A striking feature of plants is the huge variety of plant forms that can be found in nature. This enormous diversity is due to variation in the shape, size, proportion and relative position of the different organs in the aerial part of the plant. Evolutionary changes in the three-dimensional organization, or architecture, of plant shoots have played a central role in the morphological diversification of plant species. Moreover, plant architecture is a determining factor in the agronomic performance of crop plants. Most plant architecture traits can be directly retraced to changes in activity and/or size of the shoot apical meristem (SAM) and derived meristems, such as lateral or axillary meristems (AMs) and floral meristems (FMs). The activity of these meristems is determined both by the plant’s genetic program and by environmental factors. Our work focuses on unravelling corresponding signalling pathways involved in controlling shoot meristem activity in Arabidopsis, lettuce, potato and tulip. Developmental processes that have our special attention are rosette formation and bolting in rosette plants, and stolon development in potato and tulip.
The role of TALE homeodomain proteins in shoot architecture
Plant members of the TALE (three-amino acid loop extension)-superclass of homeodomain (HD) transcription factor (TF) proteins play essential roles in the regulation of various aspects of plant architecture, including shoot apical meristem (SAM) maintenance, floral transition, plant height, and internode patterning. In plants, the TALE HD protein class comprises two subfamilies: the BELL (BEL1-like) class and the Knotted1-like homeobox (KNOX) class. BELL proteins associate with KNOX proteins to form heterodimers to compose functional complexes that regulate plant development. Our work aims to unravel BELL-KNOX regulatory networks involved in reproductive phase change and the bolting process that is normally accompanied with it. Current research focuses on the combinatorial mapping of primary targets of selected BELL-KNOX heterodimers to obtain essential information on the molecular processes that contribute to establishment and maintenance of above-ground plant architecture.
Metabolic control of meristem activity
Plant growth and development critically depend on carbon nutrient status. Processes that especially require significant energy input are phase transitions and the initiation and outgrowth of new shoot organs. These processes are of vital importance to plant productivity and have major impact on reproductive output and thereby yield in many crops. Most of these traits are directly linked to changes in activity and/or size of shoot meristems. Previous research points to the importance of carbon nutrients controlling meristem activity for plant growth, development, and yield. We are currently using combined natural variation and transcriptome analyses to identify loci/genes that coordinate shoot apical meristem activity changes according to the sugar availability and energy status of the plant.