The Nag1 N-acetylglucosaminidase of Trichoderma atroviride is essential for chitinase induction by chitin and of major relevance to biocontrol

被引:98
作者
Brunner, K
Peterbauer, CK
Mach, RL
Lorito, M
Zeilinger, S
Kubicek, CP
机构
[1] Vienna Univ Technol, Abt Angew Biochem & Gentech, Inst Verfahrenstech, Umwelttech & Tech Biowissen, A-1060 Vienna, Austria
[2] Univ Naples Federico II, Dipartimento Arboricoltura Bot & Patol Vegetale, Sez Patol Vegetale, I-80050 Portici, NA, Italy
[3] CNR, CETELOBI, I-80050 Portici, NA, Italy
[4] Univ Bodenkultur Wien, Inst Lebensmitteltechnol, A-1190 Vienna, Austria
基金
奥地利科学基金会;
关键词
Trichoderma; biocontrol; induction chitinase regulation;
D O I
10.1007/s00294-003-0399-y
中图分类号
Q3 [遗传学];
学科分类号
071007 ; 090102 ;
摘要
The nag1 gene of the mycoparasitic fungus Trichoderma atroviride encodes a 73-kDa N-acetyl-beta-D-glucosaminidase, which is secreted into the medium and partially bound to the cell wall. To elucidate the role of this enzyme in chitinase induction and biocontrol, a nag1-disruption mutant was prepared. It displayed only 4% of the original N-acetyl-beta-D-glucosaminidase activity, indicating that the nag1 gene product accounts for the majority of this activity in T. atroviride. The nag1-disruption strain was indistinguishable from the parent strain in growth and morphology, but exhibited delayed autolysis. Northern analysis showed that colloidal chitin disruption does not induce ech42 gene transcription in the nag1-disruption strain. Enzyme activities capable of hydrolysing 1-nitrophenyl-N,N-diacetylchitobloside and p-nitrophenyl-N,N-diacetylchitotriose were also absent from the nag1-disruption strain under the same conditions. Retransformation of the T. atroviride nag1-disruption strain with the nag1 gene essentially led to the parent-type behaviour in all these experiments. However, addition of N-acetyl-beta-D-glucosaminidase to the medium of the nag1-disruption strain did not rescue the mutant phenotype. The disruption-nag1 strain showed 30% reduced ability to protect beans against infection by Rhizoctonia solani and Sclerotinia sclerotiorum. The data indicate that nag1 is essential for triggering chitinase gene expression in T. atroviride and that its functional impairment reduces biocontrol by T. atroviride by a significant extent.
引用
收藏
页码:289 / 295
页数:7
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