chairholder: Daniel Philippe Matton
Last year, the Chair’s research using a high-throughput sequencing technique combined with a comparative analysis of ovules capable or incapable of attracting pollen tubes led us to identify gene candidates involved in the directional guidance of pollen tubes toward ovules in solanaceae. Producing the ovule and pollen transcriptome thereby opened up two new avenues of research, for which we were able to obtain new funding. One project that grew out of the Chair’s discoveries focuses on the role of proteins that seem to be involved in speciation, that is, the evolutive process by which new living species appear, and its corollary, how these closely related species can remain distinct.
In our view, a form of “intraspecific preference” exists in the signals exchanged between pollen tube and ovule. In other words, a pollen tube is not only better guided and attracted by the ovule when both are of the same species, but its capacitation is different depending on the species on which it germinates, even in a closely related species. We know, in fact, that several species of wild solanaceae cohabit in their natural habitats in Latin America; that they flower at the same time; and that many are physiologically capable of cross-breeding. Despite this, the proportion of hybrids is low. How can we explain this paradox? The answer could lie in an interspecific variation of signaling proteins that we are attempting to isolate, by comparing the transcriptomes of closely related species of various wild solanaceae. In April, we travelled to Argentina, to the province of Salta, to collect individuals of different species sharing the same area of distribution, in order to complete our greenhouse collection and validate our hypotheses.
The production of transcriptomes in several species of solanaceae also led us to discover that, contrary to several sequenced model species (Arabidopsis, rice, poplar), certain protein families involved in signalization increase in number during pollen and ovule development. Some members are even specific to solanaceae, suggesting the acquisition of new roles in plant sexual reproduction over the course of evolution.
This research was possible in part thanks to financial support from the Canada Research Chairs program.