Zygotic combinatorial process in plants

Experimental data that prove the existence of the zygotic combinatorial process occurring in an embryogenesis-entering zygote are presented in the paper. The zygotic combinatorial process is found when analyzing F1 hybrid plants obtained from crossing homozygous forms different, minimum, in two marker enzymes, and it is found in that hybrid plant which, with one marker enzyme heterozygous spectrum, has a homozygous spectrum of the other. The zygotic combinatorial process leads to F1 hybrids uniformity aberration. The zygotic combinatory process revealed in the study is supposed to be conditioned by chromosome polyteny in mother plant cells and diminution of chromatin excess from the embryogenesisentering zygote. An obligatory condition for combinatorial process is the presence of free exchange of chromatides among homological chromosomes in an embryogenesis-entering cell, i.e. the presence of crossing-over analogous to the one proceeding at meiosis.

Post-meiotic apozygotic combinatory process in sugar beet (<i>Beta vulgaris</i>L.)

The effect of colchicine on phenotypic classes ratio of the enzyme locus controlling alcohol dehydrogenase (ADH1) in sugar beet agamospermous progenies was analysed. The obtained data are indicative of the thing that colchicine causes polytenization of homological chromosome regions carrying marker locus Adh1 alleles. Theoretical calculation of the formation of egg cells frequencies and those of further development of cells entering embryogenesis without fertilization, also the diminution calculation of excessive chromosome regions carrying marker locus alleles have been made. The coincidence of theoretical and experimental ratios of phenotypic classes indicates the existence of post-meiotic apozygotic combinatory process in plants.

Phenotypic Class Ratios as Marker Signs of Different Types of Agamospermy

This article focuses on the development of the method for the genetic classification of agamospermous reproduction types in plants using sugar beet as an example. The classification feasibility is ensured by the use of isozymes as genetic markers allowing the identification of all three phenotypic classes in the progeny of individual heterozygous diploid plant and is based on different phenotypic class ratios in the progenies obtained by meiotic and mitotic agamospermy. The data indicate that for studied forms of sugar beet meiotic agamospermy is the more typical because 10 of 12 explored progenies were classified as those which arisen under meiotic agamospermy and only 2 as arisen under mitotic agamospermy.

Influence of external conditions on the combinatorial processes at agamospermy

The estimation of the influence of external conditions on marker enzymes phenotypic classes ratios in agamospermous sugar beet progenies has been carried out. It has been shown that different ways of flowering sugar beet plant branches isolation lead to different ratios of marker enzyme phenotypes in a developing agamospermous seed progeny. The obtained data are an additional confirmation of the hypothesis about the presence of differential chromosomes polyteny and its dependence on external conditions.