October 4, 2011

Tomatoland Chapter One: The Importance of Genetic Diversity

The first chapter of Tomatoland is spent at my alma mater, the University of California Davis. UC Davis is home to the C.M. Rick Tomato Genetic Resource Center, a living seed bank on campus. Seed is stored and shared as plants are actively collected from around the world and then regenerated in campus greenhouses for scientific purposes. I've spent the last three years becoming involved with the preservation of genetic diversity through my place of work, the National Clonal Germplasm Repository (NCGR) at UC Davis. The NCGR is like a living seed bank except that all of our stock is actually living, and sharing occurs through dormant cuttings. Since the cuttings are the same material as the trees they come from, this is considered clonal propagation.

[Educational aside: When a plant shuts down for the winter, it is considered dormant. At this point, you can cut off portions of the woody plant and then re-grow the plant from this cutting. Not all plants do this as well as others. Grapes and figs are really easy to propagate - you can practically stick a dormant cutting in a fresh pot of soil and get a whole new plant. For most stone fruit (peaches, plums, apricots - found in the Prunus family) propagation is more difficult, and most people bud. The growing point on a plant is at the bud, like the 'eyes' on the potato. On dormant wood, you can carefully cut this portion out then attach it to a living plant of the same family. Attaching involves several different techniques, and you have to be somewhat scientific about it, but it's rather neat that you can do this. If you're inclined to be crafty, you can bud several different kinds of peaches onto one peach tree, or different apples on one apple tree, and end up with a bouquet of different fruit all on the same tree.]

The experimental orchards owned and maintained by the NCGR are absolutely amazing. Our mission is to keep and maintain any and all varieties and cultivars of trees and vines that grow well in Mediterranean climates. We have thousands of different kinds of grapes, hundreds upon hundreds of various pomegranates, tons of mulberries, kiwis, figs, pistachios, walnuts, persimmons, peaches, plums, apricots, cherries and so on. The grapes make up the biggest part of our collection, and I spent an entire summer attempting to take physical data on all of our table and wine grapes that make up 1,300 plants of the collection alone (and they're all cultivars from the same family and species, Vitis vinifera). The diversity of the collection is amazing - if you walk through the vineyards, you'll taste grapes that have a distinctive concord flavor, ones that are purely Muscat, some that taste like nothing, others with floral tones, some that are just sweet, others that are more musky - and that's just flavor. Some grapes grow up, others down, some with big leaves, others with small, fuzzy backs  and still others that are nice and smooth - and all of this variety is found within the same species. Wine thrives off of the diversity with different kinds of grapes getting different wine varieties: pinot noir, chardonnay, zinfandel, etc - all different cultivars of grapes, all with different growing requirements and habits. It's truly amazing.

When you go to the grocery store, usually you can buy two types of grapes: white and red. It's a shame that our current agricultural techniques do not provide for the variety available by the species of Vinefera, but that is a topic for another discussion. I'm more interested, as is author of Tomatoland Barry Estabrook, in why diversity matters. All of the various cultivars and varieties of these different plants provide unlimited genetic potential. Not only do these different plants taste and grow differently, but they all have different resistances to terrible plant diseases. It's possible to breed resistance to certain diseases into more popularly grown varieties, and thus prevent over-usage of pesticides and better, stronger plants. I am currently a part of a project that is trying to find resistance of crown gall, a bacterial disease that causes big galls on the crown of walnut plants, reducing production and causing eventual tree death. In this project, we are inoculating all varieties available at the NCGR in hopes that a handful won't be affected by the bacteria, and will therefore have genetic material to breed into popular walnut varieties.

It's important to keep and maintain as much genetic diversity as possible to provide for resistance of known, and future unknown, diseases. We owe much of our ability to grow plants all over the world to this goal of science. The potential of this diversity does not stop at disease resistance - scientists are attempting to improve the nutritional content, drought resistance, and production output of many of the fruits and vegetables we eat on a daily basis through the usage of weird and wild related plants out of cultivation.

While at work today, I took a handful of pictures to display the variety in grape leaves around the greenhouses. I really enjoy the diversity of our collections, and I hope you can enjoy how different all of these leaves look while still being a part of the same family (and relations). It's sort of like the human species - we're not at all alike to one another but we all are considered humans. I'm sure you'd be bummed if you only could find varieties of me for friendship around the world, just as I'm bummed you can only find one kind of grape at the grocery store. C'est la vie!
Red and fuzzy!
Not only does this leaf have multiple leaflets, but it's shiny.

I like the seperations on this leaf.
cool eh?

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