Diversity Analysis Of Disease Resistance And Endosperm Storage Protein In Common Wheat (Triticum Aestivum L.) And Related Species

Quality and disease resistance improvement are the most important objective of wheat breeding. Genetic similarity of common wheat varieties has lead to the 'bottle neck' reaction of wheat breeding. Wheat wild relatives and old landraces are full of diversity with genes or allele imported to wheat breeding. Seventy nine accessions of wheat gemplasm rom the National Gene Bank of China that were resistant or susceptiable to powdery mildew and stripe rust ten years ago, were selected in this research, including Triticum. boeoticum Boiss. (2n=2x=14, AA), T. monococcum L. (2n=2x=14, AA), T. dicoccoides Korn. (2n=4x=28, AABB), T. dicoccum Schrank. (2n=4x=28, AABB), T. durum Desf. (2n=4x=28, AABB), T. carthlicum Nevski. (2n=4x=28, AABB), T. araraticum Jakubz. (2n=4x=28, AAGG), T. timopheevii Zhuk. (2n=4x=28, AAGG), T. turgidum L. (2n=4x=28, AABB), T. spelt L. (2n=6x=42, AABBDD), Aegilops tauschii Cosson. (syn. Aegilops squarrosa, 2n=2x=14, DD) as well as common wheat (T. aestivium L. 2n=6x =42, AABBDD) landraces and cultivated lines. Their resistance reactions to powdery mildew and stripe rust disease, HMW-GS and Gliadin varieration were disclosed. Major results from this paper are as follows:(1) Total of 79 accessions including wheat related species, Chinese wheat landraces and cultivated lines were analyzed for their reactions to prevalent powdery mildew pathegen type and stripe rust isolates. Some accessions as T. boeoticum accessions BO5 and T.durum DR3 have resistance to both of the two diseases. Three selected accessions were inoculated with 21 powdery mildew isolates at seedling stage in greenhouse. Pm gene was postulated in T. boeoticum Boiss. accessions BO3 and T. monococcum MO4, MO5. which were resistant to 8 islotaes at least. BO3 and MO5 are resistance to E09 and E21 which were two of the most dangerous pathgen type in China. Fourteen selected accessions were inoculated with thirty-one stripe rust isolates at seedling stage in greenhouse. New Yr genes or alleles were postulated in T. boeoticum accession BO5, as well as three Chinese wheat landraces "Xiaobaimai", "Shanxibai" and "Laomangmai". Which were resistance to 25 islotates at least. Resistance test and genetic analysis of an F₂ population derived from the cross T. monococcum MO5 (resistant)×T. monococcum MO4 (susceptible) indicated a single dominant gene in MO5 contributed to the resistance to E09 and E21. Stripe rust resistance test and genetic analysis of an F₂ population derived from the cross T. boeoticum Boiss BO5 (resistant) x T. monococcum L MO4 (susceptible) indicated a single recessive gene in BO5 contributed to the resistance to CY32. The diversity of resistance in wheat related species and landraces was discussed.(2) High molecular weight glutenin subunits were investigated using one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis in 63 accessions of wheat related species, Chinese wheat landraces and cultivated lines. Six allelic variations were found at Glu-A1 locus with the most common subunits 1 and 2^*. Ten allelic variations were found at Glu-B1 locus, while 7+8 and 6+8 was the prevalent subunits composition. Fourteen alleles were found at Glu-D1 locus, and 2+12 was appeared with high frequency. A high degree of variation was evident for the HMW-GS in T. araraticum Jakubz, T. dicoccoides Korn. and Aegilops tauschii Coss., compared to T. carthlicum and T. durum and some entries of wild emmer with 14+15 and 17+18 is the important gene resources for bread wheat quality improvement. Subunits A1 detected in T. monococcum and subunits G12.1 in T. araraticum have not been previously described. Diversity of HMW-GS in different genomes and their potential in wheat improvement and genome evolution were discussed.(3) The gliadin composition of 63 accessions from wheat related species, Chinese wheat landraces and cultivated lines was analyzed by A-PAGE in order to disclose genetic diversity. Comparing PIC value to different genomes, wheat related species with AA, AABB or AAGG genome have higher PIC in a gliadin, while Chinese wheat landraces with lower PIC in a gliadin. In cultivated lines, the value increases to the level of related species. The frequence of different band indicated thatω,γandβgliadin are rich in relatively high frequency bands, while a gliadin are rich in low frequency bands. Some bands are genome or species specifitic. Cluster based on the similarity index showed that the cluster reflected the genetic distance although some relatives close related and new cultivated lines of common wheat can not be differentiated by gliadins. The distribution of different giliadin in related species of different genomes and it is potential in the improvement of common wheat was discussed.Major conclusion could be drawn as follows:(1) Accessions with both good risistance and good quality, such as commen wheat cultivated lines Xingzi 9104, T. dicoccum DM32, T. boeoticum MO5 and T. araraticum AR1 was important Materials for breeding.(2) One dominant powdery mildew resistance genes was found in T. monococcum accessions MO5, one recessive stripe rust resistance genes was disclosed in T. boeoticum BO5. HMW-GS A1 in T. boeoticum BO1 and BO3 with moving ability slower than 1, and G12.1 in T. araraticum AR3 moving faster than 10 and 12 are new alleles.(3) Wheat related species are important to diversitify the genetic background of common wheat, especially the genetic background of a gliadin. While other character important to breeding could be included by gliadin in the same time when cultivated wheat was widely crossed with wild relatives.(4) Wheat related species are rich in diversity between species and accessions, on the respect of resistance to disease and HMW-GS as well as gliadin polymorphism. Heterogeneity within one accession was found in both disease resistance and endosperm storage protein.