The role of cytokinins in chloroplast lamellar development.

The accumulation of chlorophyll, production of two specific lamellar chlorophyll-protein complexes, onset of O(2) evolution, and detection of P700 were examined in intact Jack bean (Canavalia ensiformis [L.] D.C.) leaves treated with 10(-5)m kinetin or benzyladenine and allowed to green under low (30-35%) and high (80-85%) relative humidity. In contrast to reports of the promotion of chlorophyll accumulation by cytokinin treatment in excised tissue or cotyledons, intact greening leaves showed neither promotion of chlorophyll accumulation nor alteration in formation of the lamellar chlorophyll-protein complexes or development of photosynthetic function. Furthermore, cytokinin was ineffective in relieving the consequences of low relative humidity water stress on chlorophyll accumulation and on the formation of at least one lamellar chlorophyll-protein.