Journal of Plant Physiology and Breeding
Volume:9 Issue: 2, Summer-Autumn 2019

Purslane, Portulaca olaracea, is an annual plant used as potherb and traditional medicine. A factorial experiment was carried out to investigate the effects of different levels of salicylic acid(0.0, 0.5 and 1.0 mM) on growth characteristics and photosynthetic pigments of purslane under salinity stress (0.0, 40, and 80 mM). The treatment combinations were arranged in a completely randomized design with three replications. The measured traits were as follows: root and shoot dry weights, root and shoot lengths, leaf length and width, relative water content, number of leaves, total chlorophyll, chlorophyll a, b and carotenoids. Results showed that salinity had negative and decreasing effects on the majority of morphological traits and relative water content, whereas SA increased the growth and pigment contents of the purslane plant. For example, application of salicylic acid (1 mM) increased the content of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids from 0.43, 0.23, 0.65 and 4.49 mg/g under normal condition to 0.65, 0.46, 1.11 and 8.45 mg/g under saline condition, respectively. In conclusion, application of SA as a foliar agent improved the detrimental effects of salinity stress.

This research was undertaken to assess the ameliorative effect of salicylic acid (0.5 mM) on photosystem II (PS II) in two basil (Ocimum basilicum L.) varieties (Iranian and Italian) infested with field dodder (Cuscuta campestris Yunk.) in the greenhouse of University of Tabriz, Iran, in 2017. The treatments were arranged as factorial using randomized complete block design with four replications. Results indicated that application of salicylic acid improved the maximum quantum efficiency of photosystem II (Fv/Fm) and performance index (PI) of basil plants infested by field dodder. The time span from F0 to Fm (TFM) and the energy necessary for the closure of all reaction centers (Sm) were significantly increased and the size of the plastoquinone pool (Area) declined in plants exposed to field dodder infestation. Application of salicylic acid increased the chlorophyll a fluorescence parameters studied in both basil varieties, especially in the Italian variety.

In order to investigate the effect of soil application of humic acid on grain yield and yield components inchickpea (Cicer arietinum L.), an experiment was conducted as factorial based on randomized complete block design with three replications in 2016 and 2017. Factors were irrigation at two levels of full irrigation and drought stress (20% of full irrigation from flowering to harvesting) and humic acid at four levels of 0, 2.5, 5 and 7.5 mg per pot. The results showed that drought stress reduced dry weight of leaf, number of grains and pods, total dry weight and grain yield. Application of humic acid in two years increased the value of all studied traits under full irrigation. In the first year, application of 2.5 and 5 mg humic acid increased 1000-grain weight, and total and leaf dry weight under drought stress conditions, respectively. In the second year, with higher consumption of humic acid, grain yield, total dry weight and harvest index increased significantly under drought stress conditions. Application of 7.5 mg humic acid in the second year, produced the highest proline under optimum irrigation (393.10 mg kg-1 DW) and drought stress (507.90 mg kg-1 DW) conditions.

Drought stress is a significant environmental factor retarding plant growth as well as productivity. Plants adapt to environmental stress via numerous strategies such as changes in plant height, biomass, carbohydrate content and phytohomnonal levels. Therefore, a split plot experiment based on randomized complete block design with three replications was carried out to determine possible drought tolerance mechanisms in Satureja sahendica Bornm. induced by penconazole (PEN). The determined water (100, 60 and 30% FC) and PEN (0, 10 and 20 mg.l-1) levels were applied. Result showed that drought stress significantly decreased plant height, fresh and dry weight, indoleacetic acid (IAA), gibberellic acid (GA) and induced accumulation of carbohydrates, glucose, sucrose, fructose and abscisic acid (ABA). PEN treatment even decreased further plant height, IAA, GA and increased fresh and dry weight, carbohydrate content, glucose, sucrose, fructose and ABA. PEN increased fructose and ABA up to 2.5 folds and 3.5 to 4.5 folds, respectively compared to the control, especially at the second harvest. The significant decrease in growth hormones along with significant increase of the inhibitor hormone by elevating drought stress and PEN application led to significant augmentation in (GA+IAA)/ABA ratio (~70% at 30% FC and 20 mg.l-1 PEN) compared to the control. Altogether, the application of 20 mg.l-1 PEN together with 60% FC seems an appropriate treatment for planting Satureja sahendica in dry regions. Furthermore, the improved fructose production and ABA level induced by PEN had outstanding role on drought tolerance of this plant

