Cytogenetic And Morphological Studies On Seven Populations Of Roegneria Kamoji Ohwi(Poaceae:Triticeae)

The tribe of Triticeae,an economically important group of plants for genetic improvement of wheat crops,forage breeding and the development of turf-grass,has a large number of high quality and stress resistance genes.Roegneria kamoji Ohwi(2n=6x=42,StStYYHH)is a perennial species in Roegneria of Triticeae with large fleshy leaves,and is a member of the tertiary gene pool of common wheat.R.kamoji is widely distributed in China except Tibet.It is also distributed in Japan,Korea and North America of Prince Edward Island.According to the Flora of China,R.kamoji Ohwi var.kamoji and R.kamoji Ohwi var.macerrima Keng were two varieties of R.kamoji.R.kamoji was classified as a species of Campeiostachys by Yen C and Yang J L(2011)for it containing the St,Y and H genomes.Three varieties of C.kamoji were found:C.kamoji Ohwi var.kamoji,C.kamoji Ohwi var.pilosiphylla,C.kamoji Ohvi var.macerrima Keng.Thus,it shows that R.kamoji exist genetic variations and different variation types.In order to explore the differentiation and evolution of different populations of R.kamoji,we used morphology comparison,thremmatology and genome analysis studies for exploring the genetic variations of seven populations of R.kamoji from Sichuan,Qinghai,Xinjiang,Zhejiang and Shandong.The main results were as follows:1.Seven F1 hybrids were successfully obtained in this study,and all of them could be heading.The variation of hybrid seed setting rate of F1 hybrids ranged from 7.1%to 40%.The seed set of reciprocal cross combinations between R.kamoji from Ya'an and Shandong was relatively lower with 10%and 13.2%,while that was higher between R.kamoji from Yibin and Zhejiang with 40%and 30.3%,respectively.2.The morphological characteristics of parents and F1 hybrids were observed and analyzed.The results showed that the height,length of spike,length of flag leaf,length of lemma of the populations of Zhejiang,Xinjiang,Shandong was smaller than those of Sichuan,Qinghai.The phenotypic traits of the seven F1 hybrids were better than their parents.The height,length of spike,length of flag leaf of the F1 hybrid between R.kamoji from Zhejiang and Yibin was higher than their parents.However,in some hybrids,the floret number and width of glume of hybrids was inferior to their parents.3.Meiotic chromosome pairing in PMCs of the parents and F1 hybrids were analyzed.The results showed that meiotic pairing in the parents were normal with 21 bivalents.Different chromosome pairing was observed in the seven F1 hybrids.Meiotic pairing in seven hybrids averaged 19.77 to 20.91 bivalents per cell,0.18 to 2.46 univalents per cell,and a low frequency of trivalents and tetravalents.2.14 and 2.46 univalents were observed in reciprocal cross between R.kamoji from Zhejiang and Yibin.A low frequency of trivalents(averaged 0.22 per cell)was observed in the F1 hybrid between R.kamoji from Ya'an and Xinjiang with the chiasmata per cell of 39.5 and C-value of 0.94.Lagging chromosomes and chromosome bridges were observed in meiotic metaphase I in all F1 hybrids.The meiotic pairing results showed that genome differentiations occurred in seven populations of R.kamoji.4.Thremmatology analysis was carried out for the parents and F1 hybrids.The fertility and natural seed set ranged from 89.93%to 95.71%,79.21%to 84.98%,respectively.The fertility and natural seed set of the F1 hybrids ranged from 78.9%to 89.67%,43.05%to 77.98%,respectively.The lowest seed set(43.05%)was found in the F1 hybrid between R.kamoji from Zhejiang and Yibin,Sichuan.The results showed that the genetic differentiations were existed in seven populations of R.kamoji from Sichuan,Qinghai,Xinjiang,Zhejiang and Shandong.Among them,the genetic differentiations between R.kamoji from Yibin and Zhejiang,Ya'an and Shandong were larger than others.5.Based on results from analyses of morphology,meiotic pairing and thremmatology,it is concluded that genetic differentiations existed in seven populations of R.kamoji.The differentiations between R.kamoji from Yibin and Zhejiang were highest.The natural seed set of this F1 hybrid is lower than 50%,which reached the level of subspecies.