Co-infection by Soil-Borne Fungal Pathogens Alters Disease Responses Among Diverse Alfalfa Varieties

• Published in: Frontiers in microbiology Vol. 12; p. 664385
• Main Authors: Fang, Xiangling, Zhang, Caixia, Wang, Zi, Duan, Tingyu, Yu, Binhua, Jia, Xitao, Pang, Jiayin, Ma, Lisong, Wang, Yanrong, Nan, Zhibiao
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 14.07.2021
• Subjects: co-infection; Fusarium oxysporum; Microbiology; Rhizoctonia solani; root rot; single infection; wilt; Fusarium oxysporum; alfalfa; co-infection; host disease resistance; Rhizoctonia solani; wilt; single infection; root rot
• DOI: 10.3389/fmicb.2021.664385
• ISSN: 1664-302X

Fusarium oxysporum f. sp. medicaginis (Fom) and Rhizoctonia solani (Rs) are the major soil-borne fungal pathogens that pose severe threats to commercial alfalfa production in China. However, the effects of Fom and Rs co-infection on alfalfa and whether co-infection alters disease resistance responses among diverse varieties remain unknown. A collection of 80 alfalfa varieties ( Medicago sativa ) originated from seven countries were used to study the effects of Fom and Rs co-infection on alfalfa and host resistance responses. The co-infection resulted in more severe disease and reductions in growth and biomass allocation across varieties in comparison with either single infection by Fom or Rs; in addition, root morphology was much more strongly altered by the co-infection. Principal component analysis based on all plant traits showed that varieties under the co-infection were related to the single infection by Rs, being separated from Fom, and hierarchical clustering found differential response patterns among varieties upon co-infection compared with either single infection, with most varieties being highly susceptible to the co-infection. Furthermore, varieties that were most resistant to either single infection were not effective to co-infection, and there was no individual variety with resistance to both pathogens singly and co-infected. This study reveals for the first time that the co-infection by Fom and Rs alters disease resistance responses among diverse alfalfa varieties and provides useful information for developing alfalfa varieties with resistance to the co-occurrence of different soil-borne pathogens.