Plant Developmental Genetics
Jorge Almeida, Collaborator
The research focuses on plant development and evolution, using Antirrhinum majus and its close relatives as models. A particular theme that can be addressed advantageously using Antirrhinum is floral symmetry. Most plants species can be included in one of two categories according to the symmetry of their flowers: actinomorphic or zygomorphic. Actinomorphic or radially symmetrical flowers have two or more planes of mirror symmetry whereas zygomorphic or bilaterally symmetrical flowers have only one plane of mirror symmetry. Bilateral symmetry can usefully be seen as a form of asymmetry relative to a dorsoventral axis of floral development. Hence, zygomorphic flowers are also known as dorsoventrally asymmetrical.
The dorsoventrally asymmetrical condition is thought to have arisen from radial symmetry several times during evolution. To understand how such transitions may have occurred, genetic interactions underlying dorsoventral asymmetry of flowers are being dissected in Antirrhinum majus, a species with bilaterally symmetrical flowers. Three genes acting in dorsal regions of the flower, CYC, DICH and RAD, determine its overall asymmetry. Mutant plants in which both CYC and DICH or RAD are inactive have completely ventralized radially symmetrical flowers. One role of the dorsal genes is to inhibit a determinant of ventral identity, DIV. In contrast to cyc,dich or rad, mutant plants for null div have flowers in which ventral regions have lateral identity. A particular aim of the research is to analyze these gene interactions at a detailed molecular level (collaboration with the group of Manuela Costa at Universidade do Minho).
The group is also interested in understanding how such genetic interactions might have evolved, through comparative studies of flower development in Antirrhinum and its close relative Linaria. Linaria’s flowers, unlike those of Antirrhinum, have a spur at the base of the ventral petal. Otherwise their corolla dorsoventral patterns are identical. With the aim of investigating mechanisms underlying these similarities and differences, steps are being undertaken to develop Linaria maroccanna as a model for genetic and molecular analysis. This has involved isolating an active copy of a transposable element that might be of use as a tool for mutagenesis and functional gene analysis. A major target for such analysis is DIV, the determinant of ventral petal identity.
- Lisete Galego, PhD
- Hugo Tavares, Master Student
- Almeida, J., Rocheta, M. and Galego, L. (1997). Genetic control of flower shape in Antirrhinum majus. Development 124: 1387-1392.
- Galego, L. and Almeida, J. (2002). Role of DIVARICATA in the control of dorsoventral asymmetry in Antirrhinum flowers. Genes Dev. 16, 880-891.
- Galego, L. and Almeida, J. (2007). Molecular genetic basis of flower colour variegation in Linaria. Genetical Research 89, 129-134.
O grupo investiga mecanismos de desenvolvimento e evolutivos que determinam diversidade morfológica em plantas. Particular atenção tem sido dedicada à variação na forma e simetria das flores, traços que influenciam o modo como as plantas interagem com polinizadores. A maioria das espécies de plantas podem ser incluidas em uma de 2 classes, de acordo com a simetria das suas flores: actinomórficas ou zigomórficas. Flores actinomórficas, ou radialmente simétricas, têm 2 ou mais planos de simetria de reflexão, enquanto flores zigomórficas, ou bilateralmente simétricas, têm apenas um plano de simetria. A simetria bilateral evoluiu independentemente em várias linhagens a partir da simetria radial. Para compreender como terão ocorrido estas transições, têm sido analisados factores genéticos que determinam a simetria bilateral das flores e o modo como estes factores influenciam as formas de órgãos florais em Antirrhinum e Linaria.