Elucidation of the Radio-Sensitivity Level of Amorphophallus paeoniifolius (Dennst.) Nicolson Embryogenic Callus Induced by Gamma Ray Irradiation

The tuber of Amorphophallus paeoniifolius (Araceae) has potential to be developed as an alternative food source. However, the tuber contains oxalate compounds which reduce the utilization of this species as a food material. Inducing genetic mutations by exposure of plant tissue to gamma-ray followed by selection process is one plant breeding method that can be used to increase genetic diversity and produce genetically improved cultivars of A. paeoniifolius. To achieve an effective gamma-ray induction, the threshold of the sensitivity level of particular plant tissue is necessary to be elucidated in advance. Hence, the objective of the current study was to determine the level of radio-sensitivity of in vitro-cultured A. paeoniifolius embryogenic callus to gamma rays. The main treatment factor in this experiment was different doses of gamma irradiation, namely 0, 5, 10, 15, and 20 Gy. A completely randomized design with five replications was used. Plant growth parameters including the number of roots, shoots, and leaflets, also height of plantlets arising from the callus were declined by applying gamma irradiation. Importantly, applying irradiation doses greater than 15 Gy significantly decreased the proportion of surviving embryogenic callus. The lethal doses 20, 30, and 50 (LD₂₀, LD₃₀, and, LD₅₀) of calluse were 1.75, 5.44, and 12.84 Gy gamma irradiation, respectively. Since the high frequency of mutation was previously often found in around LD₂₀ – LD₅₀ irradiated callus in other herbaceous species, this present study suggested that the effective gamma irradiation of A. paeoniifolius embryogenic callus was between 1.75 Gy until 12.84 Gy.