Effects of Nutrient Level on Maternal Choice and Siring Success in Cucumis sativus (Cucurbitaceae)

Abstract

Plants have evolved many mechanisms to increase the chance of gene dispersal mainly through pollen and environmental factors play an important role. Understanding the mechanism behind gene dispersal is therefore crucial in the correct evaluation of the use of genetically modified crops for cultivation. In this paper we address the question of weather nutrient availability for the female affects the outcome of pollen competition between two pollen donor cultivars of Cucumis sativus. We do this by carrying out controlled crosses of female plants grown at three different nutrient levels. We separated the effect of a specific donor from the effect of pollen tube growth rate by using reversed crosses of fast and slow pollen. Our results show that female effects on siring ability vary with nutrient level. Pollen with a high pollen tube growth rate was more successful when nutrient availability for the female was high. This could be the result of selection on the female to adjust preference according to environmental circumstances. Pollen tube growth rate was measured under nutrient rich circumstances, thus high performers possessed traits adapted to a nutrient rich situation. Due to trade-off effects, these traits might not be advantageous in poor environments. Instead, individuals adapted to low nutrient circumstances will have a higher pollen tube growth rate. If siring ability varies with the environment of the recipient plant, this means that assessments of gene flow must account for this variation and include both pollen donors and recipient plants subjected to a range of environmental circumstances. In risk assessments of transgenic plants, plants are often kept under experimental, homogenous conditions. If our results also apply to other species, estimates of gene flow under constant conditions may be misleading. Selection on siring ability and female preference have fundamental effects on gene flow and need to be considered in risk assessments of transgenic plants.

The population ecology of male gametophytes: the link between pollination and seed production

“…Such effects could reflect the genetic and physiological states of recipient plants (Haileselassie et al . ; Hedhly et al . ) and/or pollen characteristics of pollen donors in the mating neighbourhood (Stehlik et al .…”

Incidence and post-pollination mechanisms of nonrandom mating in Arabidopsis thaliana

“…Alternatively, such nonrandom mating could be due to differences in male-female complementarity; pistil favoritism towards some pollen donors, either actively or inactively, or handicapping of some pollen donors, either actively or inactively. Evidence of differential male-female complementarity is found in a number of plant systems (Haileselassie et al 2005;Marshall and Diggle 2001;Marshall and Fuller 1994;Pfahler 1967;Stephenson and Bertin 1983), but see (Shaner and Marshall 2003). If competitive differences between pollen donors were only due to pollen competition, one would predict competitive abilities of pollen grains to remain constant on pistils from different accessions.…”

“…Although nonrandom mating between compatible mates, which has been likened to animal mate choice (Marshall and Folsom 1991;Snow 1994;Stephenson and Bertin 1983), is often discussed for obligate outcrossing species, nonrandom mating is quite common in self-compatible species (Bowman 1987;Cruzan 1993;Cruzan andBarrett 1993, 1996;Haileselassie et al 2005;Quesada et al 1991;Sarigorla et al 1992;Skogsmyr and Lankinen 1999;Snow 1991;Spira 1991a, 1996). Because plants with diverse reproductive strategies and from a variety of different environments display nonrandom mating, no single species is ideal for study of all its aspects and consequences.…”

Post-pollination mechanisms in Nicotiana longiflora and N. plumbaginifolia: pollen tube growth rate, offspring paternity and hybridization

“…In plants, post-pollination mechanisms can act as selective agents determining the siring success of pollen donors (Marshall and Ellstrand 1986;Marshall 1988Marshall , 1991Snow and Spira 1991;Montalvo 1992;Walsh and Charlesworth 1992;Rigney et al 1993;Carney et al 1994;Marshall et al 1996;Eckert and Allen 1997;Skogsmyr and Lankinen 1999;Marshall and Diggle 2001;Marshall and Oliveras 2001;Lankinen and Skogsmyr 2002;Shaner and Marshall 2003;Bernasconi et al 2004;Haileselassie et al 2005;Kruszewski and Galloway 2006;Marshall et al 2007). For instance, self-incompatibility reactions are a common post-pollination mechanism present in angiosperms (de Nettancourt 2001;Franklin-Tong and Franklin 2003).…”