About the creation of sterile lines of sweet pepper in breeding for heterosis

Relevance. Development of valuable sterile lines of sweet pepper using nuclear-cytoplasmic male sterility is associated with the search for stable sterility maintainers in collection material.Material and methods. The purpose of the research is to optimize the identification of the desired genotypes and accelerate the development of sterile lines using artificial climate chambers. The research material was a sterile line msTol55, which under the conditions of a film greenhouse showed partial fertility at the beginning or at the end of the growing season. The place of cultivation is artificial climate chamber, a film spring greenhouse.50-day-old seedlings were planted in pots on 10.01, the period of growing plants in the chamber - until 20.04, then the adult plants were transplanted into a spring film greenhouse. According to the traditional technology, the cassette seedlings of the same line were planted in the greenhouse on 15.04. The number of tested plants is 16-20 pcs. Growing mode in the chamber: 12 hours were illuminated with DRLV lamps, while the temperature was at the level of 26-28°C, from 20.00 to 8.00 the lamps were not illuminated, the temperature was 14-15°C. The actual sterility / fertility of the flowers was determined by the level of contamination of the fruits at the beginning of their formation.Results. The maintained temperature regime for growing in an artificial climate chamber made it possible to identify sterile (30%) and partially fertile plants (70%) in the first 2 weeks of flowering. When adult plants were transplanted into a spring greenhouse, the number of sterile plants increased to 56%. When growing the line msTol55 in a spring greenhouse using the usual technology, partial setting of seeded and little seeded fruits on 60% of the plants was observed from the third decade of May to the second decade of July, then all plants set only non-seeded fruits. Based on the results obtained, it is advisable to identify the breeding material for the Rf gene in the ACC, since the proposed growing regime serves as a provocative background and allows for more effective control over the manifestation of sterility.

N-glycolyl groups of nonhuman chondroitin sulfates survive in ancient fossils

Biosynthesis of the common mammalian sialic acid N-glycolylneuraminic acid (Neu5Gc) was lost during human evolution due to inactivation of the CMAH gene, possibly expediting divergence of the Homo lineage, due to a partial fertility barrier. Neu5Gc catabolism generates N-glycolylhexosamines, which are potential precursors for glycoconjugate biosynthesis. We carried out metabolic labeling experiments and studies of mice with human-like Neu5Gc deficiency to show that Neu5Gc degradation is the metabolic source of UDP-GlcNGc and UDP-GalNGc and the latter allows an unexpectedly selective incorporation of N-glycolyl groups into chondroitin sulfate (CS) over other potential glycoconjugate products. Partially N-glycolylated-CS was chemically synthesized as a standard for mass spectrometry to confirm its natural occurrence. Much lower amounts of GalNGc in human CS can apparently be derived from Neu5Gc-containing foods, a finding confirmed by feeding Neu5Gc-rich chow to human-like Neu5Gc-deficient mice. Unlike the case with Neu5Gc, N-glycolyl-CS was also stable enough to be detectable in animal fossils as old as 4 My. This work opens the door for investigating the biological and immunological significance of this glycosaminoglycan modification and for an “ancient glycans” approach to dating of Neu5Gc loss during the evolution of Homo.

Squamanita contortipes, the Rosetta Stone of a mycoparasitic agaric genus

Fungal biodiversity studies on the Olympic peninsula, Washington, have uncovered the key to understanding one of the most enigmatic mushroom genera worldwide. Discovery of a mushroom (Squamanita contortipes) on another grossly distorted but identifiable agaric (Galerina sp.), which retained partial fertility and morphology, provides documentation of parasitism and gall formation by the genus Squamanita. This revelation leads to a reinterpretation of all Squamanitas as commingled hosts and parasites and supplies a simple explanation for anatomical mixtures of tissues erroneously cited as evidence linking the Agaricaceae, Tricholomataceae, and Amanitaceae. It also resolves six decades of controversy over the identity or function of enlarged bases that often bear chlamydospores. Parasitism of mushroom fruit bodies by other mushrooms is a rare phenomenon (< 20 reported species globally). With the addition of accepted Squamanita species, the number of known sporophorous parasitic agarics worldwide is increased by one-third and the number of obligate mycoparasitic mushroom genera is doubled. Key words: biodiversity, gall, taxonomy, biology, terminology, chlamydospores, Pacific Northwest, Asterophora.

