Author
Lingle, Sarah | |
Tew, Thomas |
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/4/2008 Publication Date: 5/20/2008 Citation: Lingle, S.E., Tew, T.L. 2008. A Comparison of Growth and Sucrose Metabolism in Sugarcane Germplasm from Louisiana and Hawaii. Crop Science. 48:1155-1163. Interpretive Summary: Sugarcane breeders in Louisiana (LA) are interested in using varieties from Hawaii (HI) in the breeding program to bring new combinations of genes to new LA varieties. Sugarcane varieties bred in tropical HI are selected for maximum tonnage in a two-year production cycle while those bred in temperate LA are selected for high early sucrose content after a 9-month growing season. We wanted to know how different varieties from LA are from varieties from HI. We compared growth, sugar concentration, and enzymes of sucrose metabolism in four HI and two LA varieties during the period of rapid growth (grand growth) and the period of sugar accumulation (ripening). The two groups of varieties did not consistently differ in growth rate. Sucrose concentrations were higher in LA than most HI varieties, especially at ripening. Differences in activities of the enzymes that metabolize sucrose could not explain these differences in sucrose concentration. Sucrose concentration, total sugar concentration, and sucrose:total sugar ratio in the internodes were negatively correlated with water content, soluble acid invertase (SAI) activity, and neutral invertase (NI) activity, and positively correlated with the difference between sucrose-phosphate synthase (SPS) and SAI activity. These correlations seem to be a function of stalk maturity. Using varieties adapted to HI in the LA sugarcane breeding program may bring in new genes, but at the cost of sucrose concentration. Technical Abstract: Sugarcane (Saccharum sp. hybrids) genotypes bred in tropical Hawaii are selected for maximum tonnage in a two-year production cycle while those bred in temperate Louisiana are selected for high early sucrose content after a 9-month growing season. We compared growth, sugar concentration, and enzymes of sucrose metabolism in four internodes of four Hawaii (HI) and two Louisiana (LA) genotypes during grand growth and ripening. Sucrose concentrations were generally higher in LA than HI genotypes, especially at ripening. Fresh weight activities of soluble acid invertase (SAI) and neutral invertase (NI) were not different among genotypes at either growth stage. Significant differences in activities of sucrose synthase (SuSy), sucrose-phosphate synthase (SPS), and cell wall acid invertase (CWIN) among genotypes were not consistent between types. Sucrose concentration, total sugar concentration, and sucrose:total sugar ratio in the internodes were negatively correlated with water content, SAI activity, and NI activity, and positively correlated with the difference between SPS and SAI activity. These correlations seem to be a function of internode maturity. The consistent differences in sucrose content between LA and HI genotypes indicate the Louisiana and Hawaii breeding programs have produced very different genotypes, but these differences cannot be explained by differences in enzyme activities. |