Plant Biology最新文献

Salt stress, intensified by climate change, is a significant threat to rice production, a vital staple for over half the world's population. This makes addressing salt stress in rice cultivation a pressing issue. This study investigates the role of PNSB as a biostimulant in enhancing salinity tolerance of salt-sensitive rice seedlings, addressing existing gaps in knowledge on physiological and biochemical impacts under saline stress. We inoculated salt-sensitive rice seedlings with PNSB under 80 mmol NaCl stress in a controlled environment. After a 5-day treatment, we conducted biochemical and physiological analyses. Salinity stress induced oxidative stress in salt-sensitive rice seedlings. However, application of 5-ALA-producing PNSB mitigated stress, elevated 5-ALA in shoots by 23%, roots by 190.5%, and chlorophyll content by 105.0%. PNSB treatment also reduced superoxide radicals (O₂ ^•-) and H₂O₂ by 26.7% and 38.7%, respectively, related to increased activity of the antioxidant enzymes, SOD (142.9%) and APX (41.8%). This led to lower electrolyte leakage (25.2%) and MDA (17.4%), indicating reduced ROS. Additionally, proline and soluble sugar content decreased by 29.2% and 72.5%, respectively. PNSB treatment also reduced sodium to potassium ion content in both shoots (31.2%) and roots (27.4%) of salt-stressed rice seedlings. These findings suggest that PNSB may facilitate nutrient solubilization and ion balance, thereby mitigating the adverse effects of salinity, with potential implications for sustainable agricultural practices to improve crop yield in saline environments. Future research should focus on elucidating the specific biochemical pathways involved in PNSB-mediated stress tolerance and exploring their application across diverse crop species and varying stress conditions.

In recent decades, the concept of memory has gained significant attention in plant ecophysiology research. When memory is expressed during germination, it is referred to as 'seed hydration memory'. Although numerous metrics relate to different aspects of germination, the literature lacks a method for quantifying seed hydration memory. This study aimed to develop a Germination Memory Index (GMI); a mathematical tool designed to quantify seed memory. The GMI enables comparisons of different native or cultivated species germinating under various conditions following discontinuous hydration. We tested the GMI using data from an experiment that evaluated germination of Cereus jamacaru seeds subjected to water deficit after undergoing hydration and dehydration cycles (HD cycles). The index is calculated as the arithmetic mean of gains, if any, in germination capacity, expressed as germinability, that is time to reach 50% germination, mean germination rate, uniformity of germination, synchrony and germination uncertainty, obtained from discontinuous hydration of the seeds. The memory ranges from 0 ≤ GMI ≤1. Gains are observed when HD cycles enhance germination capacity, germination rate and synchrony while reducing time to reach 50% germination, uniformity and uncertainty compared to their reference values. The absence of memory occurs when GMI ≤0, indicating that the germination process is favourable without undergoing HD cycles. When germination only occurs after discontinuous hydration, GMI = 1. Using the GMI, we can accurately measure gains in germinative behaviour provided by HD cycles, as this index reflects changes not only in germination capacity but also in germination time, speed, uniformity, synchrony and uncertainty.

Nature offers a bewildering diversity of flower colours. Understanding the ecology and evolution of this fantastic floral diversity requires knowledge about the visual systems of their natural observers, such as insect pollinators. The key question is how flower colour and pattern can be measured and represented to characterise the signals that are relevant to pollinators. A common way to interpret flower colours is using animal vision models that incorporate the spectral sensitivity of a focal observer (e.g. bees). These vision models provide a measure of colour contrast, which represents the perceived chromatic difference between two objects, such as a yellow flower against green leaves. Colour contrast is a behaviourally and physiologically validated proxy for relative conspicuousness of a stimulus. A growing number of studies attempt to interpret flower colouration through parameters that are grafted on to principles of human colour perception. A perpetuating measure to describe floral colours is via saturation, which is a metric in human perception describing a certain aspect of colourfulness and is, in pollination literature, often referred to as ‘spectral purity’. We caution against the concept, calculation and biological interpretation of ‘spectral purity’ and similar measures that rest on an anthropocentric view, because it does not represent the diversity and complexity of animal visual systems that are the natural observers of flowers. We here discuss the strengths and weaknesses of common ways to interpret flower colouration and provide concrete suggestions for future colourful research.

Plants with the C₄ photosynthetic pathway can withstand water stress better than plants with C₃ metabolism. However, it is unclear whether C₄ photosynthesis can be preliminarily activated in droughted cotton leaves, and if this contributes to increase in water use efficiency (WUE). An upland cotton (Gossypium hirsutum L., Xinluzao45) was used to determine gas exchange, stomatal and vein anatomy, phosphoenolpyruvate carboxykinase (PEPC) and Rubisco enzyme activity, and carbon isotope composition (δ¹³C) under well-watered, mild or moderate water stress. Water stress triggered reduced photosynthesis, stomatal conductance, and Rubisco activity, but higher vein density (VD), PEPC activity, and WUE. The correlations between δ¹³C and each of VD and PEPC activity implied that these coordinately contributed to higher leaf WUE via a preliminary induction of C₄ photosynthetic pathway. Preliminary C₄ photosynthesis indicated by more PEPC enzyme and veins offers an effective way to improve leaf WUE and potentially aids in acclimation to adverse growing conditions.

Isoleucic acid (ILA) was identified in human patients with maple syrup urine disease (MSUD) half a century ago. MSUD patients, who are defective in the catabolism of branched-chain amino acids (BCAAs), that is, isoleucine, leucine, and valine, have urine with a unique maple syrup odour related to the accumulation of BCAA breakdown products, largely 2-keto acid derivatives and their reduced 2-hydroxy acids including ILA. A decade ago, ILA was identified in Arabidopsis thaliana. Subsequent studies in other plant species indicated that ILA is a ubiquitously present compound. Since its identification in plants, several efforts have been made to understand the biological significance and metabolic pathway of ILA. ILA plays a positive role in plant signalling for defence responses against bacterial pathogens by increasing the abundance of salicylic acid aglycone through competitive inhibition of SA deactivation by glucosylation. Here, we review recent progress in the characterization of ILA biosynthesis and function in plants and discuss current knowledge gaps and future directions in ILA research.

Plant individuals within a species can differ markedly in their leaf chemical composition, forming so-called chemotypes. Little is known about whether such differences impact the microbial communities associated with leaves and how different environmental conditions may shape these relationships. We used Tanacetum vulgare as a model plant to study the impacts of maternal effects, leaf terpenoid chemotype, and the environment on the leaf bacterial community by growing plant clones in the field and a greenhouse. We hypothesized that all three factors affect the bacterial community of the leaves and that terpenoid and bacterial profiles as well as chemodiversity and microbial diversity are correlated. The results revealed that the leaf microbial community was significantly influenced by plant maternal effects and environmental conditions (field vs. greenhouse), but not by the leaf terpenoid profile. There was also no evidence for a correlation between terpenoid profiles and bacterial community composition and diversity. Overall, a higher number of unique amplicon sequence variants were found in the leaves of clones grown under field conditions than in those grown in the greenhouse. We also identified interactions between individual terpenoids and specific members of the leaf bacterial community. Our study suggests that terpenoid chemodiversity has, overall, little effect on the leaf bacterial community, but some terpenoids might affect specific beneficial species. While more studies are needed to investigate the relationship between plant chemodiversity and plant microbiomes, our results highlight the importance of integrating plant maternal effects, chemodiversity, and environment in understanding plant-microbiome interactions.