Pichia anomala Induced With Chitosan Triggers Defense Response of Table Grapes Against Post-harvest Blue Mold Disease

To study the mechanism by which Pichia anomala induced with chitosan (1% w/v) controls blue mold disease in table grapes caused by Penicillium expansum, this study evaluated alterations in three yeast enzymatic activities. The changes in the five primary disease defense-related enzymes and two non-enzyme activities of table grapes were assayed. The results of the study showed that chitosan (1% w/v) significantly increased the yeast β-1,3-glucanase, catalase (CAT), and malondialdehyde (MDA) activities. Furthermore, P. anomala alone or induced with chitosan (1% w/v) significantly increased the table grapes enzymatic activities of Polyphenol oxidase (PPO), phenylalanine (PAL), peroxidase (POD), and catalase (CAT) compared to the control. The RT-qPCR results also confirmed that the genes of these major disease defense enzymes were up-regulated when the table grapes were treated with P. anomala. The highest results were recorded when the fruit was treated by yeast induced with chitosan (1% w/v). The phenolic compounds, in addition to their nutritional value, can also increase the antimicrobial properties of table grapes. The current experiment determined that the total phenol and flavonoid contents of table grapes showed the highest results for fruits treated by P. anomala induced with chitosan compared with the control. Generally, the increment of these fruit enzymatic and non-enzymatic activities shows improved table grape defense against the pathogenic fungus. The induction of the yeast with chitosan also increases its bio-control efficacy against the pathogen. This study will enable future detailed investigation in the yeast pathogen control mechanisms and the use of yeasts as bio-pesticides.

Transcriptome Characterization and Expression Profiles of Disease Defense-Related Genes of Table Grapes in Response to Pichia anomala Induced with Chitosan

Transcriptome analysis (TA) was conducted to characterize the transcriptome changes in postharvest disease-related genes of table grapes following treatment with Pichia anomala induced with chitosan (1% w/v). In the current study, the difference in the gene expression of table grapes after treatment with P. anomala induced with chitosan and that of a control group was compared 72 h post-inoculation. The study revealed that postharvest treatment of table grapes with P. anomala induced with chitosan could up-regulate genes that have a pivotal role in the fruit’s disease defense. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) results also confirmed that GO terms and the KEGG pathways, which have pivotal roles in plant disease resistance, were significantly enriched. The up-regulated genes of the treatment group have a unique function in the fruit’s disease resistance compared to the control group. Generally, most genes in the plant–pathogen interaction pathway; the plant Mitogen-activated protein kinase (MAPK) signaling pathway; the plant hormone signal transduction pathway; the pathway of glutathione metabolism; the pathway of phenylalanine, tyrosine, and tryptophan biosynthesis; and the pathway of flavonoid biosynthesis were all up-regulated. These up-regulations help the fruit to synthesize disease-resistant substances, regulate the reactive oxygen species (ROS), enhance the fruit cell wall, and enrich hormone signal transduction during the pathogen’s attack. This study is useful to overcome the lags in applying transcriptomics technology in postharvest pathology, and will provide insight towards developing other alternative methods to using bio-pesticides to control postharvest diseases of perishables.

Compost Inoculated with Fungi from a Mangrove Habitat Improved the Growth and Disease Defense of Vegetable Plants

Municipal organic wastes could be exploited as fertilizers, having been given the ability to suppress plant diseases by the inoculation of the waste with certain fungi in the composting process. Our aim was to develop a novel fertilizer using composting in combination with fungi associated with mangrove forests. Nine fungal species were isolated from a mangrove forest habitat and screened for their activity against five phytopathogenic fungi, their plant-growth promotion ability, and their phosphate solubilization ability. Two fungal isolates, Penicillium vinaceum and Eupenicillium hirayama, were inoculated into organic waste before the composting experiment. After 90 days, the physico-chemical properties of the compost (color, moisture, pH, C:N ratio and cation exchange capacity (CEC)) indicated the maturity of the compost. The C:N ratio decreased and the CEC value increased most in the compost with the inoculum of both mangrove fungi. The vegetable plants grown in the mangrove fungi-inoculated composts had a higher vigor index than those grown in the control compost. The seeds collected from the plants grown in the fungi-inoculated composts had higher disease defense ability than the seeds collected from the control compost. The results indicated that the properties of the fungi shown in vitro (antagonistic and plant-growth promotion) remained in the mature compost. The seeds of the plants acquired disease defense ability, which is a remarkable observation that is useful in sustainable agriculture.

Proteome-Wide Analyses Provide New Insights into the Compatible Interaction of Rice with the Root-Knot Nematode Meloidogyne graminicola

The root-knot nematode Meloidogyne graminicola is an important pathogen in rice, causing huge yield losses annually worldwide. Details of the interaction between rice and M. graminicola and the resistance genes in rice still remain unclear. In this study, proteome-wide analyses of the compatible interaction of the japonica rice cultivar “Nipponbare” (NPB) with M. graminicola were performed. In total, 6072 proteins were identified in NPB roots with and without infection of M. graminicola by label-free quantitative mass spectrometry. Of these, 513 specifically or significantly differentially expressed proteins were identified to be uniquely caused by nematode infection. Among these unique proteins, 99 proteins were enriched on seven Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. By comparison of protein expression and gene transcription, LOC_Os01g06600 (ACX, a glutaryl-CoA dehydrogenase), LOC_Os09g23560 (CAD, a cinnamyl-alcohol dehydrogenase), LOC_Os03g39850 (GST, a glutathione S-transferase) and LOC_Os11g11960 (RPM1, a disease resistance protein) on the alpha-linolenic acid metabolism, phenylpropanoid biosynthesis, glutathione metabolism and plant–pathogen interaction pathways, respectively, were all associated with disease defense and identified to be significantly down-regulated in the compatible interaction of NPB with nematodes, while the corresponding genes were remarkably up-regulated in the roots of a resistant rice accession “Khao Pahk Maw” with infection of nematodes. These four genes likely played important roles in the compatible interaction of rice with M. graminicola. Conversely, these disease defense-related genes were hypothesized to be likely involved in the resistance of resistant rice lines to this nematode. The proteome-wide analyses provided many new insights into the interaction of rice with M. graminicola.

Proteomics Changes in Filling Seeds of Vegetable Soybean

Vegetable soybean is an important economic and nutritious crop. In this study, 48 differentially expressed proteins were identified from filling seeds of soybean (Glycine max) cv. Mindou 6 by using two-dimensional electrophoresis (2-DE) combined with liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Among them, 25% were related to protein destination and storage, 42% to energy and metabolism, 15% to disease/defense, 6% to transporters, 4% to secondary metabolism, 4% to transcription, 2% to protein synthesis, and 2% to cell growth/division. Along with the maturity of seeds, the number of unchanged abundance proteins decreased, while that of both upregulated and downregulated proteins increased. Both downregulated expression of caffeic acid O-methyltransferase (COMT) and upregulated expression of sucrose-binding protein (SBP) 2 precursor may contribute to increase in digestibility, nutritional value, and eating quality of vegetative seeds at suitable picking period. The pattern of unchanged proteins during the whole seed-filling stage may be also beneficial to the quality of vegetable soybean.