Horgan Finbarr G, Almazan Maria-Liberty P, Vu Quynh, Ramal Angelee Fame, Bernal Carmencita C, Yasui Hideshi, Fujita Daisuke
University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW 2007, Australia.
Tropical Ecosystems Research Network, 30C Nirondha, Temple Road, Piliyandala, Sri Lanka.
Crop Prot. 2019 Jan;115:47-58. doi: 10.1016/j.cropro.2018.09.013.
We tested the hypotheses that increasing the number of anti-herbivore resistance loci in crop plants will increase resistance strength, increase the spectrum of resistance (the number of species affected), and increase resistance stability. We further examined the potential ecological costs of pyramiding resistance under benign environments. In our experiments, we used 14 near-isogenic rice lines with zero (T65: recurrent parent), one, two or three resistance loci introgressed through marker-assisted selection. Lines with two or more loci that were originally bred for resistance to the green rice leafhopper, , significantly reduced egg-laying by the green leafhopper, . Declines in egg-number and in nymph weight were correlated with the numbers of resistance loci in the rice lines. To test the spectrum of resistance, we challenged the lines with a range of phloem feeders including the zig-zag leafhopper, , brown planthopper, , and whitebacked planthopper, . There was an increase in the number of tested species showing significant declines in egg-laying and nymph survival on lines with increasing numbers of loci. In a screen house trial that varied rates of nitrogenous fertilizer, a line with three loci had stable resistance against the green leafhopper and the grain yields of infested plants were maintained or increased (overcompensation). Under benign conditions, plant growth and grain yields declined with increasing numbers of resistance loci. However, under field conditions with natural exposure to herbivores, there were no significant differences in final yields. Our results clearly indicate the benefits, including unanticipated benefits such as providing resistance against multiple herbivore species, of pyramiding anti-herbivore resistance genes/loci in crop plants. We discuss our results as part of a review of existing research on pyramided resistance against leafhoppers and planthoppers in rice. We suggest that potential ecological costs may be overcome by the careful selection of gene combinations for pyramiding, avoidance of high (potentially redundant) loci numbers, and introgression of loci into robust plant types such as hybrid rice varieties.
增加作物中抗食草动物抗性基因座的数量会增强抗性强度、扩大抗性谱（受影响的物种数量）并提高抗性稳定性。我们还进一步研究了在良性环境下将抗性基因座聚合的潜在生态成本。在我们的实验中，我们使用了14个近等基因水稻品系，通过标记辅助选择导入了零个（T65：轮回亲本）、一个、两个或三个抗性基因座。最初培育用于抗绿稻叶蝉的含有两个或更多基因座的品系显著减少了绿叶蝉的产卵量。卵数和若虫体重的下降与水稻品系中抗性基因座的数量相关。为了测试抗性谱，我们用一系列刺吸式口器害虫对这些品系进行挑战，包括黑尾叶蝉、褐飞虱和白背飞虱。随着基因座数量的增加，在产卵量和若虫存活率上表现出显著下降的受试物种数量有所增加。在一个改变氮肥施用量的网室试验中，含有三个基因座的品系对绿稻叶蝉具有稳定的抗性，受虫害植株的谷物产量得以维持或增加（超补偿）。在良性条件下，植物生长和谷物产量随着抗性基因座数量的增加而下降。然而，在自然暴露于食草动物的田间条件下，最终产量没有显著差异。我们的结果清楚地表明了在作物中聚合抗食草动物抗性基因/基因座的益处，包括一些意想不到的益处，如对多种食草动物物种提供抗性。我们将我们的结果作为对水稻中针对叶蝉和飞虱的聚合抗性现有研究综述的一部分进行讨论。我们建议，通过仔细选择用于聚合的基因组合、避免高（可能冗余）的基因座数量以及将基因座导入健壮的植物类型（如杂交水稻品种），可以克服潜在的生态成本。
