Cytological And DNA Molecular Markers Studies Among Hystrix Duthiei Var.longearistata, H.duthiei And H.patula (Poaceae: Triticeae)

Hystrix Moench is a small perennial genus of the tribe Triticeae (Dumortier). Originally the only known species was described as Elymus Hystrix by Linneus (1753),on account of the strongly reduced or lacking glumes,it was later segregated in its own genus as Hystrix patula (Moench 1794). Since then 8 deferent species have been included in Hystrix,three of them grow in China. Dewey (1984) reported H. patula has StH genomes and according to genomeanalysis method,included it in Elymus. But he only studied the type specie of Hystrix------H.patula. Jensen et al. (1997) reported Elymus coreanus (H. coreand) and E. californicus (H. californicd) have the same genome constitution of Leymus (NsXm),and included them in Leymus. Thus,the taxonomy of Hystrix becomes more complicated. Until now,the definition of Hystrix and its precise taxonomic rank are still under discussion. The main controversial is included the species of Hystrix either in Hystrix,or regard it as a part of Elymus or Leymus. The objective of the present paper was to investigate the genome constitution of three species of Hystrix and their taxonomic status from cytological and molecular data. By RAPD and ISSR assay,the present study was to evaluate phylogenetic relationships among Hystrix,Leymus and Psathyrostachys,and to compare the use of two molecular markers in the genus and species of Triticeae. The main results are as follows:1. The seed set of Psathyrostachys huashanica Keng (2n=2x=14,Nsh) crossed with three species of Hystrix averaged 15.66% and ranged 4.59%-34.62%. That ofRoegneria ciliaris var. japonensis (Honda) B. R. Lu,Yen et J. L. Yang (2n=4x=28,StY) crossed with H. patula was 5.00%. All of the crosses produced hybrid seeds that developed into adult plants even if without embryo rescue culture. The hybrids were completely sterile while the pollen fertilities of parental species were normal. This suggested there are reproductive between all of five parents and they were dependent biological species.2. The mean meiotic configuration of H. duthiei ssp. longearistata with P. huashanica was 9.46 I + 5.6511+ 0.07III,the chiasma frequency was 7.08 and the C-value was 0.51. There were obvious morphological differences between two parental species and the F,plants appeared intermediate between the two parents. Therefore,we could conclude that H. duthiei ssp. longearistata and P. huashanica share one Ns genome.3. The mean meiotic configuration of H. duthiei with P. huashanica was 7.44 I + 6.55 II + 0.12III+ 0.02IV,the chiasma frequency was 9.76 and the C-value was 0.70,which indicated that H. duthiei had one Ns genome.4. The mean meiotic configuration of H. patula with P. huashanica and R. ciliaris var. japonensis were as follows:H. patula X R huashanica 20.43 I + 0.29 II,with C-value of 0.02;R. ciliaris var. japonensis X H. patula 4.48 I + 11.0211+ 0.27III + 0.23IV,with C-value of 0.64. These suggested that H. patula has St genome and no Ns genome exists.5. To assess the phylogenetic relationships among Hystrix,Leymus and Psathyrostachys,two DNA molecular markers RAPD and ISSR were used. The results indicated that the level of genetic variation of three different genera is higher than species within the genus. 4 species of Hystrix showed great genetic diversity:(1) H. duthiei var. longearistata closely related to H. duthiei and were clustered together,which corroborated the results from morphological and cytological studies by Zhou Yong-Hong (1999). (2) H. coreana was clustered with Leymus cinereus,which indicated they had closer relationships. (3) There were distinct genetic differences between H. patula and the other materials used in this study. H. patula was separated as a single group in the UPGMA dendrograms. It may suggest that H. patula had different genomes from Leymus,Psathyrostachys and the other three species of Hystrix in this study.6. Comparison between the results from RAPD and those from ISSR,it is concluded that:(1) 40 random primers were screened for RAPD fragments,20 primers produced polymorphic RAPD...