Crop Breeding Journal
Volume:8 Issue: 2, Summer-Autumn 2018

Understanding of the host-pathogen interaction is key to uncovering the defence mechanisms for being used in breeding programs and integrated disease management. Spot blotch is one of the most common foliar diseasesof barley worldwide. Bipolaris sorokiniana (Sacc.) Shoemakeris the causal agent of spot blotch and can cause other destructive diseases of barley such as common root rot, seedling blight and black point or smudge. Adequate knowledge about epidemiology and pathogenicity of the pathogen can provide great assistance to inhibit the outbreak of spot blotch. In this review, first the distribution and host range of the pathogen has beenreviewed. Then, disease symptoms and yield loss caused by spot blotch in barley are reviewed. Subsequently, virulence diversity and other pathogenic aspects ofB. Sorokinianasuch as epidemiology, primary and secondary infections, survival and effect of environmental conditions on epidemic of the disease arediscribed in detail. Later, different aspects of interaction between barley and B. Sorokinianasuch as host response and genetics of resistance has beendiscussed.The importance of molecular markers for studying population structure of the pathogen and genetics of resistance in barley genotypes are also covered. Finally, different disease control measures have beenpresented and discussed.

Development of high-yielding new barley promising lines with wide adaptation across a wide range of diverse environments is a key goal of barley breeding program in the cold regions of Iran. The main objective of the current study was to use different stability analysis approaches to analyze phenotypic stability for selecting high-yielding with yield stability barley promising lines adapted to the cold regions of Iran as well as to investigate the relationships among different stability parameters and grain yield. Eighteen barley promising lines and two check cultivars; Bahman and Jolgeh were evaluated using randomized complete block design with three replications at six research stations during 2015–2017 cropping seasons. The AMMI analysis of variance indicated that the environment, genotypes and their interaction accounted for 53.60, 5.77 and 24.59% of the total variations, respectively. The first six interaction principal components (IPCA1 to IPCA6) were highly significant, revealing differential responses of the tested lines to different environments and the necessity of stability analysis. In total, 18 parametric and non-parametric statistics were used to analyze the data. According to PCA-based biplot and correlation heat-map, the stability statistics were classified into two main groups (CI and CII): CI comprised mean grain yield, θi, TOP and bi, which are referred to the dynamic concept of stability, and CII included S1, S2, S3, S6, NP1, NP2, NP3, NP4, CV, ASV, Wi2, σ2, θ(i), Sdi2 and KR, which are referred to static concept of stability.In general, the parametric and non-parametric stability statistics indicated similar results, identifying the promising line G8 (Makouee/Jolge) as high-yielding with yield stability. Therefore, this promising line can be recommended for being grown and commercialized in the cold regions of Iran.

Barley yellow rust is becoming increasingly important in many barley growing areas in Iran, including Fars Province. This research was carried out to evaluate the responses of 27 commercial cultivars, 31 introduction lines, 36 promising lines and 12 differential barley varieties to barley yellow rust at the adult plant stage, in three locations of Fars province (Zarghan, Marvdasht and Mammassani) in two successive cropping seasons (2014-2015 and 2015-2016), and at the seedling plant stage in greenhouse. Field trials in Zarghan and Marvdasht were inoculated with barley stripe rust isolate that was collected from Passargad region. The seedling responses of the genotypes were evaluated in the greenhouse with Passargad and Mammassani barley yellow rust isolates. At the adult plant stage, the majority of the genotypes had intermediate to susceptible responses while some genotypes showed moderately resistance to resistance responses to the disease. Most of the genotypes had moderately susceptible to susceptible responses (7-8) against both rut isolates at the seedling stage. Finally, cultivars and lines with coefficient of infections (CIs) lower than 24 were selected for being recommended to farmers or used in breeding programs. Among the commercial barley cultivars, Nik, Behrohk, Fajre 30, Nimrooz, Sahra, Zarjow, Aras and Loot and from introductions and promising lines, 13 and 10 lines, respectively, were selected. Most of the barley genotypes carried adult plant resistance or in combination with seedling resistance genes. Cultivars and lines with CIs between 24 to 35 and intermediate level of resistance were also considered for further evaluation. The rust isolates from Passargad and Mammassani were determined as races PSH-74 and PSH-90, respectively, based on the reactions of barley yellow rust differential cultivars.

