Diversidad de Castanea sativa Mill. en base a marcadores genéticos relacionados con el estrés hídrico y la tolerancia a Phytophthora cinnamomi Rands

Resumo

Castanea sativa Mill (European sweet chestnut) is a multipurpose tree forest species and the only species within its genus native to Europe. The species is threatened by the more frequent occurrence of extreme climatic events such as drought induced by the current climate change, especially in Mediterranean countries, including Spain, and also impacted by ‘ink disease’, a serious root rot caused by the extremely destructive and invasive soil-borne oomycete Phytophthora cinnamomi Rands. (Pc) of Asian origin. The current global change scenario makes it urgent to evaluate functional genetic diversity associated with drought and resistance to Pc in Spanish chestnut populations. It also makes necessary to identify tolerant genotypes. In 2015, a breeding initiative was started at the Faculty of Forestry, University of Extremadura, to select native pure C. sativa trees resistant to Pc and/or tolerant to drought. Within the context of this PhD Thesis, the aim was to examine the adaptive potential in relation to drought stress tolerance (in Chapter 1: Alcaide et al., 2019) and to the impact of Pc (in Chapter 2: Alcaide et al., 2020) of four wild chestnut populations across Spain located in areas of contrasting climate conditions and subjected to different selection pressures to the impact of Pc. A relevant resistance to Pc was observed in chestnut seedlings from the population of Galicia. Therefore, it was hypothesised that resistant genes from Asian chestnut germplasm (C. crenata and C. mollissima) could be behind this high resistance, and this was experimentally tested (in Chapter 3: Alcaide et al., 2021). In this Thesis, a first link between population structure and adaptive responses to selection induced by two global change factors has been established in C. sativa. The genetic variability of the populations studied revealed the response potential of C. sativa to adapt to global change.