An experiment was conducted to evaluate the effect of textile dyes on some morphological and biochemical traits of board bean at a greenhouse of University of Tabriz, Iran, in 2016. Three types of dye (Acid Yellow, Acid Red, Direct Blue) and five dye concentrations (0, 30, 50, 70 and 90 mg/L) were studied using a factorial experiment based on randomized complete block design with three replications. Treatments were applied at seedling, pre-flowering and flowering stages. In this experiment, seed number, leaf number, peroxidase (POX) and catalase (CAT) activities, decolorization percentage and protein content were measured at all three stages of development.  Results indicated that the effect of dye concentrations was significant on POX, CAT, leaf number, seed number and decolorization percentage at pre-flowering and flowering stages, and on protein content at all stages, whereas type of dye only had significant effect on seed number, protein content at pre-flowering and on CAT activity at both pre-flowering and flowering stages. Interaction of dye type with dye concentration was only significant for decolorization percentage at pre-flowering and flowering stages. The greatest increase in POX and CAT activities, and protein content were observed with 90 mg/L dye concentration at both pre-flowering and flowering stages; however, highest seed number were observed with the control treatment (0 mg/L dye concentrations) at pre-flowering and flowering stages. We may conclude that although absorbing dye by plants imposed a stress on them, but they were able to survive under this stress. Therefore, we might consider broad bean as one of the efficient plants for phytoremediation.

The Iranian borage (Echium amoenum) is a biennial or perennial herb belonging to the family Boraginaceae. It is distributed mostly in the north of Iran and on the slopes of Alborz mountains. As a medicinal herb, Iranian borage is used for treatment of depression and some nervous diseases. Though many studies have focused on morphological and phytochemical diversity of various accessions of this plant, the number of studies focusing on cytotaxonomy of different accessions of this species is rather small. Thus, the present study focused on cytogenetic analysis of several accessions of Iranian borage. The terminal meristem of root tips was placed in a 0.002 mole 8-hydroxyquinolone for 4 hours, and then fixated in a fixator solution (3:1 acetic acid/alcohol) for 24 hours. The root tips were finally softened in 1 mole hydrochloric acid for 8 minutes in room temperature, dyed with 2% acceto-orcein stain for 10 minutes, and squashed on microscopic slide. The cells were photographed at the metaphase stage of mitosis, when the chromosomes were well separated. Long arm, short arm, long to short arm ratio and chromosome indices of metaphase cells were calculated. Figures summarized the idiogram based on the short arm length of eight pairs of chromosomes. According to our results, a basic chromosome counts of x=8 (2n=2x=16) was determined for all tested accessions. All analyzed plant cytotypeswere diploid.The largest total chromosome length belonged to the accession from Jannat Roodbar region with 78.16 µm, while the shortest came from Esfahan with 51.10 µm. Analysis of metaphase karyotypes showed that centromeres were mainly located in the center (metacentric) or close to the center (submetacentric) of the chromosomes. The number of metacentric chromosomes was 10-12 out of 16 chromosomes. Accession of Roobdar had the largest centromeric index, i.e. 0.66, while accessions from Divrood, Qazvin and Mashhad had the lowest centromeric indices of 0.38-0.39. In addition, the long to short arm ratio varied between 1.51 and 1.66. Tested accessions showed lower diversity in terms of karyological characteristics and had symmetric karyotypes. However, given asymmetry indices in terms of chromosome types, overall chromosome shape, classification based on cluster and principal component analyses, and inclusion within three classes of Stebbins (A3, B2, B3), the studied accessions showed evolutionary differences with each other that could be a source of useful cytogenetic information for breeding purposes, and may be used to further understanding of evolution and accession genesis of Iranian borage species.

