The Pun1 gene for pungency in pepper encodes a putative acyltransferase
The Pun1 gene for pungency in pepper encodes a putative acyltransferase
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DOI：
10.1111/j.1365-313x.2005.02410.x
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发表时间：
2005-06-01
期刊：
影响因子：
7.2
通讯作者：
Jahn, MM
中科院分区：
文献类型：
--
作者：
Stewart, C;Kang, BC;Jahn, MM
辣椒果实的辛辣是由于辣椒碱及其类似物的积累。辣椒素的生物合成仅限于辣椒属（Capsicum），并且是芳香族部分香草胺被支链脂肪酸酰化的结果。辣椒素生物合成中涉及的许多酶没有很好地表征，并且该途径的调节也没有完全理解。基于当前的途径模型，在公共数据库和文献中鉴定候选基因，并进行遗传作图。已发表的EST与辣椒素类物质存在所需的Pun 1位点共定位。这个基因，AT3，已被分离出来，其核苷酸序列已被确定在属内的基因型阵列。AT3与BAHD超家族中的酰基转移酶有很大的相似性。该基因座的隐性等位基因在每个测试的非辛辣性加入物中包含跨越预测编码区的启动子和第一外显子的缺失。AT3的转录和蛋白表达具有组织特异性和发育调控性。病毒诱导的AT3基因沉默导致辣椒素积累减少，这与pun1表型一致。总之，基因定位，等位基因序列数据，表达谱和沉默分析共同表明，Pun1基因座在辣椒编码一个假定的酰基转移酶，和pun1等位基因，在辣椒育种中使用了近50 000年，结果从一个大的缺失在这个位点。
Pungency in Capsicum fruits is due to the accumulation of the alkaloid capsaicin and its analogs. The biosynthesis of capsaicin is restricted to the genus Capsicum and results from the acylation of an aromatic moiety, vanillylamine, by a branched-chain fatty acid. Many of the enzymes involved in capsaicin biosynthesis are not well characterized and the regulation of the pathway is not fully understood. Based on the current pathway model, candidate genes were identified in public databases and the literature, and genetically mapped. A published EST co-localized with the Pun1 locus which is required for the presence of capsaicinoids. This gene, AT3, has been isolated and its nucleotide sequence has been determined in an array of genotypes within the genus. AT3 showed significant similarity to acyltransferases in the BAHD superfamily. The recessive allele at this locus contains a deletion spanning the promoter and first exon of the predicted coding region in every non-pungent accession tested. Transcript and protein expression of AT3 was tissue-specific and developmentally regulated. Virus-induced gene silencing of AT3 resulted in a decrease in the accumulation of capsaicinoids, a phenotype consistent with pun1. In conclusion, gene mapping, allele sequence data, expression profile and silencing analysis collectively indicate that the Pun1 locus in pepper encodes a putative acyltransferase, and the pun1 allele, used in pepper breeding for nearly 50 000 years, results from a large deletion at this locus.