Transcriptome Analysis Reveals the Inducing Effect of Bacillus siamensis on Disease Resistance in Postharvest Mango Fruit

Abstract

Postharvest anthracnose, caused by the fungus Colletotrichum gloeosporioides, is one of the most important postharvest diseases of mangoes worldwide. Bacillus siamensis (B. siamensis), as a biocontrol bacteria, has significant effects on inhibiting disease and improving the quality of fruits and vegetables. In this study, pre-storage application of B. siamensis significantly induced disease resistance and decreased disease index (DI) of stored mango fruit. To investigate the induction mechanisms of B. siamensis, comparative transcriptome analysis of mango fruit samples during the storage were established. In total, 234,808 unique transcripts were assembled and 56,704 differentially expressed genes (DEGs) were identified by comparative transcriptome analysis. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of DEGs showed that most of the DEGs involved in plant-pathogen interaction, plant hormone signal transduction, and biosynthesis of resistant substances were enriched. Fourteen DEGs related to disease-resistance were validated by qRT-PCR, which well corresponded to the FPKM value obtained from the transcriptome data. These results indicate that B. siamensis treatment may act to induce disease resistance of mango fruit by affecting multiple pathways. These findings not only reveal the transcriptional regulatory mechanisms that govern postharvest disease, but also develop a biological strategy to maintain quality of post-harvest mango fruit.

Advances in Physiological, Transcriptomic, Proteomic, Metabolomic, and Molecular Genetic Approaches for Enhancing Mango Fruit Quality

“…91,92 A separate study on mango fruit peels infected with anthracnose disease caused by Colletotrichum gloeosporioides was performed. 67,93,94 Mango fruits are susceptible to anthracnose during postharvest storage resulting in 30% losses during storage and transportation. 95,96 Although the fungus infects the blossom or young fruits, the growth of the pathogen resumes when the fruit starts to ripen and postharvest anthracnose develops.…”

“…67 Several studies identified genes related to phytohormones, pathogen defense mitogenactivated protein kinase signaling pathway (MAPK), which were induced in response to C. gloeosporioides. 67,90,93,94,98 Red fruits that develop flavonols and anthocyanins are more resistant to postharvest fungal pathogens. 91 Previous studies reported that pathogens induced the defense responses in plants via stimulation of phytohormones that play an important role in boosting plants immunity.…”

“…99−101 Jiang et al also observed the up-regulation of several genes related to plantpathogen interaction, plant hormone signal transduction, and biosynthesis of resistant substances (phenols) in mango fruits. 93 Up-regulation of genes was noted when Bacillus siamensis, a biocontrol bacterium, was applied to control the infection of C. gloeosporioides before storage of mango fruits (cv. 'Tainong').…”

“…Their results concluded that the enhanced disease resistance with biocontrol agent treatment is associated with an improved stress response, induced synthesis of resistant substances, and stimulation of the immune response. 93 Based on the above studies, it can be concluded that understanding of the molecular network associated with various diseases is essential to identify the early events associated with the mango fruit defense response for effective postharvest disease management.…”

“…Differentially expressed genes detected from infected buds collected after 45, 75, and 120 days included plant hormone signal transduction, phenylpropanoid and flavonoid biosynthesis, carbohydrate metabolism, fatty acid metabolism, and several other processes . Previous studies suggested that the anthocyanins and flavonols are products of the phenylpropanoid biosynthetic pathway and are involved in plant protection against pathogens. , A separate study on mango fruit peels infected with anthracnose disease caused by Colletotrichum gloeosporioides was performed. ,, Mango fruits are susceptible to anthracnose during postharvest storage resulting in 30% losses during storage and transportation. , Although the fungus infects the blossom or young fruits, the growth of the pathogen resumes when the fruit starts to ripen and postharvest anthracnose develops . Hong et al observed up-regulation of defense-related genes after C. gloeosporioides infection in fruit peels (cv.…”