Physiologia plantarum最新文献

Bermudagrass [Cynodon dactylon (L.) Pers.] is widely used for soil remediation, livestock forage, and as turfgrass for sports fields, parks, and gardens due to its resilience and adaptability. However, low temperatures are critical factors limiting its geographical distribution and ornamental season, even preventing its safe overwintering. PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) acts as a hub transcription factor, not only regulating various light responses but also integrating multiple external stimuli to improve plant productivity and architectural adaptation under adverse stress conditions, which makes it potential as a target gene. In this study, we cloned and characterized the CdPIF4 genes in bermudagrass. Expression analysis revealed that it is predominantly expressed in leaves and is regulated by photoperiod and cold stress. Using Agrobacterium-mediated genetic modification, we successfully generated CdPIF4a-overexpressing bermudagrass lines. Under cold stress at 4°C, these transgenic plants demonstrated enhanced cold tolerance, as indicated by higher relative water content, reduced membrane damage, and lower levels of lipid peroxidation levels. Photosynthetic analysis revealed that CdPIF4a-overexpressing plants exhibited higher light energy capture and transfer efficiency at this low temperature, with less energy loss. Additionally, they showed higher antioxidant enzyme activity and lower levels of reactive oxygen species levels. The responsive regulation of cold stress-related genes further validated the role of the CdPIF4a gene in enhancing cold tolerance. This study elucidates that CdPIF4 enhances cold tolerance in bermudagrass through physiological and molecular mechanisms, offering new insights and valuable genetic resources for advancing cold resistance research in bermudagrass and other grass species.

It is known that red light irradiation enhances the biosynthesis of (E)-β-caryophyllene in plants. However, the underlying mechanism connecting red light to (E)-β-caryophyllene biosynthesis remains elusive. This study reveals a molecular cascade involving the phyB-PIF4-MYC2 module, which regulates (E)-β-caryophyllene biosynthesis in response to the red light signal in Arabidopsis thaliana. In this module, phyB positively regulates (E)-β-caryophyllene biosynthesis under red light, whereas PIF4 negatively regulates it; both regulations require the involvement of MYC2, a transcription factor that can bind directly to the promoter of the TPS21 gene which encodes (E)-β-caryophyllene synthase. Importantly, protein-protein and protein-DNA interaction assays show that PIF4 reduces the binding affinity of MYC2 to the TPS21 promoter through direct interaction with MYC2. We propose that the phyB-PIF4-MYC2 module represents a universal mechanism linking red light to sesquiterpene biosynthesis in plants.

A lack of iron (Fe) inhibits the growth and development of plants, leading to reduced agricultural yields and quality. In the last ten years, numerous studies have focused on the induction of Fe uptake and translocation under Fe deficiency, but the regulatory mechanisms governing Fe reutilization within plants are still not well understood. Here, we demonstrated the involvement of the NAM/ATAF1/2/CUC2 (NAC) transcription factor NAC50 in response to Fe shortage. The content of soluble Fe was greatly reduced in nac50 mutants, leading to increased chlorosis in the newly emerging leaves under the Fe-deficient condition. Subsequent investigation revealed that the cell wall of the nac50 mutants' roots accumulated more Fe, along with an increment in hemicellulose content, indicating that a cell wall-associated Fe reutilization pathway was involved in the NAC50-regulated Fe insufficiency response. Interestingly, the expression of NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (NCED3), a key enzyme in the abscisic acid (ABA) biosynthetic pathway, was down-regulated in the Fe-deficient nac50 mutants, resulting in decreased endogenous ABA level and Fe-deficient sensitive phenotype. Since no direct relationship was observed between NAC50 and NCED3, this suggests a potential role of NAC50 in mediating the ABA accumulation. Moreover, exogenous ABA application in the nac50 mutant restored Fe deficiency resistance to the level observed in wild-type plants (WT), indicating that NAC50 induced the cell wall Fe reutilization potentially through the regulation of ABA accumulation.

Nitrogen (N) is a crucial macronutrient for plant growth, with nitrate as a primary inorganic N source for most plants. Beyond its role as a nutrient, nitrate also functions as a signalling molecule, influencing plant morphogenetic development. While nitrate utilization and signalling mechanisms have been extensively studied in model plants, the origin, evolution, and diversification of core components in nitrate uptake, assimilation, and signalling remain largely unexplored. In our investigation, we discovered that deep sea algae living in low nitrate conditions developed a high-affinity transport system (HATS) for nitrate uptake and a pathway of nitrate primary assimilation (NR-NiR-GS-GOGAT). In contrast, low-affinity transport systems (LATS) and the plastid GS originated from the ancestors of land and seed plants, respectively. These adaptations facilitated amino acid acquisition as plants conquered terrestrial environments. Furthermore, the intricate nitrate signalling, relying on NRT1.1 and NLP7, evolved stepwise, potentially establishing systematic regulation in bryophytes for self-regulation under complex terrestrial nitrate environments. As plants underwent terrestrialization, they underwent adaptive changes to thrive in dynamic nitrate environments, continually enhancing their nitrate uptake, assimilation, and signal transduction abilities.

