Global transcriptomic analysis in avocado nursery trees reveals differential gene expression during asymptomatic infection by avocado sunblotch viroid (ASBVd)

Avocado sunblotch viroid (ASBVd) is the type species of the family Avsunviroidae and the causal agent of avocado sunblotch disease. The disease is characterised by the presence of chlorotic lesions on avocado fruit, leaves and/ or stems. Infected trees may remain without chlorosis for extended periods of time, though distorted growth and reduced yield has been observed in these cases. The molecular effects of ASBVd on avocado, and members of the Avsunviroidae on their respective hosts in general, remain poorly understood. Host global transcriptomic studies within the family Pospiviroidae have identified several host pathways that are affected during these plant-pathogen interactions. In this study, we used RNA sequencing to investigate host gene expression in asymp-tomatic avocado nursery trees infected with ASBVd. Transcriptome data showed that 631 genes were differen-tially expressed, 63 % of which were upregulated during infection. Plant defence responses, phytohormone networks, gene expression pathways, secondary metabolism, cellular transport as well as protein modification and degradation were all significantly affected by ASBVd infection. This work represents the first global gene expression study of ASBVd-infected avocado, and the transcriptional reprogramming observed during this asymptomatic infection improves our understanding of the molecular interactions underlying broader avsunviroid-host interactions.

Automated summary

This study investigated the host gene expression in asymptomatic avocado nursery trees infected with Avocado sunblotch viroid (ASBVd) using RNA sequencing. The results showed that 631 genes were differentially expressed during infection, with 63% upregulated. ASBVd infection significantly affected plant defence responses, phytohormone networks, gene expression pathways, secondary metabolism, cellular transport, as well as protein modification and degradation. This study provides insights into the molecular interactions underlying avsunviroid-host interactions.