Bell pepper (Capsicum annuum L.) fruit are susceptible to various molds, including grey mold and Alternaria rot. In this work, antagonistic bacteria isolated from disease-suppressive composts were assessed for their ability to reduce the mycelial growth of Botrytis cinerea Persoon and Alternaria alternata (Fries) Keissler as well as to suppress grey mold and Alternaria rot on bell pepper. Results showed that different bacterial antagonists reduced mycelial growth of B. cinerea and A. alternata by up to 49% and 53%, respectively. The bacteria provided inhibition of grey mold, reducing incidence and severity by as much as 43% and 67%, respectively. The isolates also provided strong inhibitory effects against Alternaria rot, decreasing incidence and severity by as much as 77% and 80%, respectively. Pseudomonas and Arthrobacter spp. were particularly suppressive to Alternaria rot. Results of this study suggest antagonistic bacteria may represent a potential method for controlling fruit rot of bell pepper.

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Root-knot nematode (RKN) infections are among the most serious soil-borne diseases in the world, and tomato is a common host of RKNs. WRKY transcription factors are involved in complex, diverse biological processes in plants. In a previous study, a resistant variety, LA3858 (Mi-3/Mi-3), was treated at different soil temperatures before RNA-seq, and six differentially expressed genes (DEGs) encoding WRKY proteins were screened. In this study, cloning and sequencing were used to identify six target DEGs encoding SlWRKY1, SlWRKY13, SlWRKY30, SlWRKY41, SlWRKY46, and SlWRKY80. Conserved domain identification and phylogenetic tree analysis showed that SlWRKY1, SlWRKY13, and SlWRKY46 have similar functions and are mainly involved in plant growth and development and abiotic stress responses. SlWRKY30 and SlWRKY41 share high homology, while AtWRKY46 and AtWRKY70, which are highly homologous to SlWRKY80, play an important role in the disease resistance of A. thaliana. Considering these findings combined with the high level of SlWRKY80 expression observed in the roots and leaves of the resistant variety Motelle (Mi-1/Mi-1) and the continuous upregulation of SlWRKY80 expression in the roots after inoculation of Motelle with M. incognita, it is speculated that SlWRKY80 plays an important role in the Mi-1-mediated disease resistance pathway. Further study revealed that SlWRKY80 is a typical nuclear-localized protein, and a virus-induced gene silencing (VIGS) assay verified that SlWRKY80 is involved in tomato resistance to RKNs as a positive regulator. SA and JA signals play an important role in Mi-1-mediated resistance to RKNs. SlWRKY80 was able to respond rapidly to treatment with both plant hormones, which indicated that SlWRKY80 might be involved in disease resistance regulation through various immune pathways.