AM真菌和胞囊线虫对大豆根内酶活性的影响*

将‘鲁豆4号’大豆接种丛枝菌根(AM)真菌聚生球囊霉Glomus fasiculatum和大豆胞囊线虫(SCN)Heterodera glycines 4号生理小种后, 定期测定大豆根系中AM真菌及线虫侵染速率、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、β-1,3葡聚糖酶及几丁质酶活性的动态变化。结果表明, 接种AM真菌大豆根系中4种酶活性高于对照水平; 先接种AM真菌后接种SCN处理根系中POD、PAL及几丁质酶的活性高于只接种SCN的处理,并且酶活性峰值出现的时间均早于或相当于后者。另外,PAL及几丁质酶活性出现高峰时期也正是AM真菌侵染率迅速升高及线虫侵染速率快速下降期。因此,AM真菌先激活了大豆的防御反应,然后使其对SCN的侵染产生快速反应,PAL及几丁质酶在AM真菌诱导的抗、耐线虫病害机制中起重要作用。值得注意的是,先接种AM真菌后接种SCN处理大豆根系中,β-1,3葡聚糖酶活性低于只接种AM真菌的处理。作者认为本试验条件下,该酶在大豆抗SCN病害中的作用表现不明显。

INFLUENCE OF ARBUSCULAR MYCORRHIZAL FUNGI AND HETERODERA GLYCINES ON ENZYME ACTIVITY IN SOYBEAN ROOTS

Soybean cultivars 慙udou 4?were inoculated with arbuscular mycorrhizal(AM) fungus, Glomus fasiculatum and soybean cyst nematode Heterodera glycines race 4. The dynamic changes of colonization of AM fungi, penetration rate of SCN, activities of peroxidase(POD), phenylalanine ammonia lyase(PAL), β-1,3-glucanase and chitinase in roots were analyzed. Results showed that activities of the four enzymes in roots colonized by G. fasiculatum were higher than those in control roots; POD, PAL and chitinase activities in roots pre-inoculated with the fungus and post-inoculated with SCN were higher than those in roots treated with SCN, while the peak of enzyme activities in the former treatment appeared earlier or in the same time as compared with the latter treatment. In addition, the time when the peak of PAL and chitinase activities occurred was just the time when the AM fungi colonization increased and SCN penetration decreased fastly in the mycorrhizal soybean roots infected with SCN in comparison with the soybean roots only inoculation with SCN. It was suggested that AM fungi could first activate the defense mechanism of soybean, and then made the roots of soybean reacting quickly to SCN infection, PAL and chitinase play critical role in the disease-resistance induced by AM fungi against nematode. While β-1,3-glucanase activities in roots of pre-inoculating with G. fasiculatum and post-inoculating with SCN were lower than those in roots treated with G. fasiculatum. Thus, the role of β-1,3-glucanase in protecting soybean from infection of SCN was not obvious under the present experiment condition.