The Frequency of Appearance of Some Teratological Modifications in X1 Generation of Groundnut

Transcription

1 The Frequency ORIGINAL of Appearance SCIENTIFIC of Some PAPER Teratological Modifications in X1 Generation of Groundnut The Frequency of Appearance of Some Teratological Modifications in X1 Generation of Groundnut University of Craiova, Libertatii Street, No. 19, Romania ( Abstract Radiation is the most known and utilized factor to induce mutations. In the present paper the data concerning the influence of X rays on the dried seeds of eight groundnut genotypes are presented. Two levels of irradiation were applied and the percent of survival of the plants from X 1 generation were noted. The obtained data indicates the fact that applied doses were under LD 50%. We did not identify any dominant mutations in X 1 generation and only some morphological modifications of the leaves, of the number of leaflets and the form of the tendrils. These were considered teratology modifications but did not prove to be stable and did not inherit in the next generations. Key words: groundnut, X rays, teratological modifications, X 1 generation, dominant mutations and recessive mutations Frekvencija pojave nekih teratoloških modifikacija u X1 generaciji kod zemnog orašca Sažetak Radijacija je najpoznatiji i najviše korišten faktor induciranih mutacija. U ovom radu su prikazani podaci o utjecaju X zraka na sušena zrna osam genotipova zemnog orašca. Primijenjene su dvije razine radijacije i bilježen je postotak preživljavanja biljaka u X 1 generaciji. Dobiveni podaci su pokazali da su korištene doze bile ispod LD 50%. Nismo ustanovili niti jednu dominantnu mutaciju u X 1 generaciji nego samo nekoliko morfoloških modifikacija listova, broja listića i vitica. To su teratološke modifikacije koje se nisu pokazale postojanim u slijedećim generacijama. Ključne riječi: zemni orašac, X zrake, teratološke modifikacije, X 1 generacija, dominantne mutacije, recesivne mutacije Introduction The process of inducing mutations leads to some recessive allele transformation into dominant allele. The frequency of dominant mutation appearance is much reduced, these being considered as rare events. Dominant mutation can appear in X 1 generation, especially when it is affected the seed issues. If ionizing radiations are being used for seeds, than the chance as the dominant mutation to appear to the plants from X 1 generation depends on the number of initially embrionare cells affected by mutation. Very often, the dominant mutation affects a part of embrionare cells and is externalize to the level of some tissues, organs, Proceedings. 43 rd Croatian and 3 rd International Symposium on Agriculture. Opatija. Croatia ( ) XXX) Genetics, Plant Breeding and Seed Production 395

2 etc. and in to the offspring one part from the individuals will present the dominant mutation (Nicolae and Nasta, 1975). Material and methods The experiment took place in Tamburesti Research Station, on a sandy soil, after randomized blocks method, in four repetitions. The first experimentation year was 2003 and since than the experimented genotypes were sown to study if the possible modifications are transmitted to the offspring. For mutation study to groundnuts it was used irradiation method before sowing, with X rays in two doses: 6000 and 9000 R. It were irradiated 100 seeds for each dose from eight groundnut genotypes, which were sowed than in the field besides another 100 un-irradiated seeds from the same genotypes takes as control. So, it was obtain X 1 generation. To these plants were made the first observations and determinations concerning the applied doses and the frequency of appearance of the possible modifications. The investigated traits were: survival dynamic, the eventual modifications of leaves and tendrils, flowers color, the percent of germinated seeds and plants reached to maturity. Because the obtained data were for only one year (2003), the average values from the tables were calculated after three simple rule for each variant, than summarize and divided to four (the number of repetitions). Results and discussion Mutagen agents, especially radiations, can be used to realize some special objectives for plants breeding. Using radiations to obtain mutations became, in time, a usual practice. From the researches made until now to groundnuts, LD 50 for dry seeds treatment with X rays can be reached to R doses (Gheorghita and Corneanu, 2002). Often, in the year of treatment it is made researches concern plants survival dynamic, the percent of morphological anomalies (chlorophyllian chimaeras, fasciations, modifications concerning the form and the size of the leaflets, etc.), vegetation period, the variability of some characters determined by biometric measurements, etc. Regarding plants behavior in X 1 generation under the ionizing radiations influence, it will be made a range of explanations, some of them basing to experimental data from original research. In our experience it was not an essential difference among experimented genotypes in radio-sensibility. In exchange, it appeared to some varieties some plants modifications, priority having chlorophyllian deficiencies and plants with a different number of leaflets. From the literature it is known the fact that these kinds of phenotypes appeared in X 1 generation as a result of mutagen treatments, are not stable, they lessening or even completely disappear in X 2 and future generations and because of that they were called teratological modifications. Plants risen in the irradiated variants were un-uniform and on small periods of time. Comparative to control variants, the irradiated ones raised with 1 6 days delay in 9000 R irradiated variants. It was noticed a stimulation of germination energy and the percent of germinated plants, especially in 6000 R irradiated variants. In vegetation period died a small number of plants because of the sensibility of the environment factors as a result of chlorophyllian deficiencies and malformations which affected the foliage, under the influence of the applied radiations doses (Table 1). After the irradiation treatment application with X rays a special attention is accorded to the morphological anomalies from X 1 known as radiomorphosis. Their phenotypic exteriorization takes diverse forms depending on specie or variety. So, to groundnut it was registered some radiomorphosis to the stems (fasciations) and leaves (leaves with more leaflets and different forms of these) and very curly tendrils (Fig.1). As concern the days to rise, there are not significant differences between control variant and irradiated variants and the percent of germinated seeds is high, among 90%, an exception making Tamburesti variety in 9000 R variant (88%). It can notice from the data from Table 2 that the frequency of plants with mutations presents higher values only to Tamburesti variety. Other genotypes registered much reduced values rd Croatian and 3rd International Symposium on Agriculture

