02435naa a2200205 a 450000100080000000500110000800800410001910000190006024501440007926000090022352017300023265000140196265000130197665300110198970000180200070000210201870000160203970000180205577301560207316556612009-01-14       2008    bl uuuu     u00u1 u    #d1 aMACHADO, M. A.  aGene expression of carotenoid biosynthesis pathway and carotenoid content in different varieties of sweet orange (Citrus sinensis L. Osb.).  c2008  aVarieties of sweet orange are usually distinguishable by the content and quality of the juice. Such traits are important to characterize early, middle and late varieties. Juice quality is a complex trait that  changes according with the content and quality of carotenoids, flavanoids, sugars and organic acids. The balance among such compounds is the main characteristic typifies the fruits of almost all varieties of sweet orange. The studies of biochemical pathway of carotenoid synthesis are hindered by the difficulties to evaluate enzyme activities which substracts and products are hydrophobic compounds. Thus the goal of this work was to evaluate the expression of genes of carotenoid synthesis in fruits of sweet orange Hamlin (early), Pera (middle), and Valencia (late), and to correlate with the content of carotenoids during fruit development. A pool of three fruits of 12 years old trees of sweet orange grafted on Rangpur lime was evaluate for fruit quality (juice content, Brix, ratio, content of total carotenoids), gene expression by Rt-qPCR in flavedo (epicarp) (Phytoene synthase, psy; Phytoene desaturase, pds; Z-carotene desaturase, zds; Carotenoid isomerase, crtiso; Lycopene cyclase, lcyb; Beta-hydroxylase, hyb; Zexanthin epoxidase, zep; Lycopene cyclase, lcye). Primers design was based on CitEST and public database. Rt-qPCR was performed using Sybergreen. The higher gene expression (7 to 19 times) was in sweet orange Hamlin at the end of the season (June, in Brazil), pointed out an active synthesis varieties the higher expression was in the middle of the cycle (July) before the picking time. Not always a direct relationship between gene expression and content of carotenoids could be inferred.  aVariedade  aVitamina  aCitros1 aÁSTUA, J. F.1 aAMARAL, A. M. do1 aMALOSSO, A.1 aMAZZAFERA, P.  tIn: INTERNATIONAL CITRUS CONGRESS, 11., 2008, Wuhan,China. Program and abstracts... Wuhan: The International Society of Citriculture, 2008. p. 60. 105.