Physiological Analysis Reveals the Possible Resistance Mechanisms of Glycine max to Fusarium solani

George Bawa,Wenyu Yang,Lingyang Feng,Xin Sun,Xiaoling Wu,Jing Shang,Yan Li,Xiaoli Chang,Junbo Du,Chunyan Liu,Yu Liu

doi:10.5539/jas.v10n11p44

Abstract

Sudden death syndrome (SDS) of soybean is a complex root rot disease caused by the semi-biotrophic fungus Fusarium solani (F. solani) and a leaf scorch disease; caused by toxins produced by pathogen in the roots. However, the mechanism of soybean resistant to F. solani is still poorly understood. Eighteen soybean cultivars were screened for SDS resistance, with one cultivar showing susceptibility and one cultivar showing resistance to F. solani infection. Histochemical analysis with diaminobenzidine (DAB) and Trypan blue staining indicated an accumulation of reactive oxygen species (ROS) and cell death in surrounding area of SDS which was higher in susceptible cultivar than in resistant cultivar. Furthermore, exogenous salicylic acid (SA) application also induced some level of resistance to F. solani by the susceptible cultivar. A biochemical study revealed that the activities of superoxide dismutase (SOD), peroxidase (POD), and enzymes involved in scavenging ROS, increased in susceptible cultivar after SDS infection. In addition, hydrogen peroxide (H2O2) and malondialdehyde (MDA) content also increased in the susceptible cultivar than in resistant cultivar. High-performance liquid chromatography (HPLC) analysis indicated that free and total salicylic acid (SA) content increased in the susceptible cultivar than in resistant cultivar. In addition, a real-time quantitative PCR analysis showed an accumulation of pathogen related (PR) genes in the resistant cultivar than in susceptible cultivar. Our results show that (i). F. solani infection can increase endogenous SA levels, antioxidase activities, ROS and cell death in susceptible soybean cultivar to induce resistance against Fusarium solani. (ii). F. solani infection induced the expression of SA marker genes in resistant soybean cultivar to enhance resistance.

Highlights

Soybean production is often affected by many diseases in major cropping areas (Wrather et al, 2010)
The plant cells stained by DAB and Trypan blue produced a high amount of reactive oxygen species (ROS) and cell death in the area of infection respectively
Enzymatic and non-enzymatic antioxidative pathways which are involved in the production of signaling molecules were increased in Jiuyuehuang

Summary

Introduction

Soybean production is often affected by many diseases in major cropping areas (Wrather et al, 2010). Sudden death syndrome (SDS) caused by Fusaruim solani (F. solani) occurs frequently in the top eight soybean producing countries in the world (Wrather et al, 2010). SDS is associated with root rot, vascular discoloration of stems, root chlorosis and necrosis, defoliation and plant death (Roy et al, 1997). SDS is more detected in soybean fields after flowering, when the leaves show interveinal choroids and necrosis. SDS can be expressed in severe and mild forms. The occurrence and geographical distribution of pathogens causing the latter is unknown (Scandiani et al, 2011)

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