CHANGES IN CHLOROPHYLL, THYLAKOID PROTEINS AND PHOTOSYNTHETIC ADAPTATION TO SUN AND SHADE ENVIRONMENTS IN DIPLOID AND TETRAPLOID ORYZA-PUNCTATA KOTSCHY AND DIPLOID ORYZA-EICHINGERI PETER

Oryza punctata Kotchy is widely distributed in Africa and comprises di ploid (2n=24, BB) and tetraploid (2n=48, BBCC) forms. The diploid form is often found in open (savanna) habitats, while the tetraploid form favours shaded (forest) ones. We described differences in the thylakoi d chlorophyll-protein complexes and in photosynthetic rates among the diploid and tetraploid forms of O. punctata and the related diploid sp ecies O. eichingeri Peter (CC). The diploid form of O. punctata did no t grow well in low light conditions either because the total amount of chlorophyll produced or in the partitioning of the thylakoid protein into core complex of photosystem II (CCII) or light-harvesting complex of photosystem II (LHCII). This contrasted with O. eichingeri and O. punctata 4x. They likely possessed much more genetic potential to adap t to shade than O. punctata 2x, and our results suggested CC genome sp ecies may have greater number of genes which confer a capacity for ada ptation to shade than BB genome species. We also discussed its consequ ences for adaptation within the habitats and its potential benefits in O. sativa.