Changes in sucrose content and related enzyme activities during pineapple inflorescence development.

摘要

The sucrose and starch contents and the activities of acid invertase (AI), neutral invertase (NI), sucrose phosphate synthase (SPS), and sucrose synthase (SS) in 'Smooth Cayenne' pineapple (Ananas comosus) stem, peduncle, peduncle bract, petal, and ovary were studied during inflorescence development. Before full inflorescence development, sucrose and total soluble sugar (TSS) contents were higher in the stem and ovary than in other tissues. During early bud and late flowering stages, TSS significantly declined in ovary, stem and peduncle. The stem and petal starch content declined while it increased in the peduncle during inflorescence development. Starch levels in the ovary and peduncle bract increased at the bud stage. A negative correlation was found between AI and NI activities with sucrose accumulation in the stem, peduncle, peduncle bract and petal, while there was a positive correlation in the ovary. Sucrose accumulation increased with a decline in SS-decomposition activity, whereas there was no relationship between SS-synthesis and SPS activities and sugar accumulation. In conclusion, during inflorescence development, ovary, stem and peduncle were the main metabolic sources of carbohydrate products in pineapple. The results suggest that the accumulation and metabolism of sucrose was mainly controlled by invertase and SS-decomposition activity and not by SS-synthesis and SPS activity.