Fine Mapping Of Lobed-leaf Gene In Rapeseed (Brassica Napus L.) And Its Application In Heterosis Utilization

The trait of lobed-leaf is an ideal morphological marker in rapeseed (Brassica napus L.) with the characters of early performance, being easily distinguished, and stable and sustained expression. In this experiment, the effect of lobed-leaf on other agronomic traits was analyzed and lobed-leaf gene BnLL1(Lobed-leaf gene1in Brassica napus L.) was finely mapped. Moreover, the lobed-leaf trait was introduced into a recessive epistatic genic male sterility system successfully. The main results are as follows:1. The genetic analysis of lobed-leaf traitFour F1combinations were derived from the reciprocal crosses between lobed-leaf line Yuye87and two entire-leaf lines, Zheyou50and Yuanye313. Then four F2populations and sixteen BC1populations were derived. The leaves of the four F1s were serrated which had an intermediate form of lobed and entire types. In each of the four F2populations, leaf shape segregation showed a ratio of1:2:1for lobed, serrated, and entire leaves, respectively. In all sixteen BC1populations, plants with F1leaf shape and plants with recurrent parent-type leaf shape were represented in a ratio of1:1. It is suggested that the lobed-leaf is controlled by one incomplete dominant gene without cytoplasmic genetic effect in rapeseed.2. The effect of lobed-leaf on other agronomic traitsIn F2populations of Yuye87x Zheyou50and Zheyou50x Yuye87, plants were divided into three leaf types:lobed, serrated, and entire. Multiple comparisons analysis was carried out for ten main agronomic traits. The results showed that the lobed-leaf trait had no significant adverse effects on the ten agronomic traits.3. Fine mapping and candidate gene prediction of BnLLlThree thousand four hundred and fifty six individuals from the F2population of Zheyou50x Yuye87were used for fine mapping of BnLLl. The gene BnLLl was finally mapped in an interval between BnaA10g26280D and BnaA10g26340D on chromosome A10of Brassica napus. The target region was narrowed down to32.10Kbp. BnaA10g26320D and BnaA10g26330D were predicted as candidate genes of BnLLl.4. Achievement of two-type and temporary maintainer lines with lobed leavesIn this study, three methods were proposed for breeding two-type and temporary maintainer lines with lobed leaves, there were F2, pedigree and backcross methods; the lobed-leaf two-type lines and lobed-leaf temporary maintainer lines were successfully bred by F2method. Lobed-leaf traits can be used as a marker to ensure the purity in the process of multiplication for two-type lines, lobed-leaf temporary maintainer lines and male sterility lines, and consequently the purity of hybrid seeds can be controlled.