ISSN:
1432-2048
Keywords:
Cell wall hydrolysis
;
Endo-β-mannanase
;
Endosperm weakening
;
α-Galactosidase
;
Germination (seed)
;
Lycopersicon (mutant, germination)
;
Mannosidase
;
Mutant (gibberellin deficient)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The weakening of the mechanical restraint of the endosperm layer in tomato (Lycopersicon esculentum Mill.) seeds, a prerequisite for germination, has been studied with the use of seeds of the gibberellin (GA)-deficientgib-1 mutant. Incubation ofgib-1 endosperms, including part of the testa, in 10 μM GA4+7, resulted within 12 h in the release of fructose, glucose, galactose and mannose into the incubation medium. Only small amounts of sugars diffused out of thegib-1 endosperms during incubation in water. Chemical hydrolysis of endosperm cell walls ofgib-1 seeds showed that they are mainly composed of mannose, and smaller quantities of glucose and galactose. Treatment with GA4+7 induced in the endosperms the production of endo-β-mannanase activity that was not detectable during incubation in water, and also increased the activities of mannohydrolase and α-galactosidase as compared with the water controls. No cellulase activity was found. It is concluded that in tomato seeds the weakening of endosperms prior to radicle protrusion is mediated by a GA-induced enzymatic degradation of the mannan-rich cell walls.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00634479
