A Leucine-rich repeat receptor kinase as a regulator in the cuticular wax deposition in sorghum

Authors: TIAN, RAN - Texas Tech University; NAJERA-GONZALEZ, HECTOR-ROGELIO - Texas Tech University; NIGAM, DEEPTI - Texas Tech University; KHAN, ADIL - Texas Tech University; HERRERA-ESTRELLA, LUIS - Texas Tech University; Chen, Junping; Xin, Zhanguo; JIAO, YINPING - Texas Tech University

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2024
Publication Date: 7/23/2024
Citation: Tian, R., Najera-Gonzalez, H., Nigam, D., Khan, A., Herrera-Estrella, L., Chen, J., Xin, Z., Jiao, Y. 2024. A Leucine-rich repeat receptor kinase as a regulator in the cuticular wax deposition in sorghum. Journal of Experimental Botany. 75(20):6331-6345. https://doi.org/10.1093/jxb/erae319.
DOI: https://doi.org/10.1093/jxb/erae319

Interpretive Summary: As a drought and heat tolerant crop, sorghum leaf and sheath surfaces are covered with a much thicker layer of wax than other plants. However, the mechanism for the surface wax accumulation is not well understood in sorghum. In collaboration with scientists from Texas Tech University, we have identified a gene that positively regulates the surface wax accumulation. Using bulk segregant analysis, we have determined the causal mutation for a sorghum mutant, bm41, that is devoid of wax accumulation on leaves and leaf sheaths. The BM41 gene encodes a leucine-rich repeat receptor kinase that regulates over 200 genes involving in the biosynthesis of components of waxy layers. This work is important to the sorghum industry and scientists working on drought tolerance in other crops.

Technical Abstract: Cuticular wax (CW) is the first defensive barrier of plants that forms a waterproof barrier, protects the plant from desiccation, and defends against insects, pathogens, and UV radiation. Sorghum, an important grass crop with high heat and drought tolerance, exhibits much higher wax production load than other grasses, and the model plant Arabidopsis. In this study, we explored the regulation of sorghum CW biosynthesis using a bloomless mutant. The CW on leaves and leaf sheaths of bloomless 41 (bm41) mutant showed significantly reduced very long-chain fatty acids (VLCFAs), triterpenoids, alcohols, and other wax components compared to that in the wild-type. Particularly, the 28-carbon and 30-carbon VLCFAs were decreased in the mutants. The causal gene of the bloomless phenotype was identified as a leucine-rich repeat transmembrane protein kinase, using by bulk segregant analysis. Transcriptome analysis of the leaf sheaths of wild-type and bm 41 mutant revealed the Bm41 gene as a positive regulator of lipid biosynthesis and steroid metabolism. The BM41 gene may regulate the CW biosynthesis pathway by affecting the sorghum gene encoding 3-ketoacyl-CoA synthase 6. Our identification of a new regulator of CW biosynthesis provides fundamental knowledge for improving the heat and drought tolerance of grass crops by increasing CW.