J Integr Plant Biol. ›› 2004, Vol. 46 ›› Issue (6): 738-743.

• Research Articles • Previous Articles     Next Articles

Identification of Amino Acids of Cladosporium fulvum CfHNNI1 Required for Function of Necrosis Induction in Plants

CAI Xin-Zhong   


Nonhost resistance is durable and broad-spectrum, which attracts more and more attention for its great potential to be exploited in crop protection against diseases. However, mechanism of nonhost resistance is largely unknown. Previously a cDNA clone of tomato leaf mould pathogen Cladosporium fulvum Cooke was isolated. It is highly homologous in sequence to bZIP transcription factors. Upon expression it results in necrosis in its host tomato (Lycopersicon esculentum Mill.) and nonhost Nicotiana spp. and confers resistance to potato virus X, and thus is named CfHNNI1 (C. fulvum host and nonhost necrosis inducer 1). The present paper reports the results on mutational analyses of the relationship between the amino acid sequences of putative DNA-binding and leucine zipper domains of CfHNNI1 and the necrosis-inducing function of CfHNNI1. Deletion of six amino acids R112-N117 (RKRQRN) or substitution of alanines for arginines R125 and R127 of DNA-binding domain almost completely abolished or severely lowered the necrosis-inducing activity of CfHNNI1, while substitution of alanines for leucine L149 or L163 of leucine zipper domain partially impaired the necrosis-inducing activity of CfHNNI1. Adding of tobacco PR-1a signal peptide to CfHNNI1 so that the mature product CfHNNI1 was secreted into extracellular compartment resulting in complete loss of the necrosis-inducing activity. It was concluded that amino acids R112-N117, R125 and R127, L149 and L163 of putative DNA-binding and leucine zipper domains of CfHNNI1 and inner cellular localization of mature protein were required for full necrosis-inducing function of CfHNNI1.

Key words: CfHNNI1, necrosis, mutational analysis, bZIP transcription factor, inner cellular localization, Cladosporium fulvum , nonhost resistance

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2022 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q