Section 13 — Plant Genetics and Breeding 



pollen proteins during the pollen tubes growth. 



Pollen proteins of Nicotiana alata were se- 

 parated into at least 14 fractions by means of 

 gel filtration and chromatography on Sephadex 

 and DEAE-cellulose. After 15 hr artificial cul- 

 tivation under aseptic conditions new protein 

 fraction was found. More than one half of the 

 total proteins of pollen tubes have been released 

 into the medium. The same fractions, but in 

 relatively different quantities, have been found 

 both in the proteins of medium and in those of 

 pollen tubes. The new fraction occurred mainly 

 in the medium. After the administration of L- 

 proline- 14 C the highest specific activity in this 

 fraction was determined. 



It is possibler, therefore, that the proper specific 

 proteins which are responsible for incompatibili- 

 ty reaction in species with a gametophytic system 

 of incompatibility are synthesized during the 

 pollen tube growth. 



The corresponding data will be published in 

 full in Biologia Plantarum, Praha. 



brids of an intermediate type. Such are P. spinosa 

 L. P. domestica L. hybrids (2 n = 40) and 

 P. ceiasus L. P. avium L. hybrids (2 n = 24). 



When these low-fertile hybrids (Fi) were pol- 

 linated with the pollen mixture of several va- 

 rieties of one of parental species, F-2 consisted 

 of quite fertile and commercially valuable 

 plants with the characteristics of both species. 



The second variation consists of the addition 

 of small amounts of own or alien pollen related 

 to maternal form to the pollen of an uncros- 

 sable species. This variation is based on the 

 fact that in the process of fertilization own or 

 alien pollen favourably affects the pistil, creat- 

 ing conditions which stimulate the growth of 

 pollen tubes and the fertilization with the pollen 

 of an uncrossable or hardly crossable species. 



The analysis of morphological characteris- 

 tics and chromosome numbers in Fi hybrids 

 shows that preferable fertilization with own or 

 closely related pollen takes place in these crosses, 

 though in some cases this method helped to 

 cross two hardly crossable species, for example, 

 Ceiasus Besseyi Bail Primus cerasifera Ehrh, 

 (2 n = 16); C. Besseyi P. spinosa. (2 n = 24.) 



13.13. Pollination with Pollen Mixture to Produce 

 Interspecific Hybrids of Plum and Cherry 

 (Prunus), K. K. Enikeyev (Moscow, 

 U.S.S.R.). 



Soviet horticulturists use the method of pol- 

 lination with pollen mixture in interspecific 

 crosses. 



This method was worked out by I. V. Michurin 

 in order to overcome incompatibility of different 

 fruit species. I. V. Michurin based this method on 

 the regularities of selective fertilization and 

 complex physiological interaction between the 

 components of pollen mixture and the pistil of a 

 maternal form. 



The author has used two variations of the 

 pollination with pollen mixture and got the 

 following results: 



The first variation consists of the pollination of 

 one species with the pollen mixture of several 

 varieties of another species which is almost or 

 entirely unable to cross with the former, it se- 

 cures the selective fertilization by means of the 

 most biologically adapted pollen grains of one 

 of the varieties of a paternal form. 



As a result of pollinating Cerasus Besseyi 

 Bail with pollen mixture of several European 

 varieties of apricot (Armeniaca vulgaris L.) quite 

 viable and fertile hybrids have been produced. 



The hybridization of several Prunus species 

 with different chromosome numbers in Fi 

 results in the development of low-fertile hy- 



13.14. Transfer of Self-Compatibility from Solanum 

 verrucosum to Diploid S. tuberosum. L. A. 



Dionne and K. M. Graham (Birmingham, 

 Great Britain, and Fredericton, Canada). 



The development of homozygous diploid lines 

 of Solanum tuberosum has been complicated by 

 the extreme selfincompatibility of the diploid 

 forms of the series Tuherosa. Attempts to isolate 

 mutations for self-compatibility from the di- 

 ploid Tuberosa have not given much encourage- 

 ment to this means of solving the problem. How- 

 ever, it has proved to be relatively easy to transfer 

 the self-compatibility of Solanum verrucosum, a 

 Mexican diploid species in the series Demissa, to 

 S. tuberosum. By this means it has been possible 

 to establish breeding lines that combine a high 

 level of self-compatibility with earliness and good 

 resistance to Phylophthora infestans. 



13.15. Aneuploids in Some Artificially induced 

 Polyploids of Cultivated Plants. Mechtild 

 Rommel (Zaragoza, Spain). 



When investigating chromosome numbers of 

 artificially induced autotetraploid barley stocks 

 (Hordeum vulgare), autotetraploid sugarbeet 

 populations (Beta vulgaris) and wheat-rye 

 derivatives (Triticum durum Secale cereale) 



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