Photosynthetic Properties of Hybrids between Diplotaxis muralis DC, a C3 Species, and Moricandia arvensis (L.) DC, a C3-C4 Intermediate Species in Brassicaceae.

Intergeneric hybrid plants were obtained by the sexual crossing of Diplotaxis muralis DC, a C3 species, and Moricandia arvensis (L.) DC, a C3-C4 intermediate species. The morphological characteristics and chromosome numbers showed that these plants were true hybrids. The hybrid had a CO2 compensation point of 27 μl/ L, nearly as low as that of M. arvensis (20 μl/L). A C3-like value of 45 μl/L for this point was found in somatic hybrids produced in our laboratory by protoplast fusion between red cabbage (Brassica oleracea L. var. capitata) or cauliflower (Brassica oleracea L. var. botrytis) and M. arvensis. However, significant differences were not found among the sexual and the somatic hybrids in the concentration or total activity of ribulose-l,5-bisphosphate carboxylase/oxygenase. The results showed that the expression, of a C3-C4 intermediate character of photosynthesis from M. arvensis appears to depend on the combination of other characters of the parental species.