Relationship between invertase (s) activity and sucrose metabolism in the leaves of high and low sugar cultivars of sugarcane (Saccharum officinarum L.)

Sugarcane (Saccharum spp. hybrids) is an important commercial crop and accounts for major global sucrose production. Nowadays consistent efforts are being made to increase sucrose content in cane through unravelling its metabolic complexities. This study was aimed at investigating the activity of foliar invertase (s) in the early maturing (high sugar) and late maturing (low sugar) sugarcane cultivars at various stages of cane maturation. In the present investigation, soluble acid invertase (SAI) and neutral invertase (NI) activities were determined in the photosynthetically active third leaf of early and late maturing sugarcane cultivars. The results showed a higher foliar SAI activity and lower NI activity in low sugar accumulating cultivars. The nature of association was also determined between specific activities of SAI/NI and sugar content. A negative correlation between SAI activity and sucrose concentration was noticed whereas there was a positive correlation between hexose content and SAI activity in the leaf. In contrast, a positive correlation between NI and sucrose level and negative correlation between NI and hexose was observed. Our results indicated that the foliar invertases, also play an essential role in regulation of sugar content in sugarcane, irrespective of their maturity behavior.