Temporal dynamics and tissue-specific variations of the blueberry phyllosphere mycobiome

Highbush blueberry (<i>Vaccinium corymbosum</i>) is an economically important fruit-bearing woody perennial. Despite the importance of microbial communities to plant health, the aboveground (phyllosphere) microbiome of blueberry is understudied. The phyllosphere is exposed to varying conditions throughout a growing season. The fruit undergoes extensive physiological change across a season from bud to fruit. This study aimed to provide a temporal characterization of the blueberry phyllosphere across a growing season and a characterization of specific tissues and phenological stages. Blueberry branches were harvested every other week across 2 years and two locations during the development process of the blueberry fruits. The internal transcribed spacer regions were amplified from DNA extracts and sequenced to perform amplicon-based characterization of the fungal microbiome across time and plant tissue. Fungal communities showed changes in α-diversity depending on the week of harvest and tissue type. Early in the season, α-diversity was high, but it decreased in midseason when flowers developed into fruit. Later in the season, as the fruit ripened, α-diversity increased again. The β-diversity of the community changed across time and tissue types during plant development. Notable members of the identified core microbiome were members of the genus <i>Alternaria</i>, <i>Peltaster</i>, and <i>Taphrina</i>, as well as the pathogenic taxa <i>Aureobasidium pullulans</i> and <i>Botrytis cinerea</i>. This research provides background for future experimentation of understanding the microbial composition in the blueberry phyllosphere in relation to the infection court of pathogens (e.g. <i>Colletotrichum fioriniae</i> and <i>B. cinerea</i>) and the temporal components of blueberry plant health and management.