Frequency Of Chlorophyll Mutations Research Articles

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

Seeds of rice cultivars Jaya, IET 5656 and Fujiminori were presoaked for 24 hours and then (a) irradiated with 4, 6, 8, 10 and 12 KR gamma rays, (b) treated with 0.001, 0.002, 0.004 and 0.005 molar solutions of sodium azide at pH 3 for 4 hours, or (c) subjected to combinations of the above with the view to study their relative effectiveness and efficiency in inducing chlorophyll mutations in rice. In all three varieties azide treated entries showed a higher frequency of chlorophyll mutants than did the gamma ray treated entries, under both single and combination treatments. In the variety Jaya sodium azide treatments showed a higher efficiency and effectiveness than gamma rays and combination treatments and they were more or less similar in both single and combination treatments in the other two varieties. The indica cultivars Jaya and IET 5656 were more sensitive than the japonica cultivar, Fujiminori to producing chlorophyll mutations. Sodium azide appears to be more efficient than gamma rays alone or in combination.

Azide mutagenesis in rice

Seeds of rice cultivars viz Jaya, IET 5656 and Fujiminori presoaked for 24 h were treated with 0·001, 0·002, 0·004 and 0·005 molar concentrations of sodium azide at pH 3 for 4 h with a view to investigate its mutagenic action in rice. The percentage of germination, survival, seedling height and leaf number decreased in the treated population with a few exceptions. Cytologically abnormal plants were not detected in any of the treated population. Plant height, panicle branches, seed set and panicle grain weight decreased in the azide treated population whereas tiller number increased in Jaya and Fujiminori cultivars. The frequency of chlorophyll mutants induced was more in Jaya less in IET 5656 and the least in Fujiminori 0·005 molar concentration was found to be the most effective for inducing chlorophyll mutations in IET 5656 and Fujiminori. The same concentration induced more morphological mutants in all the 3 cultivars. Morphological and physiological mutants isolated include the tall, semidwarf, dwarf, early and late flowering mutants, protein rich mutants, grain shape mutants and many others. Varietal differences are indicated in the induction of seedling injury and of chlorophyll and morphological mutants produced.

Caffeine potentiation of propane sultone mutagenesis in barley

Pre- and post-treatments with caffeine enhanced propane sultone (PS)-induced growth damage in barley. The caffeine post-treatments were, however, more effective in potentiating PS-induced growth damage and caused an additive effect on the frequency of chlorophyll mutations.

Increase in mutagenic efficiency of thermal neutrons through boron enrichment in rice seed

Dry seed lots of four rice varieties with different heading dates were exposed to thermal neutrons and to gamma-rays, with and without boron-enrichment pre-treatment of seed. M 1 plants were grown and their seeds were separately harvested and examined for frequencies of chlorophyll, heading date, and sterile mutations in the M 2 generation. The frequencies of chlorophyll mutations were not significantly different among the treatments. The frequencies of heading date mutations tended to be higher in the thermal neutron treatment with boron-enrichment than that without boron-enrichment. For the gamma-ray treatment, the opposite applied to the frequency of sterile mutations. The practical implication of boron-enrichment pre-treatment of seed in the use of thermal neutrons for mutation breeding of crop plants is discussed.

Screening of compounds for antimutagenic properties towards dimethylnitrosamine-induced mutagenicity inArabidopsis thaliana

The inhibitor of microsomal monooxygenase activities 9-hydroxyellipticine markedly inhibited the frequency of embryonic and chlorophyll mutations induced by the metabolism-requiring mutagen dimethylnitrosamine (DMN) in a higher plantArabidopsis thaliana, but had no effect on the frequency of mutations induced by the direct-acting mutagen N-methyl-N-nitrosourea (MNU). The presence of thiol containing compounds thiourea and cysteine before and during DMN or MNU treatment resulted in a decline of mutation frequency as compared to treatment with either nitroso compound alone. In contrast, the mutagenicity of DMN and. MNU was not altered in the presence of two other thiol compounds, thiouracil and glutathion and by six naturally occurring phenolic acids: ellagic. vanillic, cinnamic, coumaric, caffeic and ferulic acids.

