Studies On Cytology And Molecular Systematics In Kengyilia (Poaceae: Triticeae)

Kengyilia Yen et J. L. Yang (Poaceae: Triticeae) is described with Kengyilia gobicola Yen et J. L. Yang as its type species in 1990. Up to now, there are about 26 species and 6 varieties, mainly distributed in western and south-western regions of the former USSR, western China and neighboring regions with the altitude about 1100-5100 m. There are about 24 species in China, which are important components of grasslands and desert. They have characters of resistance to disease, drought, cold, and so on. Meanwhile, they are good grazing and important germplasm resources of plant breeding and improved breeds in Triticeae crops.Morphologically, Kengyilia is a genus intermediate between Roegneria and Agropyron, differing from Roegneria by having an erect with dense spikelets, lemma densely pilose or hirsute, short-awned, and differing from Agropyron by the flat glume and lemma with rounded back, not keeled from tip to bottom, a terminal spikelet more offen presented. Kengyilia is hexaploid species (2n=6x=42) and contained StYP genomes. StY genomes of Kengyilia comes from Roegneria, and that P comes from Agropyron. Now the phylogenetic status of Kengyilia has been affirmed by most of the grass taxonomists. The definition of the genus, its phylogenetic relationship, precise taxonomic rank and taxa differentiation are still under discussion. The aims of the present paper are to study systematicallykaryotypes of Kengyilia species, to evaluate the relationship among species based on molecular systematics. It will be helpful for better understanding biosystematic relationships of Kengyilia and for further ultilizing and conserving the germplasm resources of Kengyilia. The main results are showed as follows:1. The karyotypes of 14 species in Kengyilia were analyzed. Seven species of them were reported for the first time. The karyotype formulae were as follows: K. gobicola, 2n=6x=42=36m+6sm; K. mutica, 2n=6x=42=36m+6sm; K. hirsuta, 2n=6x=42 =34m+8sm; K. kokonorica, 2n=6x=42=34m+8sm; K. batalinii, 2n=6x=42=32m(2SAT) +10sm; K. rigidula, 2n=6x=42=36m+6sm; K. alatavica, 2n=6x=42=36m+6sm; K longi-glumis, 2n=6x=42=36m+6sm; K. grandiglumis, 2n=6x=42=36m-i-6sm; K, stenachyra, 2n=6x=42=36m-K>sm; K. kaschgarica, 2n=6x=42=32m+10sm; K. thoroldiana, 2n=6x= 42=36m+6sm; K. melanthera, 2n=6x=42=36m+6sm; K. nana, 2n=6x=42=34m+8sm. All the karyotypes belong to IB or 2B. No satellite chromosomes have been found except K. batalinii. Furthermore, according to Stebbins' theory of the karyotypic evolution as well as using the method of coding of cladistics, 4 significant characters and the evolutional levels of the 14 species were analyzed. The results indicated that K. rigidula was a relatively primitive species and K. thoroldiana was more advanced species among the 14 species analyzed in this study.2. The genetic variation of 32 accessions of Kengyilia, distributed to 14 species and 1 variety was analyzed by using RAPD markers. The results showed distinct genetic differences and abundant RAPD variation were present among the accessions. A total of 341 bands were produced by 46 arbitrary primers (10-mer), among which 327 out of 341 bands (95.9%) were polymorphic. 1~13 polymorphic bands could be amplified from each primer, with an average of 7.1 bands. The genetic similarity coefficients ranged from 0.164 to 0.829, with the mean of 0.332. The results of cluster analysis by using UPGMA method showed that 32 accessions could be distinguished by RAPD markers. The different accessions in a species were clustered together, respectively, which had larger genetic similarities and closer relations;Distinct genetic differences were present among the species; The RAPD variation among the species were more abundant than that of the different accessions in a species; The species with similar morphological characters and from the same areas or neighboring geographical regions were clustered together, which suggested that had some relationships; RAPD assay is a useful additional method in the systematic study in Kengyilia.3. Relationships...