Genetic analysis and molecular characterization of multilocular trait in the <italic>srb</italic> mutant of <italic>Brassica rapa</italic> L.

Abstract

<p indent=0mm>Multilocular silique is considered as a trait associated with high yield in rapeseed, and we studied the genetic regulation of the multilocular trait in <italic>B</italic>.<italic> rapa</italic> var. <italic>srb</italic>. This mutant showed a stable multilocular phenotype, ranging from 94.7% to 100% multilocular siliques per plant and 3.5 carpels per silique. Genetic analyses showed that the multilocular trait was monogenically governed by a recessive nuclear gene. Comparative sequencing analysis revealed that there was a novel C-to-G single-nucleotide mutation in the core CLE motif of BrCLV3, leading to histidine mutation at position 12 in conserved domain to aspartic acid, which was named <italic>Brclv3_Asp12</italic>. The analysis of segregated population by SNP marker showed that the C/G single-nucleotide variation in <italic>Brclv3_Asp12</italic> was co-segregated with the multilocular phenotype. Transgenic complementation studies and <italic>in vitro</italic> peptide assays further confirmed that the <italic>Brclv3_Asp12</italic> allelic mutation in <italic>srb</italic> could lead to reduced activity of the CLV3 peptide, resulting in the formation of multilocular phenotype. Therefore, the study preliminarily clarified the mechanism involved in multilocular silique formation in <italic>srb </italic>mutant.