在藓类植物歧枝绢藓中，发育中的孢子体从诱导型向组成型耐旱生态策略转变：脱水对适合度的影响。
Developing sporophytes transition from an inducible to a constitutive ecological strategy of desiccation tolerance in the moss Aloina ambigua: effects of desiccation on fitness.
作者信息
Stark Lloyd R, Brinda John C
机构信息
School of Life Sciences, University of Nevada, 4505 Maryland Parkway, Las Vegas, NV 89154-4004, USA and Missouri Botanical Garden, P.O. Box 299, St Louis, MO 63166-0299, USA
School of Life Sciences, University of Nevada, 4505 Maryland Parkway, Las Vegas, NV 89154-4004, USA and Missouri Botanical Garden, P.O. Box 299, St Louis, MO 63166-0299, USA.
出版信息
Ann Bot. 2015 Mar;115(4):593-603. doi: 10.1093/aob/mcu252. Epub 2015 Jan 11.
BACKGROUND AND AIMS
Two ecological strategies of desiccation tolerance exist in plants, constitutive and inducible. Because of difficulties in culturing sporophytes, very little is known about desiccation tolerance in this generation and how desiccation affects sexual fitness.
METHODS
Cultured sporophytes and vegetative shoots from a single genotype of the moss Aloina ambigua raised in the laboratory were tested for their strategy of desiccation tolerance by desiccating the shoot-sporophyte complex and vegetative shoots at different intensities, and comparing outcomes with those of undried shoot-sporophyte complexes and vegetative shoots. By using a dehardened clonal line, the effects of field, age and genetic variance among plants were removed.
KEY RESULTS
The gametophyte and embryonic sporophyte were found to employ a predominantly inducible strategy of desiccation tolerance, while the post-embryonic sporophyte was found to employ a moderately constitutive strategy of desiccation tolerance. Further, desiccation reduced sporophyte fitness, as measured by sporophyte mass, seta length and capsule size. However, the effects of desiccation on sporophyte fitness were reduced if the stress occurred during embryonic development as opposed to postembryonic desiccation.
CONCLUSIONS
The effects of desiccation on dehardened sporophytes of a bryophyte are shown for the first time. The transition from one desiccation tolerance strategy to the other in a single structure or generation is shown for only the second time in plants and for the first time in bryophytes. Finding degrees of inducible strategies of desiccation tolerance in different life phases prompts the formulation of a continuum hypothesis of ecological desiccation tolerance in mosses, where desiccation tolerance is not an either/or phenomenon, but varies in degree along a gradient of ecological inducibility.
背景与目的
植物中存在两种耐旱生态策略，即组成型和诱导型。由于培养孢子体存在困难，对于这一代植物的耐旱性以及干旱如何影响有性适合度知之甚少。
方法
在实验室中培养来自单一基因型的苔藓钝叶绢藓的孢子体和营养枝，通过以不同强度干燥枝 - 孢子体复合体和营养枝，测试其耐旱策略，并将结果与未干燥的枝 - 孢子体复合体和营养枝进行比较。通过使用脱硬化的克隆系，消除了田间、年龄和植物间遗传变异的影响。
主要结果
发现配子体和胚胎孢子体主要采用诱导型耐旱策略，而后胚胎孢子体采用适度的组成型耐旱策略。此外，干旱降低了孢子体适合度，以孢子体质量、蒴柄长度和孢蒴大小衡量。然而，如果胁迫发生在胚胎发育期间而非胚胎后干旱期间，干旱对孢子体适合度的影响会降低。
结论
首次展示了干旱对一种苔藓脱硬化孢子体的影响。在单一结构或世代中从一种耐旱策略向另一种耐旱策略的转变仅在植物中第二次出现，在苔藓中是首次出现。在不同生命阶段发现诱导型耐旱策略的程度促使提出苔藓生态耐旱性的连续体假说，即耐旱性不是非此即彼的现象，而是沿着生态诱导梯度在程度上有所不同。
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