Estorninho Mariana, Chozas Sergio, Mendes Angela, Colwell Filipe, Abrantes Isabel, Fonseca Luís, Fernandes Patrícia, Costa Catarina, Máguas Cristina, Correia Otília, Antunes Cristina
Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.
Infarm, Crop Science Team, Amsterdam, Netherlands.
Front Plant Sci. 2022 Mar 10;13:841707. doi: 10.3389/fpls.2022.841707. eCollection 2022.
The pinewood nematode (PWN), , responsible for the pine wilt disease (PWD), is a major threat to pine forests worldwide. Since forest mortality due to PWN might be exacerbated by climate, the concerns regarding PWD in the Mediterranean region are further emphasized by the projected scenarios of more drought events and higher temperatures. In this context, it is essential to better understand the pine species vulnerability to PWN under these conditions. To achieve that, physiological responses and wilting symptoms were monitored in artificially inoculated (), (), and () saplings under controlled temperature (25/30°C) and water availability (watered/water stressed). The results obtained showed that the impact of PWN is species-dependent, being infected and more prone to physiological and morphological damage than . For the more susceptible species ( and ), the presence of the nematode was the main driver of photosynthetic responses, regardless of their temperature or water regime conditions. Nevertheless, water potential was revealed to be highly affected by the synergy of PWN and the studied abiotic conditions, with higher temperatures () or water limitation () increasing the impact of nematodes on trees' water status. Furthermore, water limitation had an influence on nematodes density and its allocation on trees' structures, with revealing the highest nematode abundance and inner dispersion. In inoculated individuals, nematodes' population decreased significantly, emphasizing this species resistance to PWN. Our findings revealed a synergistic impact of PWN infection and stressful environmental conditions, particularly on the water status of and , triggering disease symptoms and mortality of these species. Our results suggest that predicted drought conditions might facilitate proliferation and exacerbate the impact of PWN on these two species, through xylem cavitation, leading to strong changes in pine forests of the Mediterranean regions.
松材线虫（PWN）是导致松树枯萎病（PWD）的病原体，对全球松林构成重大威胁。由于气候变化可能会加剧松材线虫导致的森林死亡，预计地中海地区干旱事件增多和气温升高的情况进一步凸显了对松树枯萎病的担忧。在此背景下，有必要更好地了解在这些条件下松树品种对松材线虫的易感性。为实现这一目标，在可控温度（25/30°C）和水分供应（浇水/水分胁迫）条件下，对人工接种的黑松、马尾松和火炬松树苗的生理反应和枯萎症状进行了监测。结果表明，松材线虫的影响因品种而异，黑松和马尾松比火炬松更容易受到生理和形态损伤。对于更易感的品种（黑松和马尾松），无论温度或水分状况如何，线虫的存在是光合反应的主要驱动因素。然而，水势被发现受到松材线虫与所研究的非生物条件协同作用的高度影响，较高温度（25°C）或水分限制会增加线虫对树木水分状况的影响。此外，水分限制对线虫密度及其在树木结构上的分布有影响，马尾松显示出线虫丰度和内部扩散最高。在接种的火炬松个体中，线虫数量显著减少，强调了该品种对松材线虫的抗性。我们的研究结果揭示了松材线虫感染与胁迫环境条件的协同影响，特别是对黑松和马尾松水分状况的影响，引发了这些品种的疾病症状和死亡。我们的结果表明，预测的干旱条件可能会通过木质部空化促进松材线虫的繁殖并加剧其对这两个品种的影响，导致地中海地区松林发生重大变化。
