Physiologia plantarum最新文献

Precise growth management is required for climate-smart and sustainable crop production in response to climate change, with the heading stage being the most important. Research on the control of heading in rice (Oryza sativa) has mainly focused on day length and temperature; however, research on the effects of insolation is limited. Therefore, this study analyzed the differences in rice growth and heading responses under different light intensity and temperature conditions. Five early-maturing and seven medium-late-maturing rice varieties were used for each japonica heading ecology type. Our results showed that leaf age development, an indirect measure of rice phenological development, was inhibited under low light intensity and low-temperature conditions. Accordingly, the heading date was also delayed by approximately 18 days at low temperatures and 21 days at low light intensity, with no difference among ecotypes. We also found an interaction between temperature and light intensity, with the light intensity-mediated delay in heading date being affected more by high temperatures. This study demonstrated that light intensity and temperature have a major effect on heading date variation, suggesting that the impact of insolation must be considered for the accurate prediction of heading stage variation. These results could shed new light on rice phenology research and contribute to the implementation of precision agriculture.

Under changing climatic conditions, plant exposure to high-intensity UV-B can be a potential threat to plant health and all plant-derived human requirements, including food. It's crucial to understand how plants respond to high UV-B radiation so that proper measures can be taken to enhance tolerance towards high UV-B stress. We found that BBX22, a B-box protein-coding gene, is strongly induced within one hour of exposure to high-intensity UV-B. Our metabolomics data indicated that BBX22 promotes the accumulation of antioxidants like ascorbic acid and proline. These antioxidants play a vital role in shielding plants exposed to high UV-B from the detrimental effects of Reactive Oxygen Species (ROS), including DNA damage. Additionally, BBX22 promotes DNA damage repair by inducing the expression of DNA repair genes like UVR1 and UVR3. BBX22 directly binds to the promoter of UVR1 to regulate its expression. Furthermore, BBX22 indirectly induces the expression of UVR1 and UVR3 by enhancing the binding of HY5 to their promoters. Together, these results suggest a multi-pronged role of BBX22 in protection against high-intensity UV-B. Enhancing BBX22 levels or its orthologs in different plant species can potentially offer DNA damage protection and tolerance against intense UV radiation.

The leaf economics spectrum (LES) characterizes a tradeoff between building a leaf for durability versus for energy capture and gas exchange, with allocation to leaf dry mass per projected surface area (LMA) being a key trait underlying this tradeoff. However, regardless of the biomass supporting the leaf, high rates of gas exchange are typically accomplished by small, densely packed stomata on the leaf surface, which is enabled by smaller genome sizes. Here, we investigate how variation in genome size-cell size allometry interacts with variation in biomass allocation (i.e. LMA) to influence the maximum surface conductance to CO₂ and the rate of resource turnover as measured by leaf water residence time. We sampled both evergreen and deciduous Rhododendron (Ericaceae) taxa from wild populations and botanical gardens, including naturally occurring putative hybrids and artificially generated hybrids. We measured genome size, anatomical traits related to cell sizes, and morphological traits related to water content and dry mass allocation. Consistent with the LES, higher LMA was associated with slower water residence times, and LMA was strongly associated with leaf thickness. Although anatomical and morphological traits varied orthogonally to each other, cell size had a pervasive impact on leaf functional anatomy: for a given leaf thickness, reducing cell size elevated the leaf surface conductance and shortened the mean water residence time. These analyses clarify how anatomical traits related to genome size-cell size allometry can influence leaf function independently of morphological traits related to leaf longevity and durability.

