儿茶素在棉苗对枯萎病抗性中的作用

 分析了枯萎病菌接种后棉苗组织内儿茶素含量的变化以及儿茶素对枯萎病菌及其多聚半乳糖醛酸酶活性的影响。健康棉苗组织中儿茶素含量随着棉苗的生长而增加。枯萎病菌接种后,病苗组织中儿茶素含量显著高于健康对照,而且抗病品种棉苗儿茶素含量的增加明显高于感病品种。经氟乐灵预处理的棉苗接种枯萎病菌后,儿茶素含量增加更快,增幅更大。说明儿茶素是品种抗性和氟乐灵诱发棉苗对枯萎病诱导抗性的机理之一。儿茶素可抑制枯萎病菌的菌丝生长、产孢及孢子萌发,对培养液中病菌的多聚半乳糖醛酸酶(PG)有抑制作用。儿茶素化学制品及棉苗组织提取液经TLC分离后获得的含儿茶素组分提取液对初步纯化的PG活性有明显的抑制作用。这些结果表明:儿茶素可能通过抑制病菌的菌丝生长、产孢以及其PG活性而在棉花对枯萎病的抗病性中起到作用。

EFFECT OF CATECHIN IN COTTON SEEDLINGS ON THEIR RESISTANCE TO FUSARIUM

Cotton seeds (Gossypium hirsutum) of resistant or susceptible cultivar were sown in soil treated with trifluralin at 2 μg/g soil.The 10 day old seedlings were inoculated with Fusarium oxysporum f.sp. vasinfectum (Fov).Catechin accumulation slowly with in the seedling leaves and stems/roots was detected.In the healthy seedlings,catechin accumulated slowly with the seedling growing.After inoculation,catechin levels in the diseased seedlings were significantly higher than those in the healthy ones.When infected,the seedlings of the resistant cv.showed markedly higher rate and levels of catechin accumulation than those of susceptible cv..The trifluralin treated seedlings showed the fastest and the greatest catechin accumulation after inoculation.The results indicated that catechin accumulation was involved in the resistance mechanisms of cotton cultivars and trifluralin induced resistance to Fusarium wilt.Catechin compound was observed to inhibit mycelial growth,sporulation and macroconidia germination of Fov,and to inactivate polygalacturonase (PG) of Fov in vitro.The activity of partial purified PG from Fov was also inhibited by catechin compound and catechin fraction from TLC separation of the 50% ethanol extracts from cotton tissues.The results presented suggested that the involvement of catechin in cotton resistance to Fusarium wilt may be related to its effects on the fungal growth,sporulation,spore germination and the PG activity of the pathogen.