Authors:J.Q. Xu, L. Wang, B.L. Liu, T.F. Xia, D.C. Liu, X. Chang, T.W. Zhang, H.G. Zhang, and Y.H. Shen
As one of the world’s earliest domesticated crops, barley is a model species for the study of evolution and domestication. Domestication is an evolutionary process whereby a population adapts, through selection; to new environments created by human cultivation. We describe the genome-scanning of molecular diversity to assess the evolution of barley in the Tibetan Plateau. We used 667 Diversity Arrays Technology (DArT) markers to genotype 185 barley landraces and wild barley accessions from the Tibetan Plateau. Genetic diversity in wild barley was greater than in landraces at both genome and chromosome levels, except for chromosome 3H. Landraces and wild barley accessions were clearly differentiated genetically, but a limited degree of introgression was still evident. Significant differences in diversity between barley subspecies at the chromosome level were observed for genes known to be related to physiological and phenotypical traits, disease resistance, abiotic stress tolerance, malting quality and agronomic traits. Selection on the genome of six-rowed naked barley has shown clear multiple targets related to both its specific end-use and the extreme environment in Tibet. Our data provide a platform to identify the genes and genetic mechanisms that underlie phenotypic changes, and provide lists of candidate domestication genes for modified breeding strategies.
Salinity is one of the major abiotic stress factors affecting series of morphological, physiological, metabolic and molecular changes in plant growth. The effect of different concentrations (0, 25, 50, 100 and 150 mM) of NaCl on the vegetative growth and some physiological parameters of karkade (Hibiscus sabdariffa var. sabdariffa) seedling were investigated. NaCl affected the germination rate, delayed emergence and retarded vegetative growth of seedlings. The length of seedling as well as the leaf area was significantly reduced. The fresh weight remained lower in NaCl treated seedlings compared to control. NaCl at 100 and 150 mM concentrations had significant effect on the dry matter contents of the treated seedlings. The chloroplast pigments in the treated seedlings were affected, suggesting that the NaCl had a significant effect on the chlorophyll and carotenoid biosynthesis. The results showed that the salt treatments induced an increase in proline concentration of the seedlings. The osmotic potential (ψs) of NaCl treated seedlings decreased with increasing NaCl concentrations. Salt treatments resulted in dramatic quantitative reduction in the total sterol percent compared with control ones. Salt stress resulted in increase and decrease of Na+ and K+ ions, respectively. NaCl salinity increased lipid peroxidation. SDS-PAGE was used to evaluate protein pattern after applying salt stress. High molecular weight proteins were intensified, while low molecular weight proteins were faint. NaCl at 100 and 150 mM concentration distinguished with new protein bands. Salt stress induced a new peroxidase bands and increased the band intensity, indicating the protective role of peroxidase enzyme.
Authors:Viktória Bőhm, Dávid Fekete, Gábor Balázs, László Gáspár, and Noémi Kappel
In order to evaluate the salinity tolerance of grafted watermelon, two sets of experiments were conducted in a growing chamber where ‘Esmeralda’ varieties were grafted onto interspecific squash (Cucurbita maxima Duch. × Cucurbita moschata Duch.) and Lagenaria siceraria rootstocks. Both non-grafted and self-garfted plants were used for control. For salt stress, 2.85 and 4.28 mM/l substrate doses of NaCl were added with each irrigation in 2 day intervals for a duration of 23 days. Interspecific-grafted plants showed the highest salinity tolerance as plant biomass and leaf area were not decreased but improved by salinity in most cases. Furthermore, transpiration and photosynthesis activity did not decrease as much as it did in the case of other grafting combinations. Interspecific and Lagenaria rootstocks showed sodium retention, as elevation of Na+ content in the leaves of these grafting combinations was negligible compared to self-grafted and non-grafted ones. Presumably abiotic stress tolerance can be enhanced by grafting per se considering measured parameters of self-grafted plants did not decrease as much as seen in non-grafted ones.
Authors:P. Martins-Lopes, B. Maças, and H. Guedes-Pinto
Genetic improvement in aluminium tolerance is one of the most cost-effective solutions to improve the productivity of wheat (
L.) in acid soils. Sources of tolerance to this abiotic stress within adapted germplasm are limited, so the identification and characterisation of new sources are of some priority for the future of plant breeding in target areas. The aim of this study was to evaluate the response to aluminium stress of an old Portuguese wheat collection and to select the most tolerant ones for genetic and breeding purposes. An old collection of Portuguese wheat cultivars and some ‘Barbela’ lines were tested and classified in relation to aluminium tolerance and compared to modern wheat cultivars using a hydroponic approach. Three bread wheat cultivars (‘Viloso Mole’, Magueija’ and ‘Ruivo’) showed greater tolerance to 5 ppm aluminium than the international wheat standard cultivar ‘BH1146’, and so represent excellent material for understanding the genetic control of aluminium tolerance. In addition, several accessions of the Portuguese landrace ‘Barbela’ were outstanding in terms of aluminium tolerance. In particular, line 7/72/92 had a pronounced advantage over ‘BH1146’ in terms of root regrowth.
