Lineages, Lineage Stability and Pattern Formation in Leaves of Variegated Chimeras of Lophostemon confertus (R. Br.) Wilson & Waterhouse and Tristaniopis laurina (Smith) Wilson & Waterhouse (Myrtaceae)

Abstract

Three variegated chimeras of L. confertus and T. laurina arise spontaneously in seedling populations: 1, white margin: green centre, 2, green margin: light green centre and 3, green margin: white centre. Types 1 and 2 are found in T. laurina and types 1 and 3 in L. confertus. We have determined chloroplast distribution in the leaf tissues by fluorescence microscopy to assess the basis for these colour patterns.

In L. confertus, a layer of collenchyma underlies the adaxial epidermis, replaces the upper layer of palisade, and does not mask mutant inner tissues, concealed by the adaxial layer of palisade in type 2 leaves of T. laurina. The central colour patterns are explained on the basis of accepted paths of cell lineage in leaf development (protoderm green in all three types; hypodermal derivatives genetically green in 2 and 3; and subhypodermal cells chlorophyll-deficient in types 2 and 3).

The cell lineages postulated are similar in both species and we show that the observations can be accounted for only by a shift in lineage path during leaf ontogeny. We conclude that some established concepts of leaf ontogeny require revision.