Improvement of drought tolerance and grain yield in common bean by overexpressing trehalose-6-phosphate synthase in rhizobia.
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.
Suárez
Ramón
R
Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca Mor. 62209, Mexico.
Wong
Arnoldo
A
Ramírez
Mario
M
Barraza
Aarón
A
Orozco
María Del Carmen
Mdel C
Cevallos
Miguel A
MA
Lara
Miguel
M
Hernández
Georgina
G
Iturriaga
Gabriel
G
D001483:Base Sequence; D018533:Biomass; D004269:DNA, Bacterial / Q000235:genetics; D004190:Disasters; D015870:Gene Expression; D005798:Genes, Bacterial; D005964:Glucosyltransferases / Q000096:biosynthesis* / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D027805:Phaseolus / Q000254:growth & development / Q000382:microbiology* / Q000502:physiology*; D042163:Rhizobium etli / Q000201:enzymology* / Q000235:genetics*; D013559:Symbiosis / Q000235:genetics / Q000502:physiology; D014199:Trehalose / Q000378:metabolism
D004269:DNA, Bacterial; D014199:Trehalose; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase