Key message

Massive infection of Populus × petrovskiana leaves by petiole gall aphids (Pemphigus spyrothecae) significantly decreased leaf dry mass per unit area, N content per dry mass and net assimilation rate per area, and increased stomatal conductance, leaf dry mass per fresh mass, and constitutive emissions of isoprene. The infection also induced emissions of green leaf volatiles, monoterpenes and benzenoids. The emissions scaled with the infection severity as assessed by dry gall mass per leaf dry mass.

Abstract

Poplar spiral gall aphid (Pemphigus spyrothecae) forms galls on the petiole in poplars (Populus) and mass infestations are frequent in poplar stands, but how these parasite gall infestations can affect the leaf lamina structure, photosynthetic rate and constitutive and stress volatile emissions is unknown. We investigated how the infestation by the petiole gall aphids affects lamina photosynthetic characteristics (net assimilation rate, stomatal conductance), C and N contents, and constitutive isoprene and induced volatile emissions in Populus × petrovskiana. The dry gall mass per leaf dry mass (M_g/M_l) was used as a quantitative measure of the severity of gall infestation. Very high fraction of leaf biomass was invested in gall formation with M_g/M_l varying between 0.5 and 2. Over the whole range of the infestation severities, net assimilation rate per area, leaf dry mass per unit area and N content decreased with increasing the severity of infestation. In contrast, stomatal conductance, leaf dry mass per fresh mass, constitutive isoprene emissions, and induced green leaf volatile (GLV), monoterpene, sesquiterpene and benzenoid emissions increased with increasing the severity of gall infestation. The rates of induced emissions were low and these emissions were associated with methyl jasmonate release from leaf laminas. The data demonstrate that petiole gall infestations lead to major changes in leaf lamina sink–source relationships and leaf water relations, thereby significantly altering lamina photosynthesis. Modifications in stress-induced emissions likely indicated systemic signaling triggered by jasmonate transported from the petiole galls to the lamina where jasmonate elicited a cascade of volatile emission responses. Enhanced isoprene emissions and induced volatile emissions can play a major role in indirect defense against other herbivores, securing the food source for the gall aphids. In conclusion, a massive infestation by petiole gall aphids can profoundly modify the foliage photosynthetic performance and volatile emission profiles in poplars.

中文翻译：

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叶柄瘿蚜（Pemphigus spyrothecae）侵染杨属 × petrovskiana 叶子会改变叶子的光合特性，并导致本构和胁迫诱导的挥发物的排放增加。

关键信息

的大规模感染胡杨× petrovskiana叶子通过叶柄瘿蚜虫（天疱疮spyrothecae）的每单位面积，每干质量和每单位面积净同化率N含量显著降低叶干质量，并增加了气孔导度，每鲜重叶干质量和组成异戊二烯的排放。感染还引起绿叶挥发物、单萜和苯类物质的排放。排放量与感染严重程度成比例，如通过每叶干质量评估的干瘿质量。

抽象的

杨螺旋瘿蚜（Pemphigus spyrothecae）在杨（Populus）的叶柄上形成瘿，在杨林中经常发生大规模侵染，但这些寄生虫瘿侵染如何影响叶层结构、光合速率以及本构和胁迫挥发物排放尚不清楚。 . 我们研究了通过将叶柄外瘿蚜虫侵染如何影响叶片光合特性（净同化率，气孔导度），C，N含量，并组成型异戊二烯和诱导挥发性散发胡杨× petrovskiana。每片叶的干瘿量（M _g / M _l) 被用作衡量胆汁感染严重程度的定量指标。非常高比例的叶生物量用于瘿形成，M _g / M _l在 0.5 和 2 之间变化。在整个侵染严重程度范围内，单位面积净同化率、单位面积叶片干重和 N 含量随着侵染严重程度的增加而降低。相比之下，气孔导度、每新鲜质量的叶干质量、组成型异戊二烯排放量和诱导的绿叶挥发物 (GLV)、单萜、倍半萜烯和苯类排放量随着胆囊侵染严重程度的增加而增加。诱导排放率很低​​，这些排放与叶叶片释放茉莉酸甲酯有关。数据表明，叶柄瘿侵染导致叶片库源关系和叶片水分关系发生重大变化，从而显着改变叶片光合作用。压力引起的排放的改变可能表明由茉莉酸从叶柄瘿转运到叶片所触发的系统性信号传导，在那里茉莉酸引发了一系列挥发性排放反应。增强的异戊二烯排放和诱发的挥发性排放可以在间接防御其他食草动物方面发挥重要作用，确保瘿蚜的食物来源。总之，叶柄瘿蚜虫的大量侵染可以深刻改变杨树的叶子光合性能和挥发性排放特征。