In many organisms females directly or indirectly select mates (or sperm) and potentially influence the fitness of their offspring. Mate choice and sexual selection in plants is more complex in some ways than in animals because plants are sessile organisms and often have to rely on external vectors, such as animals, for pollen transport. As such, there is only so much a plant can do to affect the timing of pollen arrival, or the size and diversity of deposited pollen. But can a plant control which pollen grains, of the hundreds that land on their stigmas, make it to the ovules?
Åsa Lankinen from the Swedish University of Agricultural Sciences, whose research focuses on mate choice and sexual selection in plants, teamed up with Josefin Madjidian from Lund University, Sweden, to see if they could determine whether a mechanism that plants may use to exert female choice was delayed stigma receptivity in the pistil (the female part of the flower). Delaying receptivity to pollen grains may affect aspects of pollen competition such as siring ability, paternal diversity, and offspring fitness. Their study can be found online in the July issue of the American Journal of Botany (http://www.amjbot.org/content/early/2011/06/15/ajb.1000510.full.pdf+html).
"Our study contributes to our general understanding of how and why plants choose their mates when pollen arrive repeatedly to the stigma over a period of time," said Lankinen.
Lankinen and Madjidian hand-pollinated flowers of an annual herb, Collinsia heterophylla (Plataginaceae), in a controlled greenhouse setting in a series of crosses that simulated delayed stigma receptivity.
The authors found that when stigmas were receptive, pollination arrival sequence was important: pollen from the donor that was applied first sired more offspring (up to 74%) than the second donor, even when there was only a few minutes of time lag between their depositions. This was also the case for pollinations that were done with a 24-hour lag between them. However, even in the latter scenario, a surprising proportion of the seeds were still sired by the second donor.
Interestingly, when a mixture of the two donors was applied once, all at the same time, simulating delayed stigma receptivity (because all the pollen start to grow toward the ovules at the same time), there was greater offspring diversity compared to two separate pollination events, one from each donor. In other words, the proportion of offspring sired by each donor was more even in the single pollination event of mixed pollen, rather than being dominated by a single donor.
Moreover, high paternal diversity was also associated with increased seed production, indicating a fitness advantage to delaying stigma receptivity.
"Our results indicate that in our study species the ability to enhance pollen competition between competing mates by delaying stigma receptivity is beneficial because it increases paternal diversity of the brood, which in turn is positively connected to number of seeds produced," Lankinen said. "Even though many studies have shown that enhanced pollen competition can be beneficial for the female reproductive function, the underlying reason for this association is not clear."
Given the benefit of delaying stigma receptivity, Lankinen notes that she and her colleagues "are puzzled by the fact that variation in timing of stigma receptivity is very large in wild populations," and concludes that it would be of interest to understand more about this trait under natural conditions.
Of additional interest is the potential occurrence of a sexual conflict over timing of stigma receptivity. "We have detected that some pollen donors can fertilize ovules ahead of others, presumably securing paternity by avoiding competition with later arriving pollen," Lankinen added. "Such early fertilization seems to be disadvantageous for the female function in terms of reduced seed set. Because our current study showed a benefit of delaying stigma receptivity, this further points to the presence of a sexual conflict."
Åsa Lankinen and Josefin A. Madjidian. (2011). Enhancing pollen competition by delaying stigma receptivity: Pollen deposition schedules affect siring ability, paternal diversity, and seed production in Collinsia heterophylla (Plantaginaceae). American Journal of Botany 98(7): 1191-1200. DOI: 10.3732/ajb.1000510
The full article in the link mentioned is available for no charge for 30 days following the date of this summary at http://www.amjbot.org/content/early/2011/06/15/ajb.1000510.full.pdf+html. After this date, reporters may contact Richard Hund at email@example.com for a copy of the article.
The Botanical Society of America (www.botany.org) is a non-profit membership society with a mission to promote botany, the field of basic science dealing with the study and inquiry into the form, function, development, diversity, reproduction, evolution, and uses of plants and their interactions within the biosphere. It has published the American Journal of Botany (www.amjbot.org) for nearly 100 years. In 2009, the Special Libraries Association named the American Journal of Botany one of the Top 10 Most Influential Journals of the Century in the field of Biology and Medicine.
For further information, please contact the AJB staff at firstname.lastname@example.org
Richard Hund | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences