![leaf primordia leaf primordia](http://3.bp.blogspot.com/-YkiKFZAxN8I/T8mNzLYeguI/AAAAAAAABR8/KXmWVwJWHhE/s1600/2012-06-01_18-22-18_773.jpg)
Parnis A et al (1997) The dominant developmental mutants of tomato, Mouse-ear and Curl, are associated with distinct modes of abnormal transcriptional regulation of a Knotted gene. Janssen BJ, Lund L, Sinha N (1998) Overexpression of a homeobox gene, LeT6, reveals indeterminate features in the tomato compound leaf. Hay A, Tsiantis M (2006) The genetic basis for differences in leaf form between Arabidopsis thaliana and its wild relative Cardamine hirsuta. Lincoln C, Long J, Yamaguchi J, Serikawa K, Hake S (1994) A knotted1-like homeobox gene in Arabidopsis is expressed in the vegetative meristem and dramatically alters leaf morphology when overexpressed in transgenic plants. Development 122(5):1567–1575īharathan G et al (2002) Homologies in leaf form inferred from KNOXI gene expression during development. Nature 379(6560):66–69Ĭlark SE, Jacobsen SE, Levin JZ, Meyerowitz EM (1996) The CLAVATA and SHOOT MERISTEMLESS loci competitively regulate meristem activity in Arabidopsis. Long JA, Moan EI, Medford JI, Barton MK (1996) A member of the KNOTTED class of homeodomain proteins encoded by the STM gene of Arabidopsis. Thus, these recent studies have shown that SGL1/ UNI, FCL1, and PALM1 provide a genetic framework for our understanding of compound leaf development in the legume plants. On the other hand, PALMATE-LIKE PENTAFOLIATA1 (PALM1) encoding a novel Cys(2)His(2) zinc finger transcription factor is required to suppress a morphogenetic activity at the leaf margin by negatively regulating SGL1 gene expression, and FUSED COMPOUND LEAF1 ( FCL1) encoding a class M KNOX protein is required for the development of the leaf proximo-distal axis and organ boundary separation in M. Instead, the legume FLORICAULA/LEAFY orthologues, UNIFOLIATA ( UNI) and SINGLE LEAFLET1 ( SGL1), are required for the initiation and development of lateral leaflet primordia in pea and M. Surprisingly, in Medicago truncatula and pea ( Pisum sativum) that belong to the so-called inverted repeat-lacking clade (IRLC) of legume plants, the KNOXI proteins are not reactivated in leaf primordia and therefore not likely involved in the development of compound leaves in these plants. In most of plants with compound leaves, the KNOXI proteins are reactivated in developing leaf primordia, and this reactivation is required for the development of compound leaves in these plants. In plants with simple leaves, this downregulation is permanent, consistent with leaves being determinant organs. The initiation of leaf primordia from the periphery of shoot apical meristem (SAM) requires downregulation of the class 1 knotted-like homeobox KNOXI proteins. However, the regulatory mechanisms that underpin the development of diverse leaf forms remain enigmatic. Diverse forms of leaves are present in nature.