Constitutive expression of a novel antimicrobial protein, Hcm1, confers resistance to both Verticillium and Fusarium wilts in cotton.

Tianzhen Zhang,Zhiyuan Zhang,Gongyou Chen,Jun Zhao,Lifang Zou,Lingyun Ding,Yurong Li

doi:10.1038/srep20773

Abstract

Fusarium and Verticillium wilts, two of the most important diseases in cotton, pose serious threats to cotton production. Here we introduced a novel antimicrobial protein Hcm1, which comprised harpin protein from Xanthomonas oryzae pv. oryzicola (Xoc), and the chimeric protein, cecropin A-melittin, into cotton. The transgenic cotton lines with stable Hcm1 expression showed a higher resistance to Verticillium and Fusarium wilts both in greenhouse and field trials compared to controls. Hcm1 enabled the transgenic cotton to produced a microscopic hypersensitive response (micro-HR), reactive oxygen species (ROS) burst, and caused the activation of pathogenesis-related (PR) genes in response to biotic stress, indicating that the transgenic cotton was in a primed state and ready to protect the host from pathogenic infection. Simultaneously, Hcm1 protein inhibited the growth of Verticillium dahliae (V. dahliae) and Fusarium oxysporum (F. oxysporum) in vitro. The spread of fungal biomass was also inhibited in vivo since the V. dahliae biomass was decreased dramatically in transgenic cotton plants after inoculation with V. dahliae. Together, these results demonstrate that Hcm1 could activate innate immunity and inhibit the growth of V. dahliae and F. oxysporum to protect cotton against Verticillium and Fusarium wilts.

Highlights

Fungal disease is a major threat to both crop yields and global food security[1,2,3]
Our results showed that constitutive expression of Hcm[1] in cotton plants increased their resistance to two devasting diseases: Verticillium wilt and Fusarium wilt
disease index (DI) was investigated on June 24, 2014 in Henan according to historical peak incidences. These results showed that the DIs of the three transgenic lines were reduced to 66.77%, 49.83%, and 67.99% compared to the parent W0 (Fig. 2a,c), indicating that expressing Hcm[1] in cotton conferred resistance to Fusarium wilt in a field condition

Summary

Introduction

Fungal disease is a major threat to both crop yields and global food security[1,2,3]. Some researchers report that introducing foreign genes to cotton could enhance resistance to both Verticillium and Fusarium wilts. The plant defensin NaD1, which inhibits the growth of fungal pathogens in vitro, confers resistance to Fusarium wilt and Verticillium wilt in cotton[6]. A novel chimeric protein, Hcm[1], consisting of Hpa1Xoc joined to the active domains of cecropin A-melittin, was constructed It elicited an HR in tobacco, and effectively inhibited the growth of Gram-negative and Gram-positive bacteria in vitro. Hcm[1] was found to confer resistance to a variety of diseases in cotton, including Verticillium wilt and Fusarium wilt, in both greenhouse and field conditions. Our results showed that constitutive expression of Hcm[1] in cotton plants increased their resistance to two devasting diseases: Verticillium wilt and Fusarium wilt

Methods

Results

Conclusion