B. Asthir et al., Differential response of carbon and nitrogen metabolism to fluoride application in fruiting structures of chickpea (Cicer arietinum), ACT PHYS PL, 21(1), 1999, pp. 67-73
The effect of sodium fluoride (10 and 50 mol.m(-3)) on the activities of su
crose metabolizing enzymes, transaminases and glutamine synthetase in relat
ion to the transformation of free sugars to starch and protein in the fruit
ing structures (pod wall, seed coal, cotyledons) of chickpea was studied by
culturing detached reproductive shoots in a liquid medium. Addition of flu
oride to the culture medium drastically reduced starch content of the cotyl
edons and caused a marked build-up of total free sugars comprised mainly of
reducing sugars in the pod wall and seed coat, and sucrose in the cotyledo
ns. Concomitantly, the activity of soluble invertase was stimulated in the
pod wall but reduced in the cotyledons. However, soluble protein content of
both the pod wall and the cotyledons increased in conjunction with an incr
ease in the activities of glutamate-oxaloacetate transaminase, glutamate-py
ruvate transaminase and glutamine synthetase. Disruption of starch biosynth
esis under the influence of fluoride and the resulting accumulation of free
sugars possibly resulted in their favoured utilization in nitrogen metabol
ism. Labelling studies with [U-C-14]-sucrose showed that the (14)Cincorpora
tion into total free sugars was enhanced by fluoride in the pod wall but re
duced in the seed coat and cotyledons, possibly due to an inhibitory effect
on their translocation to the developing seeds.