Exploration of teratogenic and genotoxic effects of fruit ripening retardant Alar (Daminozide) on model organism Drosophila melanogaster

Abstract

Alar (Daminozide) is a plant growth regulator which is widely used as a fruit preservative for apple and mango to prevent pre-harvest fruit drop, promote color development and to delay excessive ripening. The aim of the present work was to demonstrate the effect of Alar on several life history traits, adult morphology, Hsp70 protein expression and in vivo DNA damage in the brain of the model organism Drosophila melanogaster. We assessed the life history and morphological traits including fecundity, developmental time, pupation height, egg-to-adult viability and mean wing length, body length, arista length and sternopleural bristle number of the emerging flies. The results showed a significant delay in the developmental milestones, increase in body length, wing length, arista length, a decrease in fecundity, pupal height and variation in sternopleural bristle number in the treated flies in comparison to the controls. Overexpression of Hsp70 protein suggests alar induced subcellular molecular stress and comet assay validates genotoxicity in the form of DNA damage in the treated larvae. Mutation screening experiment revealed induction of X lined lethal mutation.

Keywords: Alar; DNA damage; Hsp 70; comet assay; drosophila melanogaster; life history traits.

Figure 1

Chemical Structure of Alar [4-(2,2-dimethylhydrazinyl)-4-oxobutanoic acid].

Figure 2

Probit line graph of acute toxicity of Alar on A) Larva and B) Pupa of Drosophila melanogaster.

Figure 3

Changes in Life history traits of Drosophila meanogaster due to the effect of Alar at a concentration of 400 ppm. A) Fecundity, B) Developmental time, C) Pupation height and D) Survival rate.

Figure 4

Wing abnormalities in Alar treated (400 ppm) flies (A, B, C).

Figure 5

Abnormally formed Pupa A) Control, B) Alar treated (400 ppm).

Figure 6

Effect of Temperature on adversity of Alar at a concentration of 200 ppm. A) Fecundity, B) Pupation time C) Adult emergence time, D) Pupation height and E) Survival rate.

Figure 7

X-gal staining of third instar larvae of transgenic Drosophila melanogaster (Hsp70-LacZ) Bg⁹ exposed to different sub-lethal concentrations of Alar. A) Control, B–D) 200, 400 and 10000 ppm Alar. (SG–Salivary Gland, PV–Proventriculus, MG–Midgut, MT–Malpighian tubules, HG– Hindgut

Figure 8

Comet assay in the cells of brain ganglia of third instar larvae of D. melanogaster. A) Images of brain cells after comet assay (Scale bar = 100 μm, 40X magnification) and B) Graph showing parameters of comet assay performed with different concentrations of Alar (Error bars indicate the standard errors from the means).

Figure 9

Scheme of cross involving attached X stock for screening X lined recessive lethal mutation induced by Alar.