Heat-Priming during Somatic Embryogenesis Increased Resilience to Drought Stress in the Generated Maritime Pine () Plants.

Drought stress is becoming the most important factor of global warming in forests, hampering the production of reproductive material with improved resilience. Previously, we reported that heat-priming maritime pine () megagametophytes during SE produced epigenetic changes that generated plants better adapted to subsequent heat stress. In this work, we tested, in an experiment performed under greenhouse conditions, whether heat-priming will produce cross-tolerance to mild drought stress (30 days) in 3-year-old priming-derived plants.

Changing Temperature Conditions during Somatic Embryo Maturation Result in Plants with Altered Response to Heat Stress.

Under the global warming scenario, obtaining plant material with improved tolerance to abiotic stresses is a challenge for afforestation programs. In this work, maritime pine ( Aiton) plants were produced from somatic embryos matured at different temperatures (18, 23, or 28 °C, named after M18, M23, and M28, respectively) and after 2 years in the greenhouse a heat stress treatment (45 °C for 3 h/day for 10 days) was applied. Temperature variation during embryo development resulted in altered phenotypes (leaf histology, proline content, photosynthetic rates, and hormone profile) before and after stress.

Priming Maritime Pine Megagametophytes during Somatic Embryogenesis Improved Plant Adaptation to Heat Stress.

In the context of global climate change, forest tree research should be addressed to provide genotypes with increased resilience to high temperature events. These improved plants can be obtained by heat priming during somatic embryogenesis (SE), which would produce an epigenetic-mediated transgenerational memory. Thereby, we applied 37 °C or 50 °C to maritime pine () megagametophytes and the obtained embryogenic masses went through the subsequent SE phases to produce plants that were further subjected to heat stress conditions.