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The high temperature-tolerant oomycete Phytophthora parsiana was considered to be limited to woody plants. In the preliminary study, the host range of the pathogen on annual herbaceous plant species using six isolates of P. parsiana including type strains from different sources was examined under greenhouse conditions. Among herbaceous species including cucurbits, pepper, pulse and oil crops, two isolates were pathogenic to pepper. Then three cultivars of pepper were used to discriminate pepper cultivars to sixteen isolates of P. parsiana. Results showed P. parsiana were pathogenic to red pepper (‘Anheim’ and ‘Casabel’cultivars) but not bell pepper. This is the first report of an herbaceous host of P. parsiana (sensu lato). Phylogenetic relationships of the pathogenic isolates of P. parsiana from pistachio to pepper and two isolates of the species from pistachio from Rafsanjan and Yazd were not pathogenic to pepper were examined. Based on sequences of the internal transcribed spacer (ITS) region of the ribosomal RNA, isolates pathogenic to pepper and one from Rafsanjan were in a group of P. parsiana belonging to clade 10 but the Yazd isolate had no genetic similarity to P. parsiana , being placed in clade 6 of the ITS tree, closely matching that of Phytophthora taxon Walnut (99-100 nucleotide identity). This is the first report of Phytophthora taxon Walnut from pistachio in Iran. [ABSTRACT FROM AUTHOR]

The effects of soil salinity and water stress on Verticillium wilt, ion composition and growth of pistachio were studied in a greenhouse experiment (18–32°C). Treatments consisted of three levels of salinity (0, 1200 and 2400 mg NaCl/kg soil), three levels of water stress (3, 7 and 14 day irrigation regimes) and two Pistachio cultivars (Sarakhs and Qazvini, common rootstocks in Iran). Infested soil containing 50 microsclerotia/g of a pistachio isolate of Verticillium dahliae was used for all treatments and non-infested soils were used as control. The experiment was arranged in a completely randomized design with three replications. Eight-week-old pistachio seedlings were transferred to infested and non-infested soil and then exposed to salt stress and thereafter water stress. Shoot dry weights of both rootstocks were reduced significantly with increasing NaCl levels; however, increasing irrigation regimes reduced salt injury. Salt stress significantly increased shoot and root colonization by V. dahliae in both cultivars. Moreover, increasing of salinity level was positively correlated with increasing concentrations of Na+, K+ and Cl− in both cultivars, but negatively correlated with increasing irrigation regimes. Based on these results, Sarakhs and Qazvini were found to be sensitive and tolerant to the effect of irrigation regimes, salinity and Verticillium wilt disease, respectively. Although there were no interactive effects of irrigation and salinity on V. dahliae infection. [ABSTRACT FROM AUTHOR]

The effects of three sodium chloride (NaCl) levels (0, 1200, and 2400 mg kg- 1 soil) and three irrigation intervals (3, 7, and 14 d) on the growth and chemical composition of two Pistacia vera rootstocks ('Sarakhs' and 'Qazvini') were investigated under greenhouse conditions. Eight-week-old pistachio seedlings were gradually exposed to salt stress which afterward, water stress was initiated. At any irrigation interval, plant height and shoot and root dry weights of both rootstocks were reduced with increasing salinity. However, increasing irrigation intervals alleviated the adverse effects of soil salinity. A negative relationship observed between relative shoot growth and electrical conductivity of soil saturation extract (ECe) confirmed the above findings. Under 3-d irrigation interval, the ECe required to cause a 50% growth reduction was lower than those under 7- and/or 14-d irrigation intervals. Shoot and root chemical analyses indicated that the salinity as well as irrigation regime affected the concentration and distribution of sodium (Na+), potassium (K+), and chloride (Cl-) in pistachio. The concentration of Na+, K+ and C1- ions increased with a rise in NaCl level, and was generally declined with increasing irrigation interval. Based on plant height, shoot and root dry weights and the concentrations of Na+, K+, and C1- in the plant tissues, at lowest irrigation intervals 'Sarakhs' shows a higher sensitivity to soil salinity than 'Qazvini', but with increasing irrigation interval, 'Sarakhs' and 'Qazvini' can be classified as resistant and sensitive to salinity, respectively. [ABSTRACT FROM AUTHOR]

The interaction between soil salinity and infection caused by Verticillium dahliae was studied in pistachio (Pistacia vera) in a greenhouse experiment. Treatments consisted of 0, 1400, 2800, and 4200 mg sodium chloride (NaCl) kg- 1 soil and three rootstocks (Sarakhs, Badami, and Qazvini cultivars). They were gradually exposed to salinity stress before and/or after root inoculation with a water suspension of 107 conidia/mL of a pistachio isolate of V. dahliae. Salt stress significantly increased rootstock shoot and root colonization by V. dahliae. All rootstocks were susceptible to V. dahliae, but symptoms of the disease appeared earlier in Sarakhs, a salt sensitive cultivar. Moreover, salinity and V. dahliae interaction increased the concentrations of sodium (Na), potassium (K) and chloride (Cl), but decreased the K/Na ratio in all rootstocks. Shoot and root tissues of inoculated Sarakhs and Qazvini (a salt tolerant) contained the highest and the lowest concentrations of Na, K,and Cl, respectively. In salinity treatments, shoot and root dry weight of all rootstocks decreased as compared with controls. Sarakhs showed smaller shoot and root dry weight than Qazvini and Badami. Also, increasing the NaCl level increased accumulation of Na, K, and Cl in shoot and root of the rootstocks. Sarakhs showed higher concentrations of ions in the shoot and root. Based on shoot and root dry weights and ion accumulation, Sarakhs and Qazvini were susceptible and tolerant to salinity, respectively. [ABSTRACT FROM AUTHOR]

Abstract: As part of a study to examine the phylogenetic history of the taxonomically challenging species Phytophthora cryptogea and P. drechsleri, a distinct monophyletic group of isolates, previously described as P. drechsleri or P. cryptogea, were characterised. Analysis of their rDNA ITS sequences indicated that these isolates were distinct from P. drechsleri, P. cryptogea, and all members of Phytophthora ITS clades 1–8, clustering instead alongside basal groups previously described as clades 9 and 10. This group comprised six isolates all of which were isolated from woody plants, such as pistachio (Pistacia vera, Iran and USA), fig (Ficus carica, Iran), and almond (Prunus dulcis, Greece). Analysis of sequence data from nuclear (β-tubulin and translation elongation factor 1α) and mitochondrial (cytochrome c oxidase subunit I) genes confirmed the ITS-based analysis as these isolates formed a distinct monophyletic group in all NJ trees. The isolates were fast growing with a relatively high optimum growth temperature of 30°C and, in most cases, rapid colony growth even at 37°C. The isolates produced complex colony patterns on almost all media, especially corn meal agar (CMA). Phylogenetic analysis and examination of all the other morphological and physiological data lead us to infer that this taxon has not been described previously. As this taxon was first isolated and described from Iran we propose that this taxon be formally designated as Phytophthora parsiana. [Copyright &y& Elsevier]