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Ten clones ofSolanum stoloniferum Schlechted (2n — 4x — 48) were selected from seedling populations that were produced by self-pollinating five introductions from the Commonwealth Potato Collection. These clones were used to produce S1, F1, F2, and testcross populations. Clones and their progeny were scored for anthocyanins and flavonol glycosides in their corollas, stems, and leaves. Thin-layer chromatography (TLC) was used to separate and identify polyphenol compounds. No segregation for eight traits was observed within S1 and F1 families. Segregation was observed in F2 and testcross populations for anthocyanins (derivatives of delphinidin and cyanidin, inhibited when the geneF is homozygous recessive); and flavonol glycosides (Q4 = quercetin 3-glucosyl-rhamnosylglucoside, controlled by the geneG1; and L1 = luteolin 7-glucoside, controlled by the geneL1) extracted from corollas. Observed ratios fitted ratios expected for disomic inheritance, differed from expected tetrasomic ratios, and provided additional evidence that the parental clones are homozygous. GenesF, G1, andL1 were genetically independent in dihybrid and trihybrid F2 crosses.

A greenish-yellow mutant was obtained after treatment of seeds of Nicotiana tabacum L. var. Xanthi n.c. with ethyl methanesulfonate (EMS). Two genetically independent mutations ( a 1 and a 2 ) were isolated. The first mutation ( a 1 ) antagonizes the function of its partially dominant a 1 + allele. The second mutation ( a 2 ) is amorphous but strongly interacts with a 1 . Among the nine possible genotypes at the two loci, five varied in somatic cells. The heterozygous state a 1 + / a 1 strongly increased the frequency of both spontaneous and induced variations. However, two homozygotes also showed variations. Variants were isolated from induced and spontaneous non-reciprocal and reciprocal variations within paliside tissues by bud induction in vitro . They were genetically tested. In this first paper, only non-reciprocal variations are reported. Green variants from the greenish-yellow ( J 1 ) dihybrid a 1 + / a 1 a 2 + / a 2 clone had two genotypes: the first was due to true reversions of a 1 to a 1 + , whereas the second was due to amorphous a 1 0 mutations from a 1 . These a 1 0 mutations may well be deletions. The lightest yellow variants from J 1 were due to mutations either from a 1 + into a 1 or from a 2 + into a 2 . Deletions at the a 1 + − a 1 locus led to either yellow variations when a 1 + was lost, or to false reversions when the antagonistic allele a 1 was lost. Amorphous alleles at the a 1 + − a 1 locus were also isolated from tissues other than J + . They gave zygotic lethality ( s ) that probably varied with the size of the deletions. Thus, true reversions and deletions at the a 1 + − a 1 locus could be distinguished from one another by progeny tests. Other variants showed higher frequencies of spontaneous variations (instability). Somatic changes observed in these unstable systems were due to modifications at the marker loci. The genetic nature of this instability is not yet known. There is strong evidence that the genetic events involved in these non-reciprocal variations were deletions, conversions and point mutations. True reversions from a 1 into a 1 + and new mutations from a 1 + into a 1 were obtained only from a 1 + / a 1 . It was therefore supposed that the changes observed took place only in heterozygotes, and the conversion hypothesis was made. Attempts are being made to prove that conversions do exist in higher plants, and to find out if this process, as deletions, is induced by radiation.

Males heterozygous for both dp-1 and dp-3 genes in chickens fail to produce diplopod embryos in the expected proportion for a dihybrid ratio when mated to females heterozygous for both genes. When backcrossed to the parental diplopodia-1 and diplopodia-3 lines and when mated with singly heterozygous females derived from the original crosses, the doubly heterozygous males also fail to produce the expected numbers of dp-1 diplopods, but give normal ratios of dp-3 embryos. Females heterozygous for both genes transmit them to progeny in normal ratios.Calculations of effective male gamete segregations from backcross data, when applied to dihybrid segregations in inter se double heterozygote matings, approximate the actual proportion of diplopods obtained if deficiencies in male dp-1 gametes and a 9:6 embryonic survival ratio are assumed. Although the double recessive embryos are predominantly indicated by this test to die prior to identification as diplopods, fit of calculated to actual data suggests that some may survive to later developmental stages.Inheritance of diplopodia-1 exhibits a distortion in transmission of alleles having many features similar to genes at the T and Low loci in the male heterozygous house mouse. The aberrant segregation of the dp-1 gene in heterozygous male chickens represents a second case of this nature found in vertebrate animals.

