CELLULAR EXPRESSION PATTERN OF THE GLYCINE DECARBOXYLASE P-PROTEIN INLEAVES OF AN INTERGENERIC HYBRID BETWEEN THE C-3-C-4 INTERMEDIATE SPECIES MORICANDIA-NITENS AND THE C-3 SPECIES BRASSICA-NAPUS

An intergeneric hybrid plant was produced between the C-3-C-4 intermed iate species Moricandia nitens and the C-3 species Brassica napus by s exual hybridization and in vitro embryo rescue. The hybrid nature of t he plant was apparent in its morphology and flower pigmentation and wa s confirmed by leaf isozyme patterns. The overall plant morphology and the shape and thickness of leaves of the hybrid plant were intermedia te between those of the parent species. However, the bundle-sheath cel ls of the hybrid resembled those of the C-3 parent and lacked the orga nelle development of the C-3-C-4 intermediate parent. Immunogold label ling for the presence of the P subunit of the mitochondrial glycine de carboxylase complex revealed a very similar labelling density on mitoc hondria in bundle-sheath and mesophyll cells in B. napus, while in M. nitens the P subunit was only detectable in bundle sheath cells. In th e hybrid the labelling density on mesophyll cell mitochondria was almo st half of that on the bundle-sheath mitochondria. The CO2 compensatio n point of the hybrid was significantly less than that of the C-3 pare nt but was not as low, nor as responsive to changes in light intensity , as for the C-3-C-4 parent.