Physiological response and sulfur metabolism of the V. dahliae-infected tomato plants in tomato/potato onion companion cropping.

Xuepeng Fu,Shouwei Liu,Fengzhi Wu,Xingang Zhou,Chunxia Li

doi:10.1038/srep36445

Xuepeng Fu, Shouwei Liu + Show 3 more

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https://doi.org/10.1038/srep36445

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Abstract

Companion cropping with potato onions (Allium cepa var. agrogatum Don.) can enhance the disease resistance of tomato plants (Solanum lycopersicum) to Verticillium dahliae infection by increasing the expressions of genes related to disease resistance. However, it is not clear how tomato plants physiologically respond to V. dahliae infection and what roles sulfur plays in the disease-resistance. Pot experiments were performed to examine changes in the physiology and sulfur metabolism of tomato roots infected by V. dahliae under the companion cropping (tomato/potato onion). The results showed that the companion cropping increased the content of total phenol, lignin and glutathione and increased the activities of peroxidase, polyphenol oxidase and phenylalanine ammonia lyase in the roots of tomato plants. RNA-seq analysis showed that the expressions of genes involved in sulfur uptake and assimilation, and the formation of sulfur-containing defense compounds (SDCs) were up-regulated in the V. dahlia-infected tomatoes in the companion cropping. In addition, the interactions among tomato, potato onion and V. dahliae induced the expression of the high- affinity sulfate transporter gene in the tomato roots. These results suggest that sulfur may play important roles in tomato disease resistance against V. dahliae.

Highlights

Companion cropping with potato onions (Allium cepa var. agrogatum Don.) can enhance the disease resistance of tomato plants (Solanum lycopersicum) to Verticillium dahliae infection by increasing the expressions of genes related to disease resistance
Previous studies have shown that companion cropping with potato onions alleviates tomato Verticillium Wilt by up-regulating the expression levels of genes related to disease resistance in tomatoes infected with V. dahliae[5], and by the inhibition effect of tomato root exudates on V. dahliae
The results showed that at 18 days after inoculation (DAI), the disease incidence was not significantly different between tomato monoculture (TM) and tomato/potato onion companion cropping (TC) but was decreased in TC compared with that in TM (p < 0.05) (Fig. 1A)

Summary

Introduction

Companion cropping with potato onions (Allium cepa var. agrogatum Don.) can enhance the disease resistance of tomato plants (Solanum lycopersicum) to Verticillium dahliae infection by increasing the expressions of genes related to disease resistance. The interactions among tomato, potato onion and V. dahliae induced the expression of the high- affinity sulfate transporter gene in the tomato roots These results suggest that sulfur may play important roles in tomato disease resistance against V. dahliae. Previous studies have shown that companion cropping with potato onions alleviates tomato Verticillium Wilt by up-regulating the expression levels of genes related to disease resistance (encoding proteins such as pathogenesis-related proteins and those involved in lignin biosynthesis, phytohormone metabolism and signal transduction) in tomatoes infected with V. dahliae[5], and by the inhibition effect of tomato root exudates on V. dahliae. The accumulation of S0 and glutathione rapidly increases in higher resistance tomato and pepper cultivars compared with lower resistance and susceptible plants[14,15] These studies have demonstrated that sulfur plays important roles in plant disease resistance. Additional studies are needed to determine whether sulfur is involved in the disease resistance of tomato plants against V. dahliae in the tomato/potato onion companion cropping system

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