3 The Frequency of Appearance of Some Teratological Modifications in X1 Generation of Groundnut Although there were different plants with teratological modifications, their number was small and none of them were considered dominant mutation. Maybe, because of the radiation influence, groundnut genotypes presented also a very high number of nodosities (Fig. 2). This is a good influence because the quantity of fertilizer can decrease. In the last years of experimentation ( ), we did not find any plants with fasciations or modified leaves and none chlorophilian defects, but in the irradiated variants it was kept the positive influence over the germination energy, the number of nodosities and quantitative characters. Table 1. Survival dynamic of groundnut plants from X1 generation (the average of four repetitions) Crt. nr. Genotype Number of sowed seeds Days to rise % of germinated seeds % of plants reached to maturity 1 Tamburesti Ct * V V Venus Ct * V V Spanish 9184 Ct * V V Black Brazilian Ct V V Jelud Ct V V Jumbo-Virginia Ct V V T242 Ct V V T25 Ct V V * - the control (Ct) is the 50 sowed seeds, but not all seeds germinated V1 = 6000 R; V2 = 9000 R These morphological modifications from the first generation did not inherit to the offspring s. It is known that very rarely in the first generation it is identify some mutations because these are recessive. Besides that, plants from the first generation have a pronounced chimaeras character (Bara, 1985). Conclusions From the morphological analysis made to the plants of X 1 generation as a result of the irradiation doses it can conclude: - Depending on genotype and dose it can appear in X 1 generation some plants modifications, but these have a chimaeras character; - Although the plants from the irradiated seeds present at the beginning a sort of germination energy and higher percent of germination, not all plants can reach maturity, some of them disappearing as a result of chlorophyllian deficiencies and malformations caused by the applied irradiation doses; - High percent of teratological modifications registered Tamburesti (both doses) and Venus varieties (9000 R dose). It is needed to mention that Tamburesti variety was also obtained by radiations application, but gamma rays. Maybe that is the cause that this genotype presented higher variability to almost all researched characters. Genetics, Plant Breeding and Seed Production 397

4 Fig. 1. Tamburesti variety plant (early stage) Fig. 2. Tamburesti variety plant (maturity) Table 2. The variation of morphological anomalies in X1 generation reporting with dose of irradiation (% comparative to survival plant)(the average of four repetition) Crt. nr. Genotype Plants with fasciations Plants with modified leaves Plants with chlorofillian defects Total modified plants 1 Tamburesti V V Venus V V Spanish 9184 V V Black Brazilian V V Jelud V V Jumbo-Virginia V V T242 V V T25 V V rd Croatian and 3rd International Symposium on Agriculture

5 The Frequency of Appearance of Some Teratological Modifications in X1 Generation of Groundnut References Bara, I., (1985). Radiosensibilitatea plantelor sub impactul factorilor modificatori. In: Elemente de radiobiologie vegetala (Ed. G. Corneanu), pp Edit. Ceres, Bucuresti. Gheorghita, G., Corneanu, G. (2002). Radiobiologie, Ed. Alma Mater, Bacau. Nicolae, I., Nasta, A. (1975).Radiogenetica, Ed. Stiintifica si Enciclopedica, Bucuresti. sa2008_0330 Genetics, Plant Breeding and Seed Production 399