Leaf mutants were isolated and genetically stabilised in diploid red clover (Trifolium pratense). The major alteration showed normal trifoliolate leaves changed into multifoliolate leaves composed of 4-, 5-, 6- and 7 leaflets. As a result of recombination with other mutant alleles several genotypes were isolated with a different mode of leaf setting, different shapes and sizes of leaflets, variations in the whole plant habit, etc. A careful description was made of the mutant morphology and the development and genetic background was estimated as (h sl (2) ). The mutants demonstrated no disturbances in their generative reproduction and as a rule set seeds better than the standards. The primary evaluation permits a conclusion that the leaf alteration (complexity) is governed by at least three recessive pairs of alleles of additive action. The phenotypic expression of the altered leaves depends simply on the number of recessive alleles. Apart from the above there were some modifying genes of incomplete penetration.
Jaranowski, J. K. (Coll. of Agriculture, ul. Wojska Polskiego 71c, Poznan, Poland.) Semisterility in the interspecific hybrid Melilotus polonica × M. alba. Amer. Jour. Bot. 48(1): 28–35. Illus. 1961.—Interspecific hybrids between Melilotus polonica (n = 8) and M. alba (n = 8) are readily secured. The F1 hybrids are intermediate between the parents and partially sterile with a mean percentage of 58.8 (ranging from 46.8 to 72.6) defective pollen grains. Six bivalents and a chain or ring of 4 chromosomes occur at diakinesis and metaphase‐I of microsporogenesis. A crossshaped configuration characteristic of a reciprocal translocation is present at pachytene, indicating that one of the parents is homozygous for an interchange of relatively large section between two of the members of the chromosome complex. Chromosome bridges, lagging chromosomes, movement of the univalents to the same pole and precocious division of the univalents lead to aberrant chromosome distribution during the course of meiosis. Reduction in self‐fertility indicates a corresponding aberrant distribution of chromosomes during megasporogenesis. Pollen sterility in the F2 generation ranged from 24.8% to 72.5% with a mean value of 54.6%. Two plants in the F2 generation which had relatively low pollen sterility proved to be aneuploids (2n + 1). Meiotic irregularities in the F2 plants were comparable to those exhibited by the F1 plants.
A mutant of melilot (<em>Melilotus</em> sp.) consisting in the formation of altared florets and inflorescences is analysed and described. The genetic background and inheritance of the changed characters are discussed.
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