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Six experiments (including pretreatment, embryonic callus induction media, preculture conditions, embryo induction media, embryo germination media, and genotypic effects) were conducted to develop an efficient cucumber (Cucumis sativus L., 2n = 2x = 14) anther culture protocol. Pretreatment and embryo induction were key factors for successful anther culture. Suitable temperature stress depended on the ecotype, i.e., cucumbers from cold areas responded well to cold shock whereas those from temperate areas responded well to heat treatment. The best medium for embryonic callus induction was MS medium supplemented with 4.44 mM BA, 2.26 mM 2, 4-D, 4.64 mM KIN, 3% sucrose and 0.8% agar. For embryo induction, MS medium supplemented with 0.54 mM NAA, 13.32 mM BA, 3% sucrose and 0.8% agar was optimal, and for embryo germination MS medium containing 2.22 mM BA, 6% sucrose and 1.2% agar was best. Using this protocol, we produced callus from 16 genotypes and regenerated plants from three of 20 evaluated. Three embryos per anther and 42 DH per 45 anthers (93% success) were obtained for cv. Ningjia No. 1, which was an improved result over a previous report. The origin of regenerants from microspores was determined by cytological, morphological and AFLP analyses.

The nutritional value of cucumber (Cucumis sativus L.) can be improved by the introgression of b-carotene (i.e., provitamin A and/or orange flesh) genes from ''Xishuangbanna gourd'' (XIS; Cucumis sativus var. xishuangbannanesis Qi et Yuan) into US pickling cucumber. However, the genetics of b-carotene content has not been clearly defined in this US market type. Thus, three previous populations derived from a US pickling cucumber ('Addis') 9 XIS mating were evaluated for b-carotene content, from which the high b-carotene inbred line (S 4 ), 'EOM 402-10', was developed. A cross was then made between the US pickling cucumber inbred line 'Gy7' [gynoecious, no b-carotene, white flesh; P 1 ] and 'EOM 402-10' [monoecious, possessing b-carotene, orange flesh; P 2 ] to determine the inheritance of b-carotene in fruit mesocarp and endocarp tissue. Parents and derived cross-progenies () were evaluated for b-carotene content in a greenhouse in Madison, Wisconsin. While F 1 and BC 1 P 1 progeny produced mature fruits possessing white, light-green, and green (0.01-0.02 lg g -1 b-carotene) mesocarp, the F 2 and BC 1 P 2 progeny mesocarp segregated in various hues of white, green, yellow (0.01-0.34 lg g -1 b-carotene), and orange (1.90-2.72 lg g -1 b-carotene). Mesocarp and endocarp F 2 segregation adequately fit a 15:1 [lowb-carotene (0.01-0.34 lg g -1 ): high-b-carotene (1.90-2.72 lg g -1 )] and 3:1 (low-b-carotene: highb-carotene) ratio, respectively. Likewise, segregation of carotene concentration in mesocarp and endocarp tissues in BC 1 P 2 progeny adequately fit a 3:1 (lowb-carotene: high-b-carotene) and 1:1 (low-b-carotene: high-b-carotene) ratio, respectively. Progeny segregations indicate that two recessive genes control the b-carotene content in the mesocarp, while one recessive gene controls b-carotene content in the endocarp. Single marker analysis of F 2 progeny using the carotenoid biosynthesis gene Phytoene synthase determined that there was no association between this gene and the observed b-carotene variation in either fruit mesocarp or endocarp.