ORIGINAL PAPER Cloning and expression of genes related to the sucrose- metabolizing enzymes and carbohydrate changes in peach Chunhua Zhang • Zhijun Shen • Yanping Zhang • Jian Han • Ruijuan Ma • Nicholas Kibet Korir • Mingliang Yu Received: 29 February 2012 / Revised: 24 June 2012 / Accepted: 4 September 2012 / Published online: 11 October 2012 Ó Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako ´w 2012 Abstract To shed light on the relationship between sucrose metabolism and expression of genes related to sucrose-metabolizing enzymes, six genes encoding sucrose-metabolizing enzymes were isolated, and the levels of four main carbohydrates and related enzyme activities as well as the expression of these six genes were determined in fruits, leaves and phloem-enriched fraction throughout peach fruit development. Sucrose content in mature fruit ranked first followed by glucose, fructose and sorbitol in that order, while sorbitol was the highest and sucrose lowest in phloem-enriched fraction and leaves. Glucose and fructose had similar change patterns throughout fruit development. Cloning results reveal that the nucleotide sequences of the six genes have high similarity to corre- sponding genes isolated from other plants. In addition, the expression of these genes and the levels of related enzyme activities varied with tissue and stage of fruit development, suggesting a complexity in relationships between carbo- hydrates, enzymes activities and related gene expression. Sucrose phosphate synthase maybe a key enzyme involved in sucrose synthesis while sucrose synthase may mainly be responsible for sucrose synthesis in peach fruits at later stages of development. Further studies are needed to genetically and physiologically characterize these genes and enzymes in peach and to gain a better understanding of their functions and relationship with carbohydrate metabolism. Keywords Peach Á Sucrose Á Carbohydrate Á Sucrose-metabolizing enzyme Á Cloning Á Gene expression Introduction Carbohydrates are synthesized in source leaves and trans- located to sink tissues in most species in the form of sucrose to sustain heterotrophic metabolism and growth, or to be stored as sucrose or starch (Roitsch and Gonza’lez 2004). In recent years, it has become evident that sugars, notably sucrose and its breakdown products (glucose, fructose, and sorbitol), are important metabolic substances that affect the expression of different classes of genes (Koch 1996; Rolland et al. 2002) and are involved in regulation of plant development (Wobus and Weber 1999). Due to the importance of sucrose in plant life, considerable research has been done on sucrose metabolism and accu- mulation, and as a consequence, the major reactions cata- lyzed and synthesized by an array of enzymes in the sucrose metabolism pathway have been understood. Enzymes which have a close relationship with sucrose metabolism and accumulation are mainly sucrose synthase (E.C. 2.4.1.13, SS, SUS or SUSy), sucrose phosphate synthase (E.C. 2.4.1.14, SPS), sucrose transporter (SUT), and invertase (E.C. 3.2.1.26, Ivr). SUS catalyzes the reversible conversion of sucrose and UDP or ADP to UDP- or ADP-glucose and fructose (Baroja-Fernandez et al. 2003; Ji et al. 2005). SPS catalyzes the reversible conver- sion of uridine diphosphate glucose (UDPG) and fructose- 6-phosphate (F-6-P) to UDP and sucrose-6-phosphate, then Communicated by Y. Wang. C. Zhang Á Z. Shen Á R. Ma Á M. Yu (&) Institute of Horticulture, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, People’s Republic of China e-mail: mly1008@yahoo.com.cn Y. Zhang Á J. Han Á N. K. Korir College of Horticulture, Nanjing Agricultural University, Nanjing 210095, Weigang, People’s Republic of China 123 Acta Physiol Plant (2013) 35:589–602 DOI 10.1007/s11738-012-1100-1