02276nam a2200229 a 450000100080000000500110000800800410001910000170006024501150007726001570019250000140034952015010036365000180186465000110188265300200189370000240191370000170193770000210195470000200197570000280199570000230202318870592011-04-29       2011    bl uuuu     u00u1 u    #d1 aNEVES, D. M.  aFunctional analysis of 9-cis-epoxycarotenoid dioxygenase (NCEDs) genes in response to water deficit in citrus.  aIn: SIMPÓSIO BRASILEIRO DE GENÉTICA MOLECULAR DE PLANTAS, 3, 2011, Ilhéus. Resumos. [S. l.]: Sociedade Brasileira de Genética, 2011. 1 CD-ROM.c2011  apdf 34672  aAbscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. The oxidative cleavage of cis-epoxycarotenoids catalyzed by 9-cis-epoxycarotenoid dioxygenase (NCED) is considered to be the rate-limiting step in abscisic acid (ABA) biosynthesis. Here, we analyzed the expression of five NCEDs genes by RT-qPCR in roots and leaves of Rangpur lime (Citrus limonia Osb.) and Sunki mandarin (C. sunki) grown under water deficit. Based on the normalized transpiration rate and fraction of transpirable soil water, we determined three assessment points: 1) start of the water deficit; 2) intermediate stage of water deficit; and 3) permanent wilting point. In water stressed Rangpur lime, NCED2 was strongly induced in leaves and the NCED2, NCED3 and NCED4 were strongly induced in roots. Interestingly, NCED4 showed an expression approximately 15 times higher at permanent wilting point. In Sunki mandarin leaves, no significant differential expression was observed for the 5 genes, whatever the water deficit condition (stressed vs unstressed). However, in Sunki mandarin roots, NCED2, NCED4 and NCED5 were strongly induced at the permanent wilting point (23, 18 and 10 times more in plants stressed, respectively). These results suggest the involvement of the NCED enzymes in controlling the ABA level in roots when subjected to water deficit, and indicate that the multigene family of NCEDs could be considered as good candidate for analysis ABA-mediated drought in Citrus.  aabscisic acid  aCitrus  aDrought deficit1 aCOELHO FILHO, M. A.1 aSOUZA, D. T.1 aMENDES, A. F. S.1 aCOSTA, M. G. C.1 aSOARES FILHO, W. dos S.1 aGESTEIRA, A. da S.