Differential gene expression analysis of the resprouting process in Pinus canariensis provides new insights into a rare trait in conifers

Abstract

Abstract Resprouting, one of the main fire-adapted traits, is crucial in population dynamics in response to wildfires or herbivory. This trait, common in angiosperms, is rare in conifers, being Pinus canariensis one of the few species able to resprout. We analyzed gene expression during wound-induced resprouting in 5 years-old Canarian pines. RNA was extracted at three dates, including control samples from remote branches, representing immediate response to wounding (R0), resprouting initiation (R1), and elongation (R2), and then hybridized to a microarray designed with 15000 cDNAs from Pinus canariensis transcriptome of meristematic activity. We found 1164 Differentially Expressed Genes (DEGs) as response to wounding grouped in 6 clusters across time points. Genes related to defense- and stress-response were mainly found to be overexpressed at R0, including disease resistance response protein 206-like, or pathogenesis-related proteins PR-4b-like, among others. We also found DEGs coding for transcription factors such as GROWTH-REGULATING FACTOR (GRF), FLOWERING-PROMOTING FACTOR (FPF), and the HOMEODOMAIN LEUCINE ZIPPER Class IV (HD-ZIP IV), mainly related to outgrowth processes and lateral organogenesis in plants, showing overexpression at R1 and R2, when new shoots were emerging. This data was compared to differential gene expression during apical growth in P. canariensis, suggesting similarities and differences between vegetative apical growth and regulation of lateral shoot development in response to mechanical wounding.