Gene silencing of BnTT10 family genes causes retarded pigmentation and lignin reduction in the seed coat of Brassica napus

PLoS One. 2013 Apr 22;8(4):e61247. doi: 10.1371/journal.pone.0061247. Print 2013.

Abstract

Yellow-seed (i.e., yellow seed coat) is one of the most important agronomic traits of Brassica plants, which is correlated with seed oil and meal qualities. Previous studies on the Brassicaceae, including Arabidopsis and Brassica species, proposed that the seed-color trait is correlative to flavonoid and lignin biosynthesis, at the molecular level. In Arabidopsis thaliana, the oxidative polymerization of flavonoid and biosynthesis of lignin has been demonstrated to be catalyzed by laccase 15, a functional enzyme encoded by the AtTT10 gene. In this study, eight Brassica TT10 genes (three from B. napus, three from B. rapa and two from B. oleracea) were isolated and their roles in flavonoid oxidation/polymerization and lignin biosynthesis were investigated. Based on our phylogenetic analysis, these genes could be divided into two groups with obvious structural and functional differentiation. Expression studies showed that Brassica TT10 genes are active in developing seeds, but with differential expression patterns in yellow- and black-seeded near-isogenic lines. For functional analyses, three black-seeded B. napus cultivars were chosen for transgenic studies. Transgenic B. napus plants expressing antisense TT10 constructs exhibited retarded pigmentation in the seed coat. Chemical composition analysis revealed increased levels of soluble proanthocyanidins, and decreased extractable lignin in the seed coats of these transgenic plants compared with that of the controls. These findings indicate a role for the Brassica TT10 genes in proanthocyanidin polymerization and lignin biosynthesis, as well as seed coat pigmentation in B. napus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brassica napus / genetics*
  • Brassica napus / metabolism*
  • Cloning, Molecular
  • Flavonoids / metabolism
  • Gene Expression Regulation, Plant / genetics
  • Gene Silencing*
  • Genes, Plant / genetics*
  • Lignin / metabolism*
  • Pigmentation / genetics*
  • Proanthocyanidins / chemistry
  • Proanthocyanidins / metabolism
  • Seeds / genetics
  • Seeds / metabolism*
  • Sequence Analysis
  • Solubility
  • Spatio-Temporal Analysis

Substances

  • Flavonoids
  • Proanthocyanidins
  • proanthocyanidin
  • Lignin

Grant support

This work was supported by National Natural Science Foundation of China [31071450, 31171619, 31101175 and 31171177, http://www.nsfc.gov.cn], the “111” Project [B12006, http://www.moe.edu.cn], the Fundamental Research Funds for the Central Universities [XDJK2012A009, http://www.moe.edu.cn], the Specialized Research Fund for the Doctoral Program of Higher Education of China [20100182120016, http://www.moe.edu.cn], and the Chongqing Program for Key Science and Technology Project [2009AB1030, http://www.ctin.ac.cn]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.