地上与地下生物的相互联系是当代生态学研究的热点。而大气CO2浓度升高是未来发生的一种趋势。由于茉莉酸诱导抗性途径产生的系统防御信号能够贯串植物的地上、地下部分，因此研究植物的茉莉酸诱导抗性途径可以将大气CO2浓度升高和地下线虫为害有机的联系起来，探讨大气CO2浓度升高如何通过植物产生级联效应（cascading effect）影响地下生物。
中科院动物研究所种群生态与全球变化研究组科研人员在野外的开顶式CO2控制箱（OTC）中，利用茉莉酸防御途径加强型番茄35S、茉莉酸防御途径缺失型番茄spr2和野生型番茄Wt三种试验植物，研究了大气CO2浓度倍增（750ppm）环境下，三种基因型番茄对南方根结线虫抗性的变化。
研究发现，高CO2浓度增加了三种基因型番茄的碳含量和碳氮比，加快了植物的生长发育；同时，大气CO2浓度升高降低了茉莉酸防御途径加强型番茄35S对线虫的抗性，而对于野生型番茄Wt和茉莉酸防御途径缺失型番茄spr2没有影响，表明茉莉酸信号途径参与并加强了植物对线虫的防御；而对照CO2浓度环境中，茉莉酸防御途径缺失型番茄spr2与野生型番茄Wt相比，对线虫的抗性差异并不明显，说明在植物对线虫的防御过程中，茉莉酸信号途径并不是唯一的抗性途径。
研究结果提示：不同基因型的番茄，即使仅有一个基因的差异，对大气CO2浓度升高的响应也存在差异，这种差异是植株营养和防御物质的权衡表现，进而导致不同基因型番茄在未来环境下对线虫抗性的变化。
该文第一作者孙玉诚为种群生态与全球变化研究组助理研究员，通讯作者为戈峰研究员。该研究工作得到了国家重大基础研究计划（973）、中国科学院知识创新工程重要方向项目和基金委创新研究群体项目的资助。(生物谷Bioon.com)
生物谷推荐原文出处：
Plant, Cell & Environment DOI:10.1111/j.1365-3040.2009.02098.x
Elevated CO2 changes the interactions between nematode and tomato genotypes differing in the JA pathway
YUCHENG SUN, HAIFENG CAO, JIN YIN, LE KANG & FENG GE
Interactions between the root-knot nematode Meloidogyne incognita and three isogenic tomato (Lycopersicon esculentum) genotypes were examined when plants were grown under ambient (370 ppm) and elevated (750 ppm) CO2. We tested the hypothesis that, defence-recessive genotypes tend to allocate 'extra' carbon (relative to nitrogen) to growth under elevated CO2, whereas defence-dominated genotypes allocate extra carbon to defence, and thereby increases the defence against nematodes. For all three genotypes, elevated CO2 increased height, biomass, and root and leaf total non-structural carbohydrates (TNC):N ratio, and decreased amino acids and proteins in leaves. The activity of anti-oxidant enzymes (superoxide dismutase and catalase) was enhanced by nematode infection in defence-recessive genotypes. Furthermore, elevated CO2 and nematode infection did not qualitatively change the volatile organic compounds (VOC) emitted from plants. Elevated CO2 increased the VOC emission rate only for defence-dominated genotypes that were not infected with nematodes. Elevated CO2 increased the number of nematode-induced galls on defence-dominated genotypes but not on wild-types or defence-recessive genotypes roots. Our results suggest that CO2 enrichment may not only increase plant C : N ratio but can disrupt the allocation of plant resources between growth and defence in some genetically modified plants and thereby reduce their resistance to nematodes.
