Cytogenetic Analyses on Sinapis Alba Linnaeus×Brassica Oleracea Var Alboglabra and the Backcross Progenies by Brassica Oleracea Var Alboglabra

11 July 2009 0 views No Comment

Abstract:

Brassica is a genus including many species and used widely.For the use of it,it is mainly used as vegetables,spices,medicine and fodder.Although there are many species and varieties,with a pool of genotype and genetic variation,the long-term artificial selection and hybridization between species,resulting in genetic diversity decreased significantly,and increased the resources for breeding less and less.So in order to increase the exchange of gene between different genuses,many ways were taken by people such as the sexual hybridization,transformation,and protoblast fusion.Taking into account the safety of transgenic plants can not be accurately assessed,sexual hybridization and protoplast fusion are the main ways to increase the variation.In this study we made Sinapls alba L x B.oleracea var.alboglabra,and hybrids were obtained. At the same time,we used B.oleracea var.alboglabra to do backcross with the F_1,and a backcross groups were constructed.Besides,we also analysised the behavior of the chromosomes of the Sinapis alba x B.oleracea var.alboglabra F_1 and the BC_3 F_1 plants by the methods of cytogenetics and GISH..The results are as follows:1.S.alba×B.oleracea var.alboglabra were obtained by the way of culturing the 410 ovary,a total of 17 young embryos were obtained.After the stage of MS medium germination,13 seedlings were alive.The hybrids were tested by cytogenetics and GISH. As for the morphology,the hybrids hold a vigorous vegetative growth,with the morphological characteristics of the parents.The shape and color of the leaf like sinapis alba L,but fewer crack;and flower color is white.Of the hybrids,12 were non-overlapping petals,one overlap;the pod of 12 plants like S.alba but without microfillas,one like B.oleracea var.alboglabra but shorter.All the plants had many branch,and the flowering time span a long time,with some wax cover onto the leaves and the stem.2.Cytology observation of the F_1.The F_1 were grouped into two groups,the first one including 21 chromosomes,the other 30.GISH-dcFISH confirmed the result.F_1 plants were divided into two categories according to the sterile,as for the first group,it is fertile, the GISH-dcFISH showed the chromosome 21,of which 9 are from B.oleracea var,12 from S.alba.The other is 30,18 from B.oleracea var.alboglabra,12 from S.alba. Under the inducing of the colchicine,the chromosome number was doubled to 42.By the observation of meiosis of pollen mother cells(PMC) of plants,mainly had 21Ⅱ,20Ⅱ 2Ⅰat diakinesis and showed the 18:24,20:22,21:21 segregation with 18:24 being the most frequent.In some AⅠPMCs,lagging chromosomes appeared.At last,we also observed 12Ⅱand 9Ⅱgathered alone,non-simultaneous separation of chromosomes,chromosome bridges.3.B.oleracea var.alboglabra was used as male parent to backcross with the hybrids, and 647 individual were obtained.We divided the individuals into the following types according to the phenotype:1:plants with high height;2:plants with great nutrition organ;3:petal-less type;4:pod born micro- thorns;5:grow slowly;6:stigma developed mututaly.Most of the chromosomes of the plants are 19 or 18,and it appeared many lagging chromosomes in MI.but fertility is fine,with the number about 80%.Such a group can be a powerful tool to locus the gene linked the phenotype.4.Although the doubled F_1 demonstrated a good fertility,the ovary will die after pollination a few days later,and it is hard for us to harvest the seed of the hybrids,which showed the reproductive isolation between the B.oleracea var.alboglabra and Sinapils.alba,and the cytogenetic observation confirmed that.During the meiosis,it is difficult for the genes of the B.oleracea var.alboglabra and Sinapils.alba to exchange for the chromosomes from the same parent will divide into the same pole.