Abstract

RHODOTORULA SPP. AS A POTENT ANTIMUTAGEN TO PREVENT CHROMOSOMAL ABERRATION IN ALLIUM CEPA AS A RESULT OF PROLONGED UV EXPOSURE

Sukanya Chakraborty*, Ria Basu Roy, Debasmita Sinha, Archita Ray and
Dr. Arup Kumar Mitra

Abstract

The worldwide influx of solar UV radiation poses a threat to the growth of agricultural crops and also phyllospheric organisms except the epiphytic yeasts like Rhodotorula which can resist UV damage due to higher torularhodin concentrations which enhances UV-B survival in these yeasts. As onion root tips are used for radiation cytogenetic studies for assessment of chromosomal damage to plant cells, here in this study we have used Allium cepa root meristem cells. A karyotype denotes a full set of chromosomes from an individual species which is generally compared to a normal karyotype of the same species for confirmation of the detected chromosomal anomaly which occurs usually when there is an error in cell division following meiosis or mitosis. The karyotype analysis (2n=16) of root tip cells of onion showed normal mitotic metaphase, anaphase, telophase chromosomes in contrast to those onion root tips which after pretreatment were exposed to UV radiation of 254 nm for a duration of 5 and 10 minutes. Various types of chromosomal alteration were observed in terms of appearance of laggard, deletions, duplications, inversions, ring formations, and translocations. These numerical or structural aberrations reported was thus tested again using the same protocol of staining with acetoorcein and karyotype analysis after squashing the root tip cells of onion which were exposed to UV and later on allowed to grow in Rhodotorula culture suspension. Karyogenesis and ideogram thus made, helped us conclude that the total number of cells studied was 90 out of which abnormal cells were 71% and 91% of the total cell population in case of onion root tips exposed to UV for a duration of 5 and 10 minutes respectively and this figure showed a 15% reduction for 5 minute UV radiation exposure and 49.5% reduction for 10 minute UV radiation induction when treated with Rhodotorula yeast, the net result being reduction of chromosomal aberration in root tip cells treated with Rhodotorula suspension which reveals the fact that if onions are allowed to grow in soil rich with phyllospheric organisms like Rhodotorula spp. then the probable UV damage caused to onion can be reduced as there is high accumulation of carotenoid pigments which provides photoprotection against lethal photooxidation in these UV resistant yeasts.

Keywords: Rhodotorula spp., photoprotection, karyotype, ideogram, Allium cepa, chromosomal aberration.