Identification Of A Pleiotropic QTL (qKNR7.2) For Kernel Number Per Row, Ear Length And General Combining Ability Of Maize

Combining ability of an inbred line is the ultimate factor determining future usefulness and commercial potential of the line for hybrid. Dissection of the genetic basis of combining ability is useful for guiding the genetic improvement of crop plants. In this study, we employed a combination of Ye478×SL17-1(an introgression line with Ye478genetic background) to develop a set of narrow-based F2:3families, and another set of F2individuals×Testers (two single-cross hybrids) testcross progenies, in order to identify genetic loci for kernel number per row (KNR), ear length (EL), ear weight (EW), row number (RN), ear diameter (ED) and general combining ability (GCA) for the five traits. The results were mainly listed as following:1. SL17-1had12exotic chromosome segments on chromosomes1,4and7, and showing93.93%of similarity with Ye478genome based on the diversity evaluation using208simple sequence repeat (SSR) markers. Phenotypes of five yield-related traits were evaluated in Huanggang (HG) and Weifang (WF), respectively. The results showed that the KNR, EL and EW of Ye478were significantly higher than that of SL17-1, while RN and ear diameter ED of Ye478was similar to that of SL17-1. KNR and EL of SL17-1were～10%below that of Ye478, EW was～20%below that of Ye478. In term of GCA, the GCA effects for five related traits of SL17-1were lower than that of Ye478in three environments.2. For five yield related traits, a total of51QTL were identified using single marker analysis (SMA) in two environments. These QTL distributed on the chromosome1,4and7, which3QTL on the chromosome1,4QTL on the chromosome4and43QTL on the chromosome7. Of them,21QTL were commonly identified under two environments, suggesting that these QTL had widely adaptable and stable hereditary. In addition to qED4.1, the rest QTL were located on7.02bin-7.03bin of chromosome7, indicating that it was QTL-rich region.3. For GCA for five yield traits,14GCA QTL were identified using SMA in three environments. These QTL distributed on the chromosome1,4and7, which1QTL on the chromosome1,2QTL on the chromosome4and7QTL on the chromosome7. Only QTL of the GCA for KNR, EL and RN were identified. The QTL of the GCA for KNR and EL were on chromosome7, similar with KNR and EL. The QTL of the GCA for RN was on chromosome4.4. We found that the chromosome segment flanked by umc2142(7.02bin) and umc1567(7.03bin) was highly associated with KNR, EL and GCA for two traits. Furthermore, seven newly developed markers within umc2142-umc1567interval were used to reconstruct linkage map and fine map the QTL using inclusive composite interval mapping (ICIM). We detected a pleiotropic QTL (qKNR7.2) with largely additive or partial dominance effects for KNR, EL and GCA for two traits. The results provided an experimental support for the hypothesis that GCA is an indication of genes having largely additive or partial dominant effects.