Mutagenic Effects of Sodium Azide in Rice¹

Abstract

Seeds of rice (Oryza sativa L. spp. japonica) cultivar ‘M5’ were presoaked in distilled water and treated for 2 or 3 hours with 0, 0.12, 0.50, 0.75, 1.0, 1.25, 1.50, and 1.75 mM sodium azide solutions prepared in 0.1 M phosphate buffer (pH 3). After treatment the seeds were rinsed for 1 hour in 15 C tap water. Seeds receiving a 2‐hour azide treatment were redried in a fume hood at room temperature for 24, 48, 72, and 96 hours prior to planting to develop treatment procedures suitable for transporting dry, treated seeds rather than growing seedlings. Although the scope of this study did not permit field evaluation of the redried treated seeds, it was found that seeds treated for 2 hours with I mM azide and redried for 96 hours had more injury than seeds treated for 3 hours with I mM azide without redrying. Thus, a 1 mM azide treatment for 2 hours with redrying may be near the maximum permissible for sufficient field viability of the M1. Seeds with a 3‐hour azide treatment were planted immediately after rinsing. The seedlings were transported by air to the California test site and transplanted for the mutation study.Criteria used to assess the biological effects of azide on rice were germination, seedling height, and seed sterility in the M1 generation, and chlorophyll‐deficient seedlings and viable mutations in the M2 generation.In general, an increase in azide concentration, along with an increase in the post‐treatment redrying period, resulted in a decrease in M1 germination and seedling height. Azide treatment also induced sterility, the highest concentration producing maximum (62.2%) seed sterility. The same treatment induced chlorophyll mutations in 98.5% of the M1 panicle progenies and in 14% of the M2 seedlings. The viridis type of mutation was most frequent.The highest frequency of viable mutations scored in the adult plant stage was 4.64% on an M2 plant basis. All azide concentrations were mutagenic. Short‐culm and dwarf mutant types were more frequent than the early‐flowering mutant types in the azide‐induced mutation spectrum. Azide should prove useful as a mutagen for the genetics and practical breeding of rice.

Relative effectiveness and efficiency of single and combination treatments using gamma rays and sodium azide in inducing chlorophyll mutations in rice.

“…Earlier workers reported a higher frequency of albina mutants in rice (Swaminathan et al 1970, Nanda and Misra 1975, Madhu sudhana Rao and Manmada Rao 1983. However, a higher frequency of viridis than albina was reported by Afsar Awan et al (1980) in azide treated japonica cultivar M5 and Seetharami Reddi and Reddi (1984) in MMS, dMS, dEMS and dES treated indica cultivars, T(N) 1, IR 8 and Sona.…”

“…The corresponding values were 52.1 and 18.6 percent in IET 5656 and 23.5 and 6.6 percent in Fujiminori. Sarma et al (1979) and Afsar Awan et al (1980) reported that in sodium azide treated rice, the maximum frequency of chlorophyll mutation was 42.0 (per M1 panicles) and 7.8 (per M2 seedlings), respectively. The high frequency of mut tants observed in the present study with 24 hours presoaking suggests that mutation frequencies in rice are also enhanced by treatments of pregerminated seeds.…”

Induced genetic variability for yield and yield traits in aromatic rice (Oryza sativa L.)

“…In general, mutagenic treatments had resulted in decreased mean coupled with enhanced variability in both genotypes and generations as compared to their respective control, though the magnitude of shift in mean varied with the treatment, genotype and trait. The decline in means of treated population was demonstrated in rice (Jana and Roy, 1973;Awan et al, 1980;Siddiqui and Singh, 2010).…”

Induced Mutagenesis for the Improvement of Pulse Crops with Special Reference to Mung Bean: A Review Update

“…There are several reports on the effect of physical and chemical mutagens on the size, shape, and color of the seeds (Mohanasundaram et al 2001 ;Joshi and Verma 2004 ). Dwarf, short culm, and early fl owering mutants were induced in rice by azide treatment (Awan et al 1980 ).…”