02458naa a2200217 a 450000100080000000500110000800800410001902400520006010000230011224501130013526000090024852017830025765300330204065300220207365300240209570000190211970000210213870000190215970000240217877300380220221113312021-10-20       2019    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1007/s13199-019-00618-22DOI1 aSILVA, H. A. P. da  aMolecular and biochemical changes of aging-induced nodules senescence in common bean.h[electronic resource]  c2019  aIn the common bean (Phaseolus vulgaris L.), premature nodule senescence affects biological nitrogen fixation (BNF), reducing crop yield. Here, we investigated the molecular and biochemical changes in common bean nodules undergoing aging senescence. The experiments were carried out with three common bean genotypes and two nodule groups: senescent and non-senescent nodules. The expression patterns of 12 genes were assessed using RT-qPCR. In addition, global activities of ascorbate peroxidase (APX) and catalase (CAT), lipid peroxidation and total sugar content of nodules were also determined. Our results show that PvLb gene expression was down-regulated and PvGS(n-1) and PvUriII, genes involved in N metabolism, also decreased in senescent nodules. Transcripts related to the ethylene, abscisic acid and cytokinin phytohormones were up-regulated upon nodule senescence. Interestingly, PvSnakin-2 (SNAKIN-like cysteine rich protein), a gene related to plant-pathogen interaction, was induced in senescent nodules. The biochemical assays showed that in nodules undergoing senescence, APX activity was altered in only one genotype but CAT activity decreased in all common bean genotypes. Lipid peroxidation increased but total sugar content was not altered in nodules upon senescence. All these findings suggest that a delayed plant-response to Rhizobium infection is activated in common bean nodules undergoing aging senescence and this mechanism seems to be regulated by phytohormones and cell signaling as well, whereas the antioxidant defenses mediated by CAT are repressed, suggesting oxidative damage in nodules upon senescence. Our results offer insights into understanding nodule senescence metabolism and provide potential senescence markers for common bean nodules.  aBiological nitrogen fixation  aNodule senescence  aRoot nodule RT-qPCR1 aCAETANO, V. S.1 aPESSOA, D. D. V.1 aPACHECO, R. S.1 aARAUJO, J. L. S. de  tSymbiosisgv. 79, p. 33-48, 2019.