Genetic Analyses Of Progenies From Somatic Hybrids Of Brassica Rapa And B. Napus With Isatis Indigotica

Alien addition lines is an important genetic materials to study the species evolution, gene interaction and gene expression, and the genome relationship. The biennial Isatis indigotica Fort.(2n=14, II) belongs to the tribe Isatideae in Cruciferae family and is widely cultivated as medicinal and dye plants in China, which should serve as the valuable germplasm for Brassica breeding. In this study, two types of materials were used, the first from Brassica napus cv. Zhongyou 821 pollinated by the bridge hybrid(2n=43, AACII)(as the male) derived from the cross between the somatic hybrids of Brassica rapa(2n=20, AA) and I. indigotica(2n=48, AAIIII) and B. napus cv. Qingyou 14, the second from B. napus cv. Huashuang 3 pollinated by the backcrossing progeny(2n=45, AACCI) of its somatic hybrids with I. indigotica(2n=62, AACCII). Their morphological, molecular markers and cytological analyses were made and the set of addition lines were identified. The main results are as follows:1. Cytology of B. napus- I. indigotica additional lines with the cytoplasm of Zhongyou 821. By morphology, woad-specific SSR markers and GISH, seven addition lines carrying one of seven different woad chromosomes from Isatis indigotica(coded for a-g) were obtained, the line for c chromosome was trisomy addition, another one was double monosomic addition for a and f chromosomes. In pollen mother cells(PMCs) at diakinesis of these addition lines, the monosomy woad chromosome remained unpaired, while the chromosomes of B. napus appeared as 19 bivalents. At anaphaseⅠ, the unpaired woad chromosome moved to one of the cell poles and was included in the polar group with 19 chromosomes from B. napus, resulting the 19:20 segregation. But unequal segregations of the B. napus chromosomes(17: 19, 17: 21, 18: 20) occurred at low frequency, and subsequently in some PMCs at anaphase Ⅱ, some chromosomes originating from rapeseed lost, producing the micronuclei. FISH analysis with C-genome specific probe showed that each addition lines had the 18 C-genome chromosomes(9Ⅱ). FISH observations of these additional lines with woad centromeric probe indicated that only the chromosomes of diakinesis PMCs in Maf and Tc gave the hybridization signals, but those of monosomic addition lines had no the centromeric probe signal, suggesting that the translocations occurred on these alien chromosomes.2. Mophology of B. napus- I. indigotica additional lines with the cytoplasm of Zhongyou 821. These lines differed in the color and shape of leaves, flower size and shape, plant stature and branching patters. In particular, two lines expressed the brown anthers and flower fragrance from I. indigotica, respectively. Their pollen fertility and seed-set were low.3. B. napus- I. indigotica additional lines with the cytoplasm of Huashuang Five monosomic addition lines(Ma、Mb、Md、Me and Mg) and one double monosomic were identified by GISH. The alien chromosomes in these lines were labeled by the woad centromeric probes. The woad chromosomes appeared as the univalents in diakinesis PMCs. Because some chromosomes of rapeseed segregated unequally, the abnormal patterns occurred, such as 18:21, 17:20, 18:19, 17:21, bsedids the expected 19:20. At anaphase Ⅱ, some micronuclei formed with the chromosome/chromatin of rapeseed. The pollen fertility of the addition lines varied greatly.