Mutagenic response of rhodes grass (Chloris gayana Kunth.) to gamma rays. II. Studies on second (M2) generation parameters

The effect of gamma rays on parameters such as chlorophyll mutation frequency and spectrum, mutagenic effectiveness and efficiency and viable mutation frequency and spectrum were studied in M2 generation of Rhodes grass employing nine doses of gamma rays. The chlorophyll mutation frequency increased in a linear fashion at low and medium doses and was erratic at higher doses. The chlorophyll mutant spectrum ineluded albina, xantha, chlorina, viridis, tigrina, striata, albo-xantha and albo-viridis. The frequency of these mutants varied with treatments. A dose rate of 60 krad was found to be effective as well as efficient both on M1 and M2 plant basis in inducing chlorophyll mutations. The highest frequency of viable mutations was found in 50 krad treatment. Viable mutants found were: nodal variant, peduncle variant, lax ears, coxcomb ears, earhead proliferation, level of fingers, incurved fingers, gappy ears, apical sterility, partial sterility and high sterility.

Effects of repeated and alternate mutagenic method treatments with gamma-rays and ethyleneimine in successive generations on the genetic variability in rice (Studies on the utility of artificial mutations in plant breeding XIV.)

In order to evaluate whether the recurrent mutagenic treatment in successive generations would be a useful tool for mutation breeding or not, seeds of a rice variety Gimbozu were subjected to repeated treatments with 10 and 20 kR ofL gamma-rays and 0.3 and (O. 5% solution of ethyleneimine (EI), and also to alternate treatments with lOkR gammarays and 0.3% EI, then seed fertility, chlorophyll mutation frequency and genetic variations of four agronomic traits were examined in the M1, M2 and M3 generation following the final treatment, respectively. In this report, the n th generation after m th treatment was represented by mRn. Seed fertlllty mR1:In the repeated treatments the mR1 seed fertility monotonously, decreased as the number of times of treatment advanced. This tendency was more remarkable in gamma-rays than in EI and at higher dosages than at lower dosages. In the alternate treatments, the change of the seed fertility clearly depended on the kind of mutagen used in the final treatment.

Mutagenic response of rhodes grass ( Chloris gayana Kunth.) to gamma rays

In order to determine the sensitivity of Rhodes grass ( Chloris gayana Kunth.) to gamma rays and to find an optimum gamma ray dose for inducing mutations, the seeds of a local Rhodes grass cultivar were exposed to nine doses of gamma rays ranging from 10 to 90 krad. Germination, seedling growth, survival, plumule, radicle and seedling lengths, pollen fertility, and morphological variants in the M 1 generation and chlorophyll mutation frequency, and spectrum in the M 2 generation were studied. In general, there was a decrease in all biological criteria studied with an increase in dose of gamma rays in M 1 generation. A dose dependent response was observed (viz., germination, r = −0.93; seedling height, r = −0.99; survival, r = −0.98; and pollen fertility, r = −0.97) and at higher doses the effecr was drastic. The LD 50 values for all biological end points were relatively high except for pollen fertility. The morphological variants included: earhead proliferation, nodal variant, peduncle variant, leaf curl, grassy type, partial sterility, apical sterility, high sterility and gappy ears. In the M 2 generation, the chlorophyll mutation frequency increased in a linear fashion at low (10–30 krad) and medium (40–60 krad) doses and was erratic at higher doses (70–90 krad). The chlorophyll mutant spectrum included albina, xantha, chlorina, viridis, tigrina, striata, albo-xantha and albo-viridis. The frequency of these mutants varied with treatments. A dose rate of 60 krad was found to be effective as well as efficient for inducing chlorophyll mutations in M 1 and M 2 plants.

