NUCLEAR-DNA CONTENT OF 10 RICE SPECIES AS DETERMINED BY FLOW-CYTOMETRY

Accurate estimations of nuclear DNA content of rice are important beca use this crop is being used in many types of molecular studies. The ma in objective of this study was to estimate the nuclear DNA content in ten rice species by flow cytometry. Most of the values obtained were l ower than those obtained in earlier studies using Feulgen microdensito metry. Significant differences in genome size among rice species were found. Oryza glaberrima had the smallest genome (0.73-0.76 pg/2C), whi le O. minuta and O. latifolia had the largest values (ca. 2.33 pg/2C). Tetraploid species had more nuclear DNA than diploid ones. The AA gen ome had less DNA (0.86-0.96 pg/2C) than the CC (1.14-1.17 pg/2C) and E E (1.99 pg/2C) genomes. The AA genome of O. sativa was larger than the A(g)A(g) genome of O. glaberrima and the A(l)A(l) genome of O. longis taminata, which had mean values of 0.73-0.76 and 0.78 pg/2C, respectiv ely. Indica (IR36) and japonica (Yukihikari) cultivars of O. sativa al so showed significant differences. Three different nuclear DNA levels (1.93, 1.85, and 1.31 pg/2C) were found among five O. ridleyi plants a nalyzed. Flow cytometry also allowed rapid and reliable determination of the ploidy level of anther culture-derived plants.