High productivity in hybrid-poplar plantations without isoprene emission to the atmosphere
High productivity in hybrid-poplar plantations without isoprene emission to the atmosphere
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DOI：
10.1073/pnas.1912327117
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发表时间：
2020-01
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通讯作者：
R. Monson;Barbro Winkler;T. Rosenstiel;Katja Block;J. Merl-Pham;S. Strauss;Kori Ault;Jason Maxfield;D. Moore;N. Trahan;Amberly A. Neice;Ian Shiach;G. Barron‐Gafford;P. Ibsen;J. McCorkel;J. Bernhardt;J. Schnitzler
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作者：
R. Monson;Barbro Winkler;T. Rosenstiel;Katja Block;J. Merl-Pham;S. Strauss;Kori Ault;Jason Maxfield;D. Moore;N. Trahan;Amberly A. Neice;Ian Shiach;G. Barron‐Gafford;P. Ibsen;J. McCorkel;J. Bernhardt;J. Schnitzler
在2个大田试验中，杂交杨树叶片异戊二烯释放量在不影响人工林生物量生产的情况下被遗传抑制，这是一种促进树木耐受性但也影响空气质量和气候的性状。保护性蛋白质组成分补偿性增加的诱导和物候生长模式有利于在生长季节压力较小的部分生产大部分生物量，这可能解释了高人工林产量与低异戊二烯排放的明显矛盾。我们表明，在不降低空气质量的情况下，开发可持续的人工林规模的生物质资源是可行的，这些生物质资源可以作为能源生产和木质纤维素资源开发的化石燃料替代品。杂交杨树种植园提供了生物燃料和生物质的来源，但它们也增加了森林异戊二烯的排放。异戊二烯排放增加的后果包括对流层臭氧产生率增加、甲烷寿命延长和大气气溶胶产生增加，所有这些都影响到全球能源收支和/或导致空气质量退化。利用RNA干扰（RNAi）抑制异戊二烯的释放，我们发现这种被认为是对非生物胁迫的耐受性所必需的特性，在农林业环境中，即使在高水平气候胁迫的地区，也不需要高速率的光合作用和木材生物量生产。在排放或不排放大量异戊二烯的遗传系中，亚利桑那州和俄勒冈州人工林4年以上的生物量产量相似。大大降低异戊二烯排放率的品系也显示出黄酮醇色素的减少，黄酮醇色素在极端非生物胁迫下减少氧化损伤，这种模式预计会在缺乏异戊二烯的情况下扩大应激易发气候条件下的代谢功能障碍。然而，其他蛋白质组学成分表达的代偿性增加，特别是与保护性化合物（如类胡萝卜素和萜类）的产生有关的蛋白质组学成分的表达，以及大多数生物量是在生长季节最热和最干燥的部分之前产生的事实，解释了观察到的高生物量生产和低异戊二烯排放的模式。我们的研究结果表明，在维持温带农林复合人工林木质生物量生产的同时，减少异戊二烯对大气的有害影响是可能的。
Significance Leaf isoprene emission, a trait that promotes tree stress tolerance but also affects air quality and climate, has been genetically suppressed in hybrid-poplar cultivars without influencing plantation biomass production in 2 field trials. Induction of compensatory increases in protective proteomic components and a phenological growth pattern that favors most biomass production during less stressful parts of the growing season likely explain the apparent paradox of high plantation production with low isoprene emission. We show that it is feasible to develop sustainable plantation-scale biomass sources that can serve as fossil-fuel alternatives for energy generation and lignocellulosic resource development, without degrading air quality. 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.