The Moricandia syndrome in species of the Brassicaceae - Evolutionary aspects

The CO2 compensation concentration (Gamma) and leaf anatomy were determined in 107 species of six tribes of Brassicaceae. There was an abundant bundle-sheath in all investigated species. The Moricandia syndrome, characterized by a high concentration of chloroplasts in the bundle-sheath cells and Gamma values < 30 cm(3)(CO2) m(-3) was found within species of the genera Moricandia, Diplotaxis and Brassica. Available results from molecular systematics indicate a common phylogenetic ancestor, suggesting monophyletic evolution of the syndrome within the tribe Brassiceae. Nevertheless, Gamma values of about 30 cm(3) m(-3) in some other genera of the tribes Brassiceae and Sisymbrieae indicate an evolutionarily sliding, gradual transition from C-3 ancestors.