Plant Science最新文献

The Mediator (MED) complex is a multi-subunit structure crucial for RNA polymerase II-dependent transcription in eukaryotes. In this study, we investigated the function of a seed-preferential subunit of the rice Mediator complex, namely, OsMED26_2, for the first time. Knockdown of OsMED26_2 in rice reduced plant height and altered panicle morphology with shorter panicles, lesser branching, and fewer seeds per panicle. OsMED26_2 knockdown also led to shorter grains with shorter length and chalky endosperm. A significantly higher percentage of grains with chalkiness (PGWC) and degree of chalky endosperm (DCE) was observed in OsMED26_2 knockdown lines. OsMED26_2-knockdown seeds contained lower starch levels and altered proportions of amylose and amylopectin. Scanning electron microscopy further showed that these changes caused irregular, round, and loosely packed starch granules in the endosperm, contributing to the chalky phenotype. Decreased amylose content and increased grain chalkiness were corroborated by the downregulation of the Waxy (Wx) gene, which is involved in amylose synthesis, and altered expression of AMY3A, CHALK5, FLO4, GPA3, and SUSY3 genes, which regulate grain chalkiness. Our findings demonstrate that OsMED26_2 is critical in regulating panicle architecture, impacting yield, and modulating starch level and composition to control grain chalkiness and thereby suggesting its functional significance especially in manipulating yield attributing grain cooking quality traits of rice.

Dehydrins (DHNs) are among the most commonly expressed proteins in plants under a wide range of environmental constraints. Despite their functional relevance, DHNs from halophytic species are scarcely explored and their role in adaptive stress mechanisms remains largely unexplored. In this study, we investigated the role of an FSK₂-type DHN of the halophytic species Atriplex halimus (named hereafter AhDHN1) in salt and drought stress response via its overexpression in Arabidopsis thaliana. Phenotypical, physiological, and biochemical, analyses revealed that AhDHN1-overexpressing lines exhibited enhanced tolerance to salt and drought stresses. This improvement was clearly illustrated by a more vigorous root system and enhanced photosynthetic activity. Remarkably, the beneficial effect of AhDHN1 was associated with an improved ability of the transgenic lines to mitigate oxidative damage caused by salinity and drought stress, as evidenced by lower malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels and higher activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). Furthermore, the enhanced stress tolerance observed corroborates with a stronger induction of stress responsive genes in the transgenic lines. Most interestingly, AhDHN1 overexpression led to significant improvements in yield-related traits, including higher silique number and increased seed size. Overall, these findings not only highlight the importance of AhDHN1 in plant stress tolerance mechanisms but also underscore its potential for sustaining crop yields in the face of challenging environmental conditions.

Sugarcane being a high biomass producing crop, massively depletes nutrients from the soil. Thus, optimum supply of mineral nutrients has the greatest impact on growth, development, and yield in sugarcane. Amongst the essential nutrients, the major nutrients nitrogen (N), phosphorus (P) and potassium (K) assume primary importance in cane growth and their availability determines the crop yield. Currently, physiological, molecular, and genetic basis of uptake and assimilation of these nutrients in sugarcane is limited compared to other field crops especially with regard to the root system traits that enhance nutrient uptake. Nonetheless, availability of the polyploid sugarcane genome sequence and genomic information has widened the scope for molecular characterisation of candidate genes involved in uptake, transport and assimilation of N, P, and K. This review summarises the physiological, molecular, and genetic basis of nutrient use efficiency in sugarcane and envisages strategies for production of more cane/crop per unit of nutrient applied.

Heat stress is a major constraint on wheat productivity, and short-term heat-shock studies often fail to capture the complexity of field conditions. Here, we assessed heat responses in contrasting durum wheat genotypes (SSD69, SSD397, Svevo, and Kronos) exposed to prolonged high temperatures throughout their life cycle under field-like conditions. Physiological evaluations at flowering and post-flowering showed that the tolerant lines SSD69 and Svevo maintained higher PSII efficiency (Fv/Fm), stomatal conductance, and canopy cooling, thereby sustaining photosynthesis and grain set. In contrast, SSD397 exhibited PSII damage, impaired transpiration, and reduced fertility. Kronos showed intermediate behavior. Biochemical analyses revealed tissue-specific variation in lipid peroxidation: SSD397 accumulated more malondialdehyde (MDA) in spikes, while SSD69 displayed reduced MDA over time, suggesting more efficient detoxification of reactive oxygen species (ROS). Molecular assays identified differential regulation of TdHsp26 alleles. Tolerant lines showed strong TdHsp26-A1 expression, associated with PSII protection, stomatal regulation, and reduced oxidative damage. By contrast, SSD397 exhibited TdHsp26-A1 downregulation and relatively higher TdHsp26-B1 expression, correlating with stress sensitivity. Overall, our results demonstrate that natural sequence variation in TdHsp26 underpins key physiological and biochemical mechanisms of thermotolerance in durum wheat. SSD69, originating from arid North Africa, displayed traits consistent with adaptation to hot environments, including a stay-green phenotype that supports transpirational cooling and yield stability despite reduced biomass. These findings highlight the adaptive value of durum wheat germplasm and provide targets for breeding cultivars resilient to future climate scenarios.

