Comparison of bacterial and plant genes participating in proline biosynthesis with Osmotin gene, with respect to enhancing salinity tolerance of transgenic tobacco plants

In an attempt to increase tolerance to salinity stress in tobacco plants, the genes encoding the mutant form of glutamyl kinase (proB), pyrroline-5-carboxylate synthetase, and osmotin were cloned into three different shuttle vectors and were separately introduced into the tobacco plants. The transgenic lines were compared for their ability to produce shoots and grow in MS medium containing 320 mM NaCl; it was shown that the transgenic lines containing genetically handled osmotin gene are more resistant to salinity. The amount of chlorophyll a was used to show continuing growth of plant lines. The results showed that only the tobacco lines transformed with the modified osmotin gene exhibited greater tolerance to salinity. Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 1, pp. 122–127. The text was submitted by the authors in English.     

An Investigation on Strains of Clavibacter michiganensis subsp. michiganensis in North and North West of Iran

Tomato bacterial canker disease was first reported from Urmiyeh in West Azerbaijan province in Iran. The disease causes lesion (canker), wilting and dryness of infected plants, leaf and fruit spots and the decline of the whole plant. Out of 102 isolates obtained from the fields in the major tomato producing areas of understudy regions, 98 were found Gram positive, yellow‐pigmented isolates, identified as Clavibacter michiganensis subsp. michiganensis based on the morphological and biochemical characteristics described in previous studies. Among these strains, 64 were virulent and 34 showed poor virulence. A strain of Cmm (NCPPB382) was used as a check (standard) in all steps of this study. DNA fingerprinting with repetitive‐sequence‐based PCR (rep‐PCR) (BOX primer) carried out among 11 representative strains (eight strains from West Azerbaijan, two from Golestan and one as standard). The most virulent strain was chosen as representative in each location. Dendrograms were prepared using NTSYS‐pc version 2/o2e software, unweighted pair group with arithmetic average method and simple matching similarity coefficient. According to the site of cut‐off line, three groups (clusters) with 82/5% similarity and six groups with 55% similarity were separated based on biochemical and SDS‐PAGE data, and rep‐PCR reactions respectively. Low similarity among groups (55%) can be explained as high genetic diversity among the strains. One strain of west Azerbaijan and the strains of Golestan, clustered in the same group suggesting that they may have been originated from a common source. Other strains of west Azerbaijan were clustered into different groups including II, III, IV, V and VI, suggesting the possibility of occurrence of different populations in a geographical region.     

Lethal and sublethal effects of Iranian isolates of Steinernema feltiae and Heterorhabditis bacteriophora on the Colorado potato beetle, Leptinotarsa decemlineata

To determine the LC₅₀ values of two entomopathogenic nematodes against Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) prepupae, different concentrations of the nematodes were tested in soil. Because of the different temperature requirements of the two nematode species, bioassay experiments were conducted at 20 ± 1°C and 27 ± 2°C for Steinernema feltiae Filipjev (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), respectively. Both the isolates were effective against L. decemlineata. LC₅₀ values of H. bacteriophora against progeny of field-collected adults and laboratory-reared adults were estimated as 8.5 and 7.6 IJ per prepupa, respectively. For S. feltiae the value was calculated as 51.2 IJ per prepupa against offspring of laboratory-reared adults of L. decemlineata only. Cellular encapsulation of both nematode species was observed. Sublethal nematode concentrations caused wing deformation and delayed metamorphosis which may affect Colorado potato beetle adult fitness.     

Description of Crassolabium persicum sp. n. (Nematoda, Dorylaimida, Qudsianematidae), an interesting species from Iran

A new species of the genus Crassolabium, Crassolabium persicumsp. n., collected from Arasbaran rangelands of Iran, is described and illustrated. It is characterized by its body 1.92-2.40 mm long, lip region offset by constriction and 17-19 μm wide, odontostyle 16-19 μm long with aperture occupying less than one-third (27-30%) its length, neck 428-690 μm long, pharyngeal expansion 369-390 μm long or occupying 54-56% of total neck length, female genital system amphidelphic, uterus bipartite and 162-218 μm long or 2.3-3.5 times as long as body diameter, pars refringens vaginae well developed, V = 54-57.5, vulva longitudinal, prerectum bearing a blind sac, tail conical with rounded tip to conoid (25-36 μm, c=60-69, c'=0.5-0.9), spicules 68-72 μm long, precloacal pair of supplements far (22-27 μm) from cloacal aperture, and 13-17 shortly spaced ventromedian supplements with hiatus. The new taxon is compared in depth to its relatives in Crassolabium as well as other similar species of Aporcelaimellus and Amblydorylaimus.     