Inhibition of dimethylnitrosamine-induced mutagenesis in Arabidopsis thaliana by diethyldithiocarbamate and carbon monoxide

Diethyldithiocarbamate and carbon monoxide markedly inhibited the frequency of embryonic and chlorophyll mutations induced by the metabolism-requiring mutagen dimethylnitrosamine in the higher plant Arabidopsis thaliana. In contrast, the monoamine oxidase substrates, tryptamine, benzylamine and 2-phenylethylamine, had no such effect. The mutagenicity of a direct-acting mutagen, N-methyl- N-nitrosourea, was not altered by these inhibitors or substrates.

Frequency and spectrum of chlorophyll mutants induced in rice by chemical mutagens

Dry seeds of rice varieties 'T(N)1', 'IR 8' and 'Sona', with stabilised moisture content and presoaked in distilled water, were treated with chemical mutagens MMS, dMS, dEMS and dES with the purpose of evaluating chlorophyll mutation frequency and spectrum. In the M2 generation, mutants occurred in 24 lines of 'T(N)1; 94 lines of 'IR 8' but only in six of 'Sona'. They include albino, viridis, xantha and other categories of which viridis was predominant. dES was found to be most effective of all mutagens used in all the three varieties and varietal differences were observed.

Somaclonal genetics of rice, Oryza sativa L.

The inheritance and variations of some traits of more than 2,000 somatic cell derived plants of rice (Oryza sativa L.) were investigated in the second and third generations (T2 and T3) of regenerated plants (somaclones). The percentages of multiploids occurring in somaclones ranged from 0-13.3 in nine varieties (or hybrids) of 'Hsien' (indica) group, but no multiploid was found in nine varieties (or hybrid) of 'Keng' (japonica) group. A dwarf mutant with the height of only 20 cm was isolated in the T2 of 'Tai-Zhong-Yu 39'. Genetic analysis indicated that it was controlled by a single recessive gene. The frequencies of chlorophyll mutations probably controlled by cytoplasmic genes decreased gradually with the advance of generations. The variations of five quantitative traits - plant height, grain weight, etc. - in 950 T2 pedigree lines of four varieties were also studied. Only 24.4% of the lines were normal in all the traits studied. Variation frequencies of different traits were from 11.5% to 39.5%. And there was an obvious tendency for the plant height to become shorter, number of productive tillers to increase and 1,000 grain weight to be lighter, whatever the variety studied. Traits were uniform within each of more than 90% of all T2 lines studied. What is more interesting, variations phenotyped in T2 proved to breed true. Causes of somaclonal variations are discussed, as well as their potentials in breeding.

Mutagenic efficiency, effectiveness and factor of effectiveness of physical and chemical mutagens in rice.

Two varieties of rice, namely, Tella hamsa and IR-24 were utilized to study the mutagenic efficiency, effectiveness and factor of effectiveness by physical (gamma rays) and chemical mutagens (HA, NMU and MMS) in rice. The frequency of chlorophyll mutants in M2 generation and mutants per mutation showed similar trend in physical and chemical mutagen treated population of Tella hamsa but differed in IR-24. The frequency of chlorophyll mutations was highest in medium fertile group of gamma treatment in both the varieties. Whereas in chemical mutagen treated population, the frequency was highest in high fertile group in Tella hamsa and in medium fertile group in IR-24. Chemical mutagens were efficient in Tella hamsa while gamma treatment in IR-24. Chemical mutagens were markedly effective than physical mutagens in the production of chlorophyll mutants in both the varieties. The factor of effectiveness was uniformly hgth in gamma treatment over chemical mutagens in IR-24, whereas in Tella hamsa the chemical mutagen MMS recorded the highest followed by gamma rays.

