BackgroundDurum wheat often faces water scarcity and high temperatures, two events that usually occur simultaneously in the fields. Here we report on the stress responsive strategy of two durum wheat cultivars, characterized by different water use efficiency, subjected to drought, heat and a combination of both stresses.ResultsThe cv Ofanto (lower water use efficiency) activated a large set of well-known drought-related genes after drought treatment, while Cappelli (higher water use efficiency) showed the constitutive expression of several genes induced by drought in Ofanto and a modulation of a limited number of genes in response to stress. At molecular level the two cvs differed for the activation of molecular messengers, genes involved in the regulation of chromatin condensation, nuclear speckles and stomatal closure. Noteworthy, the heat response in Cappelli involved also the up-regulation of genes belonging to fatty acid β-oxidation pathway, glyoxylate cycle and senescence, suggesting an early activation of senescence in this cv. A gene of unknown function having the greatest expression difference between the two cultivars was selected and used for expression QTL analysis, the corresponding QTL was mapped on chromosome 6B.ConclusionOfanto and Cappelli are characterized by two opposite stress-responsive strategies. In Ofanto the combination of drought and heat stress led to an increased number of modulated genes, exceeding the simple cumulative effects of the two single stresses, whereas in Cappelli the same treatment triggered a number of differentially expressed genes lower than those altered in response to heat stress alone. This work provides clear evidences that the genetic system based on Cappelli and Ofanto represents an ideal tool for the genetic dissection of the molecular response to drought and other abiotic stresses.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-14-821) contains supplementary material, which is available to authorized users.

The remarkable ploidy coexistence in the G. conopsea aggregate has reshaped our perception of intrapopulational ploidy diversity under natural conditions. This system offers unique opportunities for studying processes governing the formation and establishment of polyploids and assessing the evolutionary significance of the various pre- and postzygotic mating barriers that maintain this ploidy mixture.

Reed canarygrass (Phalaris arundinacea L.) is native to Europe and North America, being invasive in the latter since the 20th century. No phenotypic differences have been found in plants from each continent; genetic analyses have been controversial—implicating or exonerating forage/ornamental cultivars for spread throughout North America. Within central Europe, particularly the Czech Republic, it is unknown whether wild genotypes and cultivars are genetically and phenotypically similar. The objectives of this study were to compare commercial forage and ornamental cultivars sold within the Czech Republic with wild genotypes from native populations along major Czech rivers and characterize the extent of phenotypic and genetic variation. Several phenotypic traits differentiated among genotypes and populations (initial tiller fresh weight, stem dry weight [DW], whole plant above‐ and belowground DW, total no. of tillers, percent cover, crown area, height, leaf and node number). Genetic markers (inter‐simple sequence repeats [ISSRs]) clearly differentiated ornamental cultivars from wild P. arundinacea. ‘Chrastava’, the Czech forage and biomass cultivar was genetically similar to wild genotypes, which have most of the genetic diversity within, rather than among, populations. Cluster analyses showed ornamental cultivar ramets to be heterogeneous, most likely due to clonal mix up or mutations.

Aim  This study aimed to document precisely the patterns of DNA ploidy variation in the native and secondary ranges of Lythrum salicaria distribution. The hypothesis that species invasiveness had been induced by a switch in ploidy level was addressed. Location  Europe, Middle East, North America. Methods  DNA ploidy levels of 1884 progenies of 578+ plants collected at 124 localities were determined by DAPI flow cytometry. Results  Large cytotype variation (2x, 3x, 4x and 6x) was found across the native area of distribution (64 populations covering 12 European and two Middle Eastern countries). DNA hexaploids were detected for the first time, and rare DNA triploids were reliably confirmed. DNA tetraploids largely prevailed across the native range studied, while DNA diploids and DNA hexaploids were recorded only in Israel and Turkey, respectively. DNA triploid progenies occurred in one population from Hungary (together with DNA tetraploids). Sympatric growth of DNA tetraploids and DNA hexaploids was repeatedly encountered in Turkey. In contrast, cytotype uniformity was a typical feature of the invasive North American plants. Sixty populations, covering 13 states of the USA and provinces of Canada, were characterized by the presence of only DNA tetraploids. Main conclusions  Several L. salicaria cytotypes (2x, 3x, 4x, 6x) occur in the native range of distribution, with much variation concentrated in the Middle Eastern countries, whereas only DNA tetraploids appeared to occur in North America. Our data show that the invasive spread of North American populations was not triggered by differences in ploidy level. Alternative explanations should be sought.

Transformation of plants is a popular tool for modifying various desirable traits. Marker genes, like those encoding for bacterial b-glucuronidase (GUS), firefly luciferase (LUC) or jellyfish green fluorescent protein (GFP) have been shown to be very useful for establishing of efficient transformation protocols. Due to favourable properties such as no need of exogenous substrates and easy visualization, GFP has been found to be superior in to other markers in many cases. However, the use of GFP fluorescence is associated with some obstacles, mostly related to the diminishing of green fluorescence in older tissues, variation in fluorescence levels among different tissues and organs, and occasional interference with other fluorescing compounds in plants. This paper briefly summarizes basic GFP properties and applications, and describes in more detail the contribution of GFP to the establishment, evaluation and improvement of transformation procedures for plants. Moreover, features and possible obstacles associated with monitoring GFP fluorescence are discussed.