Specific expression and activity of acid phosphatases in common bean nodules.

Under phosphorus (P) deficiency, sensitivity of the N 2-fixing legumes increases since the large amount of P-dependent carbon and energy turnover required during N 2 fixation are not satisfied. However, despites the fact that these crops have been widely characterized under P-deficiency and a number of tolerance traits have been identified, abilities of the nodules to cope with this environmental constraint have still to be further investigated. Increases both of activity and gene expression of acid phosphatases (APases) are among mechanisms that lead to increase both of N 2 fixation and nodule respiration under P-deficiency. Our findings have revealed that expression of phosphoenol pyruvate phosphatase (PEPase) and trehalose 6P phosphatase (TPP) genes and activities of the corresponding enzymes were positively correlated with increases both of the rhizobial symbiosis efficiency in use of P for N 2 fixation and nodule O 2 permeability. Under P-deficiency, this positive correlation was more significant for the recombinant inbred line (RIL) of Phaseolus vulgaris RIL115 that is tolerant to P-deficiency than the sensitive RIL147. Overall, the present work suggests that the tissue-specific localized PEPase and TPP transcripts of infected cells and nodule cortex play a role in adaptation to P-deficiency and are likely involved in nodule respiration linked to symbiotic nitrogen fixation (SNF).