Leaf pretreatment with senescence retardants as a basis for oat protoplast improvement

Protoplasts obtained from oat leaves floated on buffer for 18hr show high nuclease activity, low rates of incorporation ofamino acids and nucleosides into macromolecules, and high ratesof spontaneous lysis. Addition to the leaf flotation mediumof the senescence retardants cycloheximide or kinetin, of thedibasic amino acids L-lysine or L-arginine, or of the diaminesputrescine or cadaverine reduces the rise in nuclease activityand spontaneous lysis of protoplasts, and increases the rateor extent of presumptive protein and nucleic acid synthesis.The diamines, which also retard chlorophyll degradation in theexcised leaves, appear to act both on the membrane and on systemscontrolling macromolecular synthesis and breakdown. By contrast,the senescence promoter L-serine hastens chlorophyll degradationfrom excised leaves and does not improve protoplasts derivedfrom those leaves. (Received July 4, 1977; )