A nuclear gene modifying instability of fertility restoration in cytoplasmic male sterile rice

SummaryThe present study was carried out to examine the genetic mechanism responsible for reversions to fertile phenotype detected in cytoplasmic male-sterile plants of rice. The cms-bo cytoplasm of Chinsurah boro II gave rise to male-sterility in plants without a gametophytic restorer gene (Rf1). Taichung 65 (T65A) was known to be the maintainer which carries no restorer; however, Taichun 65 preserved in our laboratory (T65B) showed partial fertility (about 8% seed set) when crossed with the male-sterile plants. Unexpectedly, the seed fertility gradually increased with repeated selfings and almost fully fertile plants were obtained in the F6 generation. The cytoplasmic substitution lines revealed that reversions to fertile phenotype resulted from mutational events at the nuclear level. The genetic experiments indicated that the partial fertility observed in the F1 hybrid was controlled by a dominant gene, Ifr1, which was carried by T65B. The results obtained suggested that Ifr1 itself was associated with instability of fertility restoration in the presence of cms-bo cytoplasm since partially fertile plants carrying Ifr1 always showed a tendency for gradual increase in fertility in the later generations. The results are also discussed in relation to a rapid genetic change through intensified gametic selection combined with instability.

Genome analysis of Elymus alatavicus and E. batalinii (Poaceae: Triticeae)

Elymus alatavicus (Drob.) A. Love and E. batalinii (Krasn.) A. Love were studied to determine (i) meiotic behaviour, (ii) the mode of reproduction, (iii) the relationship between the two species, (iv) genomic constitutions, and (v) the most logical taxonomic classification of both species. A series of F1 hybrids between E. alatavicus, E. batalinii, and six "analyzer" species were developed. Chromosome pairing was studied at metaphase I to identify genomic similarities or differences. The results showed that E. alatavicus and E. batalinii are caespitose, self-fertile allohexaploids (2n = 42) with the same genomic formula SSYYXX. The F1 hybrids between E. alatavicus and E. batalinii had complete pairing (21 bivalents) at metaphase I in 7% of the cells and almost complete pairing in the remaining cells. High chromosome pairing and partial fertility (4 seeds/plant) in the F1 hybrids shows that the two species are closely related. Hybrids were obtained between E. alatavicus or E. batalinii and the following "analyzer" species with known genomic formulas: Pseudoroegneria spicata (Pursh) A. Love, 2n = 14, SS; P. cognata (Hack.) A. Love, 2n = 14, SS; E. lanceolatus (Scribn. &Smith) Gould, 2n = 28, SSHH; E. trachycaulus1 (Link) Gould ex Shinners, 2n = 28, SSHH; E. mutabilis (Drob.) Tzvelev, 2n = 28, SSHH; and E. drobovii (Nevski) Tzvelev, 2n = 42, SSHHYY. Chromosome pairing in this series of hybrids demonstrated that E. alatavicus and E. batalinii contain an S and probably a Y genome plus an unknown genome, X, that may have been derived from Psathryostachys huashanica Keng or from Agropyron. Elymus alatavicus and E. batalinii are correctly classified in the genus Elymus.Key words: cytotaxonomy, Agropyron, meiosis, chromosome.

Cytology and breeding behavior of interspecific hybrids and induced amphiploids of Zinnia elegans and Zinnia angustifolia

Cytological studies were performed on interspecific hybrids and induced amphiploids of Zinnia angustifolia HBK (2n = 22) and Zinnia elegans Jacq. (2n = 24) to ascertain their potential in serving as intermediaries in the transfer of genes for disease resistance. Partial fertility was restored in sterile F1 hybrids (2n = 23) through colchicine treatment of axillary buds. Lagging univalents and irregular distribution of chromosomes to the gametes were the major contributing factors to the sterility observed among the F1 hybrids. Bivalent associations in the F1 indicated partial homology between parental genomes. The induced amphiploids (2n = 46) formed predominantly bivalents at metaphase I owing to the suppression of pairing between homoeologous chromosomes. Consequently, these segmental allopolyploids resembled diploids in their cytological and genetic behavior and bred true to their intermediate condition with little or no segregation in later generations. It is postulated that the gene(s) controlling chromosome pairing is derived from Z. elegans. The cytological and genetic performance of colchicine-induced amphiploids of Z. elegans and Z. angustifolia suggest considerable potential for the improvement of Z. elegans cultivars with respect to disease resistance and the immediate stabilization of characters through genetic uniformity.

ENVIRONMENTAL EFFECTS ON SEED SET IN OILSEED SUNFLOWER (Helianthus annuus L.)

Incomplete seed set of certain commercial sunflower hybrids may be caused by self-incompatability, partial fertility restoration, or other factors which could be affected by the environment. Three commercial hybrids and their fertile inbred parents were planted at five locations across the central plains area of the U.S. during 1978 and 1979. Relative number and weight of developed seed were determined from six of these environments. Little difference in seed set was observed between bagged and unbagged heads of two of the hybrids and their inbred parents. The bagged heads of the third hybrid and its B-line inbred parent had consistently lower seed set. Environment affected seed set significantly. The number of developed seed in percent was consistently less than the weight of viable seed in percent.