Improvement of Drought Tolerance and Grain Yield in Common Bean by Overexpressing Trehalose-6-Phosphate Synthase in Rhizobia

• DOI: 10.1094/mpmi-21-7-0958
• Publication Date: 2008-06-05T20:02:35Z
• Authors: Ramón Suárez; Arnoldo Wong; Mario Ramírez; Aarón Barraza; María del Carmen ...; Miguel A. Cevallos; Miguel Lara; Georgina Hernández; Gabriel Iturriaga
• Keywords: DNA, Bacterial; Molecular Sequence Data; Gene Expression; TPS; OtsA; Microbiology; Rhizobium etli; Disasters; 03 medical and health sciences; Biomass; Symbiosis; Oligonucleotide Array Sequence Analysis; Phaseolus; 2. Zero hunger; 0303 health sciences; Base Sequence; Botany; Trehalose; 15. Life on land; QR1-502; 6. Clean water; Genes, Bacterial; Glucosyltransferases; QK1-989; Mutation; otsA–

Improving stress tolerance and yield in crops are major goals for agriculture. Here, we show a new strategy to increase drought tolerance and yield in legumes by overexpressing trehalose-6-phosphate synthase in the symbiotic bacterium Rhizobium etli. Phaseolus vulgaris (common beans) plants inoculated with R. etli overexpressing trehalose-6-phosphate synthase gene had more nodules with increased nitrogenase activity and higher biomass compared with plants inoculated with wild-type R. etli. In contrast, plants inoculated with an R. etli mutant in trehalose-6-phosphate synthase gene had fewer nodules and less nitrogenase activity and biomass. Three-week-old plants subjected to drought stress fully recovered whereas plants inoculated with a wild-type or mutant strain wilted and died. The yield of bean plants inoculated with R. etli overexpressing trehalose-6-phosphate synthase gene and grown with constant irrigation increased more than 50%. Macroarray analysis of 7,200 expressed sequence tags from nodules of plants inoculated with the strain overexpressing trehalose-6-phosphate synthase gene revealed upregulation of genes involved in stress tolerance and carbon and nitrogen metabolism, suggesting a signaling mechanism for trehalose. Thus, trehalose metabolism in rhizobia is key for signaling plant growth, yield, and adaptation to abiotic stress, and its manipulation has a major agronomical impact on leguminous plants.