摘要：地上与地下生物的互作联系是当代生态学研究的热点，而大气中CO2浓度升高是未来发生的必然趋势。由于茉莉酸介导的系统防御能够贯串植物的地上与地下部分，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危害有机的联系起来，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学研究组在CO2人工气候箱中，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三种试验材料，研究了大气CO2浓度倍增（750ppm）的环境下，三种基因型番茄对南方根结线虫抗性的变化。研究发现，大气CO2浓度升高降低了野生型和35S番茄中以蛋白酶抑制剂（PI）为代表的茉莉酸诱导防御水平，增加了野生型和spr2番茄中以病程相关蛋白（PR）为代表的水杨酸诱导防御水平。CO2浓度升高改变了不同番茄基因型的茉莉酸和水杨酸诱导防御途径下游基因的表达，以及总酚、黄酮和单宁等次生物质含量，从而降低了茉莉酸防御途径加强型番茄35S对线虫的抗性。
结果表明：尽管CO2浓度升高同时增加三种基因型番茄的碳氮比，加快了植物的生长发育，却改变了不同基因型内源防御途径的互作关系，进而导致不同基因型番茄在未来环境下对地下线虫抗性的变化。
以上研究发表在PLoS one（Yucheng Sun, Jin Yin, Haifeng Cao, Le Kang, Chuanyou Li & Feng Ge* 2011. Elevated CO2 influences nematode-induced defense responses of tomato genotypes differing in the JA pathway. 6（5）:e19751）。
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。
生物探索推荐英文原文摘要：
Elevated CO2 Influences Nematode-Induced Defense Responses of Tomato Genotypes Differing in the JA Pathway
Abstract
Rising atmospheric CO2 concentrations can affect the induced defense of plants against chewing herbivores but little is known about whether elevated CO2 can change the induced defense of plants against parasitic nematodes. This study examined the interactions between the root-knot nematode Meloidogyne incognita and three isogenic tomato (Lycopersicon esculentum) genotypes grown under ambient (390 ppm) and elevated (750 ppm) CO2 in growth chambers. In a previous study with open-top chambers in the field, we reported that elevated CO2 increased the number of nematode-induced root galls in a JA-defense-dominated genotype but not in a wild-type or JA-defense-recessive genotype. In the current study, we tested the hypothesis that elevated CO2 will favor the salicylic acid (SA)-pathway defense but repress the jasmonic acid (JA)-pathway defense of plants against plant-parasitic nematodes. Our data showed that elevated CO2 reduced the JA-pathway defense against M. incognita in the wild-type and in a genotype in which defense is dominated by the JA pathway (a JA-defense-dominated genotype) but up-regulated the SA-pathway defense in the wild type and in a JA-defense-recessive genotype (jasmonate-deficient mutant). Our results suggest that, in terms of defense genes, secondary metabolites, and volatile organic compounds, induced defense of nematode-infected plants could be affected by elevated CO2, and that CO2-induced changes of plant resistance may lead to genotype-specific responses of plants to nematodes under elevated CO2. The changes in resistance against nematodes, however, were small relative to those reported for chewing insects.
