Catalase inhibition accelerates dormancy release and sprouting in potato (Solanum tuberosum L.) tubers

Abstract

The involvement of hydrogen peroxide (H2O2) metabolism in dormancy release and sprouting of potato (Solanum tuberosum L.) tubers has been investigated using three complementary approaches. In the first approach, the evolution of the sprouting kinetics, H2O2 content and antioxidant enzyme activities were examined during tuber storage. The most important changes occurred at the « bud/sprout » level. In particular, dormancy release was accompanied by a transient but remarkable increase in H2O2 content. In the second approach, the effect of a catalase (CAT, EC 1.11.1.6) inhibitor (thiourea) or of exogenous H2O2 application on tuber sprouting behaviour was assessed. Both treatments resulted in a reduction of the dormancy period and in rapid and synchronised sprouting of the treated tubers when compared to the control as well as in increased sprout number per tuber. In the third approach, the effect of CAT inhibition on potato tuber dormancy and sprouting was evaluated using the transgenic technology. Plants partially repressed in their CAT activity were produced and, once again, CAT inhibition resulted in acceleration of the sprouting kinetics and in increased sprout number of the transgenic tubers compared to those from the wild type. It thus appears that tuber dormancy and sprouting can be controlled in potato by the manipulation of H2O2 metabolism via the inhibition of CAT activity. The possible mechanisms whereby CAT inhibitors or H2O2 overcome dormancy and promote sprouting in the potato tuber are discussed in relation to what is known in other plant models (seeds and fruit tree buds).

Keywords

• Antioxidant enzymes
• catalase inhibition
• post-harvest
• reactive oxygen species