Are there heteromorphic sex chromosomes in spinach (Spinacia oleracea L.)?

Summary Four varieties and two introductions of Spinacia oleracea are cytologically studied in order to determine whether there is a heteromorphic sex chromosome pair in any of the sexes. It is observed that in one and the same preparation, and regardless of the sex of the plants, different cells had homomorphic and heteromorphic condition for chromosome 1 pair. It is concluded that as a result of differential contraction of chromosomes, the arm ratios and total lengths may vary, and give a distorted impression of certain pair of chromosomes. The absence of heteromorphic pair is confirmed in male and intersex plants by meiotic studies.     

Inheritance of leaf angle in Triticum aestivum L.

Summary A 6×6 diallel was prepared to study the inheritance of leaf angle in T. aestivum L. Genetic analysis in terms of diallel cross parameters and graphic analysis indicated the control of additive gene effects in the expression of this character. The results of F₁ analysis were supported by the analysis of F₂ data.     

A comparative study on anther development in male-fertile and male-sterile plants of Pelargonium crispumL'Her. ex Ait.

Summary Anther development of male-fertile and male-sterile plants in Pelargonium crispum was anatomically examined. Three cultivars, i.e., Lemon crispum, Crispum minor and Prince Rupert, were used. Lemon crispum and Crispum minor are male-fertile, whereas Prince Rupert is male-sterile. The tapetum in every cultivar examined behaved like an amoeba. The tapetal cells of the anther form plasmodial masses. Then, the plasmodial masses fuse producing a periplasmodium. The periplasmodium degenerates and finally disappears. There are no differences in tapetal behaviour between fertile and sterile anthers. In the sterile anthers the endothecium and lip cells do not develop sufficiently. Young microspores show normal growth at early stages. After the completion of their cell wall formation, however, the microspores in the sterile anthers lose their cytoplasm and become empty. On the other hand, the microspores in the fertile anthers increase the volume of their cytoplasm and become fertile pollen grains.     

Breeding for Highly Fertile Isolates of Nectria haematococca MPVI that are Highly Virulent on Pea and In Planta Selection for Virulent Recombinants

ABSTRACT The heterothallic ascomycete Nectria haematococca mating population VI (anamorph Fusarium solani) is a broad host range pathogen. Field isolates of this fungus that are pathogenic on pea tend to be female sterile, of low fertility, and the same mating type (MAT-1), whereas female fertile isolates of either mating type that are highly fertile tend to be nonpathogenic on this plant. To facilitate genetic analysis of traits that may be important in the ability of N. haematococca to parasitize peas, a breeding project was undertaken to produce hermaphroditic isolates of each mating type that are highly fertile and highly virulent on peas. Although the association of high virulence on peas with female sterility and the MAT-1 mating type was not completely broken, isolates with high fertility and high virulence on peas were bred within two generations. Highly virulent progeny were also isolated by an alternative method in which pea plants were inoculated with a mixture of ascospores from a cross between two moderately virulent parents. Whereas all ascospores isolated without selection in planta had lower virulence than the parents, many isolates recovered from diseased tissue were more virulent than the parental isolates. Some of the recovered isolates were shown by restriction fragment length polymorphism analysis to be genetic recombinants of the parents, demonstrating that the pea tissue selected virulent recombinants. All highly virulent isolates tested had the ability to detoxify the pea phytoalexin pisatin, again showing a link between this trait and pathogenicity on the pea.     

Uterine torsion in cattle - frequency, clinical symptoms and theories about the pathogenesis

Aim of the present study was to summarize the available literature about the incidence, frequency, clinical symptoms and ideas as to the pathogenesis of uterine torsion in the cow. MATERIALS AND METHODS: Analysis of the literature using electronic libraries (Pub Med, Medline), German veterinary medicine journals and obstetrical textbooks. RESULTS: Uterine torsion is a very important maternal reason for dystocia as most cases occur during parturition. The post-cervical torsion (combined uterine and vaginal torsion, Torsio uteri and vaginae) is more commonly diagnosed than an intra-cervical or pre-cervical torsion. Torsions to the left occur more frequently than to the right. Clinical symptoms clearly vary depending on the degree of torsion. The frequency in relation to all parturitions is described as between 0.5 and 1%, whereas the percentage of uterine torsions presented to the veterinarian as a reason for dystocia varies between 2.7 and 65%. The pathogenesis of uterine torsion remains unclear; however, general agreement exists that the cow is predisposed to uterine torsion due to its anatomy. It appears that the Brown Swiss is more often affected than other cattle breeds.     

Nestedness and modularity in fragmented Shasha Forest Reserve,southwestern Nigeria

Species co-occurrence and nestedness pattern in Shasha forest reserve were investigated with a view to determining the effect of interactions to species contribution. Three distinct sites (Gmelina arborea plantation, undisturbed forest, and Pinus carribaea (plantation) were selected in the forest reserve. Four 25 m × 25 m plots were established in each of the site within the forest reserve. Species enumeration, identification,, and distribution into families of the standing vegetation were carried out. Woody species represented the most diverse life form. Plant species diversity was highest in UF and lowest in Gmelina plantation. Differences in woody species composition among the three forest types were determined by non-metric multidimensional scaling (NMDS) analysis, analysis of similarity (ANOSIM), and similarity of percentages. Using z-score and NODF (a nestedness metric based on overlap and decreasing fill). Three modules were detected and modularity score Q = 0.2. The composition analyses (NMDS and ANOSIM) revealed a significant difference in the woody species composition among the forest types. Our research may contribute to understand species assemblage in one of the diverse forests of Africa. Current work highlighted species occurrence in Shasha forest and highlighted the importance of non-random pattern which could serve as framework for conservation perspective.     

Phylogenetic studies in Citrus reticulata and related types

Summary Sixteen types of mandarins were screened for their leaf flavonoid patterns with the help of cellulose thin-layer chromatography. In general, Tanaka's classification of mandarins into 36 species is untenable, as was already concluded by Swingle (1948), Hodgson (1965) and Singh (1967). It is likely that a fine loose skinned mandarin was first evolved. Later, it hybridized with wild mandarin to give rise to numerous types and forms.Contribution No. 474 of Indian Institute of Horticultural Research, Bangalore-6, India.     

A rapid method for early generation selection of dwarf genotypes in wheat

Summary In the early generations of a breeding programme to incorporate the successful Norin 10 semidwarfing genes into adapted tall or standard lines, the bread and durum wheat breeder must be able to recognise and discard those lines that are not homozygous for the dwarfing gene. A method which exploits the gibberellin insensitive reaction of lines carrying the genes combined with a single seed descent technique is described in which most unwanted genotypes may be removed as F2 seedlings.