Knockdown of 60S Ribosomal Protein L14-2 Reveals Their Potential Regulatory Roles in Enhancing Drought and Salt Tolerance in Cotton

Abstract BackgroundCotton is an important economic crop and the primary source of natural fiber. The effects of drought and salt stresses threaten strong fiber and large quantity production. However, due to the ever-changing climatic conditions, plants have evolved various mechanisms to cope with the effects of various stress factors. One of the plant's transcription factors with positive effects in alleviating effects of drought and salt stresses is the Ribosomal protein Large (RPL) gene families. This has prompted the functional characterization of the RPL14B gene previously identified in the QTL region as a candidate gene that responds to stress and initiates mechanisms that enhance stress tolerance. ResultsComprehensive identification and functional analysis were conducted in this study, in which 26, 8, and 5 proteins containing the RPL14B domain were identified in G. hirsutum, G. raimondii, and G. arboreum, respectively. Moreover, Cis-regulatory elements associated with the RPL genes were identified. The Myb binding sites (MBS), Myb, Abscisic acid-responsive element (ABRE), CAAT-box, TATA box, TGACG-motif, and CGTCA-motif responsive to Meja, and TCA- motif responsive to salicylic acid were identified. Validation of the candidate gene through virus-induced gene silencing (VIGS) revealed that the Gh_D01G0234 (RPL14B) knockdown significantly affected the cotton seedling's performance under drought/ salt stress conditions as evidenced by a significant reduction in various morphological and physiological traits. Moreover, antioxidant enzyme levels were significantly reduced in VIGS-plants, with substantially higher oxidant enzyme levels, as evidenced by the higher concentration level of Malondialdehyde (MDA). ConclusionThe results revealed the potential role of the gene, and it can be further exploited to breed climate-smart cotton varieties resilient to drought and salt stress conditions