Changes of photosynthetic parameters in wheat/barley introgression lines during salt stress

Salt stress induced photosynthetic responses were investigated in the wheat/barley introgression lines developed in the Agricultural Research Institute, Martonvásár, Hungary, and in different parental wheat and barley Hordeum vulgare L. genotypes. An increase in NaCl concentration of the nutrient solution to 200 mmol L-1 resulted in a considerable stomatal closure and a decreased net CO2 assimilation rate (A) for wheat genotypes, barley cv. Betzes and 4H Asakaze komugi-Manas addition line while changes of these parameters were less significant for barley cv. Manas and the 7H Asakaze komugi-Manas and 6H Mv9 kr1-Betzes-Seneca addition lines. These preliminary results suggest that the 7H Akom-Manas addition line may be a good candidate for improving the salt tolerance of wheat in the future

Incorporation of Aegilops biuncialis chromosomes into wheat and their identification using fluorescent in situ hybridization

The aim of the study was to select Aegilops biuncialis chromosomes from the progeny of the BC2 and BC3 generations of the wheat xAe. biuncialis hybrids, which differ from the chromosomes 2M, 3M, 7M, 3U and 5U found in the wheat-Ae. biuncails addition lines produced earlier in Martonvásár. Besides the above mentioned addition lines exists a 5U, 6U double disomic addition line. Chromosomes of the progeny of the BC2 and BC3 generations and the 5U, 6U double disomic addition line were counted with Feulgen method, while alien (Ae. biuncialis) chromosomes were identified with fluorescent in situ hybridization (FISH) using pSc119.2 and AFA family DNA probes. During the present experiment it was found that the transmission percentage of the chromosome 5U is 67,55% in the progeny of the BC2 and BC3 generations, while in the 5U, 6U disomic addition line chromosome 5U showed 100% transmission. Besides the chromosomes incorporated in the wheat-Ae. biuncialis addition lines produced in Martonvásár, some plants containing the chromosomes 1U, 2U, 4U, 6U, 7U, 5M and 6M without the presence of the chromosome 5U exist. These plants are potential sources of the production of new wheat-Ae. biuncialis addition lines

Can the drought tolerance traits of Ae. biuncialis manifest even in the wheat genetic background?

The physiological responses to water stress induced by PEG were investigated in Aegilops biuncialis (Vis.) genotypes which differ in the annual rainfall of their habitat (1050, 550 and 225 mm/year) and in Triticum aestivum (L.) wheat genotypes differing in drought tolerance, in order to find Ae. biuncialis accessions suitable for improving wheat drought tolerance through intergeneric crossing. A decrease in the osmotic pressure of the nutrient solution from –0.027 MPa to –1.8 MPa resulted in intense water loss, a low extent of stomatal closure and a decrease in the intercellular CO2 concentration (Ci) in Aegilops genotypes originating from dry habitats, while in wheat genotypes high osmotic stress induced increased stomatal closure, resulting in a low level of water loss and high Ci. Nevertheless, under saturating light at normal atmospheric CO2 level, the rate of CO2 assimilation was higher for the Aegilops accessions under strong osmotic stress than for the wheats. Moreover, in the wheat genotypes, CO2 assimilation exhibited less or no O2 sensitivity. These physiological responses were manifested in changes in the growth rate and biomass production, since Aegilops (Ae550, Ae225) genotypes retain a higher growth rate (especially in the roots), biomass production and yield formation after drought stress than wheat. On the basis of the results it seems that Aegilops genotypes originating from a dry habitat have better drought tolerance than wheat, making them good candidates for improving the drought tolerance of wheat through intergeneric crossing

Molecular cytogenetic characterisation of Salix viminalis L. using repetitive DNA sequences

Abstract Salix viminalis L. (2n=38) is a diploid dicot species belonging to the Salix genus of the Salicaceae family. This short-rotation woody crop is one of the most important renewable bioenergy resources worldwide. In breeding for high biomass productivity, limited knowledge is available on the molecular cytogenetics of willow, which could be combined with genetic linkage mapping. The present paper describes the adaptation of a fluorescence in situ hybridisation (FISH) protocol as a new approach to analyse the genomic constitution of Salix viminalis using the heterologous DNA clones pSc119.2, pTa71, pTa794, pAs1, Afafamily, pAl1, HT100.3, ZCF1 and the GAA microsatellite marker. Three of the nine probes showed unambiguous signals on the metaphase chromosomes. FISH analysis with the pTa71 probe detected one major 18S-5.8S-26S rDNA locus on the short arm of one chromosome pair; however, the pTa794 rDNA site was not visible. One chromosome pair showed a distinct signal around the centromeric region after FISH with the telomere-specific DNA clone HT100.3. Two chromosome pairs were found to have pAs1 FISH signals, which represent a D-genome-specific insert from Aegilops tauschii. Based on the FISH study, a set of chromosomes with characteristic patterns is presented, which could be used to establish the karyotype of willow species

