CHANGES IN THE CARBOHYDRATES, PROTEINS AND NUCLEIC ACIDS IN THE OVULES OF ZEPHYRANTHES LANCASTERI AT DIFFERENT STAGES OF MATURATION

The major changes in the levels of soluble and insoluble carbohydrates,nitrogenous compounds and nucleic acids were investigated atdifferent stages of seed development in Zephyranthes lancasteri.The activities of amylases, glutamic-alanine transaminase, ribonucleaseand deoxyribonuclease were also studied. The alcohol-solublenitrogen and carbohydrates attain their maximal levels priorto the elongation ofthe cotyledon. Both of these decrease markedlyduring further maturation of the seed. The accumulation of totalnitrogen in the ovule follows a sigmoid pattern. The glutamic-alaninetransaminase activity appears to be exclusively localized inthe endosperm and is absent from the embryo. The embryo seemsto derive its organic nitrogen fromthe endosperm. The peak inthe level of DNA per ovule is attainedprior to the elongationof the cotyledon while that of RNA is foundsoon after. ¹Present address: AEC Plant Research Laboratory, Michigan StateUniversity, East Lansing, Mich., U.S.A.