豌豆蚜为害下CO2浓度升高对两种不同固氮能力蒺藜苜蓿间接防御的影响

大气CO_2浓度升高增加了豆科植物的光合作用和生物固氮能力,从而改变植物对初生和次生代谢产物的资源配置,进而影响植物与昆虫互作。为了明确CO_2浓度升高条件下豆科植物对蚜虫间接防御的影响,利用蒺藜苜蓿Medicago truncatula固氮突变体dnf1和野生型植株Jemalong研究CO_2浓度升高对不同固氮能力蒺藜苜蓿挥发物释放的影响,从而改变蒺藜苜蓿对豌豆蚜Acyrthosiphon pisum的间接防御。结果表明,豌豆蚜为害显著诱导蒺藜苜蓿野生型和固氮突变体中单萜类化合物4-蒈烯、倍半萜类挥发物(E)-β-法呢烯以及绿叶挥发物顺式-3-己烯-1-醇的释放。CO_2浓度升高降低了野生型Jemalong受害植株上2-蒈烯和柠檬烯以及绿叶挥发物顺式-3-己烯-1-醇的释放量,却没有改变固氮突变体dnf1上这几种单萜类及绿叶挥发物的释放。正常CO_2浓度下,固氮突变体dnf1受害植株上2-蒈烯、4-蒈烯、柠檬烯的释放量与野生型Jemalong受害植株无显著差异,而CO_2浓度升高条件下固氮突变体dnf1受害植株上2-蒈烯、4-蒈烯、柠檬烯的释放量显著高于野生型Jemalong受害植株。表明CO_2浓度升高条件下豆科植物对蚜虫的间接防御降低。

Elevated atmospheric CO2 concentration decreases the indirect defense of Medicago truncatula against the pea aphid by suppressing volatile release

Elevated atmospheric CO2 concentration increases the photosynthesis and biological nitrogen fixation of legume plants,which would change the resource allocation of primary and secondary metabolites,and subsequently change the interactions between plants and insects.In the present study,the Medicago truncatula nitrogen fixation mutant dnf1 and its wild type Jemalong were used to study how elevated atmospheric CO2 concentration affects the indirect defense of legume plants against the pea aphid by altering the release of plant volatiles.The results showed that aphid infestation significantly induced the release of monoterpenoids 4-carene,sesquiterpenes (E)-β-farnesene as well as green leaf volatiles (E)-2-hexenol and Z-3-hexen-1-ol of both genotypes.The atmospheric CO2 concentration decreased the release of monoterpenoids 2-carene,α-phellandrene and limonene and green leaf volatiles Z-3-hexene-1-ol in the infested wild-type plant Jemalong,but there was no change in nitrogen-fixing mutant dnf1.The infested nitrogen-fixing mutant plant dnf1 released similar amount of 2-carene,4-carene and limonene to the infested wild-type plant Jemalong under ambient CO2,but emissions of 2-carene,4-carene,and limonene were higher than the infested wild-type plant Jemalong under elevated CO2.Thus,this study provided a scientific evidence that indirect defense of legume plants against aphids would be decreased with increasing concentrations of atmospheric CO2 in the future.