Something on the Side: Axillary Meristems and Plant Development

Abstract

Axillary meristems allow the production of secondary growth axes in the shoot systems of plants. As such they make a large contribution to the plastic developmental potential of plants, allowing them to alter their architecture to suit the prevailing environment conditions. This review focuses on the formation and activity of axillary meristems, across several model species. Current topics and problems in the field are discussed.

Hormonal Regulation of Branching in Grasses

“…Many genes have been identified that regulate axillary meristem initiation and outgrowth during vegetative and reproductive development (Schmitz and Theres, 2005;Bennett and Leyser, 2006;Doust 2007b). Most of these genes have been identified as mutants that have fewer branches, because axillary meristems fail to initiate, or that are bushier than normal due to constitutive outgrowth of axillary buds.…”

Mechanisms of vegetative propagation in bulbs : a molecular approach

“…Several genes promoting axillary bud initiation have been identified in different model species (Bennett and Leyser 2006;Kebrom et al 2013) and their supposed functions could be confirmed by transgenic approaches. For instance, a transcription factor of the GRAS family characterized in tomato, rice and Arabidopsis, -Lateral suppressor (Ls), Monoculm1 (MOC1) and LATERAL SUPPRESSOR (LAS), respectively -is responsible for the establishment of an axil identity and maintenance of meristematic capacity via prevention of cell de-differentiation (Bennett and Leyser 2006;Greb et al 2003;Li et al 2003a;Schmitz and Theres 2005;Ward and Leyser 2004).…”

“…The time of formation of axillary meristems can be determined by the developmental stage of the plant (Grbić and Bleecker 2000), although this can vary according to the species. While in tomato all axillary meristems seem to appear immediately in the leaf axil when the leaf is formed, in Arabidopsis they do not all form at the same time and some leaf axils never form an axillary meristem (Bennett and Leyser 2006). In any case, the axil identity where the future axillary meristem will form needs to be established first.…”

“…For instance, a transcription factor of the GRAS family characterized in tomato, rice and Arabidopsis, -Lateral suppressor (Ls), Monoculm1 (MOC1) and LATERAL SUPPRESSOR (LAS), respectively -is responsible for the establishment of an axil identity and maintenance of meristematic capacity via prevention of cell de-differentiation (Bennett and Leyser 2006;Greb et al 2003;Li et al 2003a;Schmitz and Theres 2005;Ward and Leyser 2004). A second key regulatory gene discovered in tomato, BLIND (Bl), encodes a MYB transcription factor that also promotes axillary bud initiation but its function is independent of Ls.…”

“…Axillary meristems give rise to axillary buds, which can enter a growth arrest period after forming a few leaf primordia (Schmitz and Theres 2005). In general, after the arrest period, axillary buds sprout into lateral branches which will repeat the formation of the structures developed in the apex of the plant (Bennett and Leyser 2006). In this way, new branches are formed, but also plantlets in numerous vegetative propagated species, including various bulbous plants.…”