One of the most dangerous biotic factors that reduce the sunflower productivity is its infection by an obligate parasite of higher plants - broomrape (Orobanche cumana Wallr.). Over the past few years, a number of inbred lines of various origins that are immune to race G have been developed at V.S. Pustovoit All-Russian Research Institute of Oil Crops (VNIIMK). To combine different genes in the same sunflower genotype, it is necessary to determine their allelism. The research material was the sunflower lines – donors of resistance to race G of broomrape: RG, RGP1, RGP2, RGB, RGL1, RGL2, RGM. The identification of the race of broomrape seeds by means of lines-differentiators showed that the seeds were collected from the plants of race G. Hybrids F1 and F2 were obtained by the VNIIMK method. The mathematical processing of the segregation results was conducted by means of χ2 criterion of correspondence of the actual segregations to the theoretically expected ones in dihybrid crossings. The research results showed that, overall, the parent lines were affected by broomrape to a small degree. During the test for allelism, seven generations of F1 and F2 were obtained from pair crossing of resistant lines with each other. The tested hybrids F1 were either not affected by the parasite, or were affected to a small degree, which allowed us to classify sunflower plants as resistant. To determine the identity of resistance genes in the lines of RG with RGP1, RG with RGM, RG with RGL1, RG with RGB, RGP2 with RGL2, RGM with RGL1, RGB with RGL1, we analyzed the F2 progeny from these hybrids. The test for allelism of the resistance genes to race G of these lines showed their identity, with the possibility of some distortion of the phenotypic manifestation of the trait in various crossing combinations.

When some Mendelian populations are grown successively under different conditions for several generations, they come to have diffcrent gene constitutions. The mechanism of this alteration has been mainly explained by occurrence of individual selection in the populations. It is said, however, that gametophyte selection may play an important role in this alteration. This study was conducted to clarify the existence of gametophyte selection by high temperature treatment of F1 Spikelets of tworowed barley just before flovyering. Materials and characters used in this study are shown in Table 1, and these characters were ascertained to be controlled by one gene having no linkage relation among them. Several ears of one F1 plant were put into warm water, 36-39°C, for 4 minutes just before flowering and the remaining ears of the plant were fertilized under natural conditions as the control. Segregation ratios of some qualitative c'haracters in F2 generation of the former were compared with those of the latter. About 30 F1 plants in each cross combination were treated. Segregation ratios of the four characters -awn type, lateral floret type, awn or awnless in lateral floret, and hair or hairless in leaf sheath- in monohybrid and dihybrid F2 generations, agreed with the expected values in both cases of treament and control (cf. Tables 2, 3-a, -b, -c, 4, 5 and 6) .

