Mutation in Endo-ß-1,4-Glucanase (KORRIGAN) is responsible for thick leaf phenotype in sorghum

Authors: MENDU, LAVANYA - Montana State University; JALATHGE, GAYANI - Montana State University; DHILLON, KAMALPREET KAUR - Montana State University; SINGH, NAGENDRA PRATAP - Montana State University; BALASUBRAMANIAN, VIMAL KUMAR - Texas Tech University; FEWOU, REBECCA - University Of Angers; Gitz, Dennis; Chen, Junping; Xin, Zhanguo; MENDU, VENUGOPAL - Montana State University

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2022
Publication Date: 12/15/2022
Citation: Mendu, L., Jalathge, G., Dhillon, K., Singh, N., Balasubramanian, V., Fewou, R., Gitz, D.C., Chen, J., Xin, Z., Mendu, V. 2022. Mutation in Endo-ß-1,4-Glucanase (KORRIGAN) is responsible for thick leaf phenotype in sorghum. Plants. 11(24). https://doi.org/10.3390/plants11243531.
DOI: https://doi.org/10.3390/plants11243531

Interpretive Summary: Sorghum is an important crop for food and bioenergy. Cell wall is the main component of biomass for second generation of renewable bioenergy. However, little is known about the genes regulating sorghum cell wall biosynthesis, modification, and degradation. In collaboration with scientists from Montana State University, ARS scientists from Lubbock, Texas characterized three allelic thick leaf (thl) mutants. The causal gene for the thl phenotype was identified as endo-1,4-ß-glucanase that breaks down cell wall. The stem, leaves, and root tissues of the thl mutants displayed decreased crystalline cellulose content. Its function was confirmed by overexpressing the unmutated sorghum gene in Arabidopsis rsw2-1 mutants by Agrobacterium-mediated floral dip transformation. RT-PCR analysis results revealed the presence of the transgenic SbTHL1 gene. Overexpression of SbTHL1 by 35S promoter restored the root swelling phenotype of rsw2-1 to the Col-0 (WT) phenotype in Arabidopsis. This is the first gene identified in sorghum that regulates cell wall structure and provides means to manipulating cell wall structure for bioenergy production. This work is important to scientists in bioenergy

Technical Abstract: Sorghum [Sorghum bicolor (L.) Moench] is a resilient C4 crop that provides food, feed, and cellulosic biomass for bioenergy. Cell wall is the main component of biomass for second generation of renewable bioenergy. However, little is known about the genes regulating sorghum cell wall biosynthesis, modification, and degradation. In this study, we characterized three allelic thick leaf (thl) mutants. The causal gene for the thl phenotype was identified as endo-1,4-ß-glucanase. The Sorghum bicolor SbTHL1 protein showed 74% similarity to the Arabidopsis KORRIGAN (AtKOR) protein. The stem, leaves, and root tissues of the thl mutants displayed decreased crystalline cellulose content. To characterize the function of the THL1 gene, it was transformed into Arabidopsis rsw2-1 by Agrobacterium-mediated floral dip transformation. RT-PCR analysis results also revealed the presence of the transgenic SbTHL1 gene. Overexpression of SbTHL1 by 35S promoter restored the root swelling phenotype of rsw2-1 to the Col-0 (WT) phenotype in Arabidopsis. Thus, SbTHL1 encodes a functional endo-1,4-ß-glucanase. This study is the first gene identified in sorghum regulating cell wall structure and provides means to manipulating cell wall structure for bioenergy production.