| Plant hybrid lethality is defined as the phenomenon that the parents can grow normally, while their F1 generation always exhibits abnormal growth and development symptoms which makes the viability decline and ultimate death of plants. Currently, plant hybrid lethality is found in many plant species, such as wheat(Triticum aestivum), barley(Hordeum), tobacco(Nicotiana tabacum), cotton(Gossypium), Arabidopsis(Arabidopsis thaliana), etc. Plant hybrid lethality can be divided into interspecific(or genera) cross and intraspecific cross due to the relationship of their parents, and heredity in most cases of them conform to the Dobzhansky-Muller(DM)model. The study of plant hybrid lethality helps to understand the mechanism of reproductive isolation, provides clues for the formation and evolution of species, and also provides theoretical guidance for crop breeding by applying the lethal gene to crop breeding program.In the autumn of 2009, a F1 hybrid 09Q66(09-211 × 09-222) was found in cabbage(Brassica oleracea L. var. capitata L) which showed seedings lethality in the field, and further identification was conducted on the lethal materials. On this basis, we identified the novel hybrid lethal materials with the previous materials, conducted genetic analysis by using several three-way cross combinations and mapped the lethal gene BoHL1 by building large sample populations, which was aimed at providing basic research on gene cloning and functional analysis in cabbage. The results are as follows:1. The characteristic of cabbage hybrid lethal traitsThe growth of lethal F1 was normal at cotyledon stage. However, a few lethal hybrid seedlings showed growth retardation at the two-leaf-stage and most seedings died at the four-leaf-stage. Some individual seedings could grow to eight-leaf-stage, but all lethal plants died before the rosette stage. The special lethal symptoms performed that: the edge of leaves turned yellow, then withered, with no luster; the plant grew slowly after the appearance of lethal symptoms, and died eventually.2. Identification of lethal materials and genetic analysis of hybrid lethality in cabbageThe combinations which were obtained by the inbred lines 09-211, 09-222, 10-260 other inbred lines were used as test materials, 11-204 and 11-176 were identified as novel inbred lines with hybrid lethal gene. Among the 5 materials, 11-176, 09-222 and 10-260 were one group, 11-204 and 09-211 were the other group, the cross within the group was normal, but the cross between the groups was lethal and the materials in the same group which performed the similar genetic effect; Hybrid lethality in cabbage was controlled by two dominant complementary genes,one of lethal genes was from 09-211 or 11-204,the other one came from any of 09-222, 10-260 or 11-176, and it conformed to the Dobzhansky-Muller(DM)model.3. The mapping of cabbage hybrid lethal gene BoHL1Two segregation populations for mapping BoHL1 were built by three-way cross, 2526〔(09-211 × 87-534) × 09-222〕and 2528 〔(09-211 × 11-196) × 09-222〕. The BoHL1 was located roughly on chromosome C01, then, using developed a group of InDel primers according to the 10× resequencing data of parents, we mapped the BoHL1 between the markers HL132 and HL134, within the physical distance of 101 Kb. |
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