Gebhardt Manuela M, Eberle Karolin E, Radtke Pit, Jehle Johannes A
Institute for Biological Control, Federal Research Center for Cultivated Plants, Julius Kühn-Institut, 64287 Darmstadt, Germany; and.
Institute for Biological Control, Federal Research Center for Cultivated Plants, Julius Kühn-Institut, 64287 Darmstadt, Germany; and Department of Phytopathology, Agricultural Service Center Palatinate (DLR Rheinpfalz), 67435 Neustadt an der Weinstrasse, Germany.
Proc Natl Acad Sci U S A. 2014 Nov 4;111(44):15711-6. doi: 10.1073/pnas.1411089111. Epub 2014 Oct 20.
The baculovirus Cydia pomonella granulovirus (CpGV) is widely applied as a biocontrol agent of codling moth. After field resistance of codling moth populations had been observed against the commercially used Mexican (M) isolate of CpGV, infection experiments of larvae of the resistant codling moth strain CpRR1 showed that several other naturally occurring CpGV isolates (I12, S, E2, and I07) from different geographic origins are still infectious to resistant CpRR1. Whole-genome sequencing and phylogenetic analyses of these geographic CpGV variants revealed that their genomes share only a single common difference from that of CpGV-M, which is a mutation coding for a repeat of 24 nucleotides within the gene pe38; this mutation results in an additional repeat of eight amino acids that appears to be inserted to PE38 of CpGV-M only. Deletion of pe38 from CpGV-M totally abolished virus infection in codling moth cells and larvae, demonstrating that it is an essential gene. When the CpGV-M deletion mutant was repaired with pe38 from isolate CpGV-S, which originated from the commercial product Virosoft and is infectious for the resistant codling moth strain CpRR1, the repaired CpGV-M mutant was found to be fully infectious for CpRR1. Repair using pe38 from CpGV-M restored infectivity for the virus in sensitive codling moth strains, but not in CpRR1. Therefore, we conclude that CpGV resistance of codling moth is directed to CpGV-M but not to other virus isolates. The viral gene pe38 is not only essential for the infectivity of CpGV but it is also the key factor in overcoming CpGV resistance in codling moth.
杆状病毒苹果蠹蛾颗粒体病毒（CpGV）被广泛用作苹果蠹蛾的生物防治剂。在观察到苹果蠹蛾种群对商业使用的墨西哥（M）分离株CpGV产生田间抗性后，对抗性苹果蠹蛾品系CpRR1的幼虫进行的感染实验表明，来自不同地理来源的其他几种天然存在的CpGV分离株（I12、S、E2和I07）对抗性CpRR1仍具有感染性。对这些地理上的CpGV变体进行全基因组测序和系统发育分析发现，它们的基因组与CpGV-M的基因组仅存在一个共同差异，即基因pe38内一个编码24个核苷酸重复序列的突变；这种突变导致额外重复8个氨基酸，似乎仅插入到CpGV-M的PE38中。从CpGV-M中删除pe38完全消除了病毒在苹果蠹蛾细胞和幼虫中的感染，表明它是一个必需基因。当用来自分离株CpGV-S的pe38修复CpGV-M缺失突变体时，发现修复后的CpGV-M突变体对CpRR1具有完全感染性，CpGV-S源自商业产品Virosoft，对抗性苹果蠹蛾品系CpRR1具有感染性。用CpGV-M的pe38进行修复可恢复病毒对敏感苹果蠹蛾品系的感染性，但对CpRR1则不然。因此，我们得出结论，苹果蠹蛾对CpGV的抗性是针对CpGV-M而非其他病毒分离株。病毒基因pe38不仅对CpGV的感染性至关重要，也是克服苹果蠹蛾对CpGV抗性的关键因素。