An anomalous mode of segregation in respect to apiculus anthocyanin pigmentation observed in a fertile hybrid between a Japancse (Norin No. 1)and an Indian rice variety (Surjamkhi) was described. The apiculus color of Norin No. 1 is red and that of Surjamkhi is dark purple, whose genotypes havebeen determined as CB Spa A and CB SpA respectively after the gene symbols designated by NAGAO and TAKAIIASHI. C is a gene responsible for the production of chromogen and Sp, acting complementarily, turns it into anthocyanin. Both C and Sp form a mnultiple allelic scries, CBt>CBr>C+ and Sp>SpdSp+. F1 hybrid between them shows dark purple apiculus color. Its seedbearing fertility is nearly perfect (96%), though it shows a certain degree of pollen abortion (14%). In F2 it segregated individuals with colorless apiculus which came up to about 30 per cent of the total, instead of showing the expected segregation ratio of 3 dark purple : I red, i.e., 3 Sp : 1Spd, accompanying remarkable decrease of individuals with red apiculus color (Table 2). A large part of the colorless plants showed tawny coloration in their apiculus at ripening, showing the effect of CB observed when Sp or Spd is absent. The apiculus color at ripening of the remaining colorless plants was straw white, showing on effect of CB. Segrefation of partial sterility also occurred in F2 as shown in Table 3, in which one can detect no clear relation between the partial sterility and the types of apiculus coloration. The similar distribution of partial sterility in each of the classes is taken to show that the gametes of f1 bearing noncoloredness were equally functional as those bearing coloredness in bringing forth the F2 progeny. The mode of segregation of apiculus color observed in 83 F3 strains originated from randomly taken F2 plants, including 48 colored and 34. colorless ones, was various (Table 4 and 5 ). Some strains showed mono- and dihybrid segregation ratios, but others did rather complex ratios which could not tion between the partial sterility and the apiculus color was observed. Discussion was madd as to the mechanism which resulted in the segregation of individuals with colorless apiculus in F2. Since the frequency of the appearance of colorless plants in F2 was remarkably high, the mechanism due to autonomous mutations, CB→C+, and Spd→Sp+, was concluded to be out of qucstion. It was suggested that the anomalous segregatisn might bc due to minor structural differences of chromosomes between the parental varieties which did not affect directly the parental varieties which did not affect directly the viability of gametes produced of F1 hybrid. Though there were found some F3 plants which seemed to be deficient in the gene loci in question by crossing them with tester varieties of known genotype, the authors could not attain to a definite conclusion as to the mechanism under issue.

Under the heading of "Deformed leaves" the writer dealt with the genetic behavior of the variegated and the deficient leaves. Summing up, the results are: 1. The variegation is transmitted as a simple recessive to the wholly colored condition. 2. In some crosses of the variegated and the wholly colored leaves there appread unexpectedly a new type of variegation, called "Gejigeji," a faint variegated pattern. 3. The Gejigeji type is caused by a recessive factor, its dominant allelomorph being a normal variegation on the common basis of the double v. 4. The representation of the Gejigeji pattern is limited to the variegated individuals, the effect not being apparent in the self-colored leaves. 5. The ratio in the dihybrid segregation is a 12:3:1 with reference to the wholly colored, the commonly variegated, and the Gejigeji leaves. 6. The effect of the deficient leaf factor appears in both cotyledons and leaves. 7. The deficient leaf looks just like a symptom of some disease, yet it is caused by a genetic f...

In the last several years a rather large number of reports have been published in which chemical data have been applied to an analysis of interspecific hybrids. Some investigations were concerned with the composition of the hybrid as a means of establishing principles governing the inheritance of a number of species-specific phenolics (Williams, 1955). Other workers were primarily concerned with the techniques as means of documenting hybridization (Mirov, 1956; Pryor & Bryant, 1958; Turner and Alston, 1959). It is likely that the analyses of interspecific hybridization in Baptisia represent some of the most extensive uses of chemical criteria in the study of natural hybridization at this time. We now know that the success with such techniques in Baptisia depends upon the existence in this genus of unusually diversified flavonoid chemistry among taxa which hybridize readily. This is perhaps unfortunate for the general applicability of flavonoid chemistry to the study of interspecific hybridization. It will be helpful to review a few general principles pertinent to this work before proceeding further: 1. Flavonoid compounds similar to those found in Baptisia are genetically controlled, especially in their qualitative aspects. Mendelian dominance for specific flavonoid compounds is common. (Alston, 1964). 2. In Baptisia hybrids derived from parental species having quite complex assortments of flavonoids there is little evidence of epistasis, and the hybrid tends to approach a chemical pattern which is additive for the two parents. This result is seemingly in partial conflict with 1 above. 3. Since individual flavonoids appear to be reliable genetic markers, it is expected that in favorable situations such data will prove to be applicable to analyses of population dynamics or introgression. In Baptisia the chemical data are superior to morphological data in individual instances although the reverse is true as well. For most morphological features which distinguish parental species, the hybrid is intermediate. This intermediacy is not particularly troublesome in dihybrid populations, but in Baptisia many combinations of three actively hybridizing species may be sympatric, and one population of four hybridizing species has been analyzed (Alston and Turner, 1963). Here, morphological characters tend to blend in such a way as to introduce relative confusion into any attempt to designate the genomic origins of the various hybrid-type individuals. Another advantage of the species-specific chemical markers, assuming their reliability, is that despite the fact that there may be some quantitative variation in the expression of a chemical character among different hybrids, and even within parental species, the presence of a chemical marker indicates the presence of a specific marker gene in the population. With many of the morphological characters one is presumably farther removed from the cause of the phenotypic attribute. While the ability to express a phenotypic character in chemical terms is not in itself the epitome of a perfect character, it is advantageous to know the chemical nature of a trait under investigation whenever possible. We have been much impressed by the variation in exomorphic characters encountered among putative F1 hybrids in the field. This question will be considered again below

