Maritime Pine Rootstock Genotype Modulates Gene Expression Associated with Stress Tolerance in Grafted Stems

Area of Science:

• Forestry and Plant Science
• Climate Change Biology
• Molecular Ecology

Background:

• Climate change-induced drought threatens forest resilience, especially in the Mediterranean Basin.
• Maritime pine (Pinus pinaster) is a key species in Western Europe, valued for its genetic diversity and adaptability.
• Understanding drought tolerance mechanisms in maritime pine is crucial for forest conservation.

Purpose of the Study:

• To characterize the transcriptional profiles of maritime pine scion and rootstock stems under well-watered conditions.
• To investigate how different genotype combinations (drought-sensitive and drought-tolerant) influence gene expression.
• To identify genes and pathways associated with drought tolerance in Pinus pinaster.

Main Methods:

• Grafting of four Pinus pinaster combinations using drought-sensitive and drought-tolerant scions and rootstocks.
• Transcriptomic analysis of scion and rootstock stems.
• Differential gene expression analysis to identify key genes and pathways.

Main Results:

• Gene expression patterns were influenced by genotype origin and graft combination.
• Drought-sensitive scions, particularly on sensitive rootstocks, showed increased expression of defense and pathogen recognition genes.
• Drought tolerance genes, linked to ABA metabolism and ROS-scavenging pathways, were identified in tolerant genotypes and sensitive scions on tolerant rootstocks.

Conclusions:

• Distinct drought tolerance strategies exist in maritime pine, involving trade-offs between growth and defense.
• ABA metabolism, ROS-scavenging, and flavonoid/terpenoid pathways are key in drought response.
• Findings can inform the selection of more drought-tolerant Pinus pinaster genotypes for climate change adaptation.