Studies On Inheritance And Biochemical Mechanism Of Cotton Resistance To Fusarium Oxysporum And Verticillum Dahliae

A genetic model with genotype by environment interaction was employed to analyze the genetic behavior of cotton disease index, used the materials of Recombinant Inbred Line(RIL) derived from female parent HS46 and male parent MARCABUCAG8US-1-88 (MAR). The experiments were conducted in 2000 and 2001 in the fields in Hongzhou, Zhejiang and Fugu, Henan, inoculated with the artificial cultivated fungi. Mean time, the polypropylene ammonia gel electrophoresis was conducted to study the relation between peroxidase isozymes (POD) and superoxide dismutase (SOD). The main results were as follows:1 Inheritance of cotton resistance to Fusariiitn oxsyporumThe results showed that there was significant separation for the cotton disease index of Fusarium oxysporum among the different families of RIL. The genetic variance of disease index for RIL was significant. So the RIL could be used in analysis of the inheritance of cotton resistance to Fusarium oxysporum. The genetic by environment interaction variance was detected significantly; it indicated that the cotton resistance to Fusarium oxysporum was significantly affected by environmental factors. The ratio of resistant lines to susceptible ones was deviated from 3:1, which indicted that the inheritance of cotton resistance to Fusarium oxysporum may be controlled by recessive genes, or controlled by a recessive and a dominant gene and micro-effective multiple genes.2 Inheritance of cotton resistance to Verticilliu dahliaeThe results showed that there was significant separation in the cotton disease index of Verticilliu dahliae among different families of RIL. The genetic variance of cotton disease index to Verticilliu dahliae was significant. So the RIL could be used in analysis for inheritance of cotton resistance to Verticilliu dahliae, as well. The narrow inheritance of cotton resistance to Verticilliu dahliae was high, and the ratio of resistant lines to susceptible one was 3:1, checked by the statistical method of y?, which indicated that the inheritance of cotton resistance to Verticilliu dahliae maybe a quality trait controlled by a dormant gene.3 The genetic correlative cotton resistance to Verticilliu dahliae and fusarium oxysoruumIt was observed that there was a significant genetic correlative between the cotton disease index of Verticilliu dahliae and that of Fusarium oxysporum. So in the breeding program, the selection for high resistance to Verticilliu dahliae may also lead to high resistance to Fusarium oxysporum.4 Biochemical mechanism of cotton resistance to Verticilliu dahliae and Fusarium oxysporumThe relationship between the activity of peroxidase isozymes and cotton resistance to Verticilliu dahliae and Fusarium oxysporum was studied in this experiment, using upside third leave during the full-flowering period of cotton growth season of RILs. The results showed there were no significant relation between them. However, the activity of superoxide dismutase was significant negative correlation to the cotton disease index of Verticilliu dahliae and Fusarium oxysporum. There were no special bands among the enzymogram connected with the cotton resistance to Verticilliu dahliae and Fusarium oxysporum. One enzyme band of POD in cotton cotyledon was found to be closed linkage with cotton resistance to Verticilliu dahliae. And a special SOD enzyme zone was also found to connect with cotton resistance to Fusarium oxysporum.Finally, the materials used in the research for cotton resistance, inheritance of cotton resistance to wilts and the biochemical identification for resistance were discussed in the paper.