Plants have the fascinating ability to constantly adapt their development according to changes in the surrounding environment. This plasticity is provided by meristems, small groups of undifferentiated self-regenerating stem cells, continuously formed throughout development. Meristem number, position and activity are a major source of variability in the architecture of different plant species, since they determine if, when and how branches and flowers are formed during both vegetative and reproductive development. Plant architecture, extensively modified during the domestication of crop species, still represents a major target of selection in modern breeding. In particular, in cultivated grasses, the major worldwide food source, vegetative and reproductive branching represents a major component of yield.
Our research is aimed at understanding: i) how pluripotent meristematic cells are formed during development; ii) how meristem fate and organ initiation are regulated; iii) the role of the plant hormone auxin in shaping plant architecture and regulating meristem function (www.auxinevodevo.org); iv) the molecular mechanisms of plant domestication and evolution.
In my laboratory we investigate the molecular mechanisms behind the formation and activity of meristems, by combining the strength of traditional forward and reverse genetics with molecular biology. We use maize mutants affected in branch and flower formation to identify and understand the genes and gene networks controlling plant architecture. We isolated several genes affecting branching in both tassels and ears, the male and female inflorescences of maize. Among these, we identified two transcription factors (BARREN STALK1 and BARREN STALK FASTIGIATE1), an auxin biosynthetic enzyme (SPARSE INFLORESCENCE1) involved in the formation of new meristems, and a transcriptional corepressor (RAMOSA1 ENHANCER LOCUS2) that regulates the decision of meristems to form either a branch or a flower during development. To move towards a systemic understanding of the molecular mechanisms regulating plant architecture, it is essential to achieve a more comprehensive view of the relationships of these genes and pathways, and for this purpose we are using different genomic and proteomic approaches. We also pursue functional comparative analysis, by using different model plant systems (maize and Arabidopsis thaliana) to highlight the similarities and differences at the origin of the variability in plant architectures observed in natural and domesticated environments.