Study On The Mutant Versions And Mechanism Of Dwarf Mutant Dsh In Watermelon

For the reason that the conventional cultivated plant vines of watermelon is much longer, the rate of land use and the planting density of per unit of land area is low. However, the short vine plants has the broad prospects for development in agricultural production, which are suitable for high planting density and convenient for facilitate characteristic planting and management, so the position of new varieties breeding in watermelon with short vines and high quality is increasingly prominent. In this paper, mainly analyzed a natural dwarf mutant dsh and its wild-type and their F1、F2、BC1 generation plants so as to provide theory basis and germplasm materials of excellent and stable traits for cultivating new short vine varieties of watermelon. Then by studying the morphological index, genetics, physiological and biochemical differences, hormone sensitivity, paraffin section and water soluble protein differences between dsh and its wild-types, the results were as follows:(1) The dwarf mutant dsh is significantly different from its wild-type in the length of main vine, number of branches, length and width of leaf, number of staminate flower, weight single fruit, fruit number of per plant. The morphological indexes of F1 and the wild-type plants are similar. The genetic analysis about dsh indicats that: the vine type of watermelon was controlled by an independent allele, the dwarf mutant dsh was controlled by recessive gene, and the wild-type was controlled by dominant gene.(2) The physiological indexes of resistance and chlorophyll content of dsh at different developmental stages were difference in the wild-type. The chlorophyll content of dsh was decreasing and significantly lower than its wild-type plants after 25 days. The MDA content was rising and significantly higher than the wild-type at different developmental stages in leaf and internode of dsh, namely, the degree of membrane lipid peroxidation of dsh was more serious. But the SOD、POD and CAT activity was on the contrary. Therefore, in the process of membrane lipid peroxidation, the protective enzyme activity of the dsh plants was significantly lower than the wild-type plants.(3) The dwarf mutant dsh plants was neither hormone defect mutants nor hormone insensitive mutants. Different concentrations of BR, IAA and GA3 could not restore the vine elongation to the wild-type level, what’s more, to a certain extent, BR and IAA inhibit the growth of the vine. Therefore, the mutant type is not the hormone defect mutant. The dsh and its wild-type plants could respond to GA3 hormone, and the GA3 hormone could stimulate the length of the vine of the dsh and its wild-type plants increased by 49.40% and 69.58%, thus, the mutant type is not the hormone insensitive mutant. BR and IAA could stimulate the petiole elongation of the dsh and its wild-type plants, but they inhibit the elongation of vine. And GA3 could stimulate the elongation of the vine and petiole of both. However, it could not make the dsh plants to restore the control level of the wild-type plants.(4) The less number of cells may lead to the dwarfism of dsh plants.The hypocotyl elongation research of dsh and its wild-type shows that, the two laws of both were consistent which the elongation of them were faster in 2-4 days after germination and then entered the elongation period of stagnation after 7 days. However, the rate of hypocotyls elongation in wild type plants was faster than dsh. The cytological observation on hypocotyls after 7 days and internode paraffin section after 35 days of dsh and its wild-type shows that, the hypocotyls and internode cells volume of dsh were greater than the wild-type plants, namely, the cell number was less than the wild-type plants. The cytological observation after 35 days on the internode cells through hormone treatment shows that, the internode cells volume of dsh were still greater than the wild-type plants after the hormone treatment by BR, IAA and GA3. That is to say, the amount of the cells of the dsh plants was still small.(5) The changes of genotype of the dwarf watermelon plant dsh had no significant effect on the expression of protein bands. Protein bands of different tissue and the same tissue in different periods were different. While the protein bands of the dsh and its wild-type plants have no obvious differences in the same tissue at the same period.