Sarrocco Sabrina, Matarese Fabiola, Baroncelli Riccardo, Vannacci Giovanni, Seidl-Seiboth Verena, Kubicek Christian Peter, Vergara Mariarosaria
First, second, third, fourth, and seventh authors: Department of Agriculture, Food and Environment, University of Pisa, Italy, via del Borghetto 80, 56124 Pisa, Italy; fifth and sixth authors: Research Area Biotechnology and Microbiology, Institute of Chemical Engineering, TU Wien, 1060 Vienna, Austria; and seventh author: Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56126 Pisa, Italy.
Phytopathology. 2017 May;107(5):537-544. doi: 10.1094/PHYTO-03-16-0139-R. Epub 2017 Mar 20.
Trichoderma spp. are opportunistic fungi some of which are commonly present in the rhizosphere. Several species, such as T. virens, are also efficient biocontrol agents against phytopathogenic fungi and exert beneficial effects on plants. These effects are the consequence of interactions between Trichoderma and plant roots, which trigger enhanced plant growth and induce plant resistance. We have previously shown that T. virens I10 expresses two endopolygalacturonase genes, tvpg1 and tvpg2, during the interaction with plant roots; tvpg1 is inducible while tvpg2 is constitutively transcribed. Using the same system, the tomato polygalacturonase-inhibitor gene Lepgip1 was induced at the same time as tvpg1. Here we show by gene disruption that TvPG2 performs a regulatory role on the inducible tvpg1 gene and in triggering the plant immune response. A tvpg2-knockout strain fails to transcribe the inducible tvpg1 gene in neither in vitro in inducing media containing pectin or plant cell walls, nor during the in vivo interaction with tomato roots. Likewise, the in vivo induction of Lepgip1 does not occur, and its defense against the pathogen Botrytis cinerea is significantly reduced. Our data prove the importance of a T. virens constitutively produced endopolygalacturonase in eliciting plant induced systemic resistance against pathogenic fungi.
木霉菌是机会性真菌，其中一些常见于根际。几种木霉菌，如哈茨木霉，也是对抗植物病原真菌的高效生物防治剂，并对植物产生有益影响。这些影响是木霉菌与植物根系相互作用的结果，这种相互作用会促进植物生长并诱导植物抗性。我们之前已经表明，哈茨木霉I10在与植物根系相互作用期间表达两个内切多聚半乳糖醛酸酶基因tvpg1和tvpg2；tvpg1是可诱导的，而tvpg2是组成型转录的。使用相同的系统，番茄多聚半乳糖醛酸酶抑制剂基因Lepgip1与tvpg1同时被诱导。在这里，我们通过基因敲除表明，TvPG2对可诱导的tvpg1基因以及触发植物免疫反应发挥调节作用。tvpg2基因敲除菌株在含有果胶或植物细胞壁的诱导培养基中进行体外培养时，以及在与番茄根系进行体内相互作用期间，均无法转录可诱导的tvpg1基因。同样，Lepgip1在体内也不会被诱导，其对病原菌灰葡萄孢的防御能力显著降低。我们的数据证明了哈茨木霉组成型产生的内切多聚半乳糖醛酸酶在引发植物对病原真菌的诱导系统抗性中的重要性。
