Induction of Chlorophyll-deficient Phenotypes in Tillandsia fasciculata Swartz Var. fasciculata by Physical and Chemical Mutagens

Abstract

Seeds of Tillandsia fasciculata var. fasciculata were treated with gamma radiation, gamma and thermal neutron radiations, or ethyl methanesulfonate (EMS) and grown in vitro. Observed chlorophyll deficient phenotypes included yellowish-green, yellow, variegated and albino. The highest combined percentages of chlorophyll deficient phenotypes was 8.7% for the gamma radiation treatment (2.7 krad), 4.6% for the gamma and thermal neutron radiations treatments (combined dose of 2.7 krad at a gamma to thermal neutron ratio of 7.4:1.0), and 10.8% for the EMS treatment (0.4% EMS × 5 h). Some yellowish-green and yellow seedlings multiplied in half strength MS medium with 0.3 or 0.5 μM BA and IBA and the newly formed shoots retained their respective mutant phenotypes. However, the variegated seedlings were sectoral or mericlinal chimeras and when they multiplied, the newly formed shoots were not variegated. The chlorophyll a/chlorophyll b ratio of the wild type seedling was 1.1 whereas that of the yellowish-green and the yellow seedlings was 2.0. Electron micrographs showed that compared to the wild type chloroplasts, the chloroplasts of the yellowish-green and yellow seedlings had fewer grana and fewer thylakoids within each granum.