Citrus fruits are one of the most important fruits in the world, and their seedless character is favored by consumers. WRKY is a plant-specific transcription factor family involved in all aspects of plant growth and development. However, the molecular mechanism of seedless fruit formation in citrus and the role of the WRKY gene family in seed abortion are still poorly understood. In this study, we identified 47 WRKY family genes in the citrus fruit Citrus reticulata and comprehensively characterized the WRKY gene family through gene structure and evolutionary relationships. The expression patterns and protein interaction networks of the WRKY gene family were analyzed based on citrus seed abortion transcriptome data, and several WRKY genes that may be involved in the seed abortion regulation were excavated. Furthermore, CrWRKY48 was verified to regulate seed abortion positively in Arabidopsis thaliana, and the rate of seed abortion caused by overexpression of CrWRKY48 reached 45.48%. Using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling assays, DNA affinity purification sequencing and yeast-one-hybrid assays, we found that CrWRKY48 activated excessive programmed cell death by regulating the expression of programmed cell death-related genes such as SOBIR1. Our results show the potential regulation of the WRKY gene family for citrus seed abortion and provide novel insights into the role of CrWRKY48 in mediating citrus seed abortion by activating programmed cell death.

Mitogen-activated protein kinase kinase kinase kinases (MAP4Ks) are a class of highly conserved serine/threonine-protein kinases in eukaryotes. They participate in the typical MAPK cascade system and various signal transduction pathways regulating biological processes in plants, during stressful conditions. To date, genome-wide identification of MAP4Ks in cotton has not been reported. In this study, 77 MAP4K genes were identified in four Gossypium species. Protein characteristics, gene structures, conserved motifs and gene expression analysis were carried out. Genome-wide or fragment duplication has played an important role in the expansion of the GhMAP4K. Promoter cis-acting elements and expression patterns indicated that GhMAP4Ks are related to plant hormones (ABA, MeJA, GA, IAA, SA) and various stresses (drought, hypothermia and wound). Overexpressing GhMAP4K13 in Arabidopsis showed higher stem length in response to drought and salt stress. The wilting degree in virus-induced GhMAP4K13 gene silenced plants was substantially greater than wild type plants under drought and salt stress. Transcriptomic analysis showed that most differentially expressed genes were involved in the MAPK signaling pathway, carbon metabolism and porphyrin metabolism. Additionally, transgenic Arabidopsis and VIGS cotton showed that GhMAP4K13 was positively responsive to drought and salt stresses. This study will play an important role in understanding the function of the MAP4K gene family in response to abiotic stress in cotton.

Regulating potato tuber dormancy is crucial for crop productivity and food security. We conducted the first comprehensive physiological, transcriptomic, and metabolomic investigations of two varieties of long and short dormant potato tubers in order to clarify the mechanisms of dormancy release. In the current study, three different dormant stages of UGT (ungerminated tubers), MGT (minimally germinated tubers), and GT (germinated tubers) were obtained by treatment with the germination promoter gibberellin A₃ and the germination inhibitor chlorpropham. The results revealed that the contents of reducing reducing sugar, sucrase, glutamine synthetase, and nitrate reductase were increased in the dormancy release stages, whereas the contents of sucrose and starch were decreased, leading to a change in the phenotype of the potato tuber bud eyes. According to transcriptomic and metabolomic investigations, four metabolomic pathways were impacted by the dormancy release process. Zeatin biosynthesis was identified in both potato varieties in the dormant release stage (trans-zeatin riboside, isopentenyl adenosine, 5'-methylthioadenosine, IPT, CYP735A, CKX, and UGT73C); glutathione metabolism was identified in short-dormant potato varieties ((5-L-Glutamyl)-L-amino acid, oxidized glutathione, GPX, IDH1, GGT1_5, and GST); and the pentose phosphate pathway (D-Xylulose 5-phosphate, ribose 1-phosphate, PGD, and RPIA) and the phenylpropanoid biosynthesis (caffeic acid, sinapine, CYP98A, and CSE) were identified in long-dormant potato varieties. In conclusion, the four pathways mentioned above involve DEGs and DEMs that are crucial to the control of tuber dormancy release. This work offers a theoretical foundation and useful recommendations for potato tuber quality improvement and molecular breeding.

