Primary metabolism changes in transgenic apple plants with reduced activity of sorbitol dehydrogenase

Sorbitol is the main translocated carbohydrate in species belonging to Rosaceae. It is thought to be a key molecule for the measurement of sink strength in apple. The quantity of sorbitol in plant tissues depends on the different factors such as species, development and physiological status, and type of tissues. Objective – An analysis of met- abolic changes in primary metabolism was conduct- ed in vegetative sinks of apple transgenic plants with altered sorbitol dehydrogenase (SDH) activity. The aim of this study was to determine the effects of the transgenic modulation of the SDH gene in car- bohydrate partitioning and primary metabolism. Methods – Three antisenses and one sense transgen- ic line of cv. ‘Greensleaves’ were obtained for sorbi- tol dehydrogenase and grown in pots in a controlled environment. Results – The two antisense lines activity similarly to antisense lines previously charac- terized. The three antisense lines showed alterations of three different carbohydrates, one for each plant. A041703/H showed an increase in fructose. The last one, , presented an increase in glucose. - el of amino acids was observed such as lysine, thre- onine, serine, glutamic acid, and glycine. These met- abolic changes were associated with loss of apical dominance, reduced growth of leaf and whole plant. While threonine was also enhanced in A041703/H, - quently linked with the decrease in citrulline. Stearic acid was reduced in all three antisense transgenic lines. Conclusions – These results highlight the key role of sorbitol dehydrogenase in the establishment of sink-source relationships.