JI Rong-Long, CUI Bi-Bo, HUANG Zhi-Yong, FEI Yue-Yue, GU Ke-Yu, SUN Kou-Zhong, CHEN De-Hua
Cotton Science. 2011, 23(5): 454-459.
The objective of this study was to investigate the change of insecticidal protein content under source-sink regulation in Bt cotton boll. The experiments were conducted at Yangzhou University farm during cotton growth season from 2005 to 2006, three cultivars with different boll sizes of Bt cotton, Sikang 1(small boll), Sikang 3(middle boll), Kemian 6(big boll), were selected to study Bt endotoxin characteristics under source-sink regulation. The three cultivars were designed to be cut half leaves of the whole plant in 2005, and to be thinned half buds of the whole plant in 2006. The results showed that, with being cut half leaves of the whole plant, the boll volume, boll weight and seed weight decreased, and its effects on the boll volume and weight were greater in the big boll cultivar, reducing by 15.4% and 20.5% at 28 days after anthesis, respectively; in contrast, its effect on the seed weight was the biggest in the small boll cultivar, decreasing by 20.6% at 28 days after flowering. The Bt protein contents increased in the boll wall and seed, which increased by 23.5%～32.3%, 3.3%~18.8% at 21 days after anthesis, respectively. With half buds of the whole plant thinned, the boll volume, boll weight and seed weight were boosted, and the effects were the greatest in the big boll cultivar, increasing by 25.8%, 10.4%, 12.7% at 28 days after anthesis, respectively; in contrast, the Bt protein contents in the boll wall and seed decreased, the effects was greatest in the big boll cultivar too, reducing by 40.6%, 33.7% at 21 days after anthesis, respectively. There were significant negative correlations between the boll volume, boll weight and Bt endotoxin contents in the boll wall and seed under source-sink regulation, respectively, so was between seed weight and Bt endotoxin contents in the seed. The results suggest that the breeding and culture practice should aim at coordinating the relation between the boll development and Bt endotoxin expression.
