Physiological and molecular response to drought in somatic plants from Pinus radiata embryonal masses induced at high...

Drought and heat are among the major abiotic stresses in forest trees and are directly related with the consequences of climatic change. Many responses to abiotic stresses in plants have been associated with plant memory but mechanisms underlying this phenomenon remain unclear. Somatic embryogenesis, which is considered one of the most important methods for large-scale vegetative propagation of plants, is also used for stress induction and study the mechanisms involved in adaptation to abiotic stress. Specifically, heat stress during initiation stage of somatic embryogenesis has shown to have an impact in differential expression of stress related genes in pines. Modifications caused by a previous stress could eventually influence the stress tolerance of somatic plants years later. In this study we analysed the response to drought in 2-year-old radiata pine somatic plants, derived from embryonal masses initiated at 60 °C, at physiological, transcriptomic and amino acid accumulation level. Our results showed a more pronounce response to drought in plants coming from 60 °C treatment, which presented lower values in several physiological parameters as well as higher proline and tyrosine levels. Additionally, the transcriptomic response to drought was stronger in heat primed plants compared to control plants, suggesting a memory acquired two years before.