CHLOROPHYLL-PROTEINS FROM MAIZE SEEDLINGS GROWN UNDER INTERMITTENT LIGHT CONDITIONS - THEIR STOICHIOMETRY AND PIGMENT CONTENT

We studied the organization of the antenna system of maize (Zea mays L .) seedlings grown under intermittent light conditions for 11 d. These plants had a higher chlorophyll-a/b ratio, a higher ratio of caroteno ids to chlorophyll and a lower ratio of chlorophyll to protein than pl ants grown in continuous light. We found all chlorophyll-protein compl exes of maize to be present. However, the minor chlorophyll a/b-protei ns CP29 and CP26, and to a greater extent CP24 and the major light-har vesting complex II were reduced relative to the photosystem (PS) II co re-complex. Also the chlorophyll a/b-antennae of PSI were reduced rela tive to the reaction-centre polypeptides. When isolated by flatbed iso electrofocussing, the chlorophyll-a/b complexes of PSII showed a highe r chlorophyll-a/b ratio and a lower ratio of chlorophyll to protein th an the same complexes from continuous light; additionally, they bound more carotenoids per protein than the latter. Thus the altered organiz ation of the photosynthetic apparatus of plants from intermittent ligh t is caused by two different factors: (i) the altered stoichiometry of chlorophyll-binding proteins and (ii) a different ratio of pigment to protein within individual chlorophyll-proteins.