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https://www.ias.ac.in/article/fulltext/jgen/094/03/0445-0452

bmr-6; cinnamyl alcohol dehydrogenase; lignin biosynthesis; sorghum.

Brown midrib mutants in sorghum are associated with reduced lignin content and increased cell wall digestibility. In this study, we characterized a bmr-6 sorghum mutant, which shows reddish pigment in the midrib and stem after the fifth-leaf stage. Compared to wild type, Kalson lignin content of bmr-6 is decreased significantly. We used histological analysis to determine that the mutant exhibited a modified pattern of lignin staining and found an increased polysaccharide content. We cloned BMR-6 gene, a gene encoded a cinnamyl alcohol dehydrogenase (CAD), using a map-based cloning approach. Genetic complementation confirmed that CAD is responsible for the BMR-6 phenotype. BMR-6 gene was expressed in all tested sorghum tissues, with the highest being in midrib and stem. Transient expression assays in Nicotiana benthamiana leaves demonstrated cytomplasmic localization of BMR-6. We found that the expression level of bmr-6 was significantly decreased in the mutant but expression of SbCAD3 and SbCAD5 were significantly increased. Our results indicate that BMR-6 not only affects the distribution of lignin but also the biosynthesis of lignin in sorghum.

Jieqin Li¹ Lihua Wang¹ Qiuwen Zhan¹ Yanlong Liu¹

1. College of Agriculture, Anhui Science and Technology University, Fengyang 233100, People’s Republic of China

Published

September 2015

Manuscript received

1 December 2014

Manuscript revised

6 February 2015

Accepted

13 March 2015

Unedited version published online

16 March 2015

Early published

27 August 2015