The minimum size of seeds and spores in relation to the ontogeny of homoiohydric plants
The minimum size of seeds and spores in relation to the ontogeny of homoiohydric plants
复制标题
与同质水植物个体发育相关的种子和孢子的最小尺寸
DOI：
10.1046/j.1365-2435.1999.00293.x
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发表时间：
1999
影响因子：
5.2
通讯作者：
J. Raven
中科院分区：
文献类型：
--
作者：
J. Raven
同水合作用可以定义为非休眠陆生植物保持水分的能力，尽管没有净二氧化碳固定的能力，当土壤向植物提供水的速度低于大气在蒸腾中潜在去除水分的速度时。同水化是大多数现存维管植物孢子体的一个特征，涉及根（或功能类似的结构）、木质部、角质层、气孔和细胞间气体空间的显著分化（Raven 1977; Edwards, Abbott & Raven 1996; Bell & Mooers 1997）。同水分是胚胎植物进化过程中的一项重大生理创新，使1-100米高的植物能够在土壤水分有效性和大气蒸发需求波动的陆地生境中生长（Raven 1977,1984a, 1993,1997a, 1998）。同水特性允许非休眠孢子体结构不耐干燥，即不能在大气相对湿度低于50%（即水势为c. -100 MPa）的平衡中存活。无论陆地植物耐干燥生长营养结构高度限制在1 m以下的机制基础是什么，似乎陆地植物在1-100 m高度范围内的出现需要生长孢子体的耐干燥性与同水相结合。必须记住，干燥耐受性（如上所述）在那些生长时不耐干燥的植物的休眠结构（如种子）中很常见，并且显然与维管植物中广泛存在的一些编码“晚期胚胎发生丰富”蛋白质的密切相关基因有关，其中一组被称为脱水剂（Ingrams & Bartels 1996）。胚体进化中主要的生殖创新是异孢子的多种进化，在一些平行的异孢子进化中，种子习性的进化，最终导致植物为其生殖结构提供所需的所有水，因此地上有性生殖过程只依赖于土壤水供应
Homoiohydry may be defined as the capacity of nondormant terrestrial plants to remain hydrated, albeit without the capacity for net CO2 fixation, when the soil can supply water to the plant less rapidly than the atmosphere can potentially remove water in transpiration. Homoiohydry is an attribute of the sporophytes of most extant vascular plants and involves significant differentiation with roots (or functionally analogous structures), xylem, cuticle, stomata and intercellular gas spaces (Raven 1977; Edwards, Abbott & Raven 1996; Bell & Mooers 1997). Homoiohydry was a major physiological innovation in the evolution of embryophytes and has enabled plants 1-100 m high to grow in terrestrial habitats with fluctuating soil water availability and evaporative demand of the atmosphere (Raven 1977, 1984a, 1993, 1997a, 1998). The possession of homoiohydric characteristics permits non-dormant sporophytic structures to be desiccation-intolerant, i.e. unable to survive equilibration with an atmospheric relative humidity of less than c. 50% (i.e. a water potential of c. -100 MPa). Whatever the mechanistic basis for this height restriction of desiccation-tolerant growing vegetative structures of land plants to less than 1 m, it appears that the occurrence of terrestrial plants in the 1-100 m height range requires desiccation-intolerance in the growing sporophyte combined with homoiohydry. It must be remembered that desiccation-tolerance (as defined above) is common in dormant structures (e.g. seeds) of those plants which are desiccation-intolerant when growing and apparently relates to the widespread occurrence in vascular plants of a number of closely related genes encoding 'late-embryogenesisabundant' proteins, one group of which is termed the dehydrins (Ingrams & Bartels 1996). Major reproductive innovations in the evolution of embryophytes were the polyphyletic evolution of heterospory and, in a few of these parallel heterosporous lines of evolution, the seed habit, and culminated in the plant supplying all of the water needed to its reproductive structures, so that above-ground sexual reproductive processes relied only on soil water supply to the