Effect of 2-chloroethylphosphonic acid and vanillin on chlorophyll, protein and RNA synthesis in detached cucumber cotyledons, and chlorophyll degradation in senescing leaf discs of kale

N⁶-benzylaminopurine (BAP) and KC1 stimulated growth in detached greening cucumber cotyledons; BAP enhanced RNA synthesis whereas KCl strikingly accelerated leucine-¹⁴C incorporation into proteins. Vanillin (0.01 M) inhibited greening and protein synthesis, and nullified the stimulatory effects of KC1. a-chloroethylphosphonic acid (CEPA, 0.01 M) inhibited greening without any effect on protein synthesis when it was applied alone; CEPA decreased RNA synthesis, completely nullified the K⁺-induced synthesis of chlorophyll, and reduced the BAP^- or KCl^-induced growth. Vanillin inhibited yellowing in 'senescing leaf discs of kale kept in darkness, whereas CEPA had an opposite effect.