Molecular Cytogenetic Identification Of A Wheat-rye 1R Addition Line With Multiple Spikelets And Resistance To Powdery Mildew

Wheat(Triticum aestivum L., 2n = 6 x = 42, AABBDD) is one of the most important food crop in the world. Plenty of wheat relative species is an important gene pool of wheat breeding and possesses extensive genetic variation, which can make a positive response in biological and abiotic stress and can be used in the improvement of wheat. The introduction of alien chromosomes with excellent gene(s) into wheat from related species is an economical and important method to enrich the genetic basis of common wheat.Rye(Secale cereal L. 2n = 2 x = l4, RR) belongs to gramineae triticeae in triticeae, is the tertiary gene pool of wheat has rich genetic variations and is the most successful one of the species widely used in wheat genetic improvement currently. Rye has some excellent genetic traits that many common wheat required, such as, big spike, multiple spikelets, strong resistance, resistance to powdery mildew, rust and so on, so it is an important gene resource for improving the yield, stress resistance and disease resistance of common wheat. Using technology of hybridization breeding can import the excellent gene of rye into the wheat to improve yield and resistance of wheat varieties, the promotion of wheat production, and broaden the basis of wheat breeding. N9436 B, which with multiple spikelets and resistance to powdery mildew, was developed from the progeny of the cross of common wheat cultivar Shaanmai 611 and rye accession Austrian rye. In order to lay the foundation for the application of this material, the cytology, genomic in situ hybridization(GISH), Fluorescence in situ hybridization(FISH), molecular marker, disease resistance screening and agronomic characters investigation were used to character it. The main results are as follows:1. Cytological identification results showed that the chromosome number and the structure of N9436 B is stable and the chromosome composition is 2n = 42 + 2t = 22Ⅱat the mitotic metaphase I and the pollen mother cell meiosis metaphase I. The Austria rye genomic DNA as probe, the results showed that two chromosomes in N9436 B with the yellow green fluorescence signals at the mitosis metaphase I, so they are rye chromosomes and the two telosome chromosomes are wheat chromosomes. At the pollen mother cell meiosis metaphase I, the two rye chromosomes with the yellow green fluorescence signals is a pair of rye chromosomes. The Oligo-pSc119.2 and Oligo-pTa-535 as probe, FISH analysis was used to constructed the chromosome FISH karyotype of N9436 B and its parents Shaanmai 611 and Austria rye. The identification results of GISH and FISH showed that N9436 B contained a pair of rye chromosomes as 1R chromosomes, and the pair of wheat telosome chromosomes as 2DS chromosome arms. Meanwhile, molecular markers identification of N9436 B found that only primer pairs of 6 specific markers of 1R(NOR-R1、TSM716、NOR-1、TSM621、 CJ545184 and AF136486) from the seven homologous chromosome groups of rye amplified out the specific bands of rye in N9436 B. The above results showed that N9436 B was a wheatrye 1R addition line, and its chromosome composition is 2n=42+2t=40W+2tW+2(1R).2.The results of Agronomic performance showd that the spike length, spikelets per spike and kernels per spike of N9436 B were significantly higher than common wheat parent Shaanmai 611. Among them, the most prominent trait is the number of spikelets per spike of N9436 B for an average of 34, and parental Shaanmai 611 for 21, Austria rye for 43. So the trait of multiple spikelets of N9436 B may dervied from Austria rye.3.For testing the powdery mildew reaction at the seedling stage, N9436 B, Shaanmai 611, Austrian rye, Kavkaz and Amigo were inoculated with the Bgt(Blumeria graminis f. sp. tritici) isolate E09. Kavkaz and Amigo with the powdery mildew resistance gene Pm8 and Pm17 derived from 1RS chromosome arms of rye, respectively. For testing the powdery mildew reaction at adult stage, the plants of N9436 B, Shaanmai 611, Austrian rye, Kavkaz and Amigo were inoculated with the mixture of Bgt isolates prevalent in Guanzhong region of Shaanxi Province in China. The results showd that N9436 B and Austrian rye showed immunity to Bgt isolate at the seedling and adult stage, in contrast, Shaanmai 611, Kavkaz and Amigo were susceptible to Bgt isolate. Therefore, the powdery mildew resistant gene(s) in N9436 B should be dervied from Austrian rye and the gene(s) different from powdery mildew resistance gene Pm8 and Pm17. For testing the stripe rust(Puccinia striiformis f. sp. tritici, Pst) reaction at adult stage, the plants of N9436 B, Shaanmai 611 and Austrian rye were inoculated with the mixed stripe rust races CYR31 and CYR32. The results show that N9436 B and Austria rye showed highly resistance to stripe rust at adult stage, and Shaanmai 611 showed highly susceptible to stripe rust. Therefore, the strip rust resistance gene(s) in N9436 B may dervied from Austria rye.