Characterization of odor-contributing volatile in Capsicum chinense ‘JT-1’fruits during development and transcriptome analysis of key fruit-aroma formation periods
Zhou Heng, Xiaowan Xu, Xiaomei Xu, Hengming Wang, Lei Liu, Zhenxing Li, Zhiliang Li, Qian You, Baojuan Sun, Chao Gong, Yan Yin, Ying Li, Tao Li
Abstract
Chili pepper ( Capsicum spp.) is one of the world's most popular vegetables and spices. C. chinense is a widely consumed domesticated pepper species. Most varieties of this species have distinctive fruity aromas, a trait with high commercial value. Studies have shown that branched-chain esters are the main contributors to the fruity aroma; however, the mechanisms of their accumulation and regulation remain elusive. In this work, we conducted gas chromatography–olfactometry–mass spectrometry analysis of C. chinense pepper ‘JT-1’ fruits harvested from 1 to 7 weeks after flowering (WAF). The main odor-contributing volatile of fruity aroma in ‘JT-1’ fruits was 4-methylpentyl 3-methylbutanoate, the concentration of which dramatically increased at 4 WAF. A shift in the dominant volatile organic compound (VOC) profile from aldehydes and alcohols to esters occurred from 3 to 4 WAF. Transcriptome analysis of fruits at these two stages and qPCR results revealed that the up-regulating of CcBcat 4 may play an essential role in accumulating of 4-methylpentyl 3-methylbutanoate in chili pepper. Our findings shed light on the molecular mechanism of aroma biosynthesis in pepper and provide a theoretical basis for the molecular breeding of high-quality pepper fruits.