Chromosomal localization of the 18S-28S and 5S rRNA genes and (TTAGGG)n sequences of butterfly lizards (Leiolepis belliana belliana and Leiolepis boehmei, Agamidae, Squamata)

Chromosomal mapping of the butterfly lizards Leiolepis belliana belliana and L. boehmei was done using the 18S-28S and 5S rRNA genes and telomeric (TTAGGG)n sequences. The karyotype of L. b. belliana was 2n = 36, whereas that of L. boehmei was 2n = 34. The 18S-28S rRNA genes were located at the secondary constriction of the long arm of chromosome 1, while the 5S rRNA genes were found in the pericentromeric region of chromosome 6 in both species. Hybridization signals for the (TTAGGG)n sequence were observed at the telomeric ends of all chromosomes, as well as interstitially at the same position as the 18S-28S rRNA genes in L. boehmei. This finding suggests that in L. boehmei telomere-to-telomere fusion probably occurred between chromosome 1 and a microchromosome where the 18S-28S rRNA genes were located or, alternatively, at the secondary constriction of chromosome 1. The absence of telomeric sequence signals in chromosome 1 of L. b. belliana suggested that its chromosomes may have only a few copies of the (TTAGGG)n sequence or that there may have been a gradual loss of the repeat sequences during chromosomal evolution

Zmiennosc loci izoenzymatycznych w kolekcji podstawowej rodzaju Pisum

Zgromadzone w krajowej kolekcji Pisum w Wiatrowie zasoby obejmują dzikie populacje, odmiany uprawne i miejscowe, wyselekcjonowane mutanty spontaniczne i indukowane oraz linie pochodzące z krzyżowań w programach hodowlanych i badawczych. Utworzono z nich kolekcję podstawową rodzaju Pisum (266 obiektów), reprezentującą dotychczas opisaną zmienność monogeniczną w genotypach typowych dla alleli, liniach testowych z genami - markerami poszczególnych chromosomów oraz z nowymi genami. Dla zwiększenia przydatności kolekcji podstawowej Pisum zgromadzonej w Wiatrowie scharakteryzowano zakres zmienności loci izoenzymatycznych. Analizowano polimorfizm 18 loci izoenzymatycznych metodą rozdziału elektroforetycznego na żelu skrobiowym. Wszystkie badane loci enzymatyczne wykazały obecność 2-4 allozymów. Niektóre z wykrytych allozymów występowały bardzo rzadko, najczęściej w populacjach należących do dzikich gatunków Pisum. Zakres obserwowanej zmienności izoenzymatycznej w poszczególnych grupach obiektów posłużył do obliczenia częstości alleli i oceny polimorfizmu każdej z grup oraz porównania zmienności pomiędzy grupami. Uzyskane wyniki wykorzystano do dyskusji na temat wykorzystania markerów izoenzymatycznych do charakterystyki genotypu obiektów kolekcyjnych.The Pisum national collection at Wiatrowo covers wild populations, culti- vars and land races, selected spontaneous and induced mutants, as well as cross derivatives from breeding and research programs. There has been constituted the core collection of Pisum genus (266 accesions), representing hitherto described monogenic variability in typical genotypes for alleles, tester lines with marker genes for particular chromosomes, and with new genes. To increase the usefulness of Pisum core collection gathered at Wiatrowo, the range of isozyme loci variability was characterized. The polymorphism of 18 isozyme loci was analyzed using electrophoretic separation on starch gel. All tested loci showed the presence of 2-4 allozymes. Some of them occurred very rarely, usually in populations belonging to the wild species of Pisum. The range of observed isozyme variability in particular groups of accesions was used for statistical calculations of allele frequency and for estimating polymorphism in each group as well as for comparison of variability among groups. The results were used for discussion on utility of isozyme markers for genotype characterization of collection accessions

Using in situ seed baiting technique to isolate and identify endophytic and mycorrhizal fungi from seeds of a threatened epiphytic orchid, Dendrobium friedericksianum Rchb.f. (Orchidaceae)

