Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México.
Laboratorio de Ecología Evolutiva y Biología Floral, Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET - Universidad Nacional de Córdoba.
Am J Bot. 2024 Jul;111(7):e16377. doi: 10.1002/ajb2.16377. Epub 2024 Jul 15.
Evolution of cross-pollination efficiency depends on the genetic variation of flower traits, the pollen vector, and flower trait matching between pollen donors and recipients. Trait matching has been almost unexplored among nonheterostylous species, and we examined whether the match of anther length in pollen donors and stigma length in pollen recipients influences the efficiency of cross-pollination. To explore potential constraints for evolutionary response, we also quantified genetic variation and covariation among sepal length, petal length and width, stamen length, style length, and herkogamy.
We created 58 experimental arrays of Turnera velutina that varied in the extent of mismatch in the position of anthers and stigmas between single-flowered plants. Genetic variation and correlations among flower traits were estimated under greenhouse conditions.
Style length, but not herkogamy, influenced the efficiency of cross-pollination. Plants with stamen length that matched the style length of other plants were more efficient pollen donors, whereas those with the style protruding above the stamens of other plants were more efficient pollen recipients. Significant broad-sense heritability (0.22 > h < 0.42) and moderate genetic correlations (0.33 > r < 0.85) among floral traits were detected.
Our results demonstrated that anther-stigma mismatch between flowers contributed to variation in the efficiency of cross-pollination. The genetic correlations between stamen length and other floral traits suggests that any change in cross-pollination efficiency would be driven by changes in style rather than in stamen length.
异交效率的进化取决于花性状的遗传变异、花粉载体以及花粉供体和受体之间的花性状匹配。在非雌雄同花物种中，性状匹配几乎没有被探索过，我们研究了花粉供体的花药长度与花粉受体的柱头长度的匹配是否会影响异交效率。为了探索潜在的进化反应限制，我们还量化了花萼长度、花瓣长度和宽度、雄蕊长度、花柱长度和雌雄蕊间距之间的遗传变异和协方差。
我们创建了 58 个Turnera velutina 的实验数组，这些数组在单花植物中花药和柱头位置的不匹配程度上有所不同。在温室条件下估计了花性状的遗传变异和相关性。
花柱长度，而不是雌雄蕊间距，影响异交效率。与其他植物的花柱长度匹配的雄蕊长度的植物是更有效的花粉供体，而那些花柱突出于其他植物雄蕊之上的植物是更有效的花粉受体。检测到花性状具有显著的广义遗传力（0.22 > h < 0.42）和中度遗传相关（0.33 > r < 0.85）。
我们的研究结果表明，花之间的花药-柱头不匹配有助于异交效率的变化。雄蕊长度与其他花性状之间的遗传相关性表明，任何异交效率的变化都将由花柱而不是雄蕊长度的变化所驱动。
