Inheritance Analysis And QTL Mapping Of Parthenocarpy In Cucumber

Drought Cucumber is one of the characteristics of industrial advantages of Jidong area. Parthenocarpy is an important economic traits related to the yield and quality. In this paper, 38 South-China ecotype cucumber accessions were subjected to analysis of diversity and cluster via polymorphic SSR markers, using the method of plant quantitative traits of major gene plus polygene mixed genetic analysis. Then, a joint analysis of six-family generations from crossing a highly parthenocarpic monoecious line 6457 with a non-parthenocarpic inbred line 6429 was carried out to investigate the inheritance of the parthenocarpy in cucumber. And, QTLs related to parthenocarpy of cucumber were mapped using a F2 genetic population. The main results were as follows.1. To evaluate the genetic diversity and relationship of cucumber germplasm, 38 cucumber accessions were subjected to analysis of diversity and cluster via 450 paires of SSR markers. 133 alleles were amplified from 72 pairs of primers. The index of dissimilarity of 38 cucumber germplasm accessions varied from 0.215 to 0.704. A close genetic relationship was found between ‘Sijicuilv’ and ‘gfcs’, ‘Yufeicui’ and ‘Cuiyu’, ‘Tangshan Qiugua’ and ‘Zhenbawo’, and between ‘Zhenbawo’ and ‘Huangjialvxiu’. But the genetic relationship between ‘Jiameihanhuanggua’ and ‘Xuanfeng’ or ‘6457’, and between ‘Xinbao’ and ‘Lvzhiqiu’ were relatively distant. The clustering analysis showed that the 38 accessions were divided into two groups, group I and Ⅱ, at a threshold 0.54. Further, the group Ⅰwas subdivided intoⅠA,ⅠB, ⅠC and ⅠD subgroups while the group was subdivided intoⅡ ⅡA, ⅡB and ⅡC at the threshold 0.48.2. A joint analysis of six-family generations(P1,P2, F1, B1:2, B2:2 and F2:3) from crossing a highly parthenocarpic monoecious line ‘6457’ with a non-parthenocarpic inbred line ‘6429’ was carried out to investigate the inheritance of the parthenocarpy in cucumber in this article. The results showed that the inheritance of parthenocarpy in cucumbers was expressed as incompletely dominant, and fitted to the model D-0, i.e. controlled by an additive-dominant major gene and additive-dominant-epistatic polygenes. Additive and dominant effects of the major gene were 10.31 and 7.73 respectively. The major gene heritabilities of B1:2, B2:2 and F2:3 were 1.44%, 39.65% and 24.62% respectively. The polygenes heritabilities of B1:2,B2:2 and F2:3 were 53.31%, 0.00% and 35.21% respectively.3. F2 generation derived from across between the ‘6457’ and ‘6429’ in the present research were screened using the molecular markers AFLP、SRAP、SSR、ISSR、RAPD. A linkage map containing 5 linkage group, 48 AFLP markers, 37 SCAR markers, 6 SSR markers, 8 ISSR markers, and 8 RAPD markers, which total length was 556.1 c M and average distance between two markers was 5.2 c M. In the use of Windows QTL Cartographer V2. 5 and composite interval mapping method, 2 QTLs related to parthenocarpy of cucumber were identified with R2 of 31.6% and 12.7%. Par1.1 was between E37M69-2 and E41M47-1. Par2.1 was between ME9GA18-2 SSR03084.