Transcriptomic analysis to elucidate the molecular mechanisms underlying the growth advantage of Kluyveromyces marxianus XZ1 and the development of resistance in apple induced by XZ1

Abstract

The preceding study demonstrated that Kluyveromyces marxianus XZ1 (XZ1) exhibits potential as a biological agent for combating disease by P. expansum in apple fruit. This potential is primarily attributed to its capacity for competing for resources and space, as well as activating certain genes involved in the transduction of plant hormone signals. In this study, transcriptomic analysis was performed on the interaction system of XZ1 and apple to investigate the detail molecular mechanisms of the yeast to develop competitive advantage and the molecular mechanisms of the apple to develop defense response action at the gene expression level. The transcriptome analysis of XZ1 in apple indicated that the meiosis pathway was activated to promote rapid proliferation of the yeast in apple. Autophagy, ubiquitin-mediated proteolysis, and the starch and sucrose metabolism pathway are induced to generate vital nutrients and energy for yeast proliferation. The transcriptome analysis of apple revealed upregulation in the expression levels of genes associated with transcription factors (TFS) involved in pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) following treatment with XZ1. This finding suggests that XZ1 activates PTI and ETI in apple, thereby promoting disease resistance. Moreover, the yeast treatment induced the activation of ethylene and jasmonate signal transduction pathways, which play a crucial role in regulating disease resistance development in apple. Additionally, the yeast treatment resulted in the enhancement of lignin biosynthesis, serving as a protective mechanism for the apple against potential threats, as observed in the response to XZ1 treatment. The findings of this study establish a theoretical foundation for elucidating the molecular mechanism underlying the growth advantage of antagonistic yeast in the host and the induced resistance in apple. Additionally, this study offers a substantial repertoire of gene resources that can be utilized to enhance yeast biocontrol efficacy and bolster the disease resistance of apple through the application of molecular biology techniques.