Battling field diseases
Regenerating Pixie a crucial step in grasping grape genetics
|Nicholson holds regenerated Pixie grape plants. Photo by Brian Charles Clark|
Getting a grip on grape genetics requires not just the sequencing of entire genomes but detailed pictures of which genes do what. To get that information, scientists need a way to quickly grow sample plants that have been genetically transformed. Transformation means that a particular gene is silenced or added to the organism in order to learn what effect the change has on the plant.
|Amit Dhingra on Pixie grape research at WSU|
Nicholson is the lead author of a paper that outlines a grape regeneration technique she and her colleagues developed using Pixie, a dwarf variety that flowers continuously and reaches maturity in just a few months. Only available since 2006, Pixie appears to be an ideal candidate as a grape "lab rat”: it grows quickly, does well in the greenhouse, takes up very little space and, now, can be regenerated reliably. In other words, Nicholson and her team’s work is an important step forward in the development of a tool that can be used to understand grape genetics.
|Nathan Tarlyn, one of Nicholson’s co-authors, working on a plant tissue culturing project. Photo by Brian Charles Clark/WSU.|
Granted, Nicholson said, Pixie may not be an ideal model for studying wine grape genetics (although Pixie was developed from Pinot Meunier, an important grape used in the production of champagne.) "That’s why we are trying the same regeneration protocol on Chardonnay and Merlot,” she said.
Plants have the ability to regenerate themselves from a single cell. This ability, called totipotency, is sometimes compared to the ability of animal stem cells (which are pluripotent) to differentiate themselves into the wide variety of cells in an organism. A plant cell can divide, differentiate, and become the cells of shoots, roots, and leaves. This, anyway, is the theory: getting a few plant cells to differentiate and grow into mature plants in the lab is much more difficult.
Nicholson and her colleagues experimented with a variety of mixes of plant growth hormones and regimes of light and dark in order to find the sweet spot that encouraged the regeneration of Pixie. Starting with a tiny piece of leaf from the very top of a plant, she and her team found that a particular combination of stress-easing dark, a particular ratio of hormones, and a nutrient medium coaxed the cells to regrow into new Pixie plants.
This article is based in part on a paper by Nicholson et al. in Plant Cell, Tissue and Organ Culture and available online at http://bit.ly/Q5JyZ6.