Last night, I headed down to the beautiful Bell House in the Gowanus section of Brooklyn for the latest Secret Science Club lecture, featuring Dr Zachary Lippman of Cold Spring Harbor Laboratory. Dr Lippman studies the flowers of tomatoes, applying basic plant biology to agriculture in order to determine how to improve yields. He characterized his efforts as using a bouquet of tomato flowers to feed the world. His interest in plant biology began with his quest to grow giant pumpkins, and he displayed a photo of himself showing off a 500lb pumpkin that he had grown.
The original wild tomato was characterized by tiny fruits. The first step in increasing the yield of tomato plants was breeding plants with larger fruits. By the time the Spaniards invaded the New World, the Native Americans had bred tomatoes similar in size to modern "beefsteak" tomatoes. One determinant of fruit size is the number of locules that the fruit possesses, and a process known as fasciation can effect the number of locules. Modern attempts to increase yields concentrate on increasing the number of inflorescences, clusters of flowers, that a plant has. A typical tomato plant has six to ten inflorescences.
Dr Lippman showed a couple of videos detailing tomato farming. He has grown tomatoes extensively in both Israel and on Long Island. Tomato plants are ideal for studying flowering because the flowers have both male and female sexual organs. In order to study fruits, crosses from different varieties are made- the male portion of the flower is removed, and artificial pollination is done with a tool modified from a dissection probe.
One key to studying genetics is determining what is "normal", and then studying mutants which deviate from the "norm". There are non-heritable mutations, known as somatic mutations- these occur after fertilization. As an example of a somatic mutation, Dr Lippman displayed a photo of a tomato fruit with a long "appendage" sticking out from it.
One factor which results in higher yields is the degree of branching in a plant- more branching means more fruits here's an article by Dr Lippman describing the effect of branching on tomato yields, specifically developing compound inflorescences. A protein known as "S protein" affects the degree of branching- S protein homozygosity results in high degree of branching but poor inflorescence and slower maturation, while S protein heterozygosity results in weaker branching but higher yields.
Flowering is a reiterative process, stem cells form structures called meristems- in the production of flowers, vegetative cells in the meristems transition to reproductive cells. Environmental cues (such as temperature and amount of light), as well as genetics effect flowering, and many genes and hormones are involved in flowering. Evolution is a master "tuner" of meristem regulation and inflorescence architecture.
Florigen is a protein produced in the leaves of a plant which triggers flowering. Another protein known as antiflorigen suppresses flower formation. The actual development of flowers depends on the ratio of these two substances. If anti-florigen is absent, the plant "self prunes"- there's a tension between florigen and antiflorigen, between vegetative growth and reproductive growth. In order to maximize yield, self-pruning must be delayed, if one copy of a florigen gene is "broken", the yield will be as much as 50% higher. Florigen heterozygosity combined with S heterozygosity provides for even higher yields.
Dr Norman Borlaug was one of the architects of the Green Revolution, which largely depended on mutations which resulted in plants of smaller stature but higher yield. Dr Lippman indicated that the breeding of even higher yield plants could result in a second green revolution.
In the Q&A, some bastard in the audience asked if polyploidy were a major factor in tomato genetics. As an aside, a lot of cabbage varieties and tetraploid (they have four sets of chromosomes) and wheat is hexaploid (it has six sets of chromosomes). Dr Lippman indicated that modern tomatoes are diploid, they only possess two sets of genes, but that polyploidy may have played a role in the development of domesticated tomatoes from their small, wild forebears- polyploids can undergo diploidization and revert to two sets of chromosomes.
This lecture was another fine production of the Secret Science Club. Dr Lippman not only provided great information about plant biology, but he provided a good overview of large-scale agriculture. It was a good reminder of where our food actually comes from. Here's a brief video introduction from Dr Lippman:
On an unrelated note, Bell House impresario, and Friend of the Bastard, Andy Templar (is that the coolest name ever?) gave me a sample of his Floyd's Kentucky Beer Cheese, specifically the bacon flavored variety. I give this "Product of Kentucky, Made in Brooklyn" two thumbs up- it was so good, it was practically sinful, and I'm not a churchly guy. Spread on day-old Italian bread, it made a really good quick meal after a long night of drinking and a tedious late-night subway ride. Seriously, people, get some. You won't be disappointed!