Section 13 — Plant Genetics and Breeding 



The obtained data could be valuable in a 

 scientific as well as in a practical sense, namely 

 for selection and seed-growing. 



13.95. Effect of Genetic Albinism on the Photosyn- 

 thetic Utilization of Light. Istvan Gyurjan 

 (Budapest, Hungary). 



The efficiency of photosynthesis in plants, and 

 also the distribution of 14 C02 over the different 

 compounds are greatly influenced by the intensity 

 and the wavelength of light. Photosynthetically, 

 light affects in the first line the amount of pig- 

 ments which, in its turn, influences the extent to 

 which carbon dioxide is incorporated, and 

 influences moreover the further part of carbon 

 and oxygen. 



The assimilation of 14 CG*2 by albino maize 

 seedlings, particularly sensitive to light, has been 

 studied at different intensities of light. The 

 activity of the alcohol-soluble fractions (amino 

 acids, organic acids, sugars) revealed a linear 

 connection with the concentration of pigment at 

 the employed intensities of light (5, 100, 1000 and 

 10,000 luxes). The rate at which 14 C0 2 was 

 incorporated by alcohol-soluble compounds in 

 the range of optimum light intensity for albino 

 (from 100 to 1000 luxes) proved to be much 

 higher in albino than in normal plants. The rate 

 of incorporation became lower in strong light 

 (10,000 luxes) on account of the destruction of 

 pigment in the albino leaves. 



Qualitative and quantitative analysis of 

 autoradiograms made in respect of the alcohol- 

 soluble fractions revealed the fact that activity 

 of the organic acids became higher in albino 

 leaves, while the activity of amino acids charac- 

 teristic of photosynthesis (alanine, glycine, 

 serine, aspartic acid) as well as that of sugars 

 appeared to be higher in normal leaves. This 

 difference was wider at higher intensities of 

 light. The qualitative differences make it proba- 

 ble that deviations in the light tolerance of nor- 

 mal and albino leaves affect the mechanism 

 through which 14 CC<2 is incorporated. This mani- 

 fests itself in the fact that — apart from affecting 

 the amount of pigments — light does not uni- 

 formly influence the different ways of carbon- 

 dioxide incorporation. 



13.96. Different Types of Carotenoid Abnormalities 

 in Albino Leaves. Agnes Faludi-Daniel 

 (Budapest, Hungary). 



A considerable part of chloroplast mutants of 



higher plants possess the ability to synthesize 

 chlorophyll. These mutants have the genetic 

 block elsewhere in the metabolic pattern. 

 Investigating the carotenoid content and synthe- 

 sis of albino leaves in maize and barley we found 

 abnormalities characteristic of individual chloro- 

 plast mutants. 



We have shown that leucine is an effective 

 early precursor of carotenoid synthesis of the 

 leaves during chloroplast formation. Conse- 

 quently albinos with abnormal leucine content 

 might have disturbances in the carotenoid 

 synthesis. Another type of albinos contains 

 carotenoids with partially saturated double 

 bonds, lacking the ionon ring too (phytoen, 

 phytofluen, Z -carotene). A further type of 

 chloroplast mutants produces carotenoids 

 with normally conjugated double bonds but 

 the process of ionon cyclization is blocked 

 (lycopene). 



The qualitative and quantitative deviations in 

 the carotenoid content are related to an in- 

 creased lability of the protein-pigment complex 

 of the chloroplasts. It was found that the lack of 

 the ionon ring decreases the amount of stable 

 carotenoid-protein complexes by about 30 per 

 cent. If the lack of ionon ring is associated with 

 the unsaturation of double bonds the amount of 

 stable protein pigment complexes decreases by 

 45 per cent below the normal level. 



On the basis of our data we are able to set up 

 a hypothetical scheme concerning the localization 

 of genetic blocks in the albino mutants with 

 deviating carotenoid content. 



13.97. Variability and Inheritance of the Protein Level 

 in Plants. S. Barbacki (Poznah, Poland). 



Research of several years' duration into the 

 variability and inheritance of the protein level 

 in barley and lupin has pioved that this character 

 changes its value in dependence on the following 

 factors: climatic conditions (in main rainfall), 

 soil conditions, term of sowing, spacing, ma- 

 nuring (in main with nitrogenous fertilizers) and 

 time of harvest. The genetic background is also 

 important as it determines the metabolic type. 



The protein level cannot be studied independ- 

 ently from the environmental factors and other 

 qualities of the plant. The type of development, 

 earlier or later ripening, the accumulation of 

 other compounds — in the first place of carbohy- 

 drates — are all of importance in this case. In 

 considering these elements it is possible to 

 distinguish genotypes greatly differing by their 

 reaction to the environmental conditions, 

 carrying a tendency to accumulate lesser or 

 greater amounts of protein. Crossing of various 



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