Induction Of New Materials Of Tetraploid Non-Heading Chinese Cabbage

This article was about the induction and identification of tetraploid non-heading Chinese cabbage, and the main agronomic characters, physiological indexes, nutritional qualities and genes related to the ascorbic acid biosynthesis pathway were analyzed. At the same time, karyotype analysis of diploid and tetraploid non-heading Chinese cabbage were carried out, this could provide theoretical basis and practical methods for the genetic breeding and cytogenetics for non-heading Chinese cabbage.1. Diploid non-heading Chinese cabbage was induced by treating the apical portion of seedlings with different solution of colchicines. Autotetraploid plants were selected and identified based on morphological, anatomic, agronomic, cytological observation and flow cytometry. The results showed that the treatment with1.5g·L-1colchicine for6times yielded doubled chromosomes at highest rates and the rate of tetraploid was8.55%. Compared with the diploid plants, the autotetraploid plants showed the’enormous characteristics’in the size of stomata, the size of flower organs, the length and the width of pollen grains, the size of seeds and so on, but the plant height is lower. The thickness of ten leaves, the diameter of the seeds, the weight of50seeds, the length and width of petal, the length, the rib width, the width of silique, the length and width of pollen grain, the length and width of stomata, the chloroplast of guard cells were greater than that of diploid by23.2%,17.0%,31.3%,38.6%,66.3%,19.6%,26.5%,54.5%,16.1%,31.2%,34.9%,64.3%,44.0%and87.5%, all the differences were remarkable. The density of stomata of tetraploid was significantly decreased. The chromosome number of diploid was2n=2x=20while that of the tetraploid was2n=4x=40.2. Main agronomic characters, nutritional qualities and physiological characters of diploid and tetraploid non-heading Chinese cabbages were studied in this study. Compared with the diploid plants, the tetraploid plants were lower and deep green. The leaf width and petiole width were always bigger than the diploid during the whole growing period, but the plant height, number of leaves, petiole length, and leaf length were decreased. The soluble sugar, soluble protein, dry matter and organic acid were increased by15.7%,14.6%,16.9%and16.2%. The crude fiber were decreased by36.4%, all the differences were remarkable. The content of chlorophyll, the activity of SOD, POD and CAT were significantly increased while the content of MDA was significantly decreased.3. The contents of the ascorbic acid of different tissues in diploid and tetraploid non-heading Chinese cabbages at different periods were detected by HPLC, and the expressions of6genes related to the the L-galactose pathway were analyzed. The results showed that at the seedlings’ stage, the reproductive and total ascorbic acid of the leaves of tetraploid were increase by21.4%and10.8%%, while that in the petioles were increased by12.5%and10.3%, at the mature stage, the reproductive and total ascorbic acid of the leaves of tetraploid were increase by10.3%and6.74%, while that in the petioles were increased by25.9%and15.0%, all the differences were significant. The real-time PCR showed that no matter in the leaves or petioles, expressions of the gene BcVTCl, BcGME, BcVTC2, BcVTC4and BcGLDH were all significantly higher than in the diploid both at the seedlings’ stage and the mature stage, but there were no obvious changes in the expression of the gene BcPMM.4. Using the flower buds, karyotype analysis of diploid non-heading Chinese cabbage called’Teai Qing’ during meiosis diakinesis in pollen mother cells was conducted via conventional squash method with some improvements, and compared it to the chromosome karyotype of root tip. The results showed the same karyotype formula of non-heading Chinese cabbage was2n=2x=20=10m+8sm(2SAT)+2st, with5pairs of metacentric chromosomes (1,2,3,4,6),4pairs of submetacentric chromosomes (5,7,8,9), and a pair of sub-telocentric chromosome, and all of two satellites appeared at the third pairs of chromosomes. The karyotype belonged to2A, with ultimately symmetry karyotype. It is easy to get the phase of meiosis diakinesis when the length of the flower bud was about1.1-1.5mm.5. The immature pistil of diploid and tetraploid non-heading Chinese cabbages were used to make karyotype study by conventional squash method. The results showed that there were more metaphase stage cells in ovary than in stigma and style. Compared with the root tip, the immature ovary possessed more cells which were at metaphase stage. There were no obvious differences in patterns of the morphology chromosome in both materials; we could see satellites in both cells of two materials. No matter which material was used, the diploid non-heading Chinese cabbage karyotype formula was2n=2x=20=10m+8sm(2SAT)+2st, with5pairs metacentric chromosomes (1,2,3,4,6),4pairs submetacentric chromosomes (5,7,8,9), and5pairs sub-telocentric chromosome, and all of two satellites appeared at fifth pairs chromosomes. The karyotype belonged to2A, with ultimately symmetry karyotype. In addition, the tetraploid non-heading Chinese cabbage karyotype formula was2n=4x=20m+16sm(4SAT)+4st, the same as diploid. This provided a new method about cytology studies for more crops which have smaller chromosomes and satellites.