Compton Samuel, Stackpole Charles, Dixit Aalap, Sekhwal Manoj K, Kolb Thomas, De la Torre Amanda R
School of Forestry, Northern Arizona University, 200 E. Pine Knoll, AZ 86011, USA.
School of Earth and Sustainability, Northern Arizona University, 624 S Knoles Dr Flagstaff, AZ 86011, USA.
AoB Plants. 2023 Mar 1;15(2):plad008. doi: 10.1093/aobpla/plad008. eCollection 2023 Feb.
Severe and frequent heat and drought events challenge the survival and development of long-generation trees. In this study, we investigated the genomic basis of heat tolerance, water use efficiency and growth by performing genome-wide association studies in coastal Douglas-fir () and intervarietal ( × ) hybrid seedlings. GWAS results identified 32 candidate genes involved in primary and secondary metabolism, abiotic stress and signaling, among other functions. Water use efficiency (inferred from carbon isotope discrimination), photosynthetic capacity (inferred from %N), height and heat tolerance (inferred from electrolyte leakage in a heat stress experiment) were significantly different among Douglas-fir families and varieties. High-elevation seed sources had increased water use efficiency, which could be a result of higher photosynthetic capacity. Similarly, families with greater heat tolerance also had higher water use efficiency and slower growth, suggesting a conservative growth strategy. Intervarietal hybrids showed increased heat tolerance (lower electrolyte leakage at 50 and 55 °C) and higher water use efficiency compared with coastal families, suggesting that hybridization might be a source of pre-adapted alleles to warming climates and should be considered for large-scale reforestation projects under increasingly arid conditions.
严重且频繁的高温和干旱事件对长寿树木的生存和发育构成挑战。在本研究中，我们通过对海岸花旗松（）和种间（×）杂交幼苗进行全基因组关联研究，调查了耐热性、水分利用效率和生长的基因组基础。全基因组关联研究结果确定了32个参与初级和次级代谢、非生物胁迫和信号传导等功能的候选基因。花旗松家族和品种之间的水分利用效率（由碳同位素判别推断）、光合能力（由%N推断）、高度和耐热性（由热胁迫实验中的电解质渗漏推断）存在显著差异。高海拔种子源的水分利用效率有所提高，这可能是光合能力较高的结果。同样，耐热性较强的家族也具有较高的水分利用效率和较慢的生长速度，这表明其生长策略较为保守。与沿海家族相比，种间杂交种表现出更高的耐热性（在50和55°C时电解质渗漏较低）和更高的水分利用效率，这表明杂交可能是适应气候变暖的预先适应等位基因的一个来源，在日益干旱的条件下，大规模造林项目应考虑采用杂交种。
