Cloning and expression analysis of an anthocyanidin synthase gene homolog from Brassica juncea
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Anthocyanidin synthase (ANS) is a key enzyme of the proanthocyanidin biosynthetic pathway in Arabidopsis. In this study, we report cloning and characterization of an ANS homolog, BjANS, from Brassica juncea. The BjANS cDNA sequence is 1,377 bp long and has a 1,077-bp open reading frame encoding a deduced polypeptide of 358 amino acids with a predicted molecular weight of 40,862 Da and an estimated isoelectric point of 5.18. The putative BjANS protein shows 91–99% amino acid sequence identity with Arabidopsis thaliana, Matthiola incana, B. rapa and B. oleracea ANS proteins. The expression of BjANS was analyzed in yellow- and black-seeded B. juncea accessions to determine its physiological function. RT–PCR analysis showed that BjANS expressed in the seed coats of the black-seeded lines and in embryos of the all lines, but not in the yellow-seeded seed coats. Proanthocyanidins were also detected by histochemical analysis in the seed coat of black-seeded accessions and in embryos of all the lines, but not the yellow-seeded seed coat. Both transcriptional and histochemical analyses confirmed that BjANS was involved in the biosynthesis of proanthocyanidins and in seed coat color formation of B. juncea. Lack of BjANS expression blocked biosynthesis of proanthocyanidins in the yellow seed coat, and therefore seeds appeared yellow because of transparent testa.
KeywordsAnthocyanidin synthase Brassica juncea Cloning Expression analysis Seed coat color
We are acknowledged to Prof. Jinling Meng and Dr. Chaozhi Ma at Huazhong Agricultural University, Dr. Cunkou Qi at Jiangsu Academy of Agricultural Science, Prof. Dianrong Li at Shanxi Hybrid Rapeseed Research Center, Prof. Sheng Zhang at Innner Mongolia Agricultural University, Prof. Wanchang Sun at Gansu Agricultural University, and Prof. Nima Zhuoma at Tibet Autonomous Region Institute of Agricultural Science for providing some of the accessions for this study. This study is financially supported by the National Science Foundation of China (30471098), the Hunan Provincial Natural Science Foundation of China (09JJ6059), the Scientific Research Fund of Hunan Provincial Education Department (09B029), the Scientific Research Fund of Pre-State Key Laboratory for Germplasm Innovation and Resource Utilization Of Crops in China (200903).
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