Penconazole alleviates salt-induced damage in safflower (Carthamus tinctorius L.) plants

It has been shown that penconazole (PEN) acts as an endogenous signal molecule responsible for inducing stress tolerance in plants. The effect of PEN (15?mg?l^–1) and sodium chloride (0, 100, and 200 mM NaCl) on some biochemical and molecular responses of safflower was studied. Results revealed that chlorophylls and total soluble protein contents decreased under salinity, however total carotenoid, anthocyanin, flavonoid, and carbohydrate contents increased as well as SOS1 and NHX1 genes expression. The exogenous PEN had a positive effect on chlorophylls, carotenoid, anthocyanin, flavonoid, soluble protein and carbohydrate contents. In addition, RT-qPCR analysis showed that the exogenous PEN induced expression of SOS1 and NHX1 genes in both salt-treated and untreated plants. Our data indicate that PEN helps safflower plants to better cope with salt stress. The results can provide new insights to better realizing the responsible mechanisms to regulate salinity resistance in safflower. PEN can be considered in order to ameliorate salinity effects, due to the low price and their availability.     

<Emphasis Type="Italic">In vitro</Emphasis> organogenesis and antioxidant enzymes activity in <Emphasis Type="Italic">Acanthophyllum sordidum</Emphasis>

The effect of various hormonal combinations on callus formation and regeneration of shoot and root from leaf derived callus of Acanthophyllum sordidum Bunge ex Boiss. has been studied. Proteins and activity of antioxidant enzymes were also evaluated during shoot and root organogenesis from callus. Calli were induced from leaf explants excised from 30-d-old seedlings grown on Murashige and Skoog medium containing 4.52 μM 2,4-dichlorophenoxyacetic acid + 4.65 μM kinetin. Maximum growth of calli and the most efficient regeneration of shoots and roots occurred with 2.69 μM 1-naphthalene acetic acid (NAA), 2.69 μM NAA + 4.54 μM thidiazuron and 2.46 μM indole-3-butyric acid. Protein content decreased in calli and increased significantly during regeneration of shoots from callus. Superoxide dismutase activity decreased in calli comparing to that of seedlings, then increased in regenerated shoots and roots. High catalase activity was detected in seedlings and regenerated shoots, whereas high peroxidase activity was observed in calli and regenerated roots.     

Contractile roots are the most sensitive organ in <Emphasis Type="Italic">Crocus sativus</Emphasis> to salt stress

Crocus sativus corms were grown in Perlite and watered by half-strength modified Hoagland nutrient solution containing 0, 50, 100, 150, 200 mM NaCl. Growth parameters and contents of proteins, proline, polyphenols, minerals and saccharides were studied in fibrous roots, contractile roots, corms and leaves. All plants remained alive and did not display any sign of foliar damage even at 200 mM NaCl. However, the salinity decreased growth, relative water content and increased contents of proline and Na⁺ in all organs. Total protein content was increased in corms and contractile roots but decreased in fibrous roots. Changes in protein pattern were also observed. Polyphenol content was increased by salinity in all organs except the leaves. As salinity increased, content of soluble saccharides decreased except in the contractile roots.     

Salt stress effects on growth,pigments, proteins and lipid peroxidation in <Emphasis Type="Italic">Salicornia persica</Emphasis> and <Emphasis Type="Italic">S. europaea</Emphasis>

The effects of NaCl stress on growth, water status, contents of protein, proline, malondialdehyde (MDA), various sugars and photosynthetic pigments were investigated in seedlings of Salicornia persica and S. europaea grown in vitro. Seeds were germinated under NaCl (0, 100, 200, 300, 400, 500 and 600 mM) on Murashige and Skoog medium for 45 d. The shoot growth of both species increased under low NaCl concentration (100 mM) and then decreased with increasing NaCl concentrations. In contrast to S. persica, root length in S. europaea reduced steadily with an increase in salinity. Proline content in S. persica was higher than in S. europaea at most NaCl concentrations. Proline, reducing saccharide, oligosaccharide and soluble saccharide contents increased under salinity in both species. In contrast, contents of proteins and polysaccharides reduced in both species under salt stress. MDA content remained close to control at moderate NaCl concentrations (100 and 200 mM) and increased at higher salinities. MDA content in S. europaea was significantly higher than S. persica at higher salinities. Salt treatments decreased K⁺ and P contents in seedlings of both species. Significant reduction in contents of chlorophylls and carotenoids due to NaCl stress was also observed in seedlings of both species. Some differences appeared between S. persica and S. europaea concerning proteins profile. On the basis of the data obtained, S. persica is more salt-tolerant than S. europaea.