LRR1 involved in the abscisic acid signaling pathway to regulate the early growth and development of Arabidopsis thaliana

Background. Living organisms possess the remarkable capacity to swiftly adapt to fluctuations in their environment. In the context of cell signal transduction, a significant challenge lies in ensuring the effective perception of external signals and the execution of appropriate responses. To investigate this phenomenon, a recent study utilized Arabidopsis thaliana as a model plant and induced stress by administering abscisic acid (ABA), a plant hormone, to elucidate the involvement of leucine-rich repeat receptor- like kinase1 (LRR1) in ABA signaling pathways. Methods. Homozygous T-DNA insertion alleles for LRR1 and KIN7 were isolated. Quantitative real-time PCR (qRT-PCR) was performed to confirm the expression of the LRR1 gene. Subcellular localization and beta-glucuronidase (GUS) tissue labeling techniques were utilized to determine the expression pattern of the LRR1 gene in cells and tissues. Yeast two-hybrid complementation, bimolecular fluorescence complementation assay, and GST pull-down assays were conducted to validate the interaction of LRR1 proteins. Results. Phenotypic analyses revealed that lrr1 and kin7 mutants are less sensitive to the inhibitory effects of ABA on germination and cotyledon greening that is seen in WT. Mutants LRR1 and kinase 7 (KIN7) exhibited resistance to ABA and displayed normal growth patterns under control conditions. The double mutant lrr1kin7 showed reduced responsiveness to ABA. Conversely, overexpression lines LRR1ox2 and LRR1ox10 demonstrated heightened sensitivity to ABA, resulting in severe growth reduction. qRT-PCR assay indicated that exogenous application of ABA led to significant down- regulation of ABI3, ABI4, and ABI5 transcription factors in LRR1 material compared to wild-type WT material. An investigation was conducted to determine the expression pattern and transcriptional level of LRR1 in Arabidopsis. The results revealed ubiquitous expression of LRR1 across all developmental stages and tissue tested. Subcellular localization assays confirmed the presence of LRR1 on the plasma membrane of cells. Furthermore, BiFC assay, yeast two-hybrid complementation, and GST pull-down assays demonstrated an interaction between LRR1 and PYL6 in vitro. These findings provide substantial insights into the involvement of LRR1 in the ABA signaling pathway while regulating seed germination and cotyledon greening during early development in Arabidopsis. This study significantly advances our understanding regarding the correlation between LRR1 and ABA signaling pathways with potential applications for enhancing crop stress resistance.