Current climate changes imply an imminent risk for forest species. In this context, somatic embryogenesis is a valuable tool to study the response of plants to different abiotic stresses. Based on this, we applied a high-temperature regime (50 ºC, 5 min) during the maturation of Pinus radiata D. Don embryogenic masses in order to evaluate the development of an epigenetic memory months later.Therefore, somatic plants (SP) resulting from somatic embryos (ses) maturated at control temperature and cultivated in a greenhouse were submitted to heat stress (40 ºC, 2 h, 10 days; 23 ºC, 10 days) or at a control temperature (23 ºC, 20 days); while another 20 SP resulting from ses maturated in the two temperature regimes and cultivated in the greenhouse were submitted to drought stress or weekly irrigated. All plants were evaluated for relative water content, water potential, electrolyte leakage, stomatal conductance, transpiration, methylation (5-mC) and hydroxymethylation (5-hmC) levels. The results showed that the SP obtained from ses maturated at 50 ºC showed an adaptation to drought stress based on water potential and transpiration. Furthermore, SP kept under heat stress in a greenhouse showed lower 5-hmC levels than SP kept at 23 ºC. Furthermore, the 5-hmC and 5-hmC/5-mC ratio showed a signi cantly negative correlation with changes in water potential; and a signi cantly negative correlation was observed between the levels of stomatal conductance and 5-mC. We conclude that the manipulation of conditions during the maturation process in somatic embryogenesis modulates the physiological characteristics of the SP obtained. Key MessageApplication of high temperatures in the maturation stage of somatic embryos and the resulting Pinus radiata somatic plants provoked a drought adaptation and changes in epigenetic mechanisms.

Grapevine, a crop of global economic importance, is annually affected by diseases that can compromise the quality and quantity of the harvest, producing large economic losses. Downy mildew caused by Plasmopara viticola (Berk. & M.A. Curtis) Berl. & de Toni is one of the most important diseases in the vineyard. To fight this pathogen, winegrowers often rely on conventional chemical fungicides or copper-based formulations, whose use is determined to be reduced by the European Commission due to their environmental consequences. Hence, alternative plant protection products (PPP) in grapevine must be considered and studied. In this context, we selected several alternative commercial products, based on basic substances (BS) or low-risk active substances (LRAS), to evaluate their suitability to deal with P. viticola. We measured the preventive activity of the products, both in vitro and in planta, as well as their toxicity against the sporangia and zoospores of the pathogen. Results showed that four commercial products were effective against the pathogen directly and preventively, being composed of approved basic substances, more concretely, chitosan, Equisetum arvense, lecithins, and Salix cortex. Among those, the products composed of lecithins and Salix cortex were the most toxic and active preventively. Therefore, these basic substances should be promoted in the vineyard as an alternative to conventional treatments in order to transition to a more sustainable viticulture.

Current climate changes imply an imminent risk for forest species. In this context, somatic embryogenesis is a valuable tool to study the response of plants to different abiotic stresses. Based on this, we applied a high-temperature regime (50 ºC, 5 min) during the maturation of Pinus radiata D. Don embryogenic masses in order to evaluate the development of an epigenetic memory months later. Therefore, somatic plants (SP) resulting from somatic embryos (ses) maturated at control temperature and cultivated in a greenhouse were submitted to heat stress (40 ºC, 2 h, 10 days; 23 ºC, 10 days) or at a control temperature (23 ºC, 20 days); while another 20 SP resulting from ses maturated in the two temperature regimes and cultivated in the greenhouse were submitted to drought stress or weekly irrigated. All plants were evaluated for relative water content, water potential, electrolyte leakage, stomatal conductance, transpiration, methylation (5-mC) and hydroxymethylation (5-hmC) levels. The results showed that the SP obtained from ses maturated at 50 ºC showed an adaptation to drought stress based on water potential and transpiration. Furthermore, SP kept under heat stress in a greenhouse showed lower 5-hmC levels than SP kept at 23 ºC. Furthermore, the 5-hmC and 5-hmC/5-mC ratio showed a significantly negative correlation with changes in water potential; and a significantly negative correlation was observed between the levels of stomatal conductance and 5-mC. We conclude that the manipulation of conditions during the maturation process in somatic embryogenesis modulates the physiological characteristics of the SP obtained.