Molecular study of drought response in the Mediterranean conifer Pinus pinaster Ait.: Differential transcriptomic profiling reveals constitutive water deficit‐independent drought tolerance mechanisms

Abstract

Adaptation of long‐living forest trees to respond to environmental changes is essential to secure their performance under adverse conditions. Water deficit is one of the most significant stress factors determining tree growth and survival. Maritime pine (Pinus pinaster Ait.), the main source of softwood in southwestern Europe, is subjected to recurrent drought periods which, according to climate change predictions for the years to come, will progressively increase in the Mediterranean region. The mechanisms regulating pine adaptive responses to environment are still largely unknown. The aim of this work was to go a step further in understanding the molecular mechanisms underlying maritime pine response to water stress and drought tolerance at the whole plant level. A global transcriptomic profiling of roots, stems, and needles was conducted to analyze the performance of siblings showing contrasted responses to water deficit from an ad hoc designed full‐sib family. Although P. pinaster is considered a recalcitrant species for vegetative propagation in adult phase, the analysis was conducted using vegetatively propagated trees exposed to two treatments: well‐watered and moderate water stress. The comparative analyses led us to identify organ‐specific genes, constitutively expressed as well as differentially expressed when comparing control versus water stress conditions, in drought‐sensitive and drought‐tolerant genotypes. Different response strategies can point out, with tolerant individuals being pre‐adapted for coping with drought by constitutively expressing stress‐related genes that are detected only in latter stages on sensitive individuals subjected to drought.

Candidate regulators and target genes of drought stress in needles and roots of Norway spruce

“…2018 , Fox et al. 2018 , de María et al. 2020 ), finding variation between species and among genotypes ( de María et al.…”

“…2018 , de María et al. 2020 ), finding variation between species and among genotypes ( de María et al. 2020 ), it is also of interest to know how extensively functional knowledge generated using angiosperm species translates to coniferous species.…”

“…2011 , Du et al. 2018 , de María et al. 2020 ), although their functional role has not been elucidated.…”

Comprehensive analysis of the isomiRome in the vegetative organs of the conifer Pinus pinaster under contrasting water availability

“…Sequences were filtered based on length (18–26 nt) and abundance (at least 5 reads), and low complexity, ribosomal (rRNA) and transfer RNA (tRNA) were removed. PatMaN software (Prüfer et al, 2008) was used to map reads to an improved P. pinaster transcriptome (de María et al, 2020a) as well as the v.1.0 genome of P. taeda (Neale et al, 2014), the most phylogenetically related species with an available genome sequence. Reads showing perfect match to reference transcriptome or genome were saved in a data matrix of potential P. pinaster sRNAs including the non‐normalized total read count.…”

“…A pool made of equal amounts of RNAs from all roots samples was sent to degradome sequencing (LC Sciences, Houston, TX). The obtained data on the 5′‐ends of uncapped mRNAs, together with the list of identified sRNAs and a new enlarged and curated version of P. pinaster transcriptome (de María et al, 2020a, 2020b) were used as input to run CleaveLand for the detection of cleaved sRNA targets (Addo‐Quaye, Miller, & Axtell, 2009). The presence of significant interactions was considered for p values <.05.…”