Studies On Resistance To Cotton Bollworm And Correlative Traits Of Transgenic Bt+CpTI Cotton

Transgenic Bt+CpTI genes cotton lines (double-copy transgenic cotton)was wilder and higher resistance and its boll mumber per plant was more. While its some main characters were reduced, which were boll weight, lint percentage and growth. Using double-copy transgenic cotton and F1 hybrids, a series of researches were conducted, which were the resistance, growth and development, nutrition to cotton bollworm, expression of resistant protein, the nitrogen metabolized character and the correlation among them, inherit pattern of resistance, effect of yield and fiber quality in double-copy transgenic cotton and F1 hybrids. Results showed as follows: Laboratory bioassay determine indicated a similar mode of change in double-copy transgenic cotton, F1 hybrids and transgenic Bt gene cotton that resistance was higher at earlier development stages while declined at later stages. The resistance at flowering-boll stage was: boll>squre>flower>mature leaf on main stem. Resistance in earlier stages was slightly lower, and significantly higher in later stages fed on double-copy transgenic cotton and F1 hybrids campared with that transgenic Bt gene cotton. From 1stto4th instar larvae all developed slowly, could not pupate and eclosion then died finally while fed with the leaves of double-copy transgenic cotton, F1 hybrids and transgenic Bt gene cotton during later developmental stage whereas they could normally pupate and eclosion while fed with the leaves of Simian3. Double-copy transgenic cotton and F1 hybrids had strong affect to cotton bollworm on growth and development, nutrition. Weight of larvae and pupae were all decreased. Relative growth rate, consumption rate, approximate digestibility, efficiency of conversion and utilization of ingested obviously decreased, but relative metabolism rate increased. The leaves, buds, flowers and bolls of double-copy transgenic cotton and F1 hybrids during later developmental stage (flowering-boll stage)were not damaged in the experi- mental arer and presented significant resistance to cotton bollworms. The content of Bacillus thuringiensis (Bt) insecticide protein and CpTI protein in double-copy transgenic cotton and F1 hybrids was quantitated using Enzyme-linked Immu- nosorbent Assay (ELISA) under field condition. The results showed that the expression pattern demonstrated temporal and spatial characteristics. The content of Bt insecticide protein in double-copy transgenic cotton and F1 hybrids was higher than that of transgenic Bt gene cotton. The content of CpTI protein in double-copy transgenic cotton and F1 hybrids was significant lower than that of Bt insecticide protein. The expression pattern was the same as that in transgenic Bt gene cotton The activity of soluble protein in mature leaves main stem of double-copy transgenic cotton and F1 hybrids gradually decreased during the whole growing season. The activity of GOT and GPT in leaves showed descending trend, and slowly descending at flowering-boll stage. Nitrate-reductase(NR)activity in leaves showed a saddle shape variety trend from seeding to boll-opening. There was no dramatical change of soluble protein, GOT, GPT and NR among four varieties. And activity of F1 hybrids was higher, that of coventional cotton was highest. Soluble protein, GOT, GPT and NR activity had positive correlation with resistant protein. The inheritant pattern of double-copy transgenic cotton was presented in the paper. The F1 hybrids crossed between double-copy transgenic cotton and conventional cotton variety showed significant resistance to bollworm. The segregation of the resistance and susceptible plants in F2 hybrids and BC1 populations fit 3:1 and 1:1 ratio, which demonstrated that the resistance of double-copy transgenic cotton to bollworm was controlled by one pair of dominant gene, and was not affected by cytoplasm. Output of seed cotton and lint yield of F1 hybrids were significantly higher double-copy transgenic cotton. F1 hybrids had an apparent advantage over its male parent, boll weight increased the most, lint percentage took t...