Genetic insights into the crude protein and fiber content of ramie leaves.

Ramie ( L.) is a perennial plant with vigorously vegetative growth and high nutritive value that is an excellent source of green feed in China. Crude protein and fiber content are the most important traits associated with ramie forage quality; however, their genetic basis remains largely unknown. In this study, we investigated the genetic architecture of these two traits using an F population derived from cultivated Zhongsizhu 1 (ZSZ1) and wild var. (tenacissima). Linkage mapping identified eight quantitative trait loci (QTLs) in crude fiber and one QTL in crude protein. Of these, five were further validated by association analysis. Then, two major QTLs for crude fiber content, and , were further identified using bulked segregant analysis (BSA) sequencing, and their exact physical intervals were determined genotype analysis of F progenies with extremely low crude fiber content. In total, 10 genes in the and regions showed differential expression in ZSZ1 and tenacissima leaves, including an MYB gene from the region. Wide variation was observed in the promoter regions of , likely responsible for its downregulated expression in tenacissima. Interestingly, more fiber cells were observed in with overexpression of , indicating that the downregulated expression of this gene could have an association with the relatively low fiber content in wild tenacissima. These results provided evidence that is a logical candidate for . This study provides important insights into the genetic basis underlying ramie crude protein and fiber content, and it presents genetic loci for improving the forage quality of ramie using marker-assisted selection.