Bacteria get the upper hand on modern crops

Decades of breeding high-yielding soya-beans in fertilized soils has produced varieties that have lost the ability to interact effectively with soil bacteria, researchers have found. **Lost talent** Soya beans do not typically require fertilizer because they live together with soil bacteria that ‘fix’ atmospheric nitrogen into more useful forms, such as ammonium, that can be used by the plant. In exchange, the plants provide carbon to the bacteria. But fixing nitrogen is costly, and not all bacteria put much effort into the process. Soils contain some strains of bacterial 'swindlers', which live off plant roots without giving much nitrogen in return. Previous research has shown that soya beans tend to fight back against such swindlers, providing less carbon to cheaters and extra carbon to the more generous bacteria. This encourages the growth of beneficial bacteria. Modern agricultural practices, however, have partially relieved soya beans from having to fight this battle. #img_740#.<> Toby Kiers, now at VU University in Amsterdam, and her colleagues wondered whether new conditions might have affected the ability of soya beans to distinguish helpful bacteria from cheaters. The results suggest that modern breeds of soya beans, and possibly other crops, may now be less suited for growth in low-nutrient conditions, such as the unfertilized fields of developing countries. The results are published this week in the **Proceedings of the Royal Society Lond.** Whole article: "http://www.nature.com":[ http://www.nature.com/news/2007/071016/full/news.2007.168.html]

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