Analysis of genetic diversity in a collection of Plantago species: application of ISSR markers

Journal of Crop Science and Biotechnology - The analysis of genetic diversity in medicinal plant species can greatly facilitate germplasm conservation and selection for use in breeding schemes. The...     

Identification of the leaf rust resistance genes Lr9, Lr26, Lr28, Lr34, and Lr35 in a collection of Iranian wheat genotypes using STS and SCAR markers

Brown rust or leaf rust is one of the most important diseases of wheat occurring almost in all wheat-producing regions and reduces crop yield. In order to produce resistant cultivars, it is necessary to identify resistance genes in different germplasms and combine them in (a) suitable stock(s). To identify the presence of the leaf rust resistance genes using STS and SCAR markers, 83 Iranian wheat genotypes, Lr near-isogenic lines in Thatcher (positive controls), and the cultivar Thatcher (negative control) were used. After growing plants in the greenhouse, DNA was extracted by SDS method. Following that, polymerse chain reaction was performed for the markers of the resistance genes Lr9, Lr26, Lr28, Lr34, and Lr35 which amplified 1,100, 1,100, 378, 150, and 900 bp bands, respectively. Based on the results, the resistance genes Lr9 and Lr35 were only present in the positive controls. The resistance gene Lr26 was only detected in four cultivars; Arta, Pishtaz, Shiroodi, and Falat, and the gene Lr34 was present in six cultivars (Akbari, Bam, Tajan, Khazar 1, Sistan and Niknezhad). The Lr28 primer amplified a band of the same size in all genotypes even the negative control and therefore the presence/absence of this gene could not be validated. These results indicate the necessity for designing a specific primer for Lr28. In general, only the genes Lr26 and Lr34 were present in some genotypes. The genes Lr9 and Lr35 were not present in this collection and as based on rust surveys, no virulence has been detected for Lr9 and Lr28, so they could be transferred to suitable lines from donor sources.     

Association of DREB Genes and Microsatellite Markers Linked to NAX2 with Salt Tolerance in CIMMYT-derived Triticale,Wheat and Rye Genotypes

Journal of Crop Science and Biotechnology - Twenty-eight genotypes including triticale, wheat and rye were grown in a greenhouse under control, 14 and 21 dS/m salinity (NaCl and CaCl2, 1:1 ratio)...     

Genotype × environment interactions for wheat grain yield and antioxidant changes in association with drought stress

The phenotypic performance of a genotype is not necessarily the same under diverse agro-ecological conditions. Two commercial wheat cultivars and 33 wheat landrace varieties were selected for screening drought tolerance and the investigation of genotype × environment interactions (GEI). The study site experiences drought stress at reproductive stages. Fully irrigated along with two drought stress trials at early heading (EHS) and 50% heading stages (HDS) were performed in 2 years. The highest antioxidant and proline contents were accumulated under EHS. Reduction in cell membrane stability in EHS was 90.9% in 2011–2012. The lowest grain yield belonged to EHS (3.2 t ha^?1) while the highest (6.8 t ha^?1) was observed in the irrigated trial. GEI analysis indicated that the Pinthus’s coefficient was not an efficient index for screening GEI. Positive correlations were found between GEI parameters such as regression deviation, Wricke’s ecovalence and Shukla’s variance. Regression coefficients over trials ranged from 0.65 to 1.42, indicating genotypes had different responses to environmental changes. Regression models, GEI variances and grain yield showed that some varieties (KC4557, KC4862, KC3891, KC4495, and KC4633) had higher stability under drought stress and fully irrigated conditions and can be involved in breeding programs for drought stress tolerance.     

Regenerating salt tolerant saffron (Crocus sativus) using tissue culture with increased pharmaceutical ingredients

