| With the development of social production, the breeding of new variety with high yield and fine fiber become more and more urgent. Because of the narrow genetic basis of cultivated species,it is hard to make a breakthrough through the traditional breeding method. Wild cotton which has a lot of untapped and excellent genes is the important genetic resources for cotton improvement. Wild species of cotton represent an ample genetic repository for potential exploitation by cotton breeders worldwide. However, due to hybrid incompatibility, F1 hybrid sterility, crazy separation of offspring caused by differences in chromosome ploidy level, the majority of genetic variation in wild Gossypium species remains to be exploited. Therefore, it is very important to explore the beneficial allele of from cotton wild species and broadens the genetic basis of upland cotton.Gossypium anomalum (2n= 2x= 26, B1) is a wild species belonging to the B1 genome. As a member of the subsection of Anomala Todaro, G.anomalum possesses several desirable characters such as extremely fine fibre with high maturity, good strength, low fiber weight, resistance to insect pests, and tolerance to water deficit due to its endemic to relatively dry areas. Therefore, G. anomalum represents an inestimable source of genes that can potentially be transferred into the cultivated gene pool.1. Morphological, cytological and molecular analyses of a synthesized hexaploid derived from an interspecific hybrid between G.hirsutum and G.anomalumIn order to resolve interspecific hybrid sterility problems, triploid hybrids from a cross of G.hirsutum and G.anomalum were treated with 0.15% colchicine and putative fertile hexaploid were obtained. Morphological, molecular and cytological analyses were performed to assess the hybridity and doubled status of putative interspecific hybrids in this study. The most of morphological characteristics of the putative hexaploid were intermediate between G.hirsutum and G.anomalum. Analysis of mitotic metaphase plates showed 78 chromosomes. Genome-wide molecular analysis with different genome-derived SSR marker revealed a high level of polymorphism (96.6%) between G.hirsutum and G.anomalun. The polymorphic markers with an additive banding profile in hexaploid indicated its hybridity on the genome-wide level. All this shows that we have obtained double hexaploid hybrid.2. Identification of G.anomalum genome in a BC2F1 populationAfter F1 was backcrossed toSu6039 two times, we obtained 415 BC2F1 individuals when hexaploid hybrid F1 as female parent and upland cotton as the male parent. The phenoltype of BC2F1 populations showed severe separation. We measured the fiber length and boll weight of 138 individuals in BC2F1. The fiber length ranged from 15.9mm to 34.7mm and the boll weight from 0.3g to 4.8g. We selected 122 pairs of SSR primers which showed unambiguous amplification product to genotype the whole BC2F1 population. In total,78 typ-es of recombination and 172 recombination individuals were obtained.3. Development of G.anomal-specific markers based on De novo transcriptome sequencingA total of 13963 SSR were found throught MISA software, and 7621 pairs of SSR primers were designed,1231 of which were redundant with primers in CMD. Non-redundant primers were surveyed in silico for locus polymorphism between G.anomalum and G.hirsutum. Twenty pairs of primers were randomly selected for validation between 86-1, G.anomalum and their chromosome doubling F1. It was found that the PCR products sizes were anastomotic in agreement with e-PCR. We provided a set of effective SSR markers for G.anomalum genome detection in the next step. |
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