Modulation of Quiescent Center Genes by 24-Epibrassinolide Restores Root Phenotype and Cell Wall Architecture in Arsenate-Stressed Rice Seedlings.

Arsenic, a toxic contaminant found in agricultural fields, is known to affect crop yield negatively and is taken up by plants via the phosphate transport pathway, where accumulation reduces root shoot biomass and yield. Phytohormones are indispensable in promoting plant acclimatization to ever-changing environments by transducing environmental signals to various developmental, physiochemical, and stress responses. In the present study, using an in vitro germination model, we aim to understand the ameliorative role of 24-epibrassinolide, a synthetic brassinosteroid, in mitigating arsenate stress in rice seedlings. Further, a qRT-PCR analysis was performed to study the differential expression of genes involved in cell division, cell elongation, and those related to the biosynthesis of cell wall components. The cell wall architecture was also analyzed using scanning electron microscopy. Our study reports reversal of the toxicity symptoms caused by arsenate in the presence of 24-epibrassinolide, with a nearly 50% increase in root length and around 40% enhancement in shoot length, weight, and germination rate. Further, the expression of BR-responsive transcription factors, namely, OsBZR1, OsERF115, and OsMYB56, and their downstream targets involved in cell division and elongation at the quiescent center were significantly upregulated. 24-EBL application also increased the transcript level of key genes involved in cellulose biosynthesis, i.e., OsCesA3 and OsCesA6. In contrast, a significant decline in mRNA expression of OsPME11 and OsEXLA3 was observed with increased compactness in the arrangement of cellulose indicating restoration of cell wall architecture during arsenate stress alleviation. [ABSTRACT FROM AUTHOR]