1. The character of strong anthocyanin colour in swede was re examined, and since Kajamis’ factorP 2 fails to distinguish certain doubtful types, it has been redefined asN 1 the critical characters being thatwhen present N 1 produces self-red or self-purple on the surfaces between leaf scars on the“nech,” and, with less certainty, strong vinous mauve on the“top.” 2. A new factorN 2 is described,similar in action to, but not identical with N 1. 3. Complete absence of linkage was found between factorsN 1 andN 2, also between these andM 1 andM 2, the dihybrid factors governing flesh colour. The duplication of factors in swede is of interest in connection with the numerical chromosome number of the species.

Two Bangladeshi varieties, Aghrani and Ananda were found with normal spikes, pink auricle and non-waxy blooms. The variety Akbar resembled these characters except the auricle colour, where it was white. On the contrary, the selected line FM-147 was found with tip sterile, white auricle, and waxy bloom characters. The F 1 s in three different crosses (AG × FM-147, AN × FM-147) were found with normal spikes, white auricle, and non-waxy bloom. The F 1 population of three crosses were found to segregate in the proportion of 3:1 with normal and tip sterile plants. Backcross progenies were found to segregate into 1:1 ratio with normal and tip sterile plants. These results indicated that a recessive gene controls the tip sterility. The auricle pigmentation in F 2 s of the crosses between AG × FM-147 and AN × FM- 147 was found to show the ratio 3:1 with auricle of pink and white pigmentation. Backcross progenies showed also the ratio 1:1. The inheritance of auricle pigmentation was also found to be governed by a single recessive gene. The F 2 s in three crosses showed the ratio 3:1 with waxy bloom and non- waxy bloom. Backcross progenies showed also the ratio 1:1 for these two characters. The F 2 populations for two characters at a time were found to segregate into a dihybrid ratio of 9:3:3:1 indicating the absence of any linkage between these two characters. Keywords: Inheritance; tip sterility; hexaploid wheat. DOI: 10.3329/bjar.v35i3.6460 Bangladesh J. Agril. Res. 35(3) : 535-541

For the rather numerous species, whose chromosomes exhibit little or no size differentiation, it is suggested that some guidance in a genetic analysis may be found in calculating the theoretical distribution of groupings of m genes among the n pairs of chromosomes, by adaptations of the binomial formula, (n-1/n+1/n)m. From these the geneticist may derive the expected proportion of chromosomes carrying 0, 1, 2, 3, 4 ... m genes each; the approximate number of genes required to place at least one in each chromosome; the proportion of single and of linked genes; and the proportion of dihybrid combinations that will assort freely, or show linkage. In the tomato the observed groupings of the first 18 factors identified and located seem consistent with the assumption of their random distribution among the 12 pairs of approximately equal chromosomes. The distribution of known loci in Primula sinensis and the sweet pea also accord reasonably well with expectation.

