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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #261650
Title: ZmGns, a maize class I beta-1,3-glucanase, is induced by biotic stresses and possesses strong antimicrobial activity

Author
item XIE, YU-RONG - Louisiana State University
item RARUANG, YENJIT - Louisiana State University
item CHEN, ZHI-YUAN - Louisana State University
item Brown, Robert
item Cleveland, Thomas

Submitted to: Journal of Integrative Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2014
Publication Date: 11/17/2014
Citation: Xie, Y-R., Raruang, Y., Chen, Z-Y., Brown, R.L., Cleveland, T.E. 2014. ZmGns, a maize class I beta-1,3-glucanase, is induced by biotic stresses and possesses strong antimicrobial activity. Journal of Integrative Plant Biology. 57(3):271-283.

Interpretive Summary: The fungus named Aspergillus flavus produces a poison called aflatoxin when it infects corn kernels. Aflatoxin prevents the corn from being used commercially. The best strategy for controlling this problem is to develop corn that is resistant to aflatoxin contamination. Towards this aim, we isolated and identified through comparisons of resistant with susceptible corn lines, proteins that are produced in relatively higher amounts in the resistant lines. One of these proteins responds to biotic and abiotic stress and is called ß-1,3-glucanase and is designated ZmGns. The gene corresponding to ZmGns was cloned and the gene and protein were studied to identify properties that may be related to aflatoxin-resistance. We discovered that ZmGns was induced by biotic stress including the fungus Aspergillus flavus. We also found that ZmGns was induced by most abiotic stresses tested and that it inhibited the growth of Aspergillus flavus. This indicates a potential role in plant resistance. Further studies may determine this protein to be a marker for resistance and therefore useful to breeders developing aflatoxin-resistant commercial corn. This could lead to future savings of millions of dollars to growers, as a result of the elimination of aflatoxin contamination of corn.

Technical Abstract: Plant ß-1,3-glucanases are members of the pathogenesis-related protein 2 (PR-2) family, which is one of the 17 PR protein families and plays important roles in biotic and abiotic stress responses. One of the differentially expressed proteins (spot 842) identified in a recent proteomic comparison between five pairs of closely-related maize lines differing in aflatoxin resistance and showed high homology to glucanase was further investigated in the present study. Here, the corresponding cDNA was cloned from maize and designated as ZmGns. ZmGns is deduced to encode a premature protein of 338 amino acids containing a potential signal peptide of 29 amino acids with a calculated molecular mass and isoelectric point of 35.9 kDa and 9.33, respectively. The expression of ZmGns was detectible in the root and all aerial tissues studied with the highest level in silks. ZmGns was significantly induced by biotic stresses including the bacteria Clavibacter michiganensis subsp. nebraskensis, Erwinia stewartii and Erwinia chrysanthemi, and the fungus Aspergillus flavus. ZmGns was also induced by most abiotic stresses tested with an initial down-regulation, but inhibited by MeJA. ZmGns showed ß-1,3-glucanase specific activity in vitro with an optimal pH and temperature of 5.5 and 50ºC. Its activity was strongly inhibited by 1 mM of Ag+, Mn2+ or SDS. In addition, ZmGns showed a significant inhibitory activity against a bacterial pathogen Pseudomonas syringae pv. tomato DC3000 in vivo and a fungal pathogen A. flavus in vitro, which indicates its potential important role in host plant defense.