PEG-MEDIATED OSMOTIC STRESS RESPONSES OF WHEAT-BARLEY ADDITION LINES

Photosynthetic responses of three wheat-barley addition (add) lines exposed to PEG-induced drought stress and under rewatering period were investigated in order to improve wheat drought tolerance by the help of barley chromosomes. The wheat-barley disomic addition lines (2H, 3H, 4H) the wheat line (Triticum aestivum L. cv. ’Mv9kr1’) were found to have better responses to osmotic stress relative to the parental barley cultivar (Hordeum vulgare L. cv. ’Igri’). Addition lines with 2H and 4H chromosome from barley used similar strategy of acclimation to osmotic stress. These lines were able to avoid drastic water loss as well as exhibiting only a slight decrease in stomatal conductance (gs) in contrast to barley. At the same time, photosynthetic processes in 4H addition seemed to be more sensitive to the decreased relative water content (RWC) of leaves caused by 21% PEG resulting reduction in stomatal to non-stomatal limitation ratio and impaired recovery ability. 3H addition line could be characterized as the most dehydration tolerant among the examined lines on the basis of water wasting responses shown by high gs, decreased intrinsic water use efficiency and more successfully sustained shoot biomass production in contrast to root. Changes in Y(II) parameters were moderate in the addition lines indicating that the electron transport processes were not damaged by osmotic stress. Our results suggest that wheat line also avoided being dehydrated similar to 2H and 4H add but the relatively high RWC under severe water deficit was primarily due to the pronounced stomatal closure. Changes in shoot-root ratio and net CO2 assimilation rate (PN) was also similar to those in 4H add. Although the maintained root growth and strong decreased gs may be the indicators of drought avoidance in barley, in spite of these traits low RWC was observed which contributed to the significantly impaired PN primarily limited by the non-stomatal processes. Considering to drought sensibility, we concluded that barley genotype Igri is not the most suitable gene source for improving water stress tolerance of wheat but 2H addition line seemed to be more resistant to osmotic treatments than wheat and could be used in wheat breeding programs in the future

Root development and drought tolerance of wheat-barley introgression lines

Interspecific hybridization makes it possible to transfer useful traits, such as stress tolerance, earliness and various desirable traits from one species into another. Addition, substitution and translocation lines developed from wheat-barley (Triticum aestivum L. x Hordeum vulgare L.) hybrids were analyzed to determine how the added barley chromosomes (or segments) influence agronomy traits in wheat. Experiments were carried out at Georgikon Faculty, Keszthely. First we checked the seeds germinating power and the early development of shoots and roots. The drought-tolerance was tested under rain shelter in the field. The morphological and agronomic traits of the introgression lines were studied. Data were obtained for root-shoot ratio (EC: 30-31), heading time (earliness), plant height, morphology and length of ear, components of grain yield. The use of this genetic material in wheat breeding programs can result in new varieties with better adaptation

Molecular cytogenetic identification and phenotypic description of a new synthetic amphiploid, Triticum timococcum (AtAtGGAmAm)

A recently developed synthetic amphiploid, Triticum timococcum Kost., nom. nud. (2n = 6x = 42, AtAtGGAmAm) is described in the present study. This hexaploid taxon was developed by colchicine treatment in Martonva´sa´r from the hybrid of a selected accession of Triticum timopheevii Zhuk. (2n = 4x = 28, AtAtGG) and a prebred semi-dwarf line of Triticum monococcum L. (2n = 2x = 14, AmAm). A detailed cytomolecular examination was carried out using the sequential multicolour fluorescence and genomic in situ hybridization techniques (FISH and mcGISH). It was proved that T. timococcum has 42 chromosomes originating from its parents. The chromosomes of the A genomes of T. monococcum and T. timopheevii could be distinguished in the amphiploid using FISH. The successful discrimination of the chromosomes was supported by the karyotypes of the three genomes and the successful optimization of the mcGISH technique for the A and G chromosomes achieved in the present study. A phenotypic evaluation was also carried out under natural and artificial growing conditions in 2012 and 2013. Based on the results, T. timococcum has intermediate characteristics in terms of spike (spikelet) shape and plant height, while it is similar to the female parent, T. timopheevii regarding pubescence. Like its parents, T. timococcum showed outstanding resistance to the main fungal diseases of wheat. T. timococcum headed later and developed longer and looser spikes, fewer tillers and only a third as many seeds than its parents. The third generation of T. timococcum was able to develop an acceptable number of seeds, even taking into account the reduced germination ability in the field

EFFECTS OF WATER DEFICIT AND SALT STRESS ON SOME PHOTOSYNTHESIS PARAMETERS IN WHEAT AND AEGILOPS COMOSA LINES

Abstract: Photosynthetic responses of Aegilops comosa genotypes were compared to those of wheat Mv9kr1 and Chinese spring in order to verify whether Ae. comosa TA2760 and MvGB1039 genotypes are potentially suitable gene sources for improving the drought and salt tolerance of bread wheat. Although there are some differences between the non-stressed plants and the measure of the decrease of the net-photosynthesis (PN), it was strongly inhibited by water deficit. Salt stress had similar effect on PN but at the highest (300 mM) NaCl concentration PN of the genotypes showed some activity. Severe drought induced a strong decrease in the effective quantum yield of PS II (ɸPSII) in the genotypes, while it was moderate in the case of salt treatment. Moreover, ɸPSII was unaffected by the increase of NaCl concentration in wheat lines. Parallel with the decrease in ɸPSII, the photoprotective mechanisms were enhanced in the wheat and wild wheat genotypes during water deficit. These results suggest that the Ae. comosa genotypes seem to respond to these stress factors with similar photosynthetic activity to the wheat lines. Thus, based on the above-mentioned facts, the examined Ae. comosa lines are not particularly good candidates for improving drought tolerance of wheat