Exploring the role of Light Sensitive Short Hypocotyl 9 (LSH9) in light-mediated seedling development in Arabidopsis thaliana

Brahmachari, Ananya (2025) Exploring the role of Light Sensitive Short Hypocotyl 9 (LSH9) in light-mediated seedling development in Arabidopsis thaliana. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Ananya Brahmachari (20MS160)) 20MS160_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

Light Sensitive Short Hypocotyl 9 (LSH9) belongs to a family of proteins called ARABIDOPSIS LIGHT DEPENDENT SHORT HYPOCOTYLS 1 and Oryza sativa G1/LIGHT-DEPENDENT SHORT HYPOCOTYLS (ALOG/LSHs) that are known to be highly conserved across plant lineages, ranging from moss to higher flowering plants, indicating their essential role in several developmental processes, as in vegetative and reproductive programs. Some previous research has reported a possible relationship of LSH9 with Early Flowering 3 (ELF3) through genetic studies, while in another study where LSH9 transcripts showed light-dependent circadian regulation strongest in the hypocotyls and roots, pointing to the fact that light-dependent circadian rhythm is important for LSH gene expression. Here, we show that LSH9 is an important component of the light signaling pathway. The lsh9 mutant showed strong sensitivity to varying intensities of both white and blue light. Our results showed that LSH9 is an essential component in controlling hypocotyl growth and photo-pigment accumulation. Besides, pharmacological studies reveal that LSH9-mediated seedling photomorphogenesis is strongly linked to growth hormones, auxin, gibberellic acid, and brassinosteroid biosynthesis and signaling. Further, the lsh9 mutant showed differential regulation of light-sensitive gene markers, suggesting its potential role in light signaling. Collectively, our study reveals the novel role of LSH9 in negatively regulating light-mediated seedling photomorphogenesis in Arabidopsis. Understanding the molecular pathway of light signaling is critical in predicting how plants cope with several light-mediated stresses, and this knowledge can be used to promote seedling photomorphogenesis in crops.

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