Throughout the entire cycle of leaf phenological events, leaf colour undergoes changes that are influenced by either abiotic stress or biotic infection. These changes in colouration are closely linked to the quantity and quality of photosynthetic pigments, which directly impact the primary productivity of plants. Therefore, monitoring and quantifying leaf colouration changes are crucial for distinguishing damage caused by pine wilt nematodes from natural tree senescence. In this study, a hyperspectral camera sensor was employed for the non-invasive and non-destructive evaluation of needle colour changes in coniferous trees grown in field tests. Three distinct needle colour variations of six coniferous tree species were selected and monitored using a hyperspectral sensor: those displaying seasonal autumn colours, undergoing nematode-infected necrosis processes, and experiencing natural death. To mitigate the inherently mixed spectral properties of hyperspectral data, endmembers were extracted from individual images using the Purity Pixel Index algorithm under the assumption of linear mixing of endmembers. From a total of 1,321 endmembers extracted from 378 hyperspectral images of six pine species, eight endmembers were ultimately chosen to reconstruct hyperspectral images and generate abundance maps. Among these eight endmembers, four represent varying levels of photosynthetic pigment contents-ranging from very low to high. Consequently, these coniferous endmembers hold promise for assessing seasonal leaf phenology and the extent of damage in pine trees infected by pine wilt nematodes. This comprehensive approach underscores the effectiveness of spectral unmixing of hyperspectral images in advancing precision forestry through meticulous coniferous needle trait analysis.

Underwater CO₂ concentration fluctuates extremely in natural water bodies. Under low CO₂, the unique CO₂ concentrating mechanism in aquatic plants, bicarbonate use, can suppress photorespiration. However, it remains unknown (1) to what extent bicarbonate use reduces photorespiration, (2) how exactly photorespiration varies between bicarbonate-users and CO₂-obligate users under CO₂-fluctuated environments, and (3) what are differences in Rubisco characteristics between these two types of aquatic plants. In the present study, the bicarbonate user Ottelia alismoides and its phylogenetically close CO₂-obligate user Blyxa japonica were chosen to answer these questions. The results showed that bicarbonate use saved ~13% carbon loss under low CO₂ via decreasing photorespiration in O. alismoides. Through bicarbonate use, the photorespiration of O. alismoides was kept stable both under high and low underwater CO₂ concentrations, while the photorespiration significantly increased in the CO₂-obligate user B. japonica under low CO₂. However, B. japonica showed a significantly higher photosynthesis rate than O. alsimoides when CO₂ was sufficient. These differences could be related to the kinetic characteristics of Rubisco showing a higher carboxylation turnover rate (Kcat) in B. japonica, and the similar affinity to CO₂ (Kc) and specificity factor (Sc/o) in these two species that might be determined by the variation of six amino acid residuals in Rubisco large subunit sequences, especially the site 281 (A vs. S) and 282 (H vs. F). All these differences in photorespiration and kinetic characteristics of Rubisco could explain the distribution patterns of bicarbonate users and CO₂-obligate users in the field.

Nitric oxide has been shown to influence oxidative metabolism in plants, enhancing their resilience to various biotic and abiotic stresses. Post-harvest oxidative stress is a key factor leading to quality deterioration in litchi (Litchi chinensis Sonn.) fruit, with visible symptoms that significantly reduce shelf life and consumer acceptability. Therefore, the effect of exogenous sodium nitroprusside (SNP; 1.0 mM and 2.0 mM) on litchi (cv. Purbi) fruit was examined during storage at 7 ± 1°C. Different biochemical changes related to post-harvest quality and pericarp browning of litchi were evaluated. The results suggested that SNP (2.0 mM) was significantly effective in reducing weight loss, the pericarp browning index and decay loss. The fruit subjected to SNP (2.0 mM) treatment retained more total anthocyanins and total phenolic content with reduced peroxidase and polyphenol oxidase enzyme activity. Other quality attributes, such as total soluble solids (TSS), titratable acidity and ascorbic acid, were also recorded to be greater in the SNP (2.0 mM)-treated fruits. These results were consistent with the expression profiles of LcPPO, LcPOD and Laccase genes. The expression levels of these genes were highly suppressed in the nitric oxide-treated fruits compared to those in the control fruits. Therefore, SNP (2.0 mM) treatment could reduce litchi pericarp browning and prolong the post-harvest life of fruit for up to eighteen days during cold storage.