Nitrosomethylurea Induces Nuclear and Cytoplasmic Chlorophyll Mutations in Nicotiana glauca Grahm

Abstract

Pigment markers, critical for developmental analysis, were not previously available in Nicotiana glauca Grahm. Imbibed seed soaked in 1m M solution of the mutagen nitrosomethylurea (NMU) yielded variegated variants whereas water-soaked seed gave rise to no variants. Two of the variants were characterized via progeny analysis and transmission electron microscopy. Both M1variants were male sterile but female fertile. Variant 97–105 was a yellow-green seedling possessing somewhat normal plastids and displaying characteristics of a codominant nuclear mutation. When variant 97–105 females were crossed with wild-type males, restored male fertility was evident in some seedlings. Variant 97–411 was variegated with green, light green and white leaf regions. Whiter regions displayed highly aberrant plastids. Eventually, plastid 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 effective in obtaining both nuclear and cytoplasmic pigment mutants in a species where none have been previously reported.