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Understanding the genetic-based variability in plant phytochemical compounds provides insight into the evolutionary and ecological processes affecting those traits. In some cases, it is an advantage to quantify the holistic phytochemical profile of a sample rather than focus on individual compounds of known interest. Near-infrared (NIR) reflectance spectroscopy provides a means to rapidly characterise the holistic physicochemical profile of biological materials (known as the spectral phenome). To date, most studies examining differences in the spectral phenome between groups and species have not been conducted in such a way as to enable the quantitative genetic basis of the variation in the spectral phenome to be determined. Here, we investigate the genetic-based variation in the spectral phenome of eucalypts focussing on comparisons at multiple scales of the genetic hierarchy using a tree species of global economic importance, Eucalyptus globulus. Using foliage collected from common-environment field trials we were able to use the spectral phenome to accurately differentiate advanced generation inter-specific hybrids and their parents and examine the pattern of inheritance of the holistic chemical profile. We also found intra-specific variability in the spectral phenome at the race, sub-race and family within race levels, and could identify clear genomic positions influencing the spectral phenome. We have used Eucalyptus as a test system to demonstrate the general approach of using the spectral phenome in genetic-based analyses, an approach that is readily transferrable to other plant systems. [ABSTRACT FROM AUTHOR]

The possible drivers and implications of an observed latitudinal cline in disease resistance of a host tree were examined. Mycosphaerella leaf disease (MLD) damage, caused by Teratosphaeria species, was assessed in five Eucalyptus globulus (Tasmanian blue gum) common garden trials containing open-pollinated progeny from 13 native-forest populations. Significant population and family within population variation in MLD resistance was detected, which was relatively stable across different combinations of trial sites, ages, seasons and epidemics. A distinct genetic-based latitudinal cline in MLD damage among host populations was evident. Two lines of evidence argue that the observed genetic-based latitudinal trend was the result of direct pathogen-imposed selection for MLD resistance. First, MLD damage was positively associated with temperature and negatively associated with a prediction of disease risk in the native environment of these populations; and, second, the quantitative inbreeding coefficient (QST) significantly exceeded neutral marker FST at the trial that exhibited the greatest MLD damage, suggesting that diversifying selection contributed to differentiation in MLD resistance among populations. This study highlights the potential for spatial variation in pathogen risk to drive adaptive differentiation across the geographic range of a foundation host tree species. [ABSTRACT FROM AUTHOR]

Colchicine-induced neoautotetraploid genotypes of Acacia mangium were cloned and planted in mixture with a set of diploid clones in an orchard in southern Vietnam. Following good general flowering, open-pollinated seed was collected from trees of both cytotypes and microsatellite markers were used to determine the breeding system as characterised by the proportion of outcrosses in young seedling progeny. As predicted from the literature, the progeny of diploid clones were predominantly outcrossed ( t = 0.97). In contrast, the progeny of the tetraploid clones were almost entirely selfs ( t = 0.02; 3 of 161 seedlings assayed were tetraploid outcrosses and there were no triploids). Segregation at loci heterozygous in the tetraploid mothers followed expected ratios, indicating sexual reproduction rather than apomixis. Post-zygotic factors are primarily responsible for divergence of the breeding systems. Commonly, less than 1 % of Acacia flowers mature as a pod, and after mixed pollination, diploid outcrossed seed normally develops at the expense of selfs. Selfs of the tetraploid trees appear to express less genetic load and have a higher probability of maturing. However, this does not fully explain the observed deficiency of outcross tetraploid progeny. Presumably, there are cytogenetic reasons which remain to be investigated. In nature, selfing would increase the probability of establishment of neotetraploids irrespective of cytotype frequency in the population. Breeders need to review their open-pollinated breeding and seed production strategies. It remains to be seen whether this is an ephemeral problem, with strong fertility selection restoring potential for outcrossing over generations. [ABSTRACT FROM AUTHOR]

The nonlinear Schrödinger equation with attractive quintic nonlinearity in periodic potential in 1D, modeling a dilute-gas Bose-Einstein condensate in a lattice potential, is considered and one family of exact stationary solutions is discussed. Some of these solutions have an analog neither in the linear Schrödinger equation nor in the integrable nonlinear Schrödinger equation. Their stability is examined analytically and numerically. [ABSTRACT FROM AUTHOR]

