Hung Tin Hang, Gooda Rosemary, Rizzuto Gabriele, So Thea, Thammavong Bansa, Tran Hoa Thi, Jalonen Riina, Boshier David H, MacKay John J
Department of Plant Sciences University of Oxford Oxford UK.
Institute of Forest and Wildlife Research and Development Phnom Penh Cambodia.
Ecol Evol. 2020 Sep 9;10(19):10872-10885. doi: 10.1002/ece3.6744. eCollection 2020 Oct.
and are classified as vulnerable and endangered, respectively, in the IUCN Red List and under continued threat from deforestation and illegal harvesting for rosewood. Despite emerging efforts to conserve and restore these species, little is known of their responses to drought and heat stress, which are expected to increase in the Greater Mekong Subregion where the species co-occur and are endemic. In this study of isolated and combined drought and heat effects, we found that had an earlier stomatal closure and more constant midday water potential in response to increasing drought level, suggesting that is relatively isohydric while is relatively anisohydric. Heat shock and drought had synergistic effects on stomatal closure. Our results indicate contrasting relationships in water relations, photosynthetic pigment levels, and total soluble sugars. An increase in chlorophyll a was observed in during drought, and a concomitant increase in carotenoid content likely afforded protection against photo-oxidation. These physiological changes correlated with higher total soluble sugars in . By contrast, avoided drought by reducing chlorophyll content and compromising productivity. Anisohydry and drought tolerance in are adaptations which fit well with its ecological niche as a pioneering species with faster growth in young trees. We believe this understanding of the stress responses of both species will be crucial to their effective regeneration and conservation in degraded habitats and in the face of climate change.
[物种名称1]和[物种名称2]在世界自然保护联盟红色名录中分别被列为易危和濒危物种，并且持续受到森林砍伐和红木非法采伐的威胁。尽管人们已开始努力保护和恢复这些物种，但对于它们对干旱和热胁迫的反应却知之甚少，而在这两个物种共同出现且为本地特有的湄公河次区域，干旱和热胁迫预计将会增加。在这项关于干旱和热胁迫单独及综合影响的研究中，我们发现[物种名称1]随着干旱程度的增加气孔关闭更早，中午水势更稳定，这表明[物种名称1]相对等水，而[物种名称2]相对非等水。热激和干旱对气孔关闭具有协同作用。我们的结果表明，在水分关系、光合色素水平和总可溶性糖方面存在不同的关系。干旱期间[物种名称1]的叶绿素a增加，同时类胡萝卜素含量的增加可能提供了对光氧化的保护。这些生理变化与[物种名称1]中较高的总可溶性糖相关。相比之下，[物种名称2]通过降低叶绿素含量和牺牲生产力来避免干旱。[物种名称2]的非等水性和耐旱性是一种适应，与其作为幼树生长较快的先锋物种的生态位相契合。我们相信，对这两个物种胁迫反应的这种理解对于它们在退化栖息地以及面对气候变化时的有效再生和保护至关重要。
