McHaffie H S, Legg C J, Ennos R A
The Royal Botanic Garden Edinburgh, Inverleith Row, Edinburgh EH3 5LR, UK.
Institute of Ecology and Resource Management, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JU, UK.
New Phytol. 2001 Dec;152(3):491-500. doi: 10.1046/j.0028-646X.2001.00269.x.
• Experiments were conducted to determine the genetic relationship between the alpine fern Athyrium distentifolium and the Scottish endemic taxon A. distentifolium var. flexile. • Segregation of the taxa was studied after growing sporophytes from spore families, and after selfing and crossing gametophytes. The growth of both gametophytes and sporophytes was measured under a range of nutrient regimes. • The distinction between the two taxa is due to variation at a single gene with pleiotropic effects expressed at both the sporophyte and gametophyte stages. A. distentifolium sporophytes (genotypes A /A or A /A ) are taller, have fewer fronds, and produce fewer spores than A. distentifolium var. flexile sporophytes (genotype A /A ). Gametophytes containing the A allele have a 50% higher growth rate than those with the A allele on a range of media. • The polymorphism may be maintained by a balance between selection for and against the A allele at the gametophyte and sporophyte stages of the life cycle, respectively. Implications for the conservation of the A. distentifolium var. flexile taxon are discussed.
• 开展了实验以确定高山蕨类植物疏叶蹄盖蕨（Athyrium distentifolium）与苏格兰特有分类群疏叶蹄盖蕨柔韧变种（A. distentifolium var. flexile）之间的遗传关系。• 从孢子家族培育出孢子体后，以及对配子体进行自交和杂交后，研究了分类群的分离情况。在一系列营养条件下测量了配子体和孢子体的生长情况。• 这两个分类群的区别在于一个具有多效性的单基因变异，该变异在孢子体和配子体阶段均有表达。疏叶蹄盖蕨的孢子体（基因型A/A或A/A）比疏叶蹄盖蕨柔韧变种的孢子体（基因型A/A）更高，叶片更少，产生的孢子也更少。在一系列培养基上，含有A等位基因的配子体的生长速度比含有A等位基因的配子体高50%。• 这种多态性可能分别通过在生命周期的配子体和孢子体阶段对A等位基因的正向和负向选择之间的平衡来维持。讨论了对疏叶蹄盖蕨柔韧变种分类群保护的影响。