HE actions of genes controlling quantitative characters may be described the use of gene models. FISHER (1918) constructed a gene model which included dominance at a single locus. He stated that there may be a deviation from the simple additive effects between loci, similar to dominance at one locus, if more than one locus affected a given character. He called the deviation epistacy and introduced the term dual epistacy to indicate the interaction of all possible pairs of loci affecting the given character. Later, FISHER, IMMER and TEDIN (1932) used this gene model to describe the actions of any number of genes on a given character assuming there was no epistacy. GRIFFING (1950) introduced an epistatic parameter into a model, but the model is not easily extended to an arbitrary number of loci. The present paper contains a model based on the factorial model used in the design of experiments and some applications of this model to some data. THE FACTORIAL GENE MODEL The factorial model may be exemplified by the case of a dihybrid. The relative frequencies of the nine genotypes obtained from selfing the complete heterozygote may be represented in the following manner

Heat treatments were applied to barley seeds and 10 different mutant characters were observed in the progeny, viz.; xantha1 and 2, dwarf1,2,3 and 4, virescent1 and 2, chlorina and albino. Typical Mendelian ratios were not obtained in the first segregating generation owing to the small size of the sector affected in the generation of treatment. In the second and third segregating generations, good fits were obtained in all cases to either monohybrid or dihybrid ratios. Both 3:1 and 15:1 ratios were observed in lines segregating for xantha1 and albino characters. The postulation of the duplicate factor hypothesis was necessary to explain this situation. Chlorina and dwarf mutants segregated in all the cases investigated as simple Mendelian recessives. One virescent strain was believed to have arisen through plastid mutation and was maternally inherited.The heat treatment significantly increased the natural mutation rate for the xantha characters but apparently had no effect on the albino mutation rate. Dwarf, virescent and chlorina mutants were observed in the segregating generation after heat treatment, but were not detected in untreated populations.

Foliaceous stipule, a recessive mutant in Arachis hypogaea, was expressed only when transmitted through the pollen parent. Genetic studies indicated a dihybrid model in which both recessive genes have to be present in pollen carrying the functional factors

IT is quite often said that Mendel was very fortunate not to run into the complication of linkage during his experiments. He used seven genes and the pea has only seven chromosomes. Some have said that had he taken just one more, he would have had problems. This, however, is a gross oversimplification. The actual situation, most probably, is shown in Table 1. This shows that Mendel worked with three genes in chromosome 4, two genes in chromosome 1, and one gene in each of chromosome 5 and 7. It seems at first glance that, out of the 21 dihybrid combinations Mendel theoretically could have studied, no less than four (that is, a–i, v–fa, v–le, fa–le) ought to have resulted in linkages. As found, however, in hundreds of crosses and shown by the genetic map of the pea1, a and i in chromosome 1 are so distantly located on the chromosome that no linkage is normally detected. The same is true for v or le on the one hand, and fa on the other, in chromosome 4. This leaves v–le, which ought to have shown linkage.

In common strain of yellow lupine, Lmpinus luteus L., a positive reaction for alkaloid occurs, denoting purple colour in various parts of young plant. On the other hahd, sweet lupine (strain) has no colouring and alkaloid reaction. These two strains were crossed with each other and the progenies were tested. It is found from the result that two characters inherited independently as a dihybrid type. Thus two new combinations were brought as coloured and no-alkaloid, and no-coloured and alkaloid positive. Such facts will atract our attent, ion for the cultivation of forage crops.

Four isoflavone mutations of considerable biological and practical potential are described. Genetic evidence accumulated to date suggests the mutations to be simple recessives. A single gene can control the release of bound isoflavones. Single genes apparently also control the methylation of daidzein and genistein to formononetin and biochanin A respectively, and the development of isoflavones in normal quantities. Crosses between lines carrying the individual mutations lead to modified dihybrid Mendelian ratios.