Summary• Waterlogging tolerance and its physiological basis were evaluated in Lophopyrum elongatum (a species from a salt marsh habitat), Triticum aestivum (cv. Chinese Spring), their amphiploid, and disomic chromosome addition lines.• Growth in drained or waterlogged soil and aerated or deoxygenated stagnant nutrient solution were evaluated. Porosity, aerenchyma, rates of O 2 consumption, radial O 2 loss, and ethanolic fermentation in adventitious roots of selected genotypes were also measured.• L. elongatum was more tolerant of deoxygenated stagnant nutrient solution or waterlogged soil (0 -48% reductions in growth, respectively) than 'Chinese Spring' (63 -84% reductions), the amphiploid (49 -81% reductions), or the addition lines (56 -92% reductions). Roots of L. elongatum had a higher constitutive porosity than 'Chinese Spring', resulting in greater internal O 2 movement in these roots when intact plants were first transferred to an O 2 -free root medium. This trait, as well as the slower growth and development of L. elongatum , might have contributed to its greater waterlogging tolerance.• Despite the differences between L. elongatum and 'Chinese Spring' in some traits, none of the Lophopyrum × wheat lines showed substantial improvement in waterlogging tolerance.
The Nicaraguan teosinte Zea nicaraguensis was studied cytologically to determine its chromosome number and C-banding pattern. The C-banding pattern was compared with that of the close relative Zea luxurians as well as with Zea diploperennis and cultivated maize, Zea mays ssp. mays. Karyograms were constructed for the four Zea species. It is shown that Z. nicaraguensis, like most other Zea species, is a diploid with 2n=20 chromosomes. The C-banding pattern shows that Z. nicaraguensis is very similar to Z. luxurians and more similar to Z. luxurians than to Z. diploperennis and cultivated maize. Whether or not Z. nicaraguensis and Z. luxurians should be regarded as subspecies instead of individual species is, however, not possible to conclude from this study.
Wood barley, Hordelymus europaeus, was compared with other Triticeae species by Southern and fluorescence in situ hybridisation using total genomic DNA and repetitive sequences as probes. On Southern blots, the total genomic probe from H. europaeus hybridised strongly to DNA of its own species and to Leymus and Psathyrostachys, indicating the presence of Ns genome in H. europaeus. Furthermore, the total genomic probe from P. fragilis hybridised to DNA of H. europaeus as much as to all of the Psathyrostachys and Leymus species examined. Ns genome-specific DNA sequences isolated from L. mollis (pLmIs1, pLmIs44 and pLmIs53) hybridised essentially to H. europaeus and all of the species of Leymus and Psathyrostachys. Chromosomal localization of these clones on H. europaeus confirmed the presence of Ns genome-specific DNA on all chromosomes, indiscriminately. Under moderate hybridisation stringency the Ns genome-specific probes, together with repetitive sequences pTa71 and pAesKB7, produced species-specific RFLP banding profiles on Southern blots. A phenetic tree based on these profiles revealed a distinct Ns species cluster within the Triticeae, represented by Leymus and Psathyrostachys species. Hordelymus europaeus belonged to this Ns cluster. Chromosomal mapping of the 18S-25S and the 5S ribosomal genes, together with the repetitive sequence pLrTaiI, corroborated that H. europaeus was most probably related to Leymus, especially the European/Eurasian members of sect. Leymus. In an attempt to identify the genome of H. europaeus, different approaches were employed; the results clearly showed that wood barley had the Ns basic genome and nothing else.
Alloploids, most of them hexaploid, from crosses between tetraploid wheat, Triticum carthlicum, and the perennial tetraploid Thinopyrum junceiforme were analysed for chromosome composition, stability and fertility using genomic in situ hybridization and meiotic analysis. The alloploids differed in their total number of chromosomes, 38-47 + telocentrics in "hexaploids" and 54 and 56 in "octoploids", and also in their number of Thinopyrum chromosomes (8-15). Translocations, mostly Robertsonian ones, were frequently found and intergenomic pairing was found to occur during meiosis. The stability was low which is reflected in the variability in chromosome number and in the number of univalents per PMC (2.3-4.0). The seedset was lower than in wheat, but high enough to secure a safe propagation and preservation. The alloploids are discussed in relation to widening the genetic variation of breadwheat and wheat breeding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.