MaSMG7-Mediated Degradation of MaERF12 Facilitates Fusarium oxysporum f. sp. cubense Tropical Race 4 Infection in Musa acuminata.

Modern plant breeding relies heavily on the deployment of susceptibility and resistance genes to defend crops against diseases. The expression of these genes is usually regulated by transcription factors including members of the AP2/ERF family. While these factors are a vital component of the plant immune response, little is known of their specific roles in defense against Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) in banana plants. In this study, we discovered that MaERF12, a pathogen-induced ERF in bananas, acts as a resistance gene against Foc TR4. The yeast two-hybrid assays and protein-protein docking analyses verified the interaction between this gene and MaSMG7, which plays a role in nonsense-mediated RNA decay. The transient expression of MaERF12 in Nicotiana benthamiana was found to induce strong cell death, which could be inhibited by MaSMG7 during co-expression. Furthermore, the immunoblot analyses have revealed the potential degradation of MaERF12 by MaSMG7 through the 26S proteasome pathway. These findings demonstrate that MaSMG7 acts as a susceptibility factor and interferes with MaERF12 to facilitate Foc TR4 infection in banana plants. Our study provides novel insights into the biological functions of the MaERF12 as a resistance gene and MaSMG7 as a susceptibility gene in banana plants. Furthermore, the first discovery of interactions between MaERF12 and MaSMG7 could facilitate future research on disease resistance or susceptibility genes for the genetic improvement of bananas.

The Autophagy-Related Musa acuminata Protein MaATG8F Interacts with MaATG4B, Regulating Banana Disease Resistance to Fusarium oxysporum f. sp. cubense Tropical Race 4.

Banana is one of the most important fruits in the world due to its status as a major food source for more than 400 million people. Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) causes substantial losses of banana crops every year, and molecular host resistance mechanisms are currently unknown. We here performed a genomewide analysis of the autophagy-related protein 8 (ATG8) family in a wild banana species. The banana genome was found to contain 10 MaATG8 genes. Four MaATG8s formed a gene cluster in the distal part of chromosome 4. Phylogenetic analysis of ATG8 families in banana, Arabidopsis thaliana, citrus, rice, and ginger revealed five major phylogenetic clades shared by all of these plant species, demonstrating evolutionary conservation of the MaATG8 families. The transcriptomic analysis of plants infected with Foc TR4 showed that nine of the MaATG8 genes were more highly induced in resistant cultivars than in susceptible cultivars. Finally, MaATG8F was found to interact with MaATG4B in vitro (with yeast two-hybrid assays), and MaATG8F and MaATG4B all positively regulated banana resistance to Foc TR4. Our study provides novel insights into the structure, distribution, evolution, and expression of the MaATG8 family in bananas. Furthermore, the discovery of interactions between MaATG8F and MaATG4B could facilitate future research of disease resistance genes for the genetic improvement of bananas.

Development of Novel Polymorphic EST-SSR Markers from the Cranberry Fruit Transcriptome.

BACKGROUND: Cranberry (Vaccinium macrocarpon Ait.) has high developmental prospects and great research value. Cranberry has a narrow genetic base, however, its morphological characteristics are not easily distinguishable. Besides, traditional breeding methods are limited, and breeding progress on cranberry cultivars has been slow. OBJECTIVE: The objective of this study was to assess polymorphic EST-SSR markers developed from a cranberry fruit transcriptomic sequencing library to provide candidate EST-SSR sequences for future research on stress resistance breeding of cranberry. MATERIALS AND METHODS: Thirteen cranberry accessions were used for EST-SSR analysis, and 16 accessions of other Vaccinium species were used to test primer transferability. Genomic DNA was extracted from young leaves of 6-year-old cranberry plants and subjected to PCR amplification. A binary matrix was established and analyzed in NTSYS-pc v.2.10e for calculation of the genetic similarity of cranberry cultivars and construction of a cluster dendrogram. RESULTS: A total of 47 stress-resistance-related primer pairs were designed, of which 7 pairs showed polymorphism. The average number of effective alleles was 1.844, and the average expected heterozygosity was 0.455. The average transfer rate was 63.39%. Genetic similarity coefficients ranged from 0.28 to 1.00, with an average of 0.76. UPGMA clustering divided the 13 cranberry accessions into four groups at a genetic similarity of 0.74. CONCLUSIONS: The seven polymorphic EST-SSR markers were able to reveal genetic relationships among 13 cranberry accessions and can be used for future research on stress resistance breeding of cranberry.