An Unique Organization Pattern of Chloroplast Nuclei (Nucleoids) in the Coleoptiles of Oryza sativa

Abstract

When seeds of rice imbibed water were incubated under a continuous light in air at 28°C, the coleoptiles began to grow from 24hr and the tips of which became green from 48 hr after imbibition. An examination on behavior of plastids and their nuclei (nucleoids) by light and fluourescence microscopy showed that proplastids in a part of the tip cells of the coleoptiles differentiated into chloroplasts at 60 hr after imbibition with a very unique organization pattern of the chioroplast nuclei (cp-nuclei). The term “unique” means that unlike the case in leaf chioroplast, in which numerous cp-nuclei scatter into the entire regions of the chloroplast envelop, the multiplied chloroplast DNA (cp-DNA) in coleoptile forms just 1 to 3 giant cp-nuclei throughout the chloroplast differentiation. This unique behavior of cp-nuclei has not been reported in tissues of plants and could have direct relations with the functions of chloroplasts.