The use of stored carbon is essential for new organ development in deciduous trees during early spring. However, the contribution of carbon to the development of new organs in early spring of subsequent years is not well understood. Using a ¹³C labelling approach, we investigated the reallocation of assimilated carbon into new aboveground organs on apple (Malus domestica) saplings in the following two years. Eight three-year-old potted saplings were exposed to ¹³CO₂ in an exposure chamber on each of eight different dates during the growth season. Some of the trees were harvested in the late autumn of the same year. The remaining trees were transferred to a field and cultivated during the two following growing seasons. We directly showed that the assimilated ¹³C was used to develop terminal and flower buds for two consecutive years after labelling. The proportions of the concentration of ¹³C remobilized to the terminal and flower buds in the second year were 5 and 24% of those in the first year after labelling, respectively. The concentration of assimilated ¹³C was higher in the terminal buds than in the flower buds in the first year after the labelling, while opposite results were found in the second year. This study demonstrates that the stored carbon used for the development of new organs was a mixture of recent- and old-stored carbon and indicates that recently-stored carbon was preferentially used to develop new organs. We also indicated that the stored carbon was remobilized to flower buds during development.

Pinellia ternata is an herb species in the Pinellia genus with significant economic value due to its medicinal properties. Understanding the accumulation and spatial distribution characteristics of metabolites during the development of the medicinal part, the rhizome of P. ternata (PR), provides a basis for targeted metabolic regulation and quality evaluation. In this study, we used matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI) and MS/MS to analyse metabolites at 5 representative stages (S1 to S5) of rhizome development in cross and longitudinal sections of the rhizome. A total of 168 metabolites were detected, with 13 being metabolites previously reported in PR. Additionally, Venn analysis revealed 12 bioactive differential metabolites during the growth process. Their spatial distribution and composition were analyzed, showing that alkaloids and amino acids were significantly distributed throughout the entire region and had higher relative contents compared to other metabolites. Flavonoids were more distributed in the outer regions of PR, potentially playing a greater role in combating biotic or abiotic stresses. Specifically, in cross-sections, arginine, nicotinamide, and 2-pentylpyridine showed a clear trend of accumulation from the outer to the inner from S1 to S5, while trigonelline, adenosine, cytidine, 3,4-dihydroxycinnamyl alcohol, raffinose, choline alfoscerate, liquiritin, and apii exhibited the opposite trend. For longitudinal sections, trigonelline, 2-pentylpyridine, choline alfoscerate and baicalein showed a trend of accumulation from the area of bud end to the far region during S1 to S5, while arginine showed opposite distribution trends. These findings deepen our understanding of the metabolic processes involved in the development of PR and have potential implications for variety improvement and quality control.

In this research, we analyzed Random Amplified Polymorphic DNA (RAPD), Inter Simple Sequence Repeats (ISSR) and Sequence-related amplified polymorphism (SRAP) markers to evaluate the genetic diversity of eighteen different onion genotypes with various resistant levels to FOC. The results showed that the polymorphism means between RAPD primers was 61.11 to 81.81%; ISSR primers, 62.50 to 81.81%; and SRAP primers, 56.25 to 76.25%. Overall, by assessing MI, PIC, I and H indices, indicating the best thrive in evaluating the genetic diversity of the related onion populations. There is a significant correlation between the generated dendrograms based on similarity matrices. The classification pattern in dendrograms shows a corresponding correlation with the FOC disease severity bunches. So in all three markers studied, 'Saba' and 'Saba - HS', the most resistant ones to FOC disease, were grouped in a branch, and the 'Sahar - HS' and 'Golden Eye', the most susceptible ones were also grouped in another branch separately. This finding indicates that predominant primers act as markers linked to resistance gene(s) against FOC, which can be used to select onions resistant to FOC disease in any breeding scheme.

