By Eilene Lyon
You might think that should read “Read ‘Em and Weep” and you’d be right. That’s almost what I felt like doing after harvesting my peas this week. Honestly, I love all kinds of peas: those lovely emerald orbs, the edible snow pea pods…
But my favorite, especially for growing myself, are the sugar snap peas – the best of both worlds: round peas and juicy, edible pods.
Every year, it seems one rogue plant erupts from my seed peas that produces shelling peas instead of edible pods. This year, ALL the peas were shelling peas. How could this happen?
It turns out that peas were foundational to our understanding of genetics. Certainly farmers were carrying out rudimentary genetic engineering (i.e. hybridization and selective breeding) long before Watson and Crick introduced the world to the double helix.
In 1854, an Augustinian monk by the name of Gregor Johann Mendel undertook a series of experiments to learn how observable traits were passed from parents to offspring. He choose the garden pea as his study subject, working with 34 different varieties with stable traits (true-breeding).
Gregor Johann Mendel
It was an excellent choice for many reasons, one being that many pea characteristics (phenotypes) tend to be controlled by a single gene (genotype), rather than a combination of many genes. Peas were also a sound subject because they germinate, flower, and go to seed in a single season. Plus they produce a lot of offspring that can be planted to observe the inherited traits.
Mendel categorized the offspring by observed characteristics and produced ratios that reflected the passing of dominant and recessive genes from each parent.
He published his results in 1865. Though they explained heredity very well, the existence of genes was still unknown, and his work was essentially forgotten for decades.
Mendelian genetics is still where students begin learning about how it all works. Thank you peas!
(Like how I threw in that bit of history and science for you?)
But how on earth did my crop end up being all shelling peas? Random mutation? Just certain I had planted sugar snap peas, I defiantly marched down to the garage to inspect the seed packet. Right there on the front it proclaimed “Sugar Daddy.” See! I thought, vindicated. Then I turned the packet over to read:
“The first truly stringless podded pea…” Wait a minute. These really are supposed to be sugar snap peas. Do you see any shelled peas on that seed packet?
I thought my lesson here was going to be, “Don’t go into the garden store without your reading glasses.” Instead, shame on Burpee! Right packet, wrong peas.
(And don’t let them fool you about that stringless bit. Those peas had some truly stupendous strings, but for shelling peas, what does it matter? They work just like a zipper.)
Russell, Peter J. 2003. Essential iGenetics. Chapter 2. Benjamin Cummings, San Francisco, CA.