Mutagenic Effects on Chlorophyll Mutation Frequencies and Spectrum in Rice

Seeds of the rice variety Co 37 were subjected to gamma rays and EMS alone and in combination with two treatments. The effects of frequency and spectrum were studied. The frequency of mutations estimated as number of mutants per 100 My spikes was as- efficient as the number of mutants per 100 M, plants. Gamma rays proved more potent in inducing chlorophyll mutations than EMS. The combination of treatments induced a higher frequency of chlorophyll mutations than individual treatments showing antagoni stic effect on M, spike and additive effect on M, seedling basis, Regarding the spectrum. of chlorophyll mutations gamma rays induced Albina, Xantha and Striate types, whereas EMS and combination treatments produced Virescent in addition to three types obtained through gamma rays. Albine and Xantha occurred more frequently than other types in all the treatments but the combination treatments produced more Albina than individual treatments.

Studies on the Utility of Artificial Mutations in Plant Breeding : XIII. Mutagenicity of Several Alkylating Agents in Rice

Five alkylating agents, ethylenimine (EI), ethyl methanesuifonate (EMS), N-nitroso-N -ethyl urea (NEUA), N-nitroso-N-methyl urea (NMUA) and N-nitroso-N-methyl urethane (NMUT), were compared on the mutagenic effectiveness and efficiency in a few agronomic characters of rice. The modes of dose-response of seedling height, survival rate of seedlings and seed fertility in M1 generation were remarkably different with the different agents used : Methylating agents brought about more toxic effects on M1 plants than ethylating agents. The data obtained in M2 indicated that ethylating agents induced the mutations in chlorophyll, heading date and culm length more easily than methylating agents : In comparison of the highest frequency of chlorophyll mutants and variants in the two agronomic characters, NEUA ranked first, followed by EMS, EI, NMUA and NMUT in turn. The orders of the effectiveness and efficiency of mutagens were NEUA>NMUA >EI>NMUT>EMS and NEUA>EI>EMS>NMUA>NMUT, respectively. These results suggest that NEUA is one of the best mutagens in practical plant breeding. The frequency of variants in each of two agronomic characters was quite exactly proportional to that of chlorophyll mutations throughout all the agents applied.

Mutagenic activity of antibiotics alone and in conjunction with alkanesulfonates

Abstract Differential and combined effects of 0.25 and 0.50% antibiotics (ampicillin, neomycin, furadentine) and alkylating agents (ethyl methanesulfonate, methyl ethanesulfonate, methyl methanesulfonate) were assayed on Phaseolus vulgaris L. (2 n = 22) at the M 2 generation for chlorophyll mutations. The general types scored were Albino, Xantha, Virescens and Maculata. Yellowish-green leaves having red mid-veins and veinlets were observed only amongst the progeny raised after treatment with 0.25% ethyl methanesulfonate or 0.25% methyl ethanesulfonate + 0.25% ampicillin. The frequency of chlorophyll mutation after combined treatments in general was higher than after differential treatments. Methyl methanesulfonate among alkanesulfonates and neomycin among antibiotics induced higher frequencies of chlorophyll mutations. No chlorophyll mutant was produced by ampicillin. Although antibiotics induced a lower frequency of chlorophyll mutation than alkylating agents, the frequency and pattern of spectra of chlorophyll mutants showed an action of antibiotics in inducing mutation similar to that of alkylating agents. Therefore, it is considered that antibiotics are potential mutagens.

Modification of the mutagenic activity of propane sultone by some phenolic antioxidants

The effects of three phenolic antioxidants, butylated hydroxyanisole, butylated hydroxy toluene and propyl gallate on the mutagenic activity of propane sultone were studied using barley as the test system. The antioxidants produced seedling injury marginally but did not produce any chromosomal aberrations. When administered either prior to propane sultone treatment or in a mixture with it, the seedling injury, chromosomal aberrations, mutations per 100 M 1 spikes as well as M 2 chlorophyll mutation frequency, were enhanced. On the other hand, however, posttreatments reduced M 1 spike sterility, mutations per 100 M 1 spikes and M 2 chlorophyll mutation frequency. The spectrum of chlorophyll mutations was also broadened in the presence of these antioxidants.

