Genetic Rules And Genome-wide Single-marker Analysis Of Monoterpenoids In Grapes

Monoterpenoids are the main aroma components in grape berry and wine,which are widely concerned in the variety development and improvement of table grape and wine grape.At present,the genetic rules and the molecular mechanism of monoterpenoids biosynthesis in grape are not fully understood.In this study,Vitis vinifera grape ’Italy’ and ’Tamina’ and their hybrid F1 offsprings were used as research materials.The free and glycoside bound monoterpenes in grape fruits were quantitatively analyzed by headspace solid phase microextraction and gas chromatography-mass spectrometry(HSSPME-GC-MS).High-density SNP markers was obtained by whole genome resequencing,and the single marker association analysis of monoterpenoids was carried out.The main results were as follows:(1)176 F1 fruits were harvested in 2017 and 2018,free and glycoside-bound monoterpenoids in fruits were analyzed respectively.A total of 26 monoterpenes including 15 chain monoterpenes and 11 cyclic monoterpenes were identified.Most of the components showed Poisson distribution,while some showed normal distribution.The composition of monoterpenoids in different individual offspring is basically the same,but the content is different,leading to the significant variation of aromatic profile in different grape.(2)There were three genotypes at the chr5:3854251 site of the monoterpenoids biosynthesis gene Vv DXS in the studied population.Most of the bound and free monterpenoids in the genotype TT are more abundant than genotype GT,then followed by the genotype GG,and GG type mutants with aromatic flavor were found in F1 offspring.(3)Based on the results of genome-wide re-sequencing,a total of 207,951 SNPs were selected for single marker association analysis of monoterpenoids.19,6,10,17,19 and 29 SNPs in chr5,chr11,chr12,chr15,chr16 and chr17 were significantly associated with specific monoterpenoids content.(4)A total of 9 candidate genes that involved in the monoterpene synthesis were identified near the above SNP sites: Vv GPPS(VIT＿215s0024g0085),Vv DXS(VIT＿211s0052g01240),Vv TPS(VIT＿212s01 3g00020、VIT＿212s0134g00030、VIT＿212s0134g00040、VIT＿212s0134g00090、VIT＿212s0134g00140)and Vv GTs(VIT＿216s0115g00340 、 VIT＿216s0115g00360).However,the effect of these genes on monoterpene content still needs to be proved by further experiments.This study not only might help to undertand the inheritance of monoterpenoids in grape fruits,but also provides important candidate genes for further analysis and regulation of grape monoterpenoids biosynthesis.