The majority of plant expressed sequence tags (ESTs) available in the public databases are from non-woody species such as Arabidopsis, maize, soybean, and rice, with the exception of the model tree species, Populus. In this study, we report the first EST database constructed from the commercially important tree species Acacia. ESTs were generated from pooled RNA extracted from the mature, intermediate, and young inner bark tissues of an Acacia auriculiformis x Acacia mangium hybrid. Finally, 3,182 high-quality ESTs were analyzed representing a total of 1,982 unique transcripts (663 contigs and 1,319 singletons) for the inner bark cDNA library. A total of 1,053 unigenes (1,750 ESTs) showed similarities with protein sequences in public database where 867 were significant matches ( E value ≤ e). Further analysis performed on unigenes with significant matches and known functions identified 231 genes including genes involved in cellulose, lignin, and hemicellulose biosynthesis. For cDNA library validation, quantitative real-time RT-PCR was performed to study the expression levels of the cellulose and lignin genes identified from this EST database in the phloem tissue of A. mangium, A. auriculiformis, and A. auriculiformis x A. mangium hybrid. All the seven candidate genes were expressed in all the individuals studied confirming the dependability of the EST database. The cDNA library and the EST database constructed are valuable resources for forest tree research aiming towards understanding the genetic control of wood formation and in the future endeavors to modify wood and fiber profile through marker-assisted breeding programs. [ABSTRACT FROM AUTHOR]

Acacia mangium is a major plantation species for the pulp and paper industry in south-east Asia and there are a number of active breeding programs. The species is predominantly outcrossing, but with a demonstrated capacity to set selfed seed where outcross pollen is limited, with consequent inbreeding depression in the progeny. Current controlled pollination methods therefore include a time-consuming emasculation step. We used microsatellite genotyping of seedlings to determine the consequences of outcross pollination with and without emasculation. Only 1 of 3 mother trees set a small amount (5%) of selfed seed. Using whole inflorescences from the male parent as the pollen applicator rather than sieved pollen reduced outcross contamination rates from 19.1 to 8.7% and substantially increased worker productivity. Application of sugar solution to the female flowers immediately prior to pollination increased yield of sound seeds per spike. Additional improvements to the pollination protocols are discussed. [ABSTRACT FROM AUTHOR]

In this paper a coupled mono-inductance transmission line is considered and the envelope modulation is reduced to the generalized 2D-Ginzburg-Landau system (2D-GL system). The case of scalar equation is also considered and we deduce from the obtained 2D-GL system a 2D-cubic Ginzburg-Landau equation (2D-GL equation) containing the derivatives with respect to one spatial variable in the cubic terms. The obtained 2D-GL system and 2D-GL equation admit spatial wave solutions. The modulational instability of these spatial wave solutions is investigated. In the case of the 2D-GL system we have restricted ourselves in the zero wavenumber of the perturbations, and the obtained modulational instability conditions depends only on the system's coefficients and the wavenumber of the carriers. The modulational instability criterion is established for non zero wavenumber of the perturbation, and depends on both the wavenumber of the perturbation and the carrier. For the 2D-GL system we also study the coherent structures and present some numerical studies. [ABSTRACT FROM AUTHOR]

Eucalypt chloroplast DNA (cpDNA) provides useful markers for phylogenetic and population research including gene flow and maternity studies. All cpDNA studies in Eucalyptus to date have been based on the RFLP technique, which requires relatively large amounts of clean DNA. The objective of this study was to develop PCR-based cpDNA markers for Eucalyptus. The chloroplast genome of Eucalyptus, like that of most angiosperms, possesses inverted repeats (IR). The two junctions between the IRs and the large single copy (LSC) regions are defined as JLA andJLB. The region surrounding the JLA junction was sequenced from 26 Eucalyptus DNA samples (21 of E. globulus, plus 5 other species), andtheJLB region was sequenced using 5 of these samples. The samples were chosen to represent all major haplotypes identified in previous cpDNA RFLP studies. The JLA products were 150–210 bp in size, while those fromJLB were approximately 500 bp in size. Eighteen mutations were scored in total. Extensive variation was found in the IR within the intergenic spacer between rpl2 and the IR/LSC junctions. Many of these characters were complex indels. One sample of E. globulus possessed a relatively large (38 bp) insertion which caused displacement of the IR/LSC junctions. This is the first report of intraspecific variation in the position of IR/LSC junctions; interspecific variation was also found. The LSC region near JLB had a low rate of mutation and none were informative. The LSC region near JLA possessed 2 informative mutations. The variation revealed from these sequences reflects the differentiation previously uncovered in an extensive RLFP analysis on the same samples. These results suggest that the JLA region will provide very useful cpDNA polymorphisms for future studies in Eucalyptus. [ABSTRACT FROM AUTHOR]

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