Search Results (3)

Seed germination is a crucial phase where a plant embryo transitions from dormancy to active growth, emerging as a seedling. This intricate process is highly susceptible to environmental cues, particularly abiotic stress factors including drought, salinity, and temperature extremes, which can profoundly influence both germination success and subsequent plant development. Among the various cellular components that modulate plant responses to these stresses, Rho of Plants (ROP) emerges as a pivotal regulator. Under abiotic stress, ROP signaling components integrate with the core abscisic acid (ABA) signaling pathway by regulating gene transcription and protein stability, modulating subcellular localization, converting protein activity, and engaging in competitive interactions. This review summarizes recent findings on roles of ROP signaling in regulating plant adaptive responses to abiotic stress, whilst explores potential involvement of ROPs in seed germination. This review summarizes the effects of ROP proteins and their effectors, such as GEF, on the seed germination process. It preliminarily elucidates the crosstalk mechanisms between these proteins and the ABA signaling pathway, thereby gaining a deeper understanding of the role of ROP signaling in regulating plant adaptive responses to abiotic stresses. Full article

In plants, RopGEF-mediated ROP signaling is pivotal in cellular signaling pathways, including apical growth, pollen germination and perception, intercellular recognition, as well as in responses to biotic and abiotic stresses. In this study, we retrieved a total of 37 RopGEF members from three C₄ Crops, of which 11 are from millet, 11 from sorghum, and 15 from maize. Based on their phylogenetic relationships and structural characteristics, all RopGEF members are classified into four subfamilies. The qRT-PCR technique was utilized to evaluate the expression profiles of 11 SiRopGEFs across different tissues in foxtail millet. The findings indicated that the majority of the SiRopGEFs exhibited higher expression levels in leaves as opposed to roots and stems. The levels of expression of SiRopGEF genes were examined in response to abiotic stress and plant hormones. SiRopGEF1, SiRopGEF5, SiRopGEF6, and SiRopGEF8 showed significant induction under abiotic stresses such as salt, cold, and heat. On the other hand, SiRopGEF1, SiRopGEF2, and SiRopGEF7 were consistently upregulated, while SiRopGEF3, SiRopGEF4, SiRopGEF6, SiRopGEF9, and SiRopGEF10 were downregulated upon exposure to abscisic acid (ABA), ethylene (ET), salicylic acid (SA), and gibberellic acid (GA₃) hormones. The alterations in the expression patterns of RopGEF members imply their potential functions in plant growth and development, abiotic stress response, and hormone signal transduction. These discoveries suggest that the RopGEF genes may function as a potential genetic marker to facilitate future studies in elucidating the functional characteristics of RopGEFs. Full article

Guanine nucleotide-exchange factors (GEFs) genes play key roles in plant root and pollen tube growth, phytohormone responses, and abiotic stress responses. RopGEF genes in Brassica rapa have not yet been explored. Here, GEF genes were found to be distributed across eight chromosomes in B. rapa and were classified into three subfamilies. Promoter sequence analysis of BrRopGEFs revealed the presence of cis-elements characteristic of BrRopGEF promoters, and these cis-elements play a role in regulating abiotic stress tolerance and stress-related hormone responses. Organ-specific expression profiling demonstrated that BrRopGEFs were ubiquitously expressed in all organs, especially the roots, suggesting that they play a role in diverse biological processes. Gene expression analysis revealed that the expression of BrRopGEF13 was significantly up-regulated under osmotic stress and salt stress. RT-qPCR analysis revealed that the expression of BrRopGEF13 was significantly down-regulated under various types of abiotic stress. Protein–protein interaction (PPI) network analysis revealed interactions between RopGEF11, the homolog of BrRopGEF9, and the VPS34 protein in Arabidopsis thaliana, as well as interactions between AtRopGEF1, the homolog of BrRopGEF13 in Arabidopsis, and the ABI1, HAB1, PP2CA, and CPK4 proteins. VPS34, ABI1, HAB1, PP2CA, and CPK4 have previously been shown to confer resistance to unfavorable environments. Overall, our findings suggest that BrRopGEF9 and BrRopGEF13 play significant roles in regulating abiotic stress tolerance. These findings will aid future studies aimed at clarifying the functional characteristics of BrRopGEFs. Full article