Nitrosomethylurea induces nuclear and cytoplasmic chlorophyll mutations inNicotiana glauca Grahm

Pigment markers, critical for developmental analysis, were not previously a vailable in Nicotiana glauca Grahm. Imbibed seed soaked in 1 mM solution of the mutagen nitrosomethylurea (NMU) yielded variegated variants whereas wa ter-soaked seed gave rise to no variants. Two of the variants were characte rized via progeny analysis and transmission electron microscopy. Both M-1 v ariants were male sterile but female fertile. Variant 97-105 was a yellow-g reen seedling possessing somewhat normal plastids and displaying characteri stics of a codominant nuclear mutation. When variant 97-105 females were cr ossed with wild-type males, restored male fertility was evident in some see dlings. Variant 97-411 was variegated with green, light green and white lea f regions. Whiter regions displayed highly aberrant plastids. Eventually, p lastid sorting-out in 97-411 resulted in a periclinal chloroplast chimera. Progeny of heteroplastidic shoots of 97-411 segregated to variegated, green , or white seedlings when 97-411 was used as the maternal parent. NMU was e ffective in obtaining both nuclear and cytoplasmic pigment mutants in a spe cies where none have been previously reported. (C) 2000 Annals of Botany Co mpany.