Evaluation Of Germplasm In Brassica Oleracea And The Wild Species

As one of the three basic crop species in Brassica,Brassica oleracea(CC,2n=18)contained a number of cultivars and wild species.The germplasm in B.oleracea was evaluated in the present research based on the genetic diversity and the resistance to Sclerotinia sclerotiorum.Meanwhile,the utilization of germplasm in B.oleracea was studied through the interspecific hybridization between B.oleracea and B.napus.1.Genetic diversity in B.oleraceaAFLP and SSR were used to evaluate the genetic diversity in 58 accessions of Brassica,including 30 wide and 14 cultivars in B.oleracea,6 B.napus,4 B.rapa,2 B.nigra and 2 Raphanus sativus. The results and conclusions are as follows:(1)Rich genetic diversity can be found in B.oleracea revealed by the AFLP and SSR markers.The average genetic distance(Nei72)within B.oleracea wild species(0.40)is larger than that within cultivars(0.24).(2)Four groups can be classified among accessions of wild.B.oleracea:B.incana,B.bourgeaui, B.oleracea ssp.oleracea,B.macrocarpa and B.insularis are in the first group while the second group is composed or B.montana,B.rupestris and B.villosa,B.hilarionis and B.cretica composed respectively the third and fourth group.Among the wild species,B.oleracea L.,B.incana,B. bourgeaui and B.oleracea ssp.oleracea in the first group,seem to be more closely related to the cultivars.(3)The species B.oleracea has a closer relationship with B.napus.As to genetic distance,the value between B.oleracea and B.napus(0.50)was the smallest one,then B.rapa(0.91),B.nigra next(0.93)and R.sativus the last(1.08).(4)The C genome in B.napus is closely related with.B.oleracea L.,B.oleracea var.acephala,B. bourgeaui,B.oleracea var.gongylodes and B.incana by comparison of 6 natural B.napus with putative B.napus derived from B.oleracea and B.rapa for genetic diversity.2.Evaluation of the resistance to S.sclerotiorum in B.oleraceaIt aims to evaluate resistance to S.sclerotiorum in Brassica by observing lesion phenotype of the detached-leaf after inoculation at room temperature.Results and conclusions are as follows: (1)B.oleracea,especially the wild species has a highest resistance to S.sclerotiorum,following B. napus and B.carinata,while B.rapa exhibit highest susceptibility.(2)Ideal sources with high resistance to S.sclerotiorum maybe exist in the wild species of B. oleracea.In contrast with Zhongyou 821 recognized as a tolerant sample to S.sclerotiorum,8 accessions of wild species and 2 of cultivars in B.oleracea shown a higher resistance to S. sclerotiorum at the 0.05 level,and 4 of the 8 wild accessions shown the marked higher resistance at the p=0.01 level.The similar result can be found in comparison with the other sample with a rather tolerance to S.sclerotiorum,Ningyou 7.3.Interspecific hybridization between B.oleracea and B.napus74 F₁ plants were produced in the interspecific hybridization between B.oleracea and B.napus through ovary culture,and 3 real interspecific hybrids and 1 peculiar plant with various chromosome numbers in somatic cells were gained after morphological,pollen fertility,cytological and molecular marker identifications.The result indicates that the B.oleracea is a utilize-worthy species for it's possible to produce interspecific hybrids and valuable materials by the assistance of embryo rescue, although reproductive isolation does exist in different species.