| Eggplant (Solanum melongena L.) is an economically and nutritionally important crop, which is cultivated around the world, especially in such developing countries as China and India. Despite of its economic importance,its molecular genetics has been rather less intensively explored than those of the other leading solanaceous crop species (tomato, pepper and potato), for all of which have high-density linkage maps. Therefore, it is of great necessity to genetically study one of the most important traits—fruit character. These studies will be useful in future eggplant breeding.A total of 116 solanum accessions, including cultivated eggplants and related species, were morphologically evaluated. Results showed that there was a high level of variation among related species for all the traits, except for plant height (PH), leaf length (LL) and fruit shape (FS), and among the cultivated species except for PH, LL, leaf prickle (LP) and leaf lobe (LLOB) A dendrogram based on morphological data showed that all materials were divided into three groups at the Euclidean distance of 0.62. Group I only consisted of Guiyangyeshengqie (S. surattense Burm f.); GroupⅡincluded Hongqie72, Gangguoqie, Guanshangqie, Hongqie and Ribenhongqie, whose scarlet fruit color was characteristic of S. aethiopicum species. GroupⅢwas made up of weedy forms of S. melongena (group F, group G) and the cultivated ones (group H). Most of accessions of S. melongena group H clustered together according to FS.These materials were also molecularly evaluated by SRAP and SSR techniques. Results showed that the polymorphism was excellent in wild species and was poor in the cultivated eggplants, indicating that a relatively low genetic background. A dendrogram based on molecular data demonstrated the same clusters as morphological grouping from related species to S. melongena group F and group G. However, there was relatively large distinctness of classifications in S. melongena group H.Two morphologically and molecularly distinguished inbred lines, CYN126 and CYN132, were selected for mapping parents. CYN126 is a non-spiny commercial type eggplant line that bears large, purple, unstriped, oblong fruit, whereas CYN132 is a spiny S. melongena group F eggplant and bears small, green, striped, round fruit. Two hundred F2 individuals were produced through one single F1 plant. Through self-pollination by single-seed descent (SSD), 180 F6 progeny were obtained. A total of 127 markers (111 SRAPs, 16 SSRs) was grouped into thirteen large linkage groups (LGs) at a LOD score threshold of 3.0. The map spanned 713.2 cM with an average marker interval of 5.62 cM. The markers were distributed relatively evenly. LGs ranged in size from 8.1 cM (LG13) to 83.6 cM (LG1) and included 3 to 17 markers.Five fruit related traits, i.e. fruit weight (FW), fruit length (FL), fruit diameter (FD), FS and fruit anthocyanin intensity (FAI) were determined and QTL mapped. Results showed that eight QTLs were detected and FW, FL and FAI were found to be controlled by two QTLs and FD and FS by one QTL, respectively. Two fruit weight QTL, fw2.1 and fw10.1, were localized to the interval EM7PM101-ME3ODD9 on LG2 and SA17GA5a- OD8GA34 on LG10. Of all the QTLs, fl2.1 explained 23.36% of the variation for fruit length. For all of the QTLs, the S. melongena alleles were associated with an increase in FW, FL, FD, FS except one QTL for FAI, fai7.1. Moreover, loci for FW, FL and FD were localized the same interval. |
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