Studies On Inter-specific Hybridization Between Brassica Juncea L. And B.oleracea Var.alboglabra Bailey

Distant hybridization can break the boundary between two species on a certain extent and promote the exchange of genetic materials. Different generas and species'genome can be combined together by distant hybridization, therefore you can create a new crop type or new specie; alien chromosome or chromosome fragments imported, can create different addition lines, alien substitution lines and translocation lines; solitary female productivity induced or one of the parent chromosomes eliminated and so the haploid plants obtained, carry on haploid breeding; provide a theoretical basis for species evolution and the genetic relationship between species together with cytology and molecular biology studies. In addition, wide hybridization is an important factor in biological evolution, but also an important way for the formation of species. Brassica juncea L. has resistance to barren and drought, anti-black shank, crack pod, yellow seed, high oil content, thin seed coat, low-fiber and other fine features. B.oleracea var.alboglabra Bailey (Chinese kale) is native to southern China's annual cruciferous Brassica oleracea vegetable crops, and strong resistance to virus diseases. This article studied on interspecific hybridization between Brassica juncea and B. oleracea var.alboglabra Bailey and obtained the interspecific hybrids, besides we carried on microspore culture of one interspecific hybrid and obtained microspore culture offspring.The main results as follows:1.16 Brassica juncea and 4 B. oleracea var.alboglabra Bailey selected as parental materials for the reciprocal crosses (B.juncea×B. oleracea as orthogonal, B. oleracea×B.juncea as anti-cross)with 24 crosses, pollinated 7577 buds in total(6877orthogonal buds in it); transplanted 147 hybrid offspring clones in the field, from which 31 true hybrids identified, the percent of true hybrids was 21.09%.2. After pollination 35d,the percent of the remained ovaries varied between 4.17% and 80.47%,an average of 59.50%,of which significantly different in the crosses. We stripped the embryos from the remained ovaries and rescued them in laboratory. The average efficiency was 12.51 embryos/100buds; orthogonal combinations were much better than anti-cross combinations. In the 24 crosses, only 09D215×09D230 obtained none embryo, the efficiency of the others varied between 0.66 embryo/100buds and 32.54 embryos/100buds.We got 948 immature embryos in total and inoculated on four culture mediums. However, the result showed that 1/2MS suited for B.juncea×B.oleracea embryo rescue.3. We selected four cross groups in the 24 and carried out four treatments on each group(pollination once, pollination once+10% NaCl applied the stigmas, pollination twice, pollination twice+10% NaCl applied the stigmas, respectively), the results indicated that neither of repollination and 10% NaCl solution applied stigma can improve the efficiency of interspecific hybridization. After 10d of pollination, we surveyed the remained ovaries of four groups four times every four days, the results showed that the percent level of 10 after pollination can reflect the remained ovaries'level.4. We surveyed the morphological of the interspecific hybrids and found many morphological traits between their parents, such as:leaves dark green, leaf tip oval, split less, nick shallow, little or no leaf surface bristles, smooth leaf, vigorous growth (tend to B.napus L.) in the seedlings; the true hybrids can be divided into two categories from the appearance in the flowering:the completely sterile or highly infertile type and a little pollen fertility type. The pollen fertility of 12 interspecific hybrids tested, the results showed the pollen fertility low and ranged from 0 to 47.87%, lower than the parent materials. Self-rate was only 0.31%, indicated poor seed set, however, the hybrids showed strong vegetative heterocyst.5. We found B.juncea×B.oleracea F1 hybrids has 27 chromosomes or between 27 and 36.The meiosis behavior of the hybrids was unmoral, there were more behind chromosomes and (or) chromosome bridge(s).6. B.juncea×B.oleracea F1 hybrids as mother crossed 4104 buds with B.napus and carried on three treatments (ovary culture, immature embryo culture and natural growth to harvest in the field).The results showed the immature embryo culture best.The average efficiency of ovary culture (seeds/pollinated buds* 100%) reached 5.32%and best in MS medium (7.22%).In the embryo culture, the percent of remained pods ranged from 13.85% to 100.00%. an average of 60.72%; the percent of stripped embryos ranged from 4.41% to 62.75%, an average of 22.57%.The stripped embryos cultured in four mediums, we found that the percent of germination averaged 4.97%, ranged from 0 to 25.00% and significantly different in combinations, best in 1/2MS medium (7.53%) and worst in M medium (1.12%).The percent of remained pods, setting rate and germination averaged 39.42%,5.14% and 2.25% respectively.The leaf traits of (B.juncea×B.oleracea)×B.napus F1 hybrids had many differences and tended to B.napus. The pollen fertility rate of (B.juncea×B.oleracea)×B.napus F1 hybrids ranged between 17.69% and 73.15% was better than B.juncea×B.oleracea F1 hybrids'. 7. B.juncea×B.oleracea F1 hybrids as mother crossed with B.juncea and B.oleracea respectively. The results indicated (B.juncea×B.oleracea)×B.oleracea has poor compatibility, only got three dead seeds from 1042 pollinated buds and none germinated, the average percent of remained pods was 18.14%; (B.juncea×B.oleracea)×B.juncea has much better compatibility, crossed 732 pollinated buds, the average percent of remained pods was 26.64%, the average percent of seed rate was 5.05%, however, the seed germination rate was very low.8. We selected B.juncea×B.oleraceahybrids 10D903 and carried on microspore culture.245 coryledon-type embryos were gained but only 92 individuals can survive in the field. We found that the microspore culture offsprings were obviously different and the range of variation widely. They can be divided into two categories. The first kind have the following traits:dark green leaves, strong growth and tend to B.napus; the second kind have the following traits:shallower leaf, thinner growth. The pollen fertility of 10D903 microspore culture progenies were mainly distributed between 60.00% and 70.00% and many achieved or exceeded the pollen fertility of 10D903.We found the chromosomes'number of 10D903 microspore culture progenies were not only much different in different clones, but also may be different in different cells in the same clone.This article studied the interspecific hybridization between B.juncea and B.oleracea var.alboglabra Bailey and their hybrids. We obtained B.juncea×B.oleracea var.alboglabra Bailey F1 and microspore culture offsprings of 10D903.These new materials can be used for the genetic improvement of B.napus and further relationships study of Brassica genomes.