Essay --

1. One of the main questions addressed is; why do plants choose rhizobia with nitrogen fixing strains (as nitrogen is metabolically costly) over plants with non-fixing strains that can also lead to nodulated plant (Gubry-Rangin et al, 2010). It should be noted that strains with different fixing levels have been reported in populations of rhizobia and when picking a rhizobium a plant must take into consideration its symbiotic efficacy, as rhizobia cannot be vertically transmitted. 2. The test hypothesis was that there existed partner choice and sanction in the plant-bacteria symbiotic relationship of the Medicago truncatula-Sinorhizobium meliloti. 3. Figure number What method gave these data? What do these data show? 1a) The biomass was calculated by taking counting the number of nodules each plant produced and taking the shoot of each plant, letting in dry for 48h and then weighing it. It is shown that the black color or the strain STM 5480 is more efficient in nitrogen fixing than the white color or STM 5472 strain in the singe-inoculation assay. It is also seen that the biomass...