EXPRESSION OF SUCROSE METABOLISM GENES IN TWO SACCHARUM SPECIES CLONES

¹ Texas Agr. Exp. Stn., 2415 E. Highway 83, Weslaco, TX 78596 USA

² USDA-ARS-SRRC, P.O. Box 19687, New Orleans, LA 70179 USA

Identification of genetic control involved in sugar accumulation in sugarcane (Saccharum sp. hybrids) may aid in production of transgenic plants and selection of genotypes with higher sucrose concentration. Representatives of two Saccharum species, S. officinarum var. 'Green German', and S. spontaneum var. 'IND81-146' were used to determine expression of sucrose metabolism genes in storage tissue by analysis of Northern blots. Internodes of Green German accumulated much more sugar than internodes of IND81-146. However, sucrose concentrations in the five youngest internodes were approximately the same in both clones. Expression of the sucrose synthase-2 gene was highest in the elongating internodes, but persisted in older internodes of Green German than of IND81-146. Levels of soluble acid invertase mRNA were similar to sucrose synthase. The presence of acid invertase mRNA in older internodes of Green German was surprising given the accumulation of sucrose in those internodes. Results from a sucrose-phosphate synthase probe and sucrose synthase-1 probe will also be presented.