The gene GAD1 encodes a glutamate decarboxylase, which is a rate-limiting enzyme for the biosynthesis of endogenous γ-aminobutyrate acid (GABA), but a potential role of GAD1 in regulating cadmium (Cd) tolerance needs to be further elucidated in plants. The objective of this study was to investigate Cd tolerance of creeping bentgrass (Agrostis stolonifera) and transgenic yeast (Saccharomyces cerevisiae) or Arabidopsis thaliana overexpressing AsGAD1. The Cd-tolerant creeping bentgrass cultivar LOFTSL-93 accumulated more endogenous GABA in relation to a significant upregulation of AsGAD1 in leaf and root than the Cd-sensitive W66569 in response to Cd stress. The overexpression of AsGAD1 significantly enhanced Cd tolerance of yeast or A. thaliana associated with improved endogenous GABA content, low oxidative damage, and high cell membrane stability and photochemical efficiency. Compared with wild type, AsGAD1-overexpressing plants or the atgad1 mutant maintained significantly lower or higher Cd content in leaf and root by down-regulating or up-regulating transcript levels of AtNRAMP1/2/3/4/5 and AtZIP1/2, respectively. Moreover, overexpression of AsGAD1 significantly up-regulated transcript levels of AtHMA1/3, contributing to better Cd compartmentalization from chloroplast into cytoplasm and then into vacuoles. AsGAD1 overexpression also induced expressions of AsMT1A/1B/1C/2/3, AsGSH1/2, and AsPCS1/2, indicating better capacity of Cd chelation in cytosol and vacuoles for Cd detoxification. Hence, AsGAD1-regulated detoxification mechanism of Cd could be related to Cd uptake, transport, and chelation. In addition, lipid contents (PC, PG, and DGDG) and the DGDG/MGDG and PC/PG ratios were improved by the AsGAD1 overexpression, which favors membrane stability and functionality under Cd stress. These findings provide new insight into the regulatory role of GAD1 in Cd tolerance in plants.

In the context of climate changing environments, microalgae can be excellent organisms to understand molecular mechanisms that activate survival strategies under stress. Chlamydomonas reinhardtii signalling mutants are extremely useful to decipher which strategies photosynthetic organisms use to cope with changeable environments. The mutant vip1-1 has an altered profile of pyroinositol polyphosphates (PP-InsPs), which are signalling molecules present in all eukaryotes and have been connected to P signalling in other organisms including plants, but their implications in other nutrient signalling are still under evaluation. In this study, we conducted prolonged starvation in WT and vip1-1 Chlamydomonas cells. After N and P had been consumed, they showed important differences in the levels of chlorophyll, photosystem II (PSII) activity and ultrastructural morphology, including differences in the cell size and cell division. Metabolomic analysis under these conditions revealed an overall decrease in different organic compounds such as amino acids, including arginine and its precursors and tryptophan, which is considered a signalling molecule itself in plants. In addition, we observed significant differences in RNA levels of genes related to N assimilation that are under the control of the NIT2 transcription factor. These data are of important relevance in understanding the signalling role of PP-InsPs in nutrient sensing, especially regarding N, which has not directly been connected to these molecules in green organisms before. Additionally, the PP-InsPs regulation over cell size and photosynthesis supports novel strategies for the generation of resilient strains, expanding the biotechnological applications of green microalgae.

An elicitor, chitosan (CHT), induces stomatal closure in plants, which is accompanied by salicylhydroxamic acid (SHAM)-sensitive peroxidases-mediated reactive oxygen species (ROS) production in guard cells. Reactive carbonyl species (RCS) function downstream of ROS in abscisic acid (ABA) and methyl jasmonate (MeJA) signalling in guard cells. However, the involvement of RCS in CHT-induced stomatal closure is still unknown. In this study, we used transgenic tobacco (Nicotiana tabacum) plants overexpressing Arabidopsis thaliana 2-alkenal reductase (AER-OE tobacco) and Arabidopsis wild-type (WT) plants to investigate whether RCS is involved in CHT-induced stomatal closure. Chitosan-induced stomatal closure was inhibited in the tobacco AER-OE plants. In the WT tobacco and Arabidopsis plants, CHT-induced stomatal closure was inhibited by RCS scavengers, carnosine and pyridoxamine. Chitosan significantly increased RCS production in the WT tobacco and Arabidopsis, but in the tobacco AER-OE plants, chitosan did not increase significantly RCS accumulation. Moreover, neither the application of RCS scavengers to both WT plants nor scavenging RCS by AER-OE affected the CHT-induced ROS accumulation. However, treatment with a peroxidase inhibitor, SHAM, significantly inhibited CHT-induced RCS accumulation in WT tobacco and Arabidopsis plants. Taken together, these results suggest that RCS acts downstream of ROS production in CHT signalling in guard cells of A. thaliana and N. tabacum.