA signal were intensified in CS to maintain growth, while greater flavonoid and promoted JA synthesis were induced in FS for cold survival. Understanding the molecular of growth-defense under cold stress would provide a foundation for the development of breeding strategies.

Soybean (Glycine max (L.) Merrill), one of the most valuable crops in the world, faces serious challenges due to drought and insect herbivory. Although well studied independently, we lack a comprehensive understanding of interactive effects of drought × herbivory on both soybean and herbivore traits. A holistic examination of soybean morpho-physiology (above and below-ground traits including root morphology) and herbivore performance can help us understand the potential consequences of these two major stressors on soybean yield and fitness. To this end, we imposed simulated-drought and herbivory by soybean looper (SBL) (Chrysodeixis includens Walker) and assessed both host and herbivore performance. Morpho-physiological traits of soybean including shoot height, chlorophyll content, root morphology, photosynthesis, stomatal conductance, and transpiration were measured. Additionally, growth and feeding behavior of SBL were also assessed to analyze the impacts of drought × herbivory on both host and herbivore. Our results show that certain physiological traits were significantly upregulated under drought × herbivory indicating compensation. We also observed that SBL frass weight, and scale of damage was lower on simulated-drought-experienced plants and, in choice assays, SBL preferred well-watered plants. In addition to lower yields observed under simulated-drought and herbivory interaction, soybeans that experienced both drought and herbivory had the highest number of aborted pods. Our study shows that simulated drought and herbivory have synergistic negative impacts on soybean morpho-physiology and support plant vigor hypothesis. Simulated drought negatively impacted SBL performance and made them less attracted to the soybeans that experienced water stress. Ultimately, the interactive effects of these stressors have negative consequences on soybean yield and fitness. This study demonstrates the need to integrate biotic and abiotic stressors for a better understanding of interactive effects on host and herbivores to make informed decisions for breeding and pest management strategies.

In rice, silicon can mitigate abiotic and biotic stresses. We therefore investigated the effect of Si on key root traits related to soil flooding and salinity tolerance with emphasis on the outer apoplastic barrier and cortical aerenchyma. We tested the hypothesis that Si application alters the phenotypic response of these root traits by growing rice in nutrient solutions without or with Si, designed to mimic drained or flooded soils. We measured the barrier strength through resistance to O₂ and water of the outer parts of adventitious roots along with cortical aerenchyma and other root structural traits. We found that Si delayed the barrier formation and caused lower amounts of inducible cortical aerenchyma. The delay in barrier formation resulted in higher xylem loading of Na⁺ and Cl^-, i.e., the sap flux of both ions was significantly higher for plants with access to Si. The increased ion fluxes correlated with lower lignin and suberin deposition in the outer part of the root. Consequently, we do not recommend using Si application to alleviate combined stress of salinity and soil flooding in rice, since the barrier was more permeable to O₂, and the aerenchyma formation was less pronounced in roots with Si.

The frequency of climate change is increasing globally, which makes predictions challenging. Cold spells during the rice seedling stage can significantly reduce yield, prompting a constant need for cold-tolerant cultivars, which is a major breeding goal. However, the traditional crossbreeding of rice cultivars requires substantial time and effort. Recently, the application of CRISPR/Cas9 to reduce defects in elite cultivars has become a more cost-effective and time-efficient method for breeding cultivars than cross-breeding methods and can alleviate food insecurity. In the present study, CRISPR/Cas9-mediated genome editing was performed for OsCS511 a gene involved in cold susceptibility, identified using quantitative trait loci (QTL) mapping in Ilmi (Oryza sativa L. spp. Japonica cv. Ilmi). In Ilmi, CRISPR/Cas9 tool-edited OsCS511 homozygous lines were used in T₀ and advanced generations in the field. CRISPR/Cas9 induced variations in the DNA sequence and plants with insertions or deletions compared to OsCS511 of Ilmi were selected as genome-edited lines. Agricultural traits, reactive oxygen species scavenging capacity, and stress-tolerance-related gene expression levels were evaluated under normal and cold stress conditions. Under normal conditions, all traits evaluated in the Ilmi and OsCS511 genome-edited lines exhibited similar results; however, when subjected to cold stress, the cold tolerance of OsCS511 genome-edited lines improved or reached the same level as that of Ilmi. OsCS511 genome-edited lines recovered and survived. From a breeding perspective, we suggest that CRISPR/Cas9 technology can precisely reduce defects in existing superior rice cultivars with high efficiency and speed.

