Genome-Wide Association Study Discovered Favorable Single Nucleotide Poly Morphisms and Candidate Genes Associated with Ramie (Boehmeria Nivea L.) Colloidal Matters

Ramie (Boehmeria nivea L.) bast fiber is one of the most ancient natural fibers, which is used for textile only after degumming. Hemicellulose, pectin, and hydrotrope are the main colloidal matters in ramie fiber, which are removed when degumming. However, the genetic variation and control loci are poorly understood. Here, we analyzed the genetic variation of the colloidal matters and discovered the favorable single nucleotide poly morphisms (SNP) by genome-wide association study using 319 ramie core germplasms. In total, 21, 5, and 10 SNPs were found to be the significantly key control loci associated with hemicellulose, pectin, and hydrotrope, respectively, which changed the amino acid sequences of the reference genes. Fourteen key genes involved in various sugars biosynthesis and metabolism pathways were identified to regulate the hemicellulose content in ramie. Meanwhile, 7 calcium transporting or binding related genes were identified to involve in the biosynthesis of calcium magnesium pectinate-the main component of pectin. Moreover, 306 genes related to hydrotrope were identified and their function were also discussed. Our study first reveals the genetic variation and candidate genes related to the colloidal matters of ramie bast fiber, and provides tools for marker-assisted selection in improvement of agricultural traits.