大多数陆生植物的根与土壤传播的丛枝菌根真菌(AMF)形成共生关系(菌根)。许多研究表明,菌根定植增强了植物对病原真菌的抗性。然而,菌根诱导的抗病机制仍然是模棱两可。在这项研究中,我们发现,用AMF真菌菌根接种可显着缓解番茄(SolanumlycopersicumMill。)由solaniSorouer引起的早期疫病。AMF预接种导致β-1,3-葡聚糖酶活性显着增加,几丁质酶,接种病原体后番茄叶片中的苯丙氨酸解氨酶(PAL)和脂氧合酶(LOX)。单独的菌根接种不会影响大多数测试基因的转录本。然而,病原体对接种AMF的植物的攻击引起了编码致病相关蛋白的三个基因的强烈防御反应,PR1、PR2和PR3,以及防御相关基因LOX,AOC,PAL,在番茄叶中。在存在病原体感染的情况下,AMF预接种植物中防御反应的诱导比未接种植物高得多,也更快。三种番茄基因型:Castlemart野生型(WT)植物,茉莉酸(JA)生物合成突变体(spr2),和过表达前系统蛋白的35S::PS植物用于检查JA信号通路在AMF引发的疾病防御中的作用。与WT植物相比,菌根35S::PS植物上的病原体感染导致防御相关基因和酶的诱导更高。然而,病原体感染在菌根spr2突变体植物中没有诱导这些基因和酶。生物测定表明,与WT植物相比,35S::PS植物更具抗性,spr2植物更容易受到早疫病的影响。我们的发现表明,菌根定植通过引发系统防御反应来增强番茄对早期疫病的抗性,而JA信号通路对于菌根引发的抗病性至关重要。
Roots of most terrestrial plants form symbiotic associations (mycorrhiza) with soil- borne arbuscular mycorrhizal fungi (AMF). Many studies show that mycorrhizal colonization enhances plant resistance against pathogenic fungi. However, the mechanism of mycorrhiza-induced disease resistance remains equivocal. In this study, we found that mycorrhizal inoculation with AMF Funneliformis mosseae significantly alleviated tomato (Solanum lycopersicum Mill.) early blight disease caused by Alternaria solani Sorauer. AMF pre-inoculation led to significant increases in activities of β-1,3-glucanase, chitinase, phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX) in tomato leaves upon pathogen inoculation. Mycorrhizal inoculation alone did not influence the transcripts of most genes tested. However, pathogen attack on AMF-inoculated plants provoked strong defense responses of three genes encoding pathogenesis-related proteins, PR1, PR2, and PR3, as well as defense-related genes LOX, AOC, and PAL, in tomato leaves. The induction of defense responses in AMF pre-inoculated plants was much higher and more rapid than that in un-inoculated plants in present of pathogen infection. Three tomato genotypes: a Castlemart wild-type (WT) plant, a jasmonate (JA) biosynthesis mutant (spr2), and a prosystemin-overexpressing 35S::PS plant were used to examine the role of the JA signaling pathway in AMF-primed disease defense. Pathogen infection on mycorrhizal 35S::PS plants led to higher induction of defense-related genes and enzymes relative to WT plants. However, pathogen infection did not induce these genes and enzymes in mycorrhizal spr2 mutant plants. Bioassays showed that 35S::PS plants were more resistant and spr2 plants were more susceptible to early blight compared with WT plants. Our finding indicates that mycorrhizal colonization enhances tomato resistance to early blight by priming systemic defense response, and the JA signaling pathway is essential for mycorrhiza-primed disease resistance.