Melatonin (MEL) has recently received ample attention as a potential biostimulator in agriculture. MEL has been considered a feasible and effective approach for improving crop output and resilience to various abiotic factors. The first step of MEL biosynthesis in plants is tryptophan (an amino acid), made de novo via the shikimic acid pathway. The processes involved in MEL biosynthesis and plant regulation are described in this review, providing a foundation for understanding the hormone's numerous physiological actions. The research delves into the intricate relationships between MEL and abiotic stresses, such as exposure to drought, salt, heat, cold, and heavy metals. This review provides an overview of recent research on the potential roles of MEL on seed germination, growth, and development in plants, highlighting its benefits for improving crop yield and quality and mitigating the detrimental effects of several abiotic stresses. It also discusses the current understanding of MEL's role as a biostimulator in agriculture, promoting root development, flowering, fruit ripening, and preventing leaf senescence. Furthermore, it summarizes the interplay of MEL with various phytohormones, including cytokinin (CK), auxin (Aux), ethylene (ETH), gibberellic acid (GA), salicylic acid (SA), abscisic acid (ABA), jasmonic acid (JA), polyamines (PAs), brassinosteroid (BR), and signalling molecules such as NO, H₂O₂, H₂S, and Ca²⁺. MEL shows synergistic interactions with GA, CK, PAs, JA, SA, and BR while exhibiting synergistic and antagonistic regulation with Aux, ETH, and ABA. Also, this review establishes the framework for developing novel MEL-based strategies to enhance agricultural sustainability in the face of increasingly severe environmental conditions.

Salinization has emerged as a worldwide concern hampering the progression of agriculture and husbandry. Arbuscular mycorrhizal (AM) fungi, which abundantly distributed in the Songnen Plain, was considered to possess great potential for combating salinity. To elucidate the relationship between AM fungal community and saline-alkali ecological remediation, a 70-days pot experiment, with the soil in the late succession stage of Songnen saline-alkali habitat was taken as substrate, the dominant plant in the latter as research object, and the rhizosphere soil from three stages as inoculants, was conducted. Simultaneously, Chloris virgate was cultivated to ascertain the accompanying role on mycorrhizal effects and soil improvement. The results revealed that AM fungi effectively regulated the botanical morphogenesis, photosynthesis, osmotic concentration, and antioxidant enzymatic activity under saline-alkali conditions. Specifically, the net photosynthetic rate increased by 1.11–2.44 μmol·(m²)⁻¹·s⁻¹, and the total root length grew by 41.15–148.98 cm after inoculation. Furthermore, the soil salinization and nutrient sequestration were modulated by AM fungi, and that leaded to a notable reduction in soil pH by 0.3 %-1.64 % and an increase in nitrogen content by 52.17 %-118.84 %. In a comprehensive assessment, the utmost ecological advantage appeared in the group inoculated AM fungi procured from the identical stage as the host, with a peak mycorrhizal dependency of 2.93. Additionally, despite enhancing salinization restoration compared to the non-companion group, the associated plants reduced the mycorrhizal dependency of neighbour by a range of 27.04–51.46 %, and significantly decreased the dry weight by 0.09–0.28 g. These results confirmed the occurrence of symbiotic matching phenomenon in saline-alkali habitats and suggested that the mechanism should be considered as utilizing AM fungi for ecological restoration. However, the introduction of companion should be cautious due to their complex effects.