In this study, we selected two known pathogen-inducible cis-acting elements, F and E17, to construct synthetic pathogen-inducible promoters for analysis in transformed canola (Brassica napus L.). The synthetic promoter approach was used, which involved the insertion of dimers and combining two cis-acting elements (E17 and F) upstream of the minimal CaMV 35S promoter. Canola plants were transformed by three constructs, pGEE, pGFF, pGFFEE containing synthetic promoters (SP), SP-EE, SP-FF and SP-FFEE, respectively. Analyses of histochemical and fluorometric GUS expression indicated that synthetic promoters responded to fungal elicitors and phytohormone treatments. The SP-FF promoter showed high responses against methyl jasmonate and Sclerotinia sclerotiorum, while SP-EE demonstrated inducibility only in response to salicylic acid and Rhizoctonia solani. The SP-EE promoter similar to SP-FFEE, did not respond to S. sclerotiorum and methyl jasmonate. However, SP-FFEE was highly induced by R. solani elicitors and showed that the level of GUS expression was greater than that by either of E17 or F elements alone. These three synthetic promoters did not activate the expression of the reporter gene in response to cold, heat, UV and wounding.

Introduction of a foreign gene coding for a pathogen resistant protein into the target plant and constitutive expression of Resistance (R) proteins may confer high level of resistance. However, genetic engineering could lead to reprogramming of molecular mechanisms that manage physiological behavior, which in turn could lead to undesired results. Therefore, using a pathogen-inducible synthetic promoter approach, response to pathogens could be more specific. Ascochyta rabiei is a destructive fungal pathogen in chickpea production. In this study, we analyzed the expression pattern of three synthetic promoters in response to pathogen and two defense hormones. We have tested three synthetic pathogen-inducible promoters designated as (1) synthetic promoter-D box-D box (SP-DD), (2) synthetic promoter-F element-F element (SP-FF) and (3) synthetic promoter-F element-F element-D box-D box (SP-FFDD) via Agrobacterium transient expression assay. The cis-acting element designated as ‘D’ is a 31 base pair sequence from the promoter of parsley pathogenesis-related gene 2 (PR2 gene) and the cis-acting element designated as ‘F’ is a 39 base pairs sequence from the promoter of Arabidopsis AtCMPG1 gene. We used mycelial extracts from two pathotypes of A. rabiei as elicitor to define the responsiveness of the promoters against pathogen. Plant phytohormones including salicylic acid and methyl jasmonate were also used to study the promoter sensitivity in plant signaling pathways. Our results showed that the SP-FF promoter was highly inducible to A. rabiei and methyl jasmonate as well, while the SP-DD promoter was more sensitive to salicylic acid. The SP-FFDD promoter was equally responsive to both pathotypes of A. rabiei which is probably due to the complex nature of box D cis-acting element.

Due to lack of water resources in irrigated agriculture, genetically improving plants to abiotic stresses such as salinity is a necessity for food and feed production. In this respect, the new third man-made amphiploid cereal, tritipyrum (2n=6x=42, AABBE, is an example which is capable of tolerating a high level of NaCl. In order to determine the salinity tolerance mechanisms of this new cereal, an experiment was conducted using hydroponic technique. Ten tritipyrum lines and two wheat cultivars were tested under three levels of salinity (50, 100 and 200mM NaCl). The effect of salinity stress on Na + and K + concentration of leaf, shoot and root, proline and chlorophyll content were measured at 50% ear emergence and their grain yield plant -1 was evaluated at physiological maturity. Leaf Na + concentration in tritipyrum lines increased with increasing salinity while K + concentration did not show any especial pattern. The chlorophyll and proline content in tritipyrum lines were higher than that of wheat cultivars. Despite the high sodium concentration in tritipyrum lines in comparison with wheat, the grain yield of tritipyrum lines were less affected than that of wheat. There was also a negative correlation between proline content and grain yield plant -1 in tritipyrum lines. It can be concluded that mechanisms such as higher Na + uptake along with appropriate ion compartmentation could be used by tritipyrum lines to combat with salt stress like some halophytes and it can make tritipyrum lines suitable for planting in saline soils and improving the salinity tolerance of wheat. Keywords:Halophytic wild ancestors, Proline, Salt tolerance mechanism, Tritipyrum. Abbreviations: LNa_ leaf sodium concentration; LK_ leaf potassium concentration; LK:Na or L K + /Na + _ leaf potassium to sodium ratio; SN_ stem sodium concentration; SK_ stem potassium concentration; SK:Na_ stem potassium to sodium ratio; RN_ root sodium concentration; RK_ root potassium concentration; RK:Na_ root potassium to sodium ratio; Chl a_chlorophyll a concentration; Chl b_ chlorophyll b concentration; Chl a/b_ chlorophyll a to chlorophyll b ratio; T Chl_ total chlorophyll; GY_ grain yield plant

The novel salt tolerant cereal, Tritipyrum, was suggested as a potential species for cultivation in saline soils to improve s alt tolerance in wheat via breeding programs. Hence, investigation of its reaction to salinity stress, especially at different growth stages, seems to be necessary. For this purpose, an experiment was conducted using hydroponic technique in controlled as well as field conditions. Nine tritipyrum lines were tested under three levels of salinity (50, 100 and 200 mM NaCl) in hydroponic culture. Then, based on the results, three tritipyrum lines along with one wheat cultivar were cultivated in the field under three levels of salinity of irrigation water (control, 7dS/m and 14dS/m). In the hydroponic test, according to the statistical analysis of the genotypes based on their vegetative, reproductive and seed maturity traits, tritipyrum lines were more salt tolerant than salt tolerant wheat cultivar. Also cluster analysis showed that (St/b)×(Cr/b), F4 and Az/b were the most salt tolerant tritipyrum lines. Furthermore, based on the field trial, tritipyrum lines showed better performance and produced higher grain yield as well as higher grain protein content than wheat cultivar in saline condition. Based on our results, it is conceivable to improve the salt tolerance of wheat through breeding programs. Tritipyrum lines can also be cultivated in saline soils as fodder or forage crop.

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