Hairy Vetch Mulch Activates Genes for Phytonutrients in Tomatoes

Hairy vetch mulch activates, in regular tomatoes, some of the same metabolic pathways and genes that are activated in biotech tomatoes by the insertion of the ySAMdc gene, which makes tomato plants more vigorous and makes their fruit more tasty and nutritious.

In collaborative work with Purdue University's Avtar Handa and the Italian National Research Agency's Annalaura Segre, Agricultural Research Service (ARS) plant physiologist Autar K. Mattoo made this finding after growing transgenic and non-transgenic tomato lines in both black plastic and hairy vetch mulch. Mattoo works at the ARS Sustainable Agricultural Systems Laboratory in Beltsville, Md.

The transformed gene creates higher levels of polyamines, which are organic nitrogen compounds that make tomato plants more vigorous and makes the tomatoes more tasty and nutritious. Findings indicate that polyamines might act as signaling molecules and steer metabolic pathways so fruits produce more phytonutrients.

Mattoo found that tomatoes reacted to the extra polyamines produced by the new gene the same way that they reacted to the yet-to-be-determined compounds or signals from hairy vetch. He saw significant buildup of amino acids and choline, an essential micronutrient for brain development, as well as other nutrients or antioxidants in both transgenic and non-transgenic plants grown in hairy vetch.

The study’s results testify to the power of organic legume cover crops or mulches like hairy vetch. Also, when transgenic tomatoes engineered to accumulate polyamines in the fruit are planted in hairy vetch, there is a synergy that causes these fruits to have even more nutrients than the non-transgenic fruits.

These findings will be published in a forthcoming issue of The Journal of Experimental Botany.

ARS is the U.S. Department of Agriculture's chief scientific research agency.