EFFECTS OF RED AND BLUE-LIGHT ON THE COMPOSITION AND MORPHOLOGY OF MAIZE KERNELS GROWN IN-VITRO

Growth and development of plants are known to be affected by exposure to red and blue light. Mechanisms by which light quality influences ge ne expression in maize (Zea mays L.) embryos have not been explored. M aize kernels can be cultured in vitro allowing experimental manipulati on of environmental factors during seed development. We used the in vi tro kernel culture system to investigate the response of developing ma ize seeds, which normally develop without exposure to light, to contro lled light quality. Kernels grown under red light accumulated more dry weight than those grown in darkness, whereas kernels grown under blue light accumulated less. Reciprocal color shift experiments showed tha t light quality during the first week in culture had more influence on kernel weight than during the subsequent three weeks in culture. Solu ble sugars were higher in both light treatments than in darkness. Blue -grown kernels had higher amino acid and lower lipid levels than red-o r dark-grown kernels. Embryo morphology was markedly affected by red l ight, under which the upper shoot axis was longer than under blue ligh t or in darkness. Embryo morphology was influenced by light quality du ring the later stages of development rather than the first week. We su ggest, based on these results, that gene expression in the embryo and endosperm of developing maize seeds is sensitive to light quality, and the mechanism and time dependence of this effect warrant further stud y. In vitro maize kernel culture affords a convenient system for such light quality experiments.