STARCH SYNTHASE IN ANTHERS FROM BULBS OF TULIP CV. APELDOORN STORED AT 5 OR 17 °C

ISHS Acta Horticulturae 266: V International Symposium on Flower Buds

STARCH SYNTHASE IN ANTHERS FROM BULBS OF TULIP CV. APELDOORN STORED AT 5 OR 17 °C

Authors:

N. Gorin, F.G. van Dam

Abstract:
Specific catalytic activity of soluble starch synthase (UDPglucose: glycogen alpha

-4-glucosyltransferase, EC 2.4.1.11) was estimated in anthers from tulip bulbs precooled at 5 °C for 12 weeks and subsequently kept at 17 °C for 1 week (transport simulation), and from a control batch kept at 17 °C.

The activity increased similarly for both classes of anthers until week 6, but thereafter the increase was greater in anthers from the precooled bulbs than from the controls.

It is postulated that, in control bulbs, the catalytic activity of starch synthase counteracts the continuous increase of alpha -amylase activity, thus preventing a continuous decrease of starch content in the anthers.

In precooled bulbs the increase of starch content in the anthers during the first week can be explained by the continuous increase of starch synthase activity. However, the starch content remains virtually constant from weeks 1 to 12. As alpha -amylase is constantly low, we suggest that other hydrolytic processes counteracted the effect of starch synthase. Thus, the changes in the contents of starch in the anthers during storage of bulbs cannot be explained completely by the activities of alpha -amylase and starch synthase.

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