Gramig Greta G, Harris Marion O
Department of Plant Sciences, North Dakota State University, Fargo, ND 58102.
Department of Entomology, North Dakota State University, Fargo, ND 58102.
Environ Entomol. 2015 Jun;44(3):601-9. doi: 10.1093/ee/nvv028. Epub 2015 Mar 31.
Gall-inducing insects are known for altering source-sink relationships within plants. Changes in photosynthesis may contribute to this phenomenon. We investigated photosynthetic responses in wheat [Triticum aestivum L. (Poaceae: Triticeae)] seedlings attacked by the Hessian fly [Mayetiola destructor (Say) (Diptera: Cecidomyiidae], which uses a salivary effector-based strategy to induce a gall nutritive tissue in susceptible plants. Resistant plants have surveillance systems mediated by products of Resistance (R) genes. Detection of a specific salivary effector triggers downstream responses that result in a resistance that kills neonate larvae. A 2 × 2 factorial design was used to study maximum leaf photosynthetic assimilation and stomatal conductance rates. The plant treatments were-resistant or susceptible wheat lines expressing or not expressing the H13 resistance gene. The insect treatments were-no attack (control) or attack by larvae killed by H13 gene-mediated resistance. Photosynthesis was measured for the second and third leaves of the seedling, the latter being the only leaf directly attacked by larvae. We predicted effector-based attack would trigger increases in photosynthetic rates in susceptible but not resistant plants. For susceptible plants, attack was associated with increases (relative to controls) in photosynthesis for the third but not the second leaf. For resistant plants, attack was associated with increases in photosynthesis for both the second and third leaves. Mechanisms underlying the increases appeared to differ. Resistant plants exhibited responses suggesting altered source-sink relationships. Susceptible plants exhibited responses suggesting a mechanism other than altered source-sink relationships, possibly changes in water relations that contributed to increased stomatal conductance.
致瘿昆虫以改变植物体内源 - 库关系而闻名。光合作用的变化可能促成了这一现象。我们研究了受黑森瘿蚊[Mayetiola destructor (Say) (双翅目：瘿蚊科)]侵害的小麦[Triticum aestivum L.（禾本科：小麦族）]幼苗的光合响应，黑森瘿蚊采用基于唾液效应子的策略在易感植物中诱导瘿营养组织。抗性植物具有由抗性（R）基因产物介导的监测系统。检测到特定的唾液效应子会触发下游反应，从而产生杀死新生幼虫的抗性。采用2×2析因设计来研究最大叶片光合同化率和气孔导度。植物处理为表达或不表达H13抗性基因的抗性或易感小麦品系。昆虫处理为无侵害（对照）或受H13基因介导的抗性杀死的幼虫侵害。对幼苗的第二片和第三片叶子进行光合作用测量，后者是唯一直接受幼虫侵害的叶子。我们预测基于效应子的侵害会触发易感但非抗性植物光合速率的增加。对于易感植物，侵害与第三片叶子而非第二片叶子的光合作用增加（相对于对照）相关。对于抗性植物，侵害与第二片和第三片叶子的光合作用增加相关。增加背后的机制似乎有所不同。抗性植物表现出表明源 - 库关系改变的反应。易感植物表现出表明除源 - 库关系改变之外的一种机制的反应，可能是导致气孔导度增加的水分关系变化。
