Section 13 — Plant Genetics and Breeding 



genotypes brings about different kinds of 

 segregations in the offspring which result among 

 others in the arising of transgressive forms. 



The elements of "crude protein" are also 

 peculiar to the genotypes. Various forms of 

 nitrogen are differently represented in them. 

 Owing to the particular importance of the level 

 of certain forms of nitrogen, in main of exogen- 

 ous amino acids, in the nutrition of man and 

 animals, it may be of practical value to study the 

 tendency of their accumulation. 



13.98. Biochemical Interspecific Differences within 

 the Genus Lathyrus. J. Przybylska (Poznah, 

 Poland). 



Within the genus Lathyrus there were found 

 clear interspecific differences in the composition 

 of free amino acids in seeds. Individual species 

 are characteristic of an accumulation of different 

 peculiar new free amino acids (a, y-diamino- 

 butyric acid, homoarginine, (3-(-2-aminopiry- 

 midine-4-yl) alanine and other substances with 

 amino acid properties unidentified as yet) which 

 suggests the existence of different pathways of 

 nitrogen metabolism. It can be assumed that the 

 amino acids accumulated in seeds and peculiar to 

 the individual species are not metabolic by- 

 products; they are rather forms of storage, or 

 storage and transport of nitrogen. These com- 

 pounds are sure to have originated as a result of 

 genetically conditioned changes in the activity 

 of enzymes involved in the amino acid transfor- 

 mations. At the present moment comparative 

 studies are being carried out on the role of 

 individual peculiar non-protein amino acids 

 in the nitrogen metabolism of several species of 

 Lathyrus. 



13.99. Genetical and Morphological Analysis of the 

 Regularity of Right- and Left-handedness in 

 Wheats. Hinako Suemoto (Kyoto, Japan). 



Right-handed and left-handed leaves (di- 

 rection of folding) and spikelets (direction of 

 first floret) alternate regularly (are "concordant") 

 along stem and spike. "Discordant" leaves and 

 spikelets are often found below the 3rd or 4th 

 foliage leaf and above the 10th spikelet. 



The degree of regularity or the intensity of 

 polarity at a given position is measured by the 

 "Concordance proportion" (C). Concordant and 

 discordant leaves or spikes are scored 1 and 

 respectively. The mean per position for a number 

 of shoots is C, with binomial standard error. 



Averaging over positions one obtains c, the 

 mean concordance proportion, which a.o. 

 serves as a measure of species differences in R/L- 

 handedness. 



Each species of Triticum and Aegilops has its 

 own specific value of c and the specific curve of 

 C. A certain relation between c-value and the 

 genome constitution is found. The results of the 

 polygenic analysis on two Einkorn species 

 (T. monococcum var. flavescens and T. aegilo- 

 poides var. boeoticum) support the view that a 

 polygenic system takes part in the species 

 difference of c-value. 



The R/L-polarity is induced at about the time 

 of germination, and is maintained throughout 

 the developmental stages and disappears, 

 according to the genotype of the plant. But the 

 type of c-curve and the direction of the polarity 

 is modified by the various artificial treatments. 

 The deficient nutrition and X-ray irradiation 

 causes a reduction of c-values of developing 

 organs. The gravity affects the induction of the 

 R/L-polarity at the time of germination. This 

 sensitivity is specific of the genotype. Further- 

 more, growth-hormone treatment modifies the 

 R/L-polarity induced by the gravity. 



These results will be reported in this paper. 



13.100. Pathogenicity of Radiation-induced Mutants 

 in Two Important Phytopathogenes of Rice. 



Yoshito Yamasaki, Takashi Suwa and 

 Nobuo Murata (Tokyo, Japan). 



Nutritional deficiency mutations were induced 

 by u v X-, and y -irradiation in Xanthomonas 

 oryzae and Piricularia oryzae, pathogens causing 

 bacterial leaf blight and blast respectively in rice, 

 and changes in pathogenicity of mutants were 

 investigated with the view to make clear the 

 significance of mutations for nutritional charac- 

 teristics in specialization in pathogenicity in 

 each of these organisms. 



In Xanthomonas, mutants requiring histidine 

 (4), nicotinic acid (2), and tryptophan (2 out of 

 6) were as pathogenic as wild strains whereas 

 those requiring arginine (2), leucine (2), isoleucine 

 and valine (4), threonine (1), and tryptophan 

 (4 out of 6) showed a marked decrease in 

 pathogenicity. 



In Piricularia, mutants with requirement of 

 NH 4 -nitrogen (6), glutamic acid, etc. (1), glycine 

 (1), leucine (2), methionine (1), cystine or 

 methionine (1), cystine, methionine or thiosul- 

 fate (1 out of 2), histidine (1) tryptophan or 

 nicotinic acid (1), nicotinic acid (1), inositol (1), 

 and choline (1) remained pathogenic and those 

 with requirement of phenylalanine (2), adenine 



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