Improvement of Verticillium Wilt Resistance by Applying Arbuscular Mycorrhizal Fungi to a Cotton Variety with High Symbiotic Efficiency under Field Conditions.

Ning Li,Fanchang Zeng,Xinpeng Gao,Jiajia Qiu,Xinhua Ding,Zhaohui Chu,Yanyun Ren,Qiang Zhang

doi:10.3390/ijms19010241

Abstract

Arbuscular mycorrhizal fungi (AMF) play an important role in nutrient cycling processes and plant stress resistance. To evaluate the effect of Rhizophagus irregularis CD1 on plant growth promotion (PGP) and Verticillium wilt disease, the symbiotic efficiency of AMF (SEA) was first investigated over a range of 3% to 94% in 17 cotton varieties. The high-SEA subgroup had significant PGP effects in a greenhouse. From these results, the highest-SEA variety of Lumian 1 was selected for a two-year field assay. Consistent with the performance from the greenhouse, the AMF-mediated PGP of Lumian 1 also produced significant results, including an increased plant height, stem diameter, number of petioles, and phosphorus content. Compared with the mock treatment, AMF colonization obviously inhibited the symptom development of Verticillium dahliae and more strongly elevated the expression of pathogenesis-related genes and lignin synthesis-related genes. These results suggest that AMF colonization could lead to the mycorrhiza-induced resistance (MIR) of Lumian 1 to V. dahliae. Interestingly, our results indicated that the AMF endosymbiont could directly inhibit the growth of phytopathogenic fungi including V. dahliae by releasing undefined volatiles. In summary, our results suggest that stronger effects of AMF application result from the high-SEA.

Highlights

Cotton (Gossypium spp.) is an essential resource for thousands of consumables and industrial products manufactured across the world
Each pot was planted with five seeds of the same cotton variety, and three seedlings of similar development were reserved for further study
We introduced the concept of symbiotic efficiency of AMF (SEA) and ascertained a broad phenotypic variation of SEA between the interaction of R. irregularis CD1 and seventeen cotton cultivars

Summary

Introduction

Cotton (Gossypium spp.) is an essential resource for thousands of consumables and industrial products manufactured across the world. Verticillium wilt caused by the soil-borne fungus Verticillium dahliae, known as the “cancer” of cotton crops, has become one of the most devastating diseases in cotton-growing areas, resulting in significant losses of plant biomass, lint yield, and fiber quality worldwide [1,2]. This pathogenic fungus can persist alone in the soil for up to 15 years by forming microsclerotia as resting structures [3]. Traditional cross-breeding between the two species has not been successful because of hybrid dysgenesis, linkage drag, or abnormal separations in the progeny [8,9]

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Conclusion