A mulch of hairy vetch makes tomato plants more vigorous and makes their fruit more tasty and nutritious.

Those are the findings of collaborative work conducted by Avtar Handa, a Purdue University researcher in West Lafayette, Ind.; Annalaura Segre, a researcher at the Italian National Research Council in Rome; and plant physiologist Autar Mattoo with the Agricultural Research Service in Beltsville, Md.

The results in regular tomatoes were similar to those obtained when the researchers inserted the ySAMdc gene into a tomato plant.

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—or plant-based nutrients.

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 found in hairy vetch. He saw a 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.

When transgenic tomatoes engineered to accumulate polyamines in the fruit were planted in hairy vetch, Mattoo found synergy that causes the fruit to have even more nutrients than the fruit from non-transgenic plants grown in the vetch.

The study's results testify to the power of legume cover crops or mulches like hairy vetch, he says.

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