CHANGES IN CARBOHYDRATES AND CARBOHYDRATE METABOLIZING ENZYMES DURING WATERMELON FRUIT SET

In sink tissues of cucurbits, including watermelon fruits, stachyose and raffinose together with sucrose are the major translocated carbohydrates.
The metabolism of imported carbohydrates in fruit is related to the fruit sink strength.
To shed light on the relationship between carbohydrates metabolism with fruit set of watermelon (Citrullus Lanatus Mansfeld), changes in carbohydrates and carbohydrate metabolizing enzymes in the non-pollinated, pollinated and both pollinated and regulator (Zuogualing) treated ovary were studied from 0 to 6 days after anthesis with cultivar ‘Jingxin 1’. Analysis for sugar content revealed that fructose and glucose were the major soluble sugar in watermelon ovary.
In the pollinated ovary, dry matter and concentrations of fructose and glucose increased rapidly.
In accordance with this, activities of acid and alkaline -galactosidase, acid invertase (AI) and natural invertase (NI) increased after anthesis and remained higher level.
In the ovary both pollinated and Zuogualing treated, activities of acid and alkaline -galactosidase, AI and NI were significantly higher than the ovary pollinated only and the increase of dry matter, fructose and glucose was also accelerated.
While in the non-pollinated ovary which became yellow gradually and aborted, there was no increase of dry matter, concentrations of soluble sugar showed a decreased trend, and activities of all the enzymes studied declined sharply.
These results suggested that fast increase of fructose and glucose was crucial to watermelon ovary development and fruit set. -Galactosidase, AI and NI played an important role in regulating accumulation of fructose and glucose during the period of fruit set.

IV International Symposium on Cucurbits

Lanchun Nie, Jifang Cui, Xueying Zhang, Bao Di

watermelon, fruit set, ovary, sugar, α-Galactosidase, sucrose metabolism enzymes

https://doi.org/10.17660/ActaHortic.2010.871.42