Leaf trichomes in Metrosideros polymorpha can contribute to avoiding extra water stress by impeding gall formation
Leaf trichomes in Metrosideros polymorpha can contribute to avoiding extra water stress by impeding gall formation
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DOI：
10.1093/aob/mcz196
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发表时间：
2020-02-14
期刊：
影响因子：
4.2
通讯作者：
Onoda, Yusuke
中科院分区：
文献类型：
--
作者：
Amada, Gaku;Keito, Kobayashi;Onoda, Yusuke
背景和目的居住在干旱环境中的植物往往具有叶毛，但其适应意义仍不清楚。已知叶毛状体在植物防御包括瘿制造者在内的食草动物中发挥作用。由于虫瘿的形成可以增加水分流失，部分通过增加表面积，我们测试了新的假设，即叶毛可以有助于避免额外的水分胁迫，阻碍虫瘿形成，这将在干旱环境中具有适应优势。夏威夷木虱（Pariaconus spp.）叶毛的数量（占叶质量的0- 40%）在M.多形。在夏威夷岛上发现了三种虫瘿类型：最大的是“圆锥”型，其次是“扁平”型和“凹坑”型。我们进行了实验室实验，以量化的程度，瘿形成与叶水关系。我们还进行了实地调查的1779个人从48个种群在整个范围内的栖息地的M。polymorpha的岛屿上的夏威夷，以评估虫瘿形成（存在和丰富）和叶毛状体的数量之间的关联。关键结果我们的实验室实验表明，叶最小电导率显着较高的叶片有更多的圆锥或扁平型虫瘿，但不是坑型虫瘿。我们的实地调查表明，无论环境因素如何，毛状体的数量与圆锥型或扁平型虫瘿的存在概率呈负相关，但与坑型虫瘿的存在概率无关。polymorpha可以通过与一些产瘿物种的相互作用来避免额外的水分胁迫，并可能增加植物在干旱条件下的适应性。
Background and Aims Plants inhabiting arid environments tend to have leaf trichomes, but their adaptive significance remains unclear. Leaf trichomes are known to play a role in plant defence against herbivores, including gall makers. Because gall formation can increase water loss partly through increased surface area, we tested the novel hypothesis that leaf trichomes could contribute to avoiding extra water stress by impeding gall formation, which would have adaptive advantages in arid environments.Methods We focused on Metrosideros polymorpha, an endemic tree species in the Hawaiian Islands, whose leaves often suffer from galls formed by specialist insects, Hawaiian psyllids (Pariaconus spp.). There is large variation in the amount of leaf trichomes (0-40 % of leaf mass) in M. polymorpha. Three gall types are found on the island of Hawaii: the largest is the 'cone' type, followed by 'flat' and 'pit' types. We conducted laboratory experiments to quantify the extent to which gall formation is associated with leaf water relations. We also conducted a field census of 1779 individuals from 48 populations across the entire range of habitats of M. polymorpha on the island of Hawaii to evaluate associations between gall formation (presence and abundance) and the amount of leaf trichomes.Key Results Our laboratory experiment showed that leaf minimum conductance was significantly higher in leaves with a greater number of cone- or flat-type galls but not pit-type galls. Our field census suggested that the amount of trichomes was negatively associated with probabilities of the presence of cone- or flat-type galls but not pit-type galls, irrespective of environmental factors.Conclusion Our results suggest that leaf trichomes in M. polymorpha can contribute to the avoidance of extra water stress through interactions with some gall-making species, and potentially increase the fitness of plants under arid conditions.