Biosystematic Studies On Roegneria Amurensis, R. Ciliaris And R. Japonensis (Poaceae: Triticeae)

Roegneria C. Koch was described by Koch in 1848 with Roegneria caucasica C. Koch, as type, Roegneria is the largest genus in the tribe Triticeae (Poaceae), including about 130 species in the world, widely distributed in the northwest, southwest and north of China. Some species of the genus are good pasturage, while some ones have characters of resistance to disease, drought, cold, and so on. It's the important resources for wheat and pasture breeding. However, morplological variations of Roegneria are complex. Taxonomists have different ideas about the definition of the genus, the ranking of species within the genus and its origin. Roegneria amurensis (Drob.) Nevski, Roegneria ciliaris (Trin.) Nevski and Roegneria japonensis (Honda) Keng are three species of the Ser. Ciliare in Rogneria. Dispute appears on the definitions of these three species. The main controversy is that R. japonensis and R. amurensis are the subspecies of R, ciliaris, or the variety of R. ciliaris, or valid species. The aims of the present paper are: (a) to investigate the genomic constitutions of R, amurensis; (b) to evaluate the relationships of the three species according to morphological comparison, karyotypes, meiotic study, fertility, gliadin and esterase isozymes analysis. The main results are:1. The karyotype formulae of the three species is 2n=4x=28, belonging to 2A type. The karyotype of R. amurensis is first reported, and the formula is 2n=4x=28= 24m(2SAT)+4sm. Karyotype formulae of the three species differs in arm ratio in mean, karyotype formulae and the proportion of chromosome with arm ratio > 1.70. Accessions in R. ciliaris and R. japonensis have different karyotype. The results indicate that there exists genetic diversity among the three species and within R. ciliaris and R. japonensis.1. Chromosome pairing behavior in meiosis of two hybrids, R. amurensis R. ciliaris and R. japonensis x/?. amurensis, was characterized by a high number of bivalents. The mean meiotic configuration of R. amurensis with R. ciliaris is 1.90I+12.35II+0.30III+0.10IV, while R. japonensis with R. amurensis is 12.67I+12.67II. The morphological characters of hybrids are intermediate compared with two parents. The results show that R. amurensis is closely related to R. ciliaris and R. japonensis, its genome constitution is StY.3. The three species are similar to each other in morphology. R. amurensis differs from R. ciliaris and R. japonenesis in cilia of leaves, glume and lemma. The same difference also lies in R. ciliaris and R. japonenesis. In geographical distribution, R. ciliaris and R. japonenesis widely distribute in China, while R. amurensis distributes only in the north-eastern area and nearby region of China.4. The pollen fertility and seed set of R. amurensis, R. ciliaris and R. japonensis are normal. Hybridizations among them are quite easy to carry out without the aids of embryo-rescue. In the two interspecific hybridizations, the seed sets are 22.00% and 20.00%, the pollen fertility are 74.08% and 81.34%, respectively. The results show that a little reproductive obstacle exists in R. amurensis and R. ciliaris, or in R. amurensis and R.japoensis.5. The gliadin patterns of three species and their accessions were analyzed by using acid polyacrylamide gel electrophoresis (A-PAGE). 22 gliadin bands with different relative mobility are found by electrophoresis. 19 of 22 bands are polymorphisms. Each accession has 9 to 16 bands. The results show: (i) three species have similar gliadin patterns, but diversity lies in the three species obviously; (ii) gliadin polymorphisms present in accessions of same species; (iii) the difference of gliadin maps among the three species is more obvious than that of accessions of the same species.6. The esterase (EST) isozymes of 22 accessions of three species were analyzed by polyacrylamid gel electrophoresis. There are 13 bands with different Rf. The results show: (i) the zymogram type of esterase isozyme was similar in the three species but not the same zymograms; (ii) the zymograms are different fro...