| Gossypium bickii(2n=26,G1G1)the diploid wild cotton which is native to Australia has many excellent traits unavailable in the cultivated cotton gene pool,such as resistance to Verticillium wilt and fusarium wilt,gossypol appearing only after the formation of the cotyledon,anti-cotton aphids and mites and so on.However,it is difficult to directly transfer these excellent traits into the cultivars by conventional methods because of their distant relationship.In crop breeding,Monosomic Alien Addition Lines(MAALs)are plants with an alien chromosome from one donor species added to the genome of another recipient species,the prime motive for producing monosomic alien addition lines is to introgressive genes of interest from wild relatives into cultivated crops.In this study,we used the amphidiploid(2n=78,AADDG1G1)of G.hirsutum-Gbickii to consecutively backcross with upland cotton TM-1 to obtain alien addition lines of individual G.bickii chromosome in G.hirsutum.We used GISH(Genomic fluorescence in situ hybridization)to identify the number of additional chromosomes in the backcross progeny and a set of G.bickii specific molecular markers used to identify which chromosome of G.bickii had be added,To the BC3 generation,in combination with GISH,molecular markers and morphological survey we generated 10 different MAALs of Gbickii to G.hirsutum and the multiple additions contains the remaining chromosomes for the separation.These MAALs are used as intermediate materials that can be used to locate and transfer G bickii excellent genes into Upland cotton,which provides useful germplasm resources for the improvement of upland cotton.At the same time,MAALs with one alien addition chromosome was used as a special material to study single chromosome behavior at the meiosis.Combine with Fluorescence in situ hybridization(FISH),we used MAALs locate genes on the alien chromosome.All the results in this study are as follows:1.A set of Gbickii chromosome-specific SSR primers was chosen from the high density genetic linkage map of G.hirsutum(TM-1)and G.barbadense genomes constructed in our institute.We chose 1506 pairs SSR primer of Dt-subgenome to screen polymorphisms between G.bickii and G.hirsutum and 183 co-dominant primers distributed each chromosome were selected to identify the alien addition chromosomes of G.bickii in G.hirsutum.It was used to track and identify the alien chromosomes of G.bikii in all backcrossing progenys.2.The allohexaploid(AADDG1G1)of Ghirsutum-Gbickii continued backcrossing with TM-1.The posterity was identified by GISH and 82 MAALs was obtained at the BC3 generation.Based on the identification of G.bickii chromosome-specific SSR primers,10 MAALs of Gbickii was isolated except chromosome 1Gb、7Gb、11Gb.3.Combined with GISH and SSR,the transmission rate of G.bickii chromosomes was calculated in the process of backcrossing.Different G.bickii chromosomes had different transmission rate and 1 Gb、7Gb、11 Gb had low transmission rate.4.Observing the chromosomes behavior in the meiosis period,univalent was found in the MAALs.The alien chromosome had on paired chromosome and easy to lose.5.The 45S and 5S rDNA was used as probe,45S and 5S site of Gbickii was successful positioned at chromosom 9Gb by FISH in 9Gb-MAALs.Anther 45 S site positioned at chromosom 5Bb.6.Morphological investigation of MAALs,We found that different MAALs inheritanced different trait of Gbickii.It wound be the foundation of transferring the target trait of Gbickii to Ghirsutum. |
