Attack of the Blue Tomatoes!

For the ninth year in a row, Macon County Master Gardeners, Green Thumb community gardeners and I have planted a selection of tomato cultivars for our annual Tomato Taste Panel. During this event, community members to join us in tasting 30-40 different heirloom and hybrid tomato cultivars. The goal is to introduce people to the incredible diversity among tomato cultivars, and encourage people to try new ones in their garden.

Each January we select the cultivars for that year's Taste Panel. Honestly, there is nothing scientific about how we do it. Typically we try to have diversity in size, color and type of tomato (slicer, paste, etc). If there are new hybrids available that sound promising, we grow some. If there are heirlooms that we haven't tried before, we grow those. We also include some "old reliable" cultivars in the Panel that we know are crowd favorites so there is something for folks to compare to at Taste Panel time.

We are growing the following deep purple "blue" cultivars for the 2014 Taste Panel: 'Indigo Rose', 'Indigo Apple', 'Blue Berries' and 'Blue Beauty'. I have 'Indigo Rose' growing in a container on my patio, and 'Blue Beauty' in a raised bed. 'Blue Beauty' looks like any other tomato plant in my garden, except for the deep purple color developing on the stem end  and shoulders of the tomatoes. 'Indigo Rose' is a very different looking plant overall, and the fruits have stopped many a seasoned gardener in their tracks this summer.

The fruits of 'Indigo Rose' are large cherry-type tomatoes, but as they grow, any part exposed to the sun develops a deep purple, almost black color due plant pigments called anthocyanins The dark color is only in the skin and outer layer of the fruit's flesh-- most of the fruit will ripen to a familiar red color. The plants themselves look different-- the stems and leaves have some purple coloring, and they are very stiff and upright in form. The Master Gardeners and I were comparing notes recently on how this cultivar looked at different locations; it is so different looking we were concerned something might be wrong!

Many people have taken one look at the unusual looks of 'Indigo Rose' growing on my patio and jumped to the conclusion it is a genetically modified organism (GMO). It is NOT a GMO, where genes are artificially inserted via laboratory techniques. The genes that produce the anthocyanins naturally occur in some wild species of tomato.  The original crosses were done back in the 1960's, crossing standard tomato cultivars with wild tomato species from Chile and the Galapagos Islands. Professor Myers' graduate students worked with these original crosses to create a population from which 'Indigo Rose' was selected.

But why breed for a high anthocyanin tomato? Although 'Indigo Rose' and other blue tomatoes are getting a lot of attention as a novelty in the garden, the hope is they might have some health benefits for those that eat them. Anthocyanins are classified as antioxidants, chemicals that have the ability to neutralize other harmful chemicals in the body, preventing damage to the body's tissues. Antioxidants first received attention when researchers described the "French Paradox" where certain populations of red-wine drinkers in France and Italy had much lower incidents of heart disease than other populations in Europe and North America. It is widely accepted that at least part of this observed health difference is due to antioxidants present in red wine.

Even if the hypothesized health benefits are never proven, most Americans can't go wrong in consuming more fresh produce. I am impatiently awaiting for the first of my 'Indigo Rose' tomatoes to ripen. The pictures accompanying this blog entry show pictures of the same tomatoes taken roughly two weeks apart. The darkening of the tomatoes has been pretty dramatic. Reportedly the entire tomato will soften somewhat and be a dull purple when ripe, and any shaded portions that remained green will ripen to a familiar red. I will post pictures when we have our first harvest!