The researchers studied different types of chlorophyll in pea plants to understand how mutations affect their photosynthesis. They looked at the fluorescent and absorption properties of chloroplasts and pigment-protein complexes in normal pea plants and two mutants. One mutant had more of a certain type of chlorophyll in its light-harvesting complex, while the other mutant had fewer reaction centers for photosynthesis. The first mutant also had less of certain chlorophyll forms near the reaction center of photosystem I. Gel electrophoresis showed that both mutants still produced all the necessary chlorophyll-protein complexes. Overall, the mutations caused changes in the photosystem complexes, with one mutant having fewer reaction centers for photosynthesis.