Diverse cadherin mutations conferring resistance to Bacillus thuringiensis toxin Cry1Ac in Helicoverpa armigera.
Diverse cadherin mutations conferring resistance to Bacillus thuringiensis toxin Cry1Ac in Helicoverpa armigera.
复制标题
DOI：
10.1016/j.ibmb.2010.01.001
复制
发表时间：
2010-02
影响因子：
3.8
通讯作者：
J. Zhao;Lin Jin;Yihua Yang;Yidong Wu
中科院分区：
文献类型：
--
作者：
J. Zhao;Lin Jin;Yihua Yang;Yidong Wu
表达苏云金芽孢杆菌（Bacillus thuringiensis, Bt）毒素的转基因棉花已被广泛用于防治棉铃虫等鳞翅目主要害虫。目标害虫对Bt棉花的抗性进化是Bt棉花持续成功的主要威胁。先前的研究结果显示，在棉铃虫中，钙粘蛋白基因（Ha_BtR）的3个空等位基因（r1-r3）赋予了Cry1Ac抗性。2008年，对江苏江浦种群的一株抗cry1ac菌株（SCD-r1， Ha_BtR的r1等位基因纯合子）与田间来源昆虫进行了123个单对家系的f1筛选。在6个候选单对家族中发现了5个新的Ha_BtR空等位基因（r4-r8）。这些空等位基因是通过插入或点突变产生的。有趣的是，在另外两个候选单对家族的两个田间来源昆虫中发现了Ha_BtR的完整等位基因。这表明这两种田间来源的昆虫可能携带Ha_BtR的新型抗性等位基因，错义突变导致无功能的钙粘蛋白蛋白，或者在钙粘蛋白以外的位点发生主要显性突变。2008年在江浦区棉铃虫种群中检测到Ha_BtR抗性等位基因频率为0.024，呈显著水平。结合前人的研究结果，从3株中国棉铃虫中鉴定出8个不同的Ha_BtR抗性等位基因。Ha_BtR的突变多样性可能影响田间Bt抗性等位基因频率的DNA筛选，应常规采用f1筛选法监测棉铃虫钙粘蛋白抗性等位基因频率。
Transgenic cotton expressing Bacillus thuringiensis (Bt) toxins has been widely adopted to control some key lepidopteran pests including the bollworm Helicoverpa armigera. Evolution of resistance to Bt cotton by target pests is a major threat to the continued success of Bt cotton. Previous results revealed 3 null alleles (r1–r3) of a cadherin gene (Ha_BtR) conferring Cry1Ac resistance in H. armigera. An F1screen of 123 single-pair families was conducted between a Cry1Ac-resistant strain (the SCD-r1 strain, homozygous for the r1 allele of Ha_BtR) and field-derived insects from Jiangpu population (Jiangsu province, China) in 2008. Five new null alleles of Ha_BtR (r4–r8) were identified in six candidate single-pair families. These null alleles were created through either an insertion or a point mutation. Interestingly, intact alleles of Ha_BtR were found in two field-derived insects from another two candidate single-pair families. It suggests that these two field-derived insects may carry novel resistance alleles of Ha_BtR, with missense mutations resulting in a non-functional cadherin protein, or a major dominant mutation at a locus other than cadherin. The resistance allele frequency of Ha_BtR was detected at an appreciable level (0.024) in the Jiangpu population of H. armigera in 2008. Together with previous findings, a total of eight different resistance alleles of Ha_BtR were identified from three Chinese strains of H. armigera. Mutational diversity of Ha_BtR could impair DNA screening for Bt resistance allele frequency in the field, and an F1screen should be used routinely for monitoring cadherin-based resistance allele frequencies in H. armigera.