Table 1.

Chemical and physical mutagens applied for induction of random mutations in rice.

	Method	Mechanism of mutation	Mutation frequency	Dose	Mutants produced	Pros	Cons
	Chemical
	EMS	Guanine alkylation, G/C to A/T transitions or G/C to C/G or G/C to T/A transversions.	2-10 mutations each Mb (Till et al., 2007)	0.2–2.0%	Plant development and metabolism (Feldman et al., 2014; Feldman et al., 2017)	Improve one or two traits with decreased rates of undesirable changes.	Manipulation of the mutagen
					Herbicide resistance (LSU AgCenter)
					Abiotic stress tolerance (Panigrahy et al., 2011; Poli et al., 2013; Mohapatra et al., 2014; Xu et al., 2017a)
	MNU	Guanine and cytosine alkylation, G/C to T/A transitions.	1 mutation each 135 Kb (Satoh et al., 2010)	0.25 - 1.00 mM	Plant development and metabolism (Cha et al., 2002; Miyoshi et al., 2004; Ikeda et al., 2005; Nagasaki et al., 2007; Kurakawa et al., 2007; Qiao et al., 2010; Akter et al., 2014; Chen et al., 2015; Zhou et al., 2017; Inahashi et al., 2018)
					Nutritional quality (Sakata et al., 2016; Kim et al., 2018b)
					Plant chemical element transporters (Ma et al., 2007; Shao et al., 2017; Kim et al., 2018a)
					Biotic stress resistance (Jung et al., 2005; Busungu et al., 2016)
					Yield and quality improvement (Itoh et al., 2017; Long et al., 2017; Seo et al., 2017)
	AS	Generates azidoalanine causing G/C to A/T transitions.	1.4 - 2.9 mutation each Mb (Tai et al., 2016)	1 - 10 mM	Industrial quality (Mo et al., 2013);
					Nutritional improvement (Jeng et al., 2011; Jeng et al., 2012)
					Abiotic stress tolerance (Hussain et al., 2012; Lin et al., 2016)
					Yield and quality improvement (Lin et al., 2011; Lin et al., 2014))
	Colchicine	Chromosome doubling, affects the microtubules promoting symmetric cell division.	−	0.04 - 0.3%	Nutritional quality (Tu et al., 2014)
					Regulatory mechanism of genome duplication (Cai et al., 2007; Zhang et al., 2015)
					Abiotic stress tolerance (Tu et al., 2014)
					Yield and quality improvement (Cai et al., 2007; Zhang et al., 2017; Guo et al., 2017)
	DEP	Guanine and adenine alkylation, deletions (1Kb) and point mutations.	−	0.004% - 0.006%	Abiotic stress tolerance(Nakhoda et al., 2012)
	Physical
	γ rays	Single nucleotide substitution, inversion and deletion.	7.5×10−6 to 9.8×10−6 (Li et al., 2016c)	50 - 350 Gy	Plant development and metabolism (Hirano et al., 2010; Han et al., 2012; Smillie et al., 2012; Li et al., 2017a; Mbaraka et al., 2017; Li et al., 2018c)	Higher DNA damage, affecting many traits.	Necessary specialized physical structure.
					Industrial quality (Kong et al., 2015)
					Nutritional quality (Chun et al., 2012; Hwang et al., 2014; (Sansenya et al., 2017)
					Abiotic stress tolerance (Song et al., 2012; Joshi et al., 2016; Hwang et al., 2017)
	IBR	Point mutation (deletion), inversion, translocation and insertion.	Survival rates from 70 to 90% mutation of 1.7%; 70% survival rates mutation of 2.0% (Yamaguchi et al., 2009)	Carbon 20 - 50 Gy (up to 220 MeV) Neon 10 Gy (60-80 keV/µm)	Nutritional quality (Ishikawa et al., 2012) Plant development and metabolism (Abe et al., 2002; Maekawa et al., 2003; Hayashi et al., 2007; Phanchaisri et al., 2007; Phanchaisri et al., 2012)
FNI		A/T to G/C transition, insertion, inversion, duplication and deletion.	28-78 genome mutations (Li et al., 2016a)	20 Gy	Industrial quality (Mei, 2010)
					Biotic stress resistance (Bart et al., 2010; Chern et al., 2014; Chern et al., 2016)
					Abiotic stress tolerance (Ruengphayak et al., 2015)
CRR		−	−	15 days space environment	Plant development and metabolism (Kim et al., 2012)

EMS, Ethyl methane sulfonate; MNU, N-methyl-N-nitrosourea; SA, Sodium azide; DEP, Diepoxybutane; IBR, Ion beam radiation; FNI, Fast-neutron irradiation; CRR, Cosmic-ray radiation.