ساناز خلیفانی

Among biotic and abiotic stresses, broomrape (Orobanche cernua L.) is the most important factor in reducing the yield of tobacco plant, so it is necessary to determine the genotypes that produce relatively acceptable yield under stress conditions. In order to identify tolerant genotypes to broomrape stress, 92 tobacco genotypes were investigated based on randomized complete block design with three replications in two control (without broomrape) and stressful (along with broomrape) environments at the research farm of Urmia tobacco research Centre during two successive years in terms of flowering date, plant height, leaf number, fresh and dry weight of root, leaf area, fresh and dry weight of leaf, fresh and dry weight of plant aerial parts. Broomrape stress was applied by mixing 0.06 grams of broomrape seeds with pot soil. The results of analysis of variance in the two experimental environments during two years showed that there is not significant difference between the experimental environments for most of the studied traits. There was a significant difference between genotypes for all of the studied traits. Genotype × environment interaction was significant for all of the studied traits indicating the presence of different reaction of genotypes within each environment. Mean comparisons showed that broomrape stress reduced the mean of all morphological traits. So that the fresh weight of shoots except leaf (23.50%) and dry weight of shoots except leaf (23.70%) had the highest decrease percentage; whereas flowering date (-0.7%) and number of leaves (5.02%) had the lowest decrease percentage. In general, based on the results of the percentage reduction of mean of studied traits, it was found that C.H.T.283-8, Kharmanli, Immni 3000, F.K.40-1, Pz17, K.B, L 16a, Rustica, C.H.T.209.12e, C.H.T.283-8, Basma 181-8, SPT 413, T.K.L and Samsun 1 are among the most susceptible genotypes to broomrape stress. While Ploudive 58, Ts 8, Mutant 3, OR-379, P.D.328, Jahrom14 and Lengeh genotypes did not show any decrease in any of the traits and are tolerant genotypes to broomrape stress.

Sunflower (Helianthus annuus L.) is an important oilseed crop that is cultivated worldwide because of its high-quality oil and be rich in linoleic acid. The present study is a review of the effects of salinity on morphological and physiological traits, resistance mechanisms, breeding, and agronomic methods to deal with salinity tolerance in sunflower. Sunflower is classified as semi-tolerant species. The negative effects of salt stress on sunflower include browning of root tips, reduction of cotyledons and root proliferation, leaf surface, accumulation of dry matter, yield, and seed oil content. Salt stress also leads to decrease in CO2 absorption, transpiration rate and stomatal conductance, and photosynthetic capacity in sunflower. The resistance reactions to salinity stress in sunflower include: modulating the expression of oubain-sensitive ATPases through calcium, delaying the degradation of membrane proteins of oil bodies, increase serotonin and melatonin, increase the expression of nitric oxide, increase S-nitrosylation of cytosolic proteins, increased content of lipid peroxide, activity of glutathione peroxidase, and the abundance of heme oxygenase-1 (HO-1) in the cells around the secretory channels . Among the important breeding approaches to cope salinity stress in sunflower are the identification of HT089, HT175, HT185, HT215, HT216, and HT227 salinity resistance genes, the identification of H. paradoxus as the most salinity resistant species, the production of HA429 and HA430 lines tolerant to salinity, the transfer of the TaNHX2 gene from wheat to sunflower that improved its salinity tolerance and the identification of genes involved in salinity stress in sunflower by next generation sequencing technology. The results of this extensive study will be important in achieving a comprehensive plan for sustainable improvement of yield and quality of sunflower oil under salt stress conditions.

Maize (Zea mays L.) is one of the most important food crops worldwide and is widely used as genetic research material for studying various traits. Identification of genetic loci controlling quantitative trait is an important subject in genetics and breeding programs. In the present study, 102 maize inbred lines was evaluated for agro-morphological traits (plant height, plant height until first ear, leaf length, leaf width, leaf surface, leaf area indexear number, chlorophyll content, grain weight per plant, cob’s dry weight, cob’s diameter in first part, cob’s diameter in middle part, cob’s length, plant dry weight, days to tassel emergence, days to first ear emergence, days to second ear emergence) in completely randomized design with six replications. In the molecular experiment, 8 retrotransposon-based molecular markers primers was used for preparing the molecular profile of lines. Eight IRAP and REMAP primer combinations amplified 40 gene loci. Thirty-eight out of 40 loci (95%) showed polymorphism. The PIC values in the studied lines ranged from 0.084 for Ac/Ds to 0.383 for Pangrangja marker. The Nei’s genetic distance between lines prepared from Mashhad and Kermanshah was 0.053, between lines from Karaj and Mashhad was 0.036 and between lines from Kermanshah and Karaj was 0.032. In the analysis of population structure based on molecular markers, 102 studied lines were grouped into two subpopulations (K = 2). In the association analysis of agro-morphological traits based on two GLM and MLM methods, 24 and 12 marker-trait relationships were identified, respectively. In this study, two commons markers; Heartbraker (480) in cob’s diameter in first part and cob’s length and UBC878 × Ruda in ear number and grain weight per plant were identified with both general linear and mixed linear models. This information can be used in selecting individuals during tobacco breeding programs and developing varieties with high yield and performance.