Effects of Sodium Azide on Seedling Injury and Chlorophyll Mutation in Rice.

Sodium azide-induced damage in M1 generation and mutation in M2 Were analized in Japonica rice variety. In treatments of dormant seeds, germination rate and seedling griwtg were reduced in proportion to both the increase of sodium azide concentration and the prolongation of treatment time. Furthermore, sodium azide delayed the seed germination. When the extent of growth reduction and of the delay of germination were plotted against the "dose" (ConcentrationXSoaking duration) man entne lot of treat ments, these indices each fltted into a single "dose"-response curve. The higrhest frequency of chlorophyll mutation was 11.1 per cent per M1 panicle and 1.22 per cent per M2 seedling. With regard to mutation in agronomic characters, Iate heading, short culm, dwarf, and sterility appeared more frequently. In presoaked seeds, chlorophyll mutation was induced more frequently in the 6, 48 and 54 hour-presoaked seeds than 12 to 42 hour-presoaked seeds. However, M1 seed fertility remained almost the same level (about 90 per cent) during this presoaking period. From these results, it appears that sodium azide when applied at the DNA synthesis stage of the first cell division of germinating process, is more effective in the induction of mutation. It also appears that the mutagenic action of sodium azide can be affected by cellular metabolism during germination.

Mutagenic Effect of Sodium Azide in Barley

The mutagenic effect of sodiurn azide was studied under several treatment conditions in dry and pre-soaked seeds of barley. In dry seeds, the germination rate and seedling growth were reduced in proportion to the increase in concentration of sodium azide. The highest limit of chlorophyll mutation frequency was about 3xlO-1 per M1 spike and lxl0-1 per M2 seedling. The percentages of various types of chlorophyll mutation under all these treatment conditions were 47.8, 36.6 and 15.6 for albina, viridis and others (xantha, striata etc.) respectively. In presoaked seeds, the growth inhibiting effects of sodium azide did not increase with the prolongation of pre-soaking time. The highest value of chlorophyll mutation frequency was observed when sodium azide was applied at the S-phase in the first postdormant mitotic cycle. The frequency of visible mutants followed the same pattern. From these results, it is concluded that sodium azide is an effective mutagen and also that this agent is most effective in inducing mutation when applied at the S-phase.

Biological Effects and Chlorophyll Mutations Induced by NG. Ragi

Two ragi varieties viz.. MS. 2698 (Bihar) and Sarada (Andhrapradesh) were treated with N-methyl-N-nitroso N-nitroguanidine. The germination, survival and seedling height at transplanting got reduced as the dose of the mutagen increased in both the varities. MS. 2698 showed a higher percentage of sterility than Sarada consquent on the chemical treatment. The LD 50 based on survival was around 10 mM for MS. 2698 and 5 mM for Sarada. The chlorophyll mutation frequency estimated on M, seedling basis was much less than that estimated on My spike basis. Sarada recorded greater mutation frequency than MS. 2698. There was a varietal difference in the spectrum of mutation also. The variety Sarada recorded albino types besides xantha and viridis types. A higher percentage of tigring was also observed in Sarada as compared to MS. 2698. The mutagenic effectiveness and efficiency were conferred by the same dose 5 mM for two hours of chemical soaking.

Induced mutagenesis in finger-millet ( Eleusine coracana Gaertn.) with gamma-rays and ethyl methane sulphonate—II. Chlorophyll mutation frequency and spectrum

The seeds of CO-1 variety were treated with gamma-rays and EMS, each in 5 doses, viz., 10–50 kR and 0.5–2.5%, respectively. The chlorophyll mutation rate was characterized by linearity at low to medium doses and saturation as well as erratic behavior at high doses. As per mutation rate, estimated on the basis of M 2 plants, EMS induced a high frequency. The spectrum consisted of albina, chlorina zantha, albo-viridis, tigrina (3 types) and striata (2 types), with tigrina being predominant. The treatments varied in their spectrum, with 2.0% yielding the widest spectrum of mutants.