Authors:V. Mladenov, B. Banjac, A. Krishna, and M. Milošević
Quality of wheat grain is a complex trait that depends mostly on the quantity and quality of protein and unified interactions between high molecular glutenin, gliadin, low molecular glutenins and abiotic stresses. The objective of this study was to evaluate the effects of genotype, environment and genotype × environment interaction on quality and some agronomic traits in wheat. Twenty divergent genotypes of winter wheat, per five from Serbia, Russia, France and Hungary were analysed in this paper. Variability was observed for quality (grain protein content and sedimentation) and agronomic traits (thousand-grain weight and test weight) in three growing seasons (2007/08, 2008/09 and 2009/10). Genotypes were statistically analysed [basic statistical parameters, AMMI biplot for the content of protein, correlation and Principal Component Analysis (PCA)] in order to assess the impact of different growing seasons on selected cultivars. AMMI analysis determined that 2008/09 was very significant for most of the genotypes. The Hungarian cultivar GK-Zugoly had the highest grain protein content (14.4%). Correlation analysis showed different relationships between the traits. PCA indicated that the total variation reflected the first two components represented with 80%, but the first principal component was more important. Results of this paper indicate that the varieties MV-Csardas and Pamyati Kalinenko can be used as a good source of genetic material for future breeding program for agro-ecological conditions of Vojvodina.
Triticum dicoccoides, wild emmer wheat, is the direct progenitor of cultivated wheats, has the same genome formula as durum wheat, and has contributed two genomes to bread wheat. It harbors many useful genes, more than can be used for wheat improvement. These genes are associated with many agronomic traits, abiotic stress tolerances, biotic stress resistances, grain protein content and micronutrient mineral concentrations. In this review, we summarized the achievements regarding gene discovery, i.e. gene identification, mapping and cloning in wild emmer wheat. These genes, controlling important agronomic traits, disease resistance, drought tolerance, high protein content and micronutrient mineral content, should be very useful for improvement of wheat production and food nutrition. However, the majority of genetic resources in wild emmer remain untapped, demonstrating the need for further exploration and utilization for wheat breeding programs. The large number of molecular markers, genomics tools and efficient cloning techniques available for wheat will greatly accelerate the application of wild emmer germplasm to wheat improvement and ensure sustainability of global wheat production.
Salinity stress is one of the important abiotic stresses affecting rice germination and reduces establishment of seedlings in the field. Six varieties of rice were included in a full diallel mating design and together with their progenies were evaluated for salinity tolerance. General combining ability (GCA) effect was significant for germination percentage reduction (GP) and radicle length reduction (RL); whereas specific combining ability (SCA) were significant for all of traits contain GP, RL, germination rate reduction (GR) and coleoptile length reduction (CL). The negative value of heterosis, due to inverse relation of reduction of traits and salinity tolerance, indicated ideal heterosis. The highest value of negative heterosis for GP, GR, RL and CL were displayed in Shahpasand × Sepidrod, Hassani × Sepidrod, Shahpasand × IRFAON-215 and Sepidrod × IRFAON-215, respectively. The parents with negative GCA are superior for salinity tolerance traits. The Genotype, Genotype-by-Environment (GGE) biplot analysis showed that Sepidrod contributed resistance to GP, GR and IRFAON-215 was the best parent for RL and CL. Respondent this view, Sepidrod and IRFAON-215 can be used either as best parents for selection programs due to their GCA effects, or as a superior parent hybrid programs on their SCA effects.
Authors:A. Mujeeb-Kazi, G. Fuentes-Davilla, Alvina Gul, and Javed Mirza
Bridge crosses utilizing the D genome synthetic hexaploids (SH),
Triticum turgidum / Aegilops tauschii
(2n = 6x = 42, AABBDD), are a potent means of improving bread wheat (
) for biotic and abiotic stresses. The synthetic germplasm enables incorporation of the genetic diversity of
cultivars together with the attributes of the
accessions. In this research, SH wheats were screened for karnal bunt in Obregon, Mexico over six crop cycles and several SHs were earlier identified with an immune response. These SHs have unique
accessions as parents. Phenologically descriptors and additional trait evaluations led us to develop a sub-set of the most desirable combinations for wheat breeding. The SH wheats are generally tall, late to mature, have good agronomic type, and are non-free threshing with a high 1000 kernel weight. All have a spring growth habit with several possessing multiple stress resistances. The resistance exhibited by SH wheats has been transferred into elite but KB susceptible bread wheat cultivars thus generating a new and unique genetic resource that can be readily exploited by conventional breeding programs.
Authors:J. Chen, G. Hu, J. Zhang, C. Chu, and Y. Wu
Drought is a severe abiotic stress that affects wheat production worldwide. In order to identify candidate genes for tolerance to water stress in wheat, sequences of 11 genes that have function of drought tolerance in other plant species were used to identify the wheat ortholog genes via homology searching in the wheat EST database. Atotal of 11 primer pairs were identified and amplified PCR products in wheat. Of them, 10 STS markers were mapped on 11 chromosomes in a set of nulli-tetrasomic lines of ‘Chinese Spring’ wheat; six were mapped on chromosomes 1A, 1B, 4B, 7A, 2B and 5D, respectively, in a spring wheat mapping population (POP1). The marker XTaABH1 mapped on 7A in POP1 was the only one mapped but characterized in a winter wheat mapping population (POP2) for grain yield, kernel weight and diameter, and height in four-field trials applied different water stress or irrigation. The marker XTaABH1 was significantly associated with grain yield under rainfed condition, with kernel weight under terminal stress and non-irrigation conditions, with kernel diameter and height under non-irrigated condition. The STS primers, map information and marker-trait association produced in the currently study would be of interest to researchers working on drought tolerance.