SHRUNKEN-1-ENCODED SUCROSE SYNTHASE IS NOT REQUIRED FOR THE SUCROSE-ETHANOL TRANSITION IN MAIZE UNDER ANAEROBIC CONDITIONS

The physiological role of the strong anaerobic induction of the sucros e synthase gene, Shrunken-1 (Sh1), is still unknown. It is likely that sucrose synthase plays an important role in the cytosolic utilization of sucrose to ethanol under conditions of limited oxygen availability , via the fermentative pathway. In this paper we examined the importan ce of the Sh1-encoded sucrose synthase for the utilization of sucrose through the alcoholic fermentative pathway in maize. The results indic ate that deficiency in the Sh1-encoded sucrose synthase does not have any effect on the rate of ethanol production. Unexpectedly, this is no t the result of enhanced invertase activity in the shl mutant but, ins tead, of the presence of Sus1-encoded sucrose synthase, which is norma lly absent in wild-type maize seedlings.