Datta, T. | bioRxiv Science

bioRxiv2024

Steroidal glycoalkaloid biosynthesis and fungal tolerance are regulated by ELONGATED HYPOCOTYL 5, SlHY5, in tomato

Tomato (Solanum lycopersicum L.) is one of the highest consumable fruit crops, rich in nutrients, and has been an important target for enhancing the accumulation of various metabolites. Tomato also contains cholesterol-derived molecules, steroidal glycoalkaloids (SGAs), which contribute to pathogen defence but are toxic to humans and considered anti-nutritional compounds. Previous studies suggest the role of various transcription factors in SGA biosynthesis; however, the role of light and associated regulatory factors has not been studied in tomatoes. Here, we demonstrated that SGA biosynthesis is regulated by light through the ELONGATED HYPOCOTYL 5 homolog, SlHY5, by binding to light-responsive G-boxes present in the promoters of the structural and regulatory genes. Our analysis suggests that SlHY5 could complement the Arabidopsis thaliana and Nicotiana tabacum, hy5 mutants at molecular, morphological, and biochemical levels. We report the development of CRISPR/Cas9-based knockout mutant plants of tomato, slhy5CR, and show down-regulation of the SGA and phenylpropanoid pathway genes leading to a significant reduction in SGA (-tomatine and dehydrotomatine) and flavonol contents, whereas SlHY5 overexpression (SlHY5OX) plants show opposite effect. An enhanced SGA and flavonol levels in SlHY5OX lines provided tolerance against Alternaria solani fungus, while SlHY5CR was susceptible to the pathogen. This study advances our understanding of the HY5-dependent light-regulated biosynthesis of SGAs and flavonoids and their role in biotic stress in tomatoes. One Sentence SummaryLight-associated transcription factor, ELONGATED HYPOCOTYL 5, regulates biosynthesis of anti-nutrient molecules, steroidal glycoalkaloids, and fungal tolerance in tomato

molecular biology↗

bioRxiv2022

miRNA408 and its encoded peptide, miPEP408, regulate arsenic stress response in Arabidopsis

MicroRNAs (miRNAs) are small non-coding RNAs that play a central role in regulating various developmental and biological processes. The expression of miRNAs is differentially modulated in response to various stresses. Based on the recent findings, it has been shown that some of the pri-miRNAs encode small regulatory peptides, microRNA-encoded peptides (miPEP). miPEPs are reported to regulate the growth and development of plants by modulating corresponding miRNA expression; however, the role of these peptides in different stresses has not been explored yet. Here, we reported that pri-miR408 encodes a small peptide, miPEP408, that regulates the expression of miR408, its targets, and associated phenotype in Arabidopsis. Plants overexpressing miR408 showed severe sensitivity under low sulphur (LS), Arsenite As(III) and LS+As(III) stress, while miR408 mutant developed through the CRISPR/Cas9 approach showed tolerance. Transgenic lines showed phenotypic alteration and modulation in the expression of genes involved in the sulphur reduction pathway and affect sulphate and glutathione accumulation. Similar to miR408 overexpressing lines, the exogenous application of synthetic miPEP408 or miPEP408 overexpression led to sensitivity in plants under LS, As(III) and combined LS+As(III) stress compared to control. This study suggests the involvement of miR408 and miPEP408 in heavy metal and nutrient deficiency responses. One-sentence summarymiR408 and peptide encoded by miR408, miPEP408, regulate arsenic stress and low sulphur responses in Arabidopsis.

plant biology↗