SWEET (Sugars Will Eventually be Exported Transporters) proteins are essential sugar transporters involved in plant growth, development, and stress responses. However, a detailed analysis of these proteins in Lotus japonicus, a model legume species, has been lacking. This study identified 25 LjSWEET proteins, each with seven transmembrane helices and two conserved domains. Based on the phylogenetic analysis, LjSWEETs were grouped into clades I, II, and III, with none assigned to clade IV. Structural analysis showed conserved motifs and varied exon-intron patterns, suggesting evolutionary conservation. The proteins were unevenly distributed across five chromosomes, with gene family expansion due to tandem and segmental duplications. Promoter analysis indicated roles in stress, hormone, and developmental responses. Expression profiling of eight LjSWEET genes showed tissue-specific patterns, with LjSWEET1a rapidly up-regulated under PEG6000-induced drought stress in leaves. LjSWEET1a localized to the plasma membrane, and yeast assays confirmed that it specifically transported fructose. Overexpressing LjSWEET1a in Arabidopsis increased fresh weight and primary root length on 1% fructose medium, but not on medium supplemented with glucose or sucrose. Subsequent analyses indicated a significant accumulation of total soluble sugars, particularly fructose, in the transgenic lines. However, these lines showed increased sugar content but reduced fresh weight and higher superoxide anion levels under drought stress (300mM mannitol). Further investigation indicated that excessive fructose disrupted sugar balance, which increased drought sensitivity in transgenic plants. This study provided insights into the evolutionary and functional characteristics of LjSWEET genes, with a particular emphasis on the function analysis of LjSWEET1a, and laid the groundwork for further research on SWEET-mediated growth and stress responses in legumes.

Myo-inositol phosphate synthase (MIPS) is a highly conserved enzyme found across a broad spectrum of organisms, from archaea to higher plants and animals. It catalyzes the first and rate-limiting step in the biosynthesis of myo-inositol (MI), a key molecule in plant metabolism. MI and its derivatives play essential roles in numerous biological processes such as phosphorus storage, auxin transport, cell wall formation, signal transduction, and programmed cell death. MIPS activity directly influences MI levels, affecting seed germination, embryogenesis, and stress tolerance through phosphate and mineral mobilization. MIPS is also central to regulating phytic acid accumulation in seeds, and transgenic silencing has shown potential for improving mineral bioavailability. Multiple isoforms of MIPS exhibit distinct spatial and temporal expression patterns across plant species. Gain-of-function and loss-of-function studies have extensively demonstrated that MIPS plays a vital role in regulating plant responses to abiotic and biotic stresses. Notably, emerging evidence points to a crucial role of MIPS in photoperiodic growth under long-day conditions. Despite the expanding knowledge on MIPS, a review synthesizing its diverse roles in plant physiology and development has been notably lacking. This review addresses this critical gap by providing an up-to-date, in-depth analysis of MIPS's multifaceted functions and regulatory mechanisms.

The Arabidopsis PHRAGMOPLAST ORIENTING KINESIN1 (POK1) and POK2 proteins belonged to kinesin-12 class play an essential role in regulating the orientation of the division plane. It has been found that the loss of function of POK1 and POK2 leads to misoriented division planes while maintaining normal cytokinesis. The pok1 pok2 mutant plants exhibit a severely dwarfed stature accompanied by miniature organ tissues. Here, we investigate the roles of POK1 and POK2 in the post-cytokinetic vesicle trafficking that is necessary for auxin signaling. The growth phenotypes, including cotyledon development, distribution of starch granule in the root cap, and patterning of cotyledon veins and roots, are defective in the pok1 pok2 mutant. Additionally, we observed a delayed root gravitropic response in response to gravity stimulus and altered auxin distribution when subjected to exogenous auxin treatment in the pok1 pok2 seedlings. Confocal imaging demonstrated that the auxin transporters, such as PIN FORMED 2 (PIN2) and AUXIN RESISTANT 1 (AUX1), mislocalize at the non-polar lateral membrane and the oblique plasma membrane (PM). Investigations into protein trafficking indicated that the endocytic recycling of the PIN2 transporter and the R-SNARE VAMP721 to the PM is hindered in the pok1 pok2 mutant seedlings. Furthermore, the roots of the pok1 pok2 mutants display abnormal organization and orientation of the actin filaments. These findings suggest that the pair of kinesins POK1 and POK2 are involved in orchestrating plant growth by effects on the membrane trafficking related to auxin distribution and responses, as well as cell division processes.