To map quantitative trait loci (QTL) for harvest index, 148 recombinant inbred lines and their parents, Yecora Rojo and an Iranian landrace line (No. 49), were evaluated under normal and terminal water deficit stress conditions in the research stations of Mahabad University and Miyandoab Agricultural Research Center, Iran, during 2014 and 2015. The experiment was carried out as design alpha lattice design with two replications. A linkage map of 51 retrotransposon and 177 microsatellite markers was used in this investigation. Quantitative trait loci (QTL) for additive effects and additive × additive interactions were determined by QTL Network 2.0 software using CIM and mixed-linear methods. QTL analysis revealed that under normal condition, six QTLs (R2A= 0.04 to 12.0%), two QTL × environment (E) interactions (R2AE= 6.28%), five additive × additive epistatic effects (R2AA= 0.7 to 8.68%) and 12 additive × additive × E (R2AAE= 3.76 to 11.4%) were significant. Under water deficit stress conditions, two QTLs (R2A= 5.0 to 7.0%), two additive × additive interactions (R2AA= 3.72 to 5.48%) and seven additive × additive × E interactions (R2AAE= 8.04 to 9.58) were identified. Among the eight QTLs identified, three QTLs were located on chromosome 2D, suggesting the importance of this chromosome in controlling harvest index, which may be used for marker assisted selection in breeding programs.

To assess the grain yield, plant height and superoxide dismutase (Cu/Zn-SOD) activity, and its expression responses of maize to water deficit stress, a field experiment using a split-plot design based on randomized complete block design was performed with three maize hybrids, SC704, SC720 and NS640, under control and water-deficit stress conditions at the Research Station of University of Tabriz, Iran. The results indicated that water deficit stress reduced grain yield and plant height. Electrophoretic analysis for Cu/Zn-SOD based on sensitivity to KCN and H2O2 inhibitors was carried out using 8% slab polyacrylamide gels. The gene expression of Cu/Zn-SOD by using Real-time PCR in maize hybrids showed that water deficit stress increased Cu/Zn-SOD expression. SC704 with higher grain yield, plant height and Cu/Zn-SOD activity ranked as a drought-tolerant hybrid in this study. It can be concluded that the increase in Cu/Zn-SOD expression may decrease damage caused by water-deficit stress in maize.

To study the morphological and agronomical traits and determine heterotic patterns at the reproductive stage of 96 mutant rice genotypes (M2), two separate experiments were carried out under drought stress and flooding conditions at Gonbad Kavous University, Iran, in 2016 using a randomized complete block design with three replications. A factor analysis was conducted to reduce the number of variables to fewer independent factors, and three and four factors were identified under the flooding and drought conditions, explaining 68.3% and 76.05% of the total variance, respectively. Cluster analysis using the selected factors by the Ward’s minimum variance method and Euclidean distance led to grouping of the mutant rice genotypes. The best cutting points of the dendrograms were determined by the discriminant function analysis and four clusters were identified at both irrigation conditions, which were also significantly different. Genotypes of the first and second clusters had the highest yield and its components under the flooding condition. In contrast, under the drought condition, genotypes of the third and fourth clusters were higher yielding and more tolerant to the drought stress. Mutants No. 4, 18, 25, 28, 29, 43, 44, 48, 53, 72, 79, 88, 90, 91, 94 and 95 were present in the first and second clusters of the flooding condition, and in the third and fourth clusters of the drought-stress condition, indicating their superiority over other mutants in terms of grain yield and drought tolerance. The results obtained from this study can be used for selecting suitable parents for hybridization from different clusters to produce new rice cultivars.

