Freeze–thaw cycles characterize varietal aroma of Vidal blanc grape during late harvest by shaping self-assembled microeukaryotic communities

Abstract

To study the effects of microeukaryotic communities on development of varietal aroma of Vidal blanc grape during late harvest, metagenomics, gas chromatography–mass spectrometry, climate factors and scanning electron microscopy were jointly used to discover how freeze–thaw stress influences grape skin and shapes the microeukaryotic consortia. Most free terpenes, monoterpenes and C13-norisoprenoids developed during late harvest. Freeze-thaw cycles caused damage of the wax layer and microfissures on the cuticle of grape berries. This increased nutrients availability and supported the dominance of oxidative and fermentative ascomycetous populations. Microbial assemblages possessed certain ecosystem functions, which correlated to the development of characteristic volatile organic compounds, such as free terpenes and phenylalanine derivatives. Significantly upregulated genes of CAZy were identified as FENNEDOB12352, OJNJMGIN252777, EGHMEMAM161340, EGHMEMAM158447, KKFIDJDF144524, BEDCFLNK31943, LHALBBHN88115, BEDCFLNK41042. Zymoseptoria tritici, Kluyveromyces lactis, Yarrowia lipolytica, and Pichia kudriavzevii were selected as key factors in yeast assemblage.