Molecular Phylogenetic Study On Kengyilia C. Yen Et J.l. Yang And Molecular Cytogenetic Analysis Of New Breeding Resources Derived From Elytrigia Desv. (triticeae: Poaceae)

Triticeae Dumortier is a very important group in the Poaceae which includes three of the most important cereal crops, for example, wheat, barley, and rye, many economically valuable forage grasses as well as a number of significantly ecological importance specices. A clear phylogentic patterns would prompt the ulitization of speices as genetic resources for improving quality and genetic diversity. Because of the affinity between wheat and its relatives, the Triticeae tribe offers a vast gene pool from which traits of agronomic interest can be extracted to enrich the genetic diversity of wheat for disease resistance and quality improvement by genetic manipulation. In fact, a number of relatives to wheat have been to identify to have superior resistance gene and utilized in wheat breeding programme.Kengyilia Yen et J. L. Yang is a recently erected genus grown in high altitude areas. Some species lives in rigorous locality, which can contribute to the improvement of resistance to cold and drought in cereal crops. Elytrigia Desv. is a wild perennial genus in Triticeae tribe. It possesses numerous beneficial traits for wheat improvement including immune or high resistance to tripe rust, leaf rust, stem rust, powder mildew, aphid, salt tolerance and so on. Therefore, Kengyilia and Elytrigia together with other perennial relative species form a huge gene pool for improvement in cereal crops. In this study, the phylogeny of Kengyilia species was evaluated and the molecular cytogenetic characterization of new germplasm materials between wheat and Elytrigia were analyzed on the basis of GISH as well as disease resistance evaluation. The main results are as follows:(1) Giemsa C-banding analysis was implementd to characterize chromosomes of the Kengyilia species. Results indicated that the eight species of Kengyilia differed in C-banding patterns. K. gobicola, K. alatavica and K. batalinii had distinct centromeric bands and no banded chromosomes, while K. hirsuta, K. longiglumis, K. melanthera, K. rigidula and K. thoroldiana had more abundant and diagnostic C-bands with interstitial and terminal bands. The chromosome structural polymorphisims suggested the differentiation regarding the origin and evolution in Kengyilia.(2) Phylogenetic analysis was conducted based on nrDNA ITS and dimeric alpha amylase inhibitor sequences in species of Kengyilia together with those of relatives by the maximum parsimony and neighbor-joining distance methods. The results indicated that species of Kengyilia had close affinities to species of Douglasdeweya, Pseudoroegneria, Roegneria and Agropyron. The species in Kengyilia was identified as two subgroups corresponding to geographic distribution, suggesting that species from the same distribution had a closer phylogenetic relationship. It is possible that the Kenyilia species from Central Asia and adjacent regions and Qinghai-Tibetan Plateau have independent alloploid origin with different P genomic donor. The clear differentiation between the Y and St was detected, which provided additional evidence for the independent origin of the Y genome in alloplooid Roegneria and Kengyilia species.(3) The levels of nucleotide diversity for atpB-rbcL and CoxII intron were obtained. The results revealed relatively high nucleotide diversity. Employing atpB-rbcL and CoxII intron sequences, the phylogenetic relationships within Kengyilia and between Kengyilia and its closely related genera were examined. The maximum parsimony analysis demonstrated that Kengyilia species were positioned into two clades corresponding to different maternal genomic donor. These results indicated that there had been two phylogenetically divergent maternal donors within Kengyilia.(4) Seven accessions of putative natural hybrids between Kengyilia and Roegneria or Elymus from Sichuan and Gansu provinces of China were analyzed using sequences of ITS, atpB-rbcL, trnH-psbA combined with meiosis observation. In summary, NHZY6 was revealed to have St, Y and P genomes, and originated from hybridization between K. melanthera and the species of Roegneria. It is concluded that K. rigidula and E. nutans as parental donors contributed to NHZY7, NHZY8 and NHZY9, and K. melanthera and E. nutans as parental donors contributed to NHZY2, NHZY3 and NHZY5. Chloroplast DNA sequences data demonstrated that K. rigidula and K. melanthera acting as maternal donors were likely to be involved in the formation of the natural hybrids. Also, K. stenachyra was confirmed to be a natural hybrid derived from hybridization between K. rigidula and E. nutans.(5) As a potential source of resistance to Fusarium head blight (FHB), Elytrigia repens has been crossed with common wheat. A total of eight BC1F9 progeny lines were characterized in this study. The chromosome number of these derived lines ranged from 42 to 56, including the lines with 44,52,53, and 54 chromosomes. All of lines were cytologically stable in terms of meiotic configuration. The univalent frequency in these lines varied between 0.34 and 2.36. Similarly, the multivalent frequency did not exceed 1% in any of the lines. GISH analyses revealed that the number of intact wheat chromosomes in the various lines varied between 40 and 44. In all lines, numerous translocated chromosomes were detected, which were involved with chromosomal segments from wheat and El. repens. Trigenomic translocated chromosomes were examined by further investigation. Moreover, the fragments introgressed into wheat chromosomes included both terminal and interstitial type. The FHB resistance of the eight lines, following point inoculation varied from 5.65%infected florets to 11.46%compared to the check cultivars 'Roblin'and'Crocus'at 100%and 85%, respectively.(6) The non-coding intergenic region of trnH-psbA was performed to assess the genetic diversity and infer the maternal origin within Elytrigia intermedia accessions. Eleven haplotypes were distinguished among the thirty-five accessions of El. intermedia. It showed a relatively low nucleotide diversity (π) of 0.00473±0.00037 and a moderately high haplotype diversity (Ha) of 0.733±0.061 within El. intermedia. In the phylogenetic analysis all accessions of El. intermedia were positioned into two clades which were corresponded to the different diploid donors, suggesting that there were two phylogenetically divergent maternal donors in El. intermedia.(7) Two partial amphyploids,08-47-50 and 08-53-55, were developed from wide crosses between durum wheat and El. intermedia. Meiotic analysis indicated that the two lines were cytologically stable, containing 42 chromosomes. Genomic in situ hybridization revealed that the two partial amphiploids carried different chromosomal compositions. Line 08-47-50 had a chromosome complement of 28DW+6St+4Ee+4Ee-St, while the line 08-53-55 had a chromosome complement of 28DW+4St+10Ee-St. The evaluations of Fusarium head blight (FHB), leaf rust and stem rust indicated that the both lines had a high level of resistance.