Studies On The Cytomorphology Of Abortion Floral Bud In Radish And Molecular Marker For Dehiscent Leaf In No-Heading Chinese Cabbage

This paper contains two parts, as cell morphological observation of abortion floral bud in radish (Raphnus sativus L.) and molecular marker for dehiscent leaf of pakchoi (Brassica campestris L. ssp. chinensis Makino var. communis Tsen et Lee). The first part is to detect genomic DNA and observe cell structure of normal and abortion floral bud in the radish male sterility material BT-18 bred by Chinese cabbage research group of Northwest A & F University. Second part is to investigate the inheritance and molecular marker for dehiscent leaf of pakchoi material bred by Chinese cabbage research group of Northwest A & F University. The main results are as follows:1. The genomic DNA in abortion and normal floral bud were extracted and were detected in agarose gel electrophoresis, the DNA ladder was found in abortion floral bud, but normal in normal floral bud.This phenomenon showed that abortion of floral bud has the features of programmed cell death.2. By observing the cytomorphology of abortion and normal floral bud at light microscope, we found many tissue degradation in abortion floral bud, such as lower epodermis and parenchyma cells degenerate in sepal, parenchyma cell degrade and disappear gradually up to residue of upper and lower epidermis in petal, and anther degrade and remain vascular bundle and anther wall.3. The ultrastructure of organelle in sepal cell was observed at electron microscope, it was showed that there was a fewer cristae and double-layer membrane was broken in mitochondria; the nuclear membrane was broken, or nucleolus become malformation and disruption and disappear in the end; the structure of grana and stroma lamellar of chloroplast were disrupted, the number and volume of plastoglobuli increased in chloroplasts, finally, the chloroplast membrane was broken and chloroplasts degenerated.4. Being tested the fitness of segregation of dehiscent leaf and round leaf in four F2 population of pakchoi ( 06X1, 06X12, 06X17, 06X19), it was demonstrated that the dehiscent leaf is a qualitative trait controlled by one dominant genic gene, and the segregation of dehiscent leaf and round leaf in F2 population coincide with the proporation of 3:1.5. Bulked segregant analysis(BSA) was emplyed to screen molecular markers linked to dehiscent leaf gene, a random primer S1396 was seleected out of 397 10-mer random primers, 23 pairs of SSR primers and 88 pairs of SRAP primers, which amplified a stable difference band between dehiscent leaf DNA pool and round leaf DNA pool. The special band about 500bp was amplified by S1396 in dehiscent DNA pool only, which has the exchange rate of 15.5% with dehiscent leaf when tested in F2 population. The genetic distance between S1396-500 and dehiscent leaf gene is 16.49 cM, calculated by Join Map 4.0. In additional, the primer SSR25 and primer combination of me1em1 that amplified a stable band in dehiscent leaf DNA pool were also found, which will be verificated in segregating population.