Due to its vegetative reproduction, saffron has a narrow genetic base and induced in vitro variations provide opportunities for expanding new cultivars. The objectives of this study were to evaluate sodium azide-induced variations in saffron’s corm culture in order to increase salt tolerance and pharmaceutical ingredients. Corm explants from the well-known ecotypes, Estahban and Kashmar, were subjected to various concentrations of sodium azide (NaN₃) (0.09, 0.12, and 0.22 mg L^?1) and NaCl (1.5, 2.5, and 4.0 dS equivalent to 0.07, 0.12, and 0.20 g NaCl in 100 mL water) in Murashige and Skoog medium supplemented with 1 mg L^?1 2-4-D, 1 mg L^?1 BAP, and 30 g L^?1 sucrose and in a second pot culture experiment. The active pharmaceutical ingredients (crocin, picrocrocin, and safranal) were measured by high-performance liquid chromatography (HPLC). Variations in sodium azide-treated plants were more broadened for callus fresh weight (0.57–7.57 g), embryo weight (1.24–10.29 g), and regenerated seedlings (3.0–21.25) compared with those (0.12–3.77 g, 0.56–4.56 g, and 0.25–11.50, respectively) that were not treated with sodium azide. Under 0.20% salt, flowering failed in some of plants developed from sodium azide-untreated corms. HPLC analysis indicated wider ranges for crocin (11.92–18.03 mg g^?1), picrocrocin (8.99–14.76 mg g^?1), and safranal (2.13–7.36 mg g^?1) in sodium azide-treated plants compared to the ranges (0.0–16.1, 0.0–12.5, and 0.0–6.66 mg g^?1, respectively) in untreated plants. From a breeding perspective, induced variations found in this study would be useful to improve saffron’s quality and salt tolerance.     

Genotype by environment interaction components underlying variations in root,sugar and white sugar yield in sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.)

The success of plant breeding programs depends on the ability to provide farmers with genotypes with guaranteed superior performance in terms of yield across a range of environmental conditions. We evaluated 49 sugar beet genotypes in four different geographical locations in 2 years aiming to identify stable genotypes with respect to root, sugar and white sugar yields, and to determine discriminating ability of environments for genotype selection and introduce representative environments for yield comparison trials. Combinations of year and location were considered as environment. Statistical analyses including additive main effects and multiplicative interactions (AMMI), genotype main effects and genotype?×?environment interaction effects (GGE) models and AMMI stability value (ASV) were used to dissect genotype by environment interactions (GEI). Based on raw data, root, sugar and white sugar yields varied from 0.95 to 104.86, 0.15 to 20.81, and 0.09 to 18.45 t/ha across environments, respectively. Based on F-Gollob validation test, three interaction principal components (IPC) were significant for each trait in the AMMI model whereas according to F ratio (F_R) test two significant IPCs were identified for root yield and sugar yield and three for white sugar yield. For model diagnosis, the actual root mean square predictive differences (RMS PD) were estimated based upon 1000 validations and the AMMI-1 model with the smallest RMS PD was identified as the most accurate model with highest predictive accuracy for the three traits. In the GGE biplot model, the first two IPCs accounted for 60.52, 62.9 and 64.69% of the GEI variation for root yield, sugar yield and white sugar yield, respectively. According to the AMMI-1 model, two mega-environments were delineated for root yield and three for sugar yield and white sugar yield. The mega-environments identified had an evident ecological gradient from long growing season to intermediate or short growing season. Environment-focused scaling GGE biplots indicated that two locations (Ekbatan and Zarghan) were the most representative testing environments with discriminating ability for the three traits tested. Environmentally stable genotypes (i.e. G21, G28 and G29) shared common parental lines in their pedigree having resistance to some sugar beet diseases (i.e. rhizomania and cyst nematodes). The results of the AMMI model were partly in accord with the results of GGE biplot analysis with respect to mega-environment delineation and winner genotypes. The outcome of this study may assist breeders to save time and costs to identify representative and discriminating environments for root and sugar yield test trials and creates a corner stone for an accelerated genotype selection to be used in sweet-based programs.     

Investigation formaize inbred lines resistance to <Emphasis Type="Italic">Maize Rough Dwarf Virus</Emphasis>(MRDV)

Maize rough dwarf virus (MRDV) is the most important disease affecting maize growth in Iran. In the present study, the putative resistance capacity of 35 maize inbred lines against the causal agents of MRDVwas studied under natural field infection in 2010 and 2011. The viral transmitter was a plant hopper known as Laodelphax steriatellus. Early sowing provided suitable temperatures for vector propagation and transmission and therefore natural infection under field conditions. Sowing single rows of SC704 as vector spreader between every five rows of inbred lines caused adequate vector propagation and viral transmission. This shows that viral infection was sufficient and possible resistance was linked to viral resistance, not failure, in vector transmission. In principal component biplot, plant height vector had wide angles with the vectors for disease severity index and MRDV incidence that showed the negative association of plant height with MRDV disease. The percentage of natural infection to MRDV in susceptible control(SC704) was about 64%. The genotypes A679, K3547/3, K3545/6, K3653/2, and B84 were more susceptible to MRDV. Only the line K3640/3 had low disease incidence and severity and it can be considered as resistant for possible use in genetic studies. Results showed that an early sowing of maize in temperate regions increases the chance of transmitting viruses via their vector.