English

Islas Flores Ignacio,Alcocer Alvarez Carmela,Canto Canche Blondy

doi:10.5897/ajb2014.14334

Abstract

The fungus Mycosphaerella fijiensis causes black Sigatoka (BS) disease, a major pathogen in the banana industry worldwide. Numerous molecular and biochemical studies have been done for the M. fijiensis, Musa acuminata interaction, but this is the first study describing the zymographic behavior of β-1,3-glucanase, chitinase and protease in the apoplast and symplast of healthy, BS-infected but asymptomatic and BS diseased banana leaves. In BS-infected tissues, β-1,3-glucanase enzymatic activity was associated with two polypeptides with retention index (R i ) values of 0.43 and 0.56. These were more notable in the apoplast than in the symplast. Chitinase activity in BS-infected tissue in both the apoplast and symplast was mainly associated with a single polypeptide (R i = 0.89). Both β-1,3-glucanase and chitinase activities were apparently more intense in BS-infected leaves than in healthy leaves. Protease activity was associated with two polypeptides (R i = 0.04 and 0.14). In both the apoplast and symplast, the Ri 0.04 polypeptide increased in intensity with disease progression, whereas R i 0.14 polypeptide intensity decreased. Overall protease activity intensity was higher in the symplast. Maximum symplast contamination of the apoplast was 2% as estimated by glucose 6-phosphate dehydrogenase activity, a biochemical marker for symplast. Accumulation of pathogenesis-related enzymatic activities in the apoplast of M. acuminata leaf tissue was caused by hostcontrolled enzyme downloading in response to M. fijiensis infection. Clear differences were identified in the electrophoretic profiles of healthy and diseased banana plants. The results further support a putative role of these enzymes in the extracellular defense repertoire of banana and, more importantly, suggest that M. fijiensis possesses a mechanism for suppression and delay of defense response in M. acuminata . Key words : Black Sigatoka, glucose 6-phosphate dehydrogenase, pathogenesis-related (PR) proteins, polyacrylamide gel electrophoresis (PAGE), retention index (Ri), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

Highlights

The apoplast is a continuous space surrounding plant cells, and is comprised of the cell wall matrix and intercellular spaces
The 32.6, 25.9, 20.6, 11 and 7.1 kDa polypeptides decreased in abundance in comparison with levels in the healthy symplast (Figure 1b, lanes 2 and 3)
The present study follows up on pilot research by Mendoza-Rodríguez et al (2006). They began focusing on isolation of apoplastic proteins from the M. fijiensis-M. acuminata interaction, but obtained very low amounts of denatured proteins

Summary

Introduction

The apoplast is a continuous space surrounding plant cells, and is comprised of the cell wall matrix and intercellular spaces. When bacteria and fungi attempt to gain access to the cell apoplast through the stomata or cuticle, the plant cell must respond to this challenge to protect itself This can be accomplished via secretion of proteins that exert protective functions (Floerl et al, 2008), including a vital group known as pathogenesis-related (PR) proteins (van Loon and Kammen, 1970; van Loon and Strien, 1999; Blein et al, 2002; Brito-Argáez et al, 2010). Extraction and characterization of the apoplastic proteins involved in pathogenesis or plant defense is an important strategy for study of specific pathosystems This method is known to be feasible in diverse plantpathogen interactions for example Cladosporium fulvumLycopersicon esculentum (Joosten and De Wit, 1989); Leptosphaeria maculans-Brassica napus (Brownfield and Howlett, 2001); non-pathogenic bacteria-Malus domestica (Kürkcüoglu et al, 2004); Verticillium longisporum-Brassica napus var. They are biologically significant, research into apoplastic proteins is hampered by their low abundance relative to overall intracellular protein concentration (Haslam et al, 2003; Mendoza-Rodríguez et al, 2006)

Methods

Results

Conclusion