Self-incompatibility is believed to be a common attribute among the most of apricot (Prunus armeniaca L.) cultivars. This research was conducted during 2015 and 2016 growing seasons to explore the selfcompatibility of 22 apricot genotypes (18 Iranian and four European) based on the field and microscopic examinations. Final fruit set following self-pollination in the field ranged from 1.16% in ‘Aybatan’ to 62.0% in ‘San Castrese’ cultivars which showed significant differences among evaluated apricots. The results revealed self-compatibility in the new Iranian promising apricot hybrid, ‘AD731’, as well as reconfirmed self-compatibility in the European cultivars; ‘Canino’, ‘San Castrese’, ‘Palumella’ and ‘Cafona’. In all cases, fluorescence microscopy information supported the self-compatibility results obtained from the field, when at least one pollen tube entered the ovary by 96 hours after the controlled pollination. In addition, all other 17 apricot genotypes showed self-incompatibility feature. The hybrid ‘AD731’ showed self-compatibility attribute, therefore further research on this genotype will warrant its future use in apricot breeding programs as well as to be considered as promising genotype for being released as a new cultivar.

Genetic relationship of 36 strawberry cultivars was analyzed using three molecular marker systems; inter simple sequence repeats (ISSR), inter-retrotransposon amplified polymorphism (IRAP) and start codon targeted (SCoT) polymorphism. SCoT, IRAP and ISSR primers generated 238, 113 and 122 bands, respectively, of which 85.2, 91.5 and 89.35% were polymorphic. IRAPs with the highest values of expected heterozygosity (He), Shanonn index (I) and resolution power (Rp) were more powerful compared with SCoT and ISSR. However, the highest value of marker index was calculated for ISSRs. The genetic relationships were estimated using Dice similarity coefficient between different pairs of cultivars which varied from 0.577 to 0.901 for SCoT, 0.547 to 0.918 for IRAP, and 0.531 to 0.983 for ISSR. The UPGMA dendrograms using the SCoT and ISSR data classified cultivars into four major clusters; whereas based on the IRAP and combined data, the cultivars were divided into three major clusters. Approximately 50% of the cultivars with affiliation to pedigree and geographic origins were assigned to their major clusters. The results demonstrated that SCoT, ISSR and IRAP marker systems are useful for identification and genetic diversity analysis of strawberry cultivars.

To study the effects of salinity on different species of Aegilops that have salinity tolerance genes, a factorial experiment was carried out using completely randomized design with three replications in Biotechnology Laboratory of Guilan University in 2014. Morphologic (length, fresh and dry weight of shoot and root, stem diameter, and number of tillers) and physiologic (Electrolyte Leakage, RWC, Chlorophyll content and antioxidants enzymes) traits of 12 Aegilops genotypes from four species; Ae. tauschii, Ae. crassa, Ae. cylindrical, and Ae. triuncialis were measured under salinity stress conditions. Assessment of morphological and physiological traits showed that genotypes belong to Ae. cylindrical had more tolerance to salinity stress than other genotypes. Genotype 575 from Ae. cylindrical as tolerant genotype and genotype 675 from Ae. crassa as susceptible genotype were identified and used for biochemical assay. The results showed peroxidase (POD) and ascorbate peroxidase (APX) enzymes' activity increased and catalase (CAT) enzyme activity decreased under salinity stress. Following stress treatment, enzyme activity in genotype 575 was higher than 675 showing antioxidant enzyme in tolerant genotype performs more than susceptible genotype

The biostimulant activity of soy protein hydrolysate on Fusarium oxysporum-inoculated cucumber plants was investigated in comparison with salicylic acid (SA). Cucumber seedlings were treated with trypsin-digested soybean (PrH) and SA followed by F. oxysporum inoculation, and were assessed for gene expression pattern, disease incidence (DI%), growth rate and biochemical responses. Results showed that F. oxysporum infection in PrH-treated plants decreased shoot and root dry weights by 4 and 18.2%, respectively, while these parameters were decreased 45 and 66.5% in SA-treated, and 42 and 65.9% in control plants. Glutathione peroxidase (GPx) activity was decreased in PrH-treated plants upon infection with higher rate compared to control plants while it was increased in SA-treated plants. Gene expression analysis revealed that, compared to other treatments, CsWRKY2 was expressed earlier and in higher rate in PrH-treated plants, and was negatively correlated with disease incidence leading to lowest disease infection (11.3 %) among treatments. These results suggest that PrH activates defense responses in cucumber plants against infection at the expense of reduced plant growth. Although the increase in CsWRKY2 expression enhances plant defense, but its over-expression higher than a threshold will negatively affect plant growth. By contrast, CsWRKY35 expression was negatively correlated with plant growth and its resistance against pathogen. The findings of the present study may pave the road for exploration of WRKY genes in cucumber breeding programs.