Comparative transcriptional profiling of orange fruit in response to the biocontrol yeast Kloeckera apiculata and its active compounds.

Pu Liu,Xiaoping Yang,Guofeng Li,Kai Chen,Chao-An Long

doi:10.1186/s12864-015-2333-3

Abstract

BackgroundThe yeast Kloeckera apiculata strain 34–9 is an antagonist that shows biological control activity against the postharvest fungal pathogens of citrus. An antifungal compound, 2-phenylethanol (PEA), has been identified from the extract of K. apiculata. To better understand the molecular processes underlying the response of citrus fruit tissue to K. apiculata, the extract and PEA, microarray analyses were performed on navel oranges using an Affymetrix Citrus GeneChip.ResultsAs many as 801, 339 and 608 differentially expressed genes (DEGs) were identified after the application of K. apiculata, the extract and PEA, respectively. In general, K. apiculata induced the expression of defence-related genes. In addition to chitinase and β-1,3-glucanase, genes involved in ethylene (ET), jasmonic acid (JA), calcium signalling, MAPK signalling and phenylalanine metabolism were induced. In contrast, monodehydroascorbate reductase, superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and carotenoid biosynthesis genes were down-regulated. The expression profiles for the extract- and PEA-treated samples were similar to that found for yeast (sharing 57.4 % DEGs), with a significant increase in the transcript levels of defence-related genes.ConclusionThis study provides a global picture of the gene expression changes in navel oranges after the application of the antagonist yeast K. apiculata, its extract and PEA. The interpretation of the DEGs revealed new insight into the molecular processes that regulate the defence responses in orange tissue.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2333-3) contains supplementary material, which is available to authorized users.

Highlights

The yeast Kloeckera apiculata strain 34–9 is an antagonist that shows biological control activity against the postharvest fungal pathogens of citrus
Global changes in citrus gene expression profiles To obtain an overall picture of the gene regulation, biocontrol yeast, the ether extract and active compound were used to treat citrus and two independent microarray analyses were performed for each treatment
All DGEs were aligned against the Arabidopsis database by using the Citrus HarvEST software, and detailed descriptions of the sequences are shown in Additional file 1

Summary

Introduction

The yeast Kloeckera apiculata strain 34–9 is an antagonist that shows biological control activity against the postharvest fungal pathogens of citrus. To better understand the molecular processes underlying the response of citrus fruit tissue to K. apiculata, the extract and PEA, microarray analyses were performed on navel oranges using an Affymetrix Citrus GeneChip. Kloeckera apiculata strain 34–9, a yeast isolated from the epiphytes of citrus roots [5], has been shown to suppress postharvest fungal pathogens in citrus, e.g., Penicillium digitatum and Penicillium italicum, the causal agent of green and blue mold, respectively [6, 7]. The yeast-induced defence response of fruit has been considered a potential means to suppress infection with plant pathogens, and growing evidences have supported this point of view [1,2,3,4].

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Discussion

Conclusion