Hybrid-poplar tree plantations provide a source for biofuel and biomass, but they also increase forest isoprene emissions. The consequences of increased isoprene emissions include higher rates of tropospheric ozone production, increases in the lifetime of methane, and increases in atmospheric aerosol production, all of which affect the global energy budget and/or lead to the degradation of air quality. Using RNA interference (RNAi) to suppress isoprene emission, we show that this trait, which is thought to be required for the tolerance of abiotic stress, is not required for high rates of photosynthesis and woody biomass production in the agroforest plantation environment, even in areas with high levels of climatic stress. Biomass production over 4 y in plantations in Arizona and Oregon was similar among genetic lines that emitted or did not emit significant amounts of isoprene. Lines that had substantially reduced isoprene emission rates also showed decreases in flavonol pigments, which reduce oxidative damage during extremes of abiotic stress, a pattern that would be expected to amplify metabolic dysfunction in the absence of isoprene production in stress-prone climate regimes. However, compensatory increases in the expression of other proteomic components, especially those associated with the production of protective compounds, such as carotenoids and terpenoids, and the fact that most biomass is produced prior to the hottest and driest part of the growing season explain the observed pattern of high biomass production with low isoprene emission. Our results show that it is possible to reduce the deleterious influences of isoprene on the atmosphere, while sustaining woody biomass production in temperate agroforest plantations.

中文翻译：

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杂种杨树人工林的高生产力而不会向大气排放异戊二烯。

杂种杨树人工林提供了生物燃料和生物量的来源，但它们也增加了森林异戊二烯的排放。异戊二烯排放量增加的后果包括增加对流层臭氧的产生率，增加甲烷的寿命以及增加大气气溶胶的产生，所有这些都会影响全球能源预算和/或导致空气质量下降。使用RNA干扰（RNAi）抑制异戊二烯的排放，我们证明了这种特性（被认为是非生物胁迫的耐受性所必需的），即使在农林种植环境中，光合作用和木质生物量的高生产率也不是必需的。气候压力高的地区。在散发或不散发大量异戊二烯的遗传系中，亚利桑那州和俄勒冈州人工林超过4年的生物量产量相似。异戊二烯排放速率大大降低的品系还显示出黄酮醇色素的减少，从而减少了在非生物胁迫极端条件下的氧化损伤，这种模式有望在易受气候影响的环境中在不存在异戊二烯产生的情况下放大代谢功能障碍。但是，其他蛋白质组学成分的表达补偿性增加，尤其是与生产保护性化合物（如类胡萝卜素和萜类化合物）相关的蛋白质组学表达，以及大多数生物质在生长期最热，最干燥的部分之前产生的事实，解释了这一现象。低异戊二烯排放的高生物质生产模式。