Inheritance and mapping of the ore gene controlling the quantity of β-carotene in cucumber (Cucumis sativus L.) endocarp

The metabolic precursor of vitamin A, beta-carotene, is essential for human health. The gene(s) controlling beta-carotene quantity (Q beta C) has been introgressed from Xishuangbanna gourd (XIS, possessing beta-carotene; Cucumis sativus L. var. xishuangbannanesis Qi et Yuan; 2n = 2x = 14) into cultivated cucumber (no beta-carotene; Cucumis sativus L.). To determine the inheritance of Q beta C in cucumber fruit endocarp, F1 progeny and a set of 124 F7 recombinant inbred lines (RILs) derived from the cultivated cucumber line CC3 and XIS line SWCC8 were evaluated for Q beta C during 2009 and 2010 in Nanjing, China. Segregation analysis revealed that endocarp Q beta C of greenhouse-grown fruit was controlled by a single recessive gene. Further, marker analysis indicated the gene controlling Q beta C was linked to seven SSR markers on linkage group 3, where their order was SSR20710-SSR19511-SSR15419-SSR07706-ore-SSR23231-SSR11633-SSR20270. These markers and the putative candidate gene were mapped to cucumber chromosome 3DS. An evaluation of 30 genetically diverse cucumber lines indicated that marker SSR07706 has utility in further genetic analyses of the Q beta C orange endocarp gene, designated ore. Moreover, the markers defined herein may have utility for marker-assisted selection directed towards the development of cucumber germplasm with high fruit beta-carotene content.