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BMC Plant Biol

Title:		Transcriptomic and metabolomic analyses provide insight into the volatile compounds of citrus leaves and flowers
Author(s):		Zhang H; Chen M; Wen H; Wang Z; Chen J; Fang L; Zhang H; Xie Z; Jiang D; Cheng Y; Xu J;
Address:		"Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China. Citrus Research Institute of Southwest University, National Citrus Germplasm Repository, Chongqing, 400712, People's Republic of China. Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China. xujuan@mail.hzau.edu.cn"
Journal Title:		BMC Plant Biol
Year:		2020
Volume:		20200106
Issue:		1
Page Number:		7 -
DOI:		10.1186/s12870-019-2222-z
ISSN/ISBN:		1471-2229 (Electronic) 1471-2229 (Linking)
Abstract:		"BACKGROUND: Previous reports have mainly focused on the volatiles in citrus fruits, and there have been few reports about the volatiles in citrus leaves and flowers. However, citrus leaves and flowers are also rich in volatile compounds with unique aromas. Here, to investigate the volatiles in citrus leaves and flowers, volatile profiling was performed on leaves from 62 germplasms and flowers from 25 germplasms. RESULTS: In total, 196 and 82 volatile compounds were identified from leaves of 62 citrus germplasms and flowers of 25 citrus germplasms, respectively. The dominant volatile terpenoids were more diverse in citrus leaves than in peels. A total of 34 volatile terpenoids were commonly detected in the leaves of at least 20 germplasms, among which 31 were overaccumulated in the leaves of wild or semiwild germplasms. This result was consistent with the high expression levels of five genes and one key gene of the mevalonate and 2-C-methyl-D-erythritol-4-phosphate (MEP) biosynthetic pathways, respectively, as well as the low expression levels of geranylgeranyl diphosphate synthase of the MEP pathway, relative to the levels in cultivars. Fully open flowers showed increased levels of four terpene alcohols and a decrease in sabinene content compared with balloon-stage flowers, especially in sweet orange. A monoterpene synthase gene was identified and functionally characterized as a sabinene synthase in vitro. CONCLUSIONS: Collectively, our results suggest that 31 important terpenoids are abundant in wild or semiwild citrus germplasms, possibly because of a negative effect of domestication on the volatiles in citrus leaves. The sweet smell of fully open flowers may be attributed to increased levels of four terpene alcohols. In addition, a sabinene synthase gene was identified by combined transcriptomic and metabolomic analyses"
Keywords:		"Citrus/*genetics/metabolism Flowers/metabolism Gene Expression Regulation, Plant Genes, Plant Metabolomics Odorants Plant Leaves/metabolism Terpenes/*metabolism Transcriptome/genetics Volatile Organic Compounds/*metabolism Citrus Stps Terpenoid biosynthes;"
Notes:		"MedlineZhang, Haipeng Chen, Mengjun Wen, Huan Wang, Zhenhua Chen, Jiajing Fang, Liu Zhang, Hongyan Xie, Zongzhou Jiang, Dong Cheng, Yunjiang Xu, Juan eng 2018YFD1000200/National Key Research and Development Program/ 31272122/National Natural Science Foundation of China/ England 2020/01/08 BMC Plant Biol. 2020 Jan 6; 20(1):7. doi: 10.1186/s12870-019-2222-z"