To study the inheritance of several agronomic and physiological traits, an experiment was conducted in the research station of the University of Tabriz, Iran, under water deficit stress and normal conditions using the generation mean and generation variance analyses. The generations were produced from the cross of Arg and Moghan3 varieties. The experiment was conducted as a split-plot design based on randomized complete blocks with two replications. The irrigation conditions were arranged in the main plots and generations in the subplots. In the stress condition, irrigation was withheld after pollination. Based on the results of generation means analysis for flag leaf length in the normal condition and flag leaf width, flag leaf area and leaf chlorophyll content in both conditions, the additive-dominance model explained variation among generation means. For other traits, including flag leaf length under water stress condition and plant height, peduncle length, spike length, fertile tillers, days to heading, number of grains per spike, head weight, straw weight, biomass, grain yield and harvest index in both water-stress and normal conditions, the six-parameter model was fit for the generation means implying the presence of non-allelic interactions in the inheritance of these traits. Broad sense heritability and narrow sense heritability for the traits were estimated as 0.70 - 0.99 and 0.03 - 0.30 in the water-stress conditions and 0.60 - 0.99 and 0.10 - 0.55 in the normal conditions, respectively. At both conditions, the dominance genetic variance was higher than the additive genetic variance for most of the traits under study. The average degree of dominance for all characters at both water-stress and normal conditions was greater than unity which showed the existence of over-dominance gene action in controlling the traits under study. These results suggest the need for exploiting non-additive gene action by producing hybrid varieties in wheat if breeders overcome the barriers of producing hybrid seed.

The karyotypes of 10 species (15 accessions) of Allium from Iran were investigated using the squash technique and 1% (w/v) aceto-iron-hematoxylin stain. The basic chromosome number was x = 8, and only in A. giganteum (1) x = 7. Karyotypes of 14 taxa of Allium were diploid with 2n = 16; only A. macrochaetum was tetraploid with 2n = 32. Satellite chromosomes were seen in A. asarense. All karyotypes were symmetrical, consisting of metacentric and submetacentric chromosome pairs. Only A. caspium and A. stipitatum (1) had subtelocentric chromosomes. Karyotype analysis according to Stebbins categories placed the studied taxa in symmetric classes of 1A and 2A, indicating a symmetric karyotype. The results of the analysis of variance showed significant differences for total chromosome length (TCL), mean chromosome length (CL), long arm length (LA), short arm length (SA) and intrachromosomal asymmetry index (A1). The longest chromosome length was detected on A. asarense, A. elburzense, A. giganteum (3), A. rotundum and A. stipitatum (3) (17.9-19.7 μm), while A. ampeloperasum demonstrated the shortest value (8.2 μm). Results of cluster analysis based on chromosomal parameters classified the taxa into four groups using the unweighted pair group method with arithmetic mean (UPGMA). Using principal component analysis, the first three components determined 97.3% of the total variation. The grouping of the taxa based on the 2-D scatter plot using the first two principal components, corresponding to the results of the karyotypic characteristics.

The response of a plant to drought stress is positively related to physiological traits and gene expression. Various recent studies suggest that membrane channel proteins, named aquaporin (AQPs), by affecting stomatal conductance behavior could be involved in plant responses to stress conditions. The sunTIP7 gene is a member of AQPs protein that is included in different environmental stress such as drought stress. In this study in order to investigate the sunTIP7 gene expression and its relation with relative water content (RWC), stomatal conductance, shoot fresh and dry weight, root area, chlorophyll index (SPAD) and electrolyte leakage (EL), six selected sunflower (Helianthus annuus L.) inbred lines were planted in a greenhouse under normal irrigation and water deficit conditions. The water deficit treatments were applied during 4th leaflet to flowering stage. Drought conditions reduced crop growth and physiological traits. The highest stomatal conductance was found in the C138 line under both conditions. Sunflower lines had different fold change expression of sunTIP7 gene under drought stress. The expression of the sunTIP7 genewas the lowest in C138, and this downregulation may explain its highest stomatal conductance. However, there was not any clear relationship between physiological traits and expression of sunTIP7 gene in all six sunflower inbred lines. These results suggest that drought tolerance in sunflower is a complex trait and there is no simple molecular explanation for drought tolerance in sunflower lines.