The Genetic Analysis Of Heterosis Of Medicago Varia L.

In this paper,the experimental materials were 24 alfalfa plants as parents and their 10 F1 hybrids, we analysed the genetic diversity of the parents﹑the genetic relationship and heterosis between parents and F1 hybrids using agronomical﹑morphological and molecular markers including RAPD,SSR,EST-SSR methods. Then the accuracy of forecasting heterosis by genetic distance based on molecular markers. The main results showed as follow:1. The clustering analysis on morphological indicated that 25 alfalfa plants could be divided into three groups.Most of high fall dormancy alfalfa plants (Medicago sativa L.)﹑low fall dormancy alfalfa plants (Medicago falcata L.and Medicago sativa L.)belonged to different groups respectively;But Falcata(Xinjiang)(Medicago falcata L.) and Longmu801(Medicago sativa L.),Falcata-2(Ximeng)(Medicago falcata L.) and Zhaodong(Medicago sativa L.) which came from different regions and had the similar characteristics,also belonged to the same groups. It suggested that the genetic basis was complex,so it was not accurately to distinguish alfalfa.2. The clustering analysis on SSR and RAPD indicated that 25 alfalfa plants could be divided into six groups and four groups respectively,compared with the morphological method,the molecular markers method was more accurately. Low fall dormancy alfalfa plants(Medicago sativa L.) were clustered into one group;Most of high fall dormancy alfalfa plants (Medicago sativa L.) and alfalfa plants (Medicago falcata L.) belonged to different groups respectively;But a small part of alfalfa plants (Medicago falcata L.and Medicago sativa L.) also belonged to the same groups.3. The biomass of alfalfa plants had a highly significant correlation with branches number﹑leaf length﹑perimeter and had a significant correlation with leaf area.In the study,we found that it had no significant correlation in the morphological traits and the RAPD﹑SSR molecular markers.4. F1 hybrids showed high heterosis in biomass﹑branch number﹑node number﹑leaf area﹑leaf width﹑leaf length﹑shape of leaf factor﹑stem length and perimeter.Among them, the hybrids 10-5﹑6-3﹑14-7 and 10-2 also showed strong superstandard heterosis and transgressive heterosis.But the hybrids 8-2 and 6-9 were opposite.5. Eight random primers﹑five SSR primer pairs and three EST-SSR primer pairs were shown to accurately distinguish the 10 F1 hybrids which showed high﹑intermediate and low heterosis in agronomical﹑morphological triats.Among the RAPD molecular markers,Primer S1 may be related to node number﹑leaf area﹑leaf width and shape of leaf factor.Primer S70 may be related to biomass and branch number.Primer S146 may be related to biomass﹑branch number﹑stem length and leaf area.Primer S152 and primer S311 may be related to biomass﹑branch number and stem length. Among the SSR and EST-SSR molecular markers, Primer Mtic12 may be related to branch number﹑stem length﹑leaf length and perimeter.Primer Mtic338 and primer afctt1 may be related to biomass﹑branch number and stem length.Primer BF106 may be related to branch number.Primer be323955 may be related to branch number and stem length.Primer al372288 may be related to biomass﹑branch number﹑stem length﹑leaf length and perimeter.Primer bf518447 may be related to branch number and stem length.6. Three SSR primer pairs and two EST-SSR primer pairs showed that the hybrids 10-2 and 10-5 which showed strong superstandard heterosis and transgressive heterosis, generated new bands different from both parents.7. Analysis on correlation between the transgressive heterosis of biomass and morphological triats for 10 F1 hybrids and genetic distance with RAPD and SSR molecular markers.It is indicated that heteroses exist extensively, but there was a low correlation between them.Therefore molecular markers still can not be used to predict heterosis in this experiment.