BGN 10: Influence of genotype on mutagenic variability in barley (H. vulgare L.) following colchicine treatment BARLEY GENETICS NEWSLETTER, VOL. 10, II. RESEARCH NOTES
Balkanjieva, pp. 7-10

II. 3. Influence of genotype on mutagenic variability in barley (H. vulgare L.) following colchicine treatment.

Juliana Balkanjieva, Institute of Genetics, 1113 Sofia, Bulgaria.

The present study was undertaken as an attempt to determine the characteristics of mutagenic variability in colchicine treated barley depending on the genotype.

Various accessions of multi-row winter barley cultivars were used as experimental material, namely:

Bulgarian cultivars - Sofia 1337 and No. 1241 (Hordeum sativum Lessen, ssp. vulgare L. gr. inaequale tetrastichum), developed by individual selection in local barley populations, and Markeli 2 (Hordeum sativum Lessen, ssp. vulgare L. gr. inaequale tetrastichum), a comparatively new cultivar obtained by gamma irradiation of the French cv. Ajer.

Rumanian cultivar - Moara Domniasca (Hordeum sativum Lessen, ssp. vulgare L. gr. inaequale tetrastichum), developed by individual selection in a local barley population.

French cultivars - Ajer and Maglon (Hordeum sativum Lessen, ssp. vulgare L. gr. inaequale tetrastichum), developed as a result of complicated intercultivar hybridization.

German cultivar - Vogelsänger Gold (Hordeum sativum Lessen, ssp. vulgare L. gr. inaequale tetrastichum), developed by intercultivar hybridization.

Seeds of the named cultivars were treated with a 0.125% water solution of colchicine. A hundred seeds of relatively equal size were selected from each cultivar and presprouted in water for 7 h. Then they were placed to germinate in the dark at room temperature (18-20°C). At the time when the coleoptiles were about 1 cm long the tips were cut and the whole sprouting seeds with rootlets and coleoptiles were immersed in 0.125% water solution of colchicine for 2.30 h, rinsed in running water and planted in pots. The plants were grown in glass houses under controlled conditions.

During the vegetation period observations were carried out on the plants concerning time and course of the phenological phases and type of changes appearing as a result of colchicine treatment. The study on C1 mitosis was performed on 5 to 51 plants of each cultivar. The chromosome number in at least 30 cells was recorded.

Results

Data obtained by the observations on the morphological and biological changes which occur in barley plants following colchicine application indicate clearly the presence of specific cultivar differences related with the biological characteristics and with accession. Considerable inhibition of plant growth and development, particularly in the first days post planting was typical for all plants treated from each cultivar. The changes became evident as soon as the first leaf appeared. It grew much wider, but shorter. The stem base gradually thickened and cracked lengthwise. These plants had wide, long, sometimes very long, succulent leaves with a clearly expressed venation. The stems were thick. Changes occurred also in spike seediness. Usually almost all spikes had seeds only in the middle part, while the lower and upper parts were completely sterile (Gentcheff, 1947; Schumann, 1971). Difference between the grain size of diploid and tetraploid plants was also observed.

The accession and the biological characteristics of the cultivar had a definite influence on plant vigor, length of vegetation period, and on yield structural elements of the individual plants.

Cultivars developed by intercultivar hybridization and mutagenesis were distinguished by higher variability rate. The inhibiting effect of colchicine was most pronounced on cv. Markeli 2, and least on cv. Sofia 1337. The plants of cv. Ajer were characterized by lowest viability (only 5% of them reached the spike formation phase), while cv. Markeli 2 plants had highest viability. CV. 1241 was distinguished by longest vegetation period, while cv. Maglon by the shortest one. Shortening of the vegetation period was observed in cv. Maglon, while prolongation of the period - in cv. Markeli 2.

The results obtained by cytological investigations on mitosis showed considerable differences between the individual cultivars concerning the changes in cell chromosome number. It is evident from data presented in Table 1 that the percentage of plants with tetraploid chromosome number of the cell varies from 0 to 29.62. Cv. Maglon is distinguished by its highest percentage of tetraploid plants. Only in cv. Sofia 1337 no changes in chromosome number were observed. In most cultivars, despite the occurring phenotypical changes in their individual characters, the predominating part of cells recorded had a diploid chromosome number. This is particularly true for cv. No. 1241 and cv. Sofia 1337 developed by individual selection, and for cv. Vogelsänger Gold.

Table 1. Chromosome number of root tip somatic cells in C1 plants

Results obtained by the investigations on mutagenic variability characteristics in various cultivars following colchicine treatment substantiate the following conclusions:

l. The multi-row winter barley cultivars studied have a specific reaction to 0.125% water solution of colchicine which depends on their genotype.

2. Cultivars developed recently by use of complicated intercultivar hybridization have higher sensitivity and are more inclined to tissue polyploidization, while those developed by individual selection in local populations do not have the aptitude of this kind.

3. Phenotypic changes observed in the cultivars as an effect of mutagenic colchicine treatment are not always accompanied by changes in their chromosome number.

References:

Gentcheff, G. 1946/47. A new technics of inducing polyploidy in plants by colchicine treatment. Annuaire de l'universte de Sofia, Faculte d'agronomie et sylviculture, tome XXV, Livre 1 - Agronomie.

Schumann, G. 1971. Kolchizinapplikationen zum Zeitpunkt der Anthese zur Erzeugung polyploider Pflanzen, untersucht an Roggen und Sommergerste, Arch. Züchtungsforsch. Bd 1. H.2. S. 139-146.

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