THE DCL GENE OF TOMATO IS REQUIRED FOR CHLOROPLAST DEVELOPMENT AND PALISADE CELL MORPHOGENESIS IN LEAVES

The defective chloroplasts and leaves-mutable (dcl-m) mutation of toma to was identified in a Ds mutagenesis screen, This unstable mutation a ffects both chloroplast development and palisade cell morphogenesis in leaves. Mutant plants are clonally variegated as a result of somatic excision of Ds and have albino leaves with green sectors, Leaf midribs and stems are light green with sectors of dark green tissue but fruit and petals are wild-type in appearance, Within dark green sectors of dcl-m leaves, palisade cells are normal, whereas in albino areas of dc l-m leaves, palisade cells do not expand to become their characteristi c columnar shape, The development of chloroplasts from proplastids in albino areas is apparently blocked at an early stage, DCL was cloned u sing Ds as a tag and encodes a novel protein of similar to 25 kDa, con taining a chloroplast transit peptide and an acidic alpha-helical regi on, DCL protein was imported into chloroplasts in vitro and processed to a mature form, Because of the ubiquitous expression of DCL and the proplastid-like appearance of dcl-affected plastids, the DCL protein m ay regulate a basic and universal function of the plastid, The novel d cl-m phenotype suggests that chloroplast development is required for c orrect palisade cell morphogenesis during leaf development.