© 2016 Kasetsart University. All orchids require association with mycorrhizal fungi for seed germination and development under natural conditions but their identification and feasibility are not known. The in situ seed baiting germination was examined of Dendrobium friedericksianum Rchb.f., a native threatened epiphytic orchid species, to detect fungi that promote germination. It was found that seed germination percentages were lowered by 0.1%, with a total of seven protocorms formed. Six endophytic fungi were isolated from seven protocorms in seed packets. Three binucleate Rhizoctonia-like fungal isolates which formed a teleomorphic state were morphologically identified as Tulasnella violea, Epulorhiza repen (anamorph Tulasnella) and Trichosporiella multisporum. The species of Beauvaria and Fusarium which are endophyte fungi were also isolated and may play an important role for plant growth and survival of D. friedericksianum. The results in this study suggested that in situ seed baiting is beneficial for screening compatible mycorrhizal fungi to promote the growth and propagation of epiphytic orchids

Epigenetic changes and transposon reactivation in Thai rice hybrids. Molecular Breeding

Inter- or intraspecific hybridization is the first step in transferring exogenous traits to the germplasm of a recipient crop. One of the complicating factors is the occurrence of epigenetic modifications of the hybrids, which in turn can change their gene expression and phenotype. In this study we present an analysis of epigenome changes in rice hybrids that were obtained by crossing rice cultivars, most of them of indica type and Thai origin. Comparing amplified fragment length polymorphism (AFLP) fingerprints of twenty-four cultivars, we calculated Nei’s indexes for measuring genetic relationships. Epigenetic changes in their hybrids were established using methylation-sensitive AFLP fingerprinting and transposon display of the rice transposable elements (TEs) Stowaway Os-1 and Mashu, leading to the question whether the relationship between parental genomes is a predictor of epigenome changes, TE reactivation and changes in TE methylation. Our study now reveals that the genetic relationship between the parents and DNA methylation changes in their hybrids is not significantly correlated. Moreover, genetic distance correlates only weakly with Mashu reactivation, whereas it does not correlate with Stowaway Os-1 reactivation. Our observations also suggest that epigenome changes in the hybrids are localized events affecting specific chromosomal regions and transposons rather than affecting the genomic methylation landscape as a whole. The weak correlation between genetic distance and Mashu methylation and reactivation points at only limited influence of genetic background on the epigenetic status of the transposon. Our study further demonstrates that hybridizations between and among specific japonica and indica cultivars induce both genomic DNA methylation and reactivation/methylation change in the Stowaway Os-1 and Mashu transposons. The observed epigenetic changes seem to affect the transposons in a clear manner, partly driven by stochastic processes, which may account for a broader phenotypic plasticity of the hybrids. A better understanding of the epigenome changes leading to such transposon activation can lead to the development of novel tools for more variability in future rice breedin

Pea rms6 mutants exhibit increased basal branching

Our studies on two branching mutants of pea (Pisum sativum L.) have identified a further Ramosus locus, Rms6, with two recessive or partially recessive mutant alleles: rms6-1 (type line S2-271) and rms6-2 (type line K586). Mutants rms6-1 and rms6-2 were derived from dwarf and tall cultivars, Solara and Torsdag, respectively. The rms6 mutants are characterized by increased branching from basal nodes. In contrast, mutants rms1 through rms5 have increased branching from both basal and aerial (upper stem) nodes. Buds at the cotyledonary node of wild-type (WT) plants remain dormant but in rms6 plants these buds were usually released from dormancy. Their growth was either subsequently inhibited, sometimes even prior to emergence above ground, or they grew into secondary stems. The mutant phenotype was strongest for rms6-1 on the dwarf background. Although rms6-2 had a weak single-mutant phenotype, the rms3-1 rms6-2 double mutant showed clear transgression and an additive branching phenotype, with a total lateral length almost 2-fold greater than rms3-1 and nearly 5-fold greater than rms6-2 . Grafting studies between WT and rms6-1 plants demonstrated the primary action of Rms6 may be confined to the shoot. Young WT and rms6-1 shoots had similar auxin levels, and decapitated plants had a similar magnitude of response to applied auxin. Abscisic acid levels were elevated 2-fold at node 2 of young rms6-1 plants. The Rms6 locus mapped to the R to Gp segment of linkage group V (chromosome 3). The rms6 mutants will be useful for basic research and also have possible agronomical value