Nadali Babaeian Jelodar

Chitinolytic and antifungal activity of a Bacillus pumilus chitinase expressed in Arabidopsis

The Bacillus pumilus SG2 chitinase gene (ChiS) and its truncated form lacking chitin binding (ChBD) and fibronectin type III (FnIII) domains were transformed to Arabidopsis plants and the expression, functionality and antifungal activity of the recombinant proteins were investigated. Results showed that while the two enzyme forms showed almost equal hydrolytic activity toward colloidal chitin, they exhibited a significant difference in antifungal activity. Recombinant ChiS in plant protein extracts displayed a high inhibitory effect on spore germination and radial growth of hyphae in Alternaria brassicicola, Fusarium graminearum and Botrytis cinerea, while the activity of the truncated enzyme was strongly abolished. These findings demonstrate that ChBD and FnIII domains are not necessary for hydrolysis of colloidal chitin but play an important role in hydrolysis of chitin–glucan complex of fungal cell walls. Twenty microgram aliquots of protein extracts from ChiS transgenic lines displayed strong antifungal activity causing up to 80% decrease in fungal spore germination. This is the first report of a Bacillus pumilus chitinase expressed in plant system.

Evaluation of rice genotypes to salt stress in different growth stages via phenotypic and random amplified polymorphic DNA (RAPD) marker assisted selection

Soil salinity represents an increasing threat to rice production. The success of salt tolerance breeding programs employing traditional screening and selection has been limited in the past decades. 40 rice genotypes were screened in saline soil of electrical conductivity (EC) of 4, 8 and 12 ds/m in vegetative growth stage in 2009. Tolerant genotypes were tested in young seedling stage in hydroponic system and then reproductive stage in 2010. Results show that vegetative growth was less affected by salt stress comparison to reproductive stage. Na and Na-K ratio in tolerant genotypes were lower than suspectible genotypes in salt condition in young seedling stage. Shastak-mohammadi, Hasani, Trom-Danesh, Line109 and Line75 were more tolerant to salt stress for the evaluated traits in reproductive stage. Molecular analysis showed that UBC-251 and UBC-244 displayed variation in the banding pattern of individual rice genotypes. Results of molecular analysis confirmed evaluation of phenotypic analysis. Key words: Oryza sativa , salt stress, different growth stage, random amplified polymorphic DNA (RAPD) markers.

Increase of Chamazulene and α-Bisabolol Contents of the Essential Oil of German Chamomile (Matricaria chamomilla L.) Using Salicylic Acid Treatments under Normal and Heat Stress Conditions

The chamazulene and α-(−)-bisabolol contents and quality of the chamomile oil are affected by genetic background and environmental conditions. Salicylic acid (SA), as a signaling molecule, plays a significant role in the plant physiological processes. The aim of this study was to evaluate the chemical profile, quantity, and improve the essential oil quality as a consequence of the increase of chamazulene and α-(−)-bisabol using salicylic acid under normal and heat stress conditions by the gas chromatography-mass spectrometry (GC-MS) technique. The factorial experiments were carried out during the 2011–2012 hot season using a randomized complete block design with three replications. The factors include four salicylic acid concentrations (0 (control), 10, 25 and 100 mg·L−1), and three chamomile cultivars (Bushehr, Bona, Bodegold) were sown on two different planting dates under field conditions. Fourteen compounds were identified from the extracted oil of the samples treated with salicylic acid under normal and heat stress conditions. The major identified oil compositions from chamomile cultivars treated with salicylic acid were chamazulene, α-(−)-bisabolol, bisabolone oxide, β-farnesene, en-yn-dicycloether, and bisabolol oxide A and B. Analysis of variance showed that the simple effects (environmental conditions, cultivar and salicylic acid) and their interaction were significant on all identified compounds, but the environmental conditions had no significant effect on bisabolol oxide A. The greatest amount of chamazulene obtained was 6.66% at the concentration of 10 mg·L−1 SA for the Bona cultivar under heat stress conditions, whereas the highest α-(−)-bisabolol amount attained was 3.41% at the concentration of 100 mg·L−1 SA for the Bona cultivar under normal conditions. The results demonstrated that the application of exogenous salicylic acid increases the quantity and essential oil quality as a consequence of the increase of chamazulene and α-(−)-bisabolol under normal and heat stress conditions.

Correction: Ghasemi, M., et al. Increase of Chamazulene and α-Bisabolol Contents of the Essential Oil of German Chamomile (Matricaria chamomilla L.) Using Salicylic Acid Treatments under Normal and Heat Stress Conditions Foods 2016, 5, 56

The authors wish to make the following corrections to their paper [...].

Study of Silicon Effects on Plant Growth and Resistance to Stem Borer in Rice

This research was conducted to evaluate silicon (Si) effects on the morphological characteristics and resistance to rice stem borer under greenhouse conditions at Sari Agricultural Sciences and Natural Resources University in 2009. The experiment was conducted as factorial in a complete randomized design (two factors) with three replications. The factors included four levels of silicon (Si) (Si0 = 0, Si1 = 5, Si2 = 10, Si3 = 20 g Si kg−1 soil) and three rice cultivars (Parto, Line 34, and Neda). The results showed Si fertilizer had a significant effect on percentage of white head, length of leaf, width of leaf, diameter of stem, and percentage of reproductive tiller. Also, increased stem Si increased the resistance to striped stem borer in the rice cultivars studied. The greatest resistance to striped stem borer was observed with the application of 20 g Si kg−1 soil. The application of Si at the rate of 20 g Si kg−1 soil significantly reduced the percentage of white head from 18.10% (without Si) to 0.11% (with 20 g Si kg−1 soil) in Parto cultivar.

Inheritance of southern root-knot nematode resistance in air-cured tobacco

The southern root-knot nematode (SRKN; Meloidogyne incognita) is one of the main pathogens for tobacco. The objectives of this study were to determine the genetic parameters and heritability of SRKN resistance in air-cured tobacco. For this purpose three resistant parents (Urmia3, KY9, K17) and two susceptible parents (Ergo, Burley TMV4) were crossed based on half diallel and analyzed by Hayman’s method for reaction to Meloidogyne incognita. Fifteen genotypes (parents and hybrids) were planted in the greenhouse in a completely randomized design with five replications and inoculated with 2500 J2 M. incognita race 2 one week after transplanting. Investigation of gall index (GI), number of egg masses (NEM) and average number of eggs per mass (AEM) showed significant differences among genotypes. Non-additive effects in AEM and additive effects in GI and NEM played an important role. Narrow-sense heritability was estimated as 0.75, 0.56 and 0.28 for GI, NEM and AEM, respectively, which revealed that AEM is not a suitable trait for nematode resistance identification. Regression analysis indicated that KY9 is an appropriate donor parent for SRKN resistance. Resistance to M. incognita race 2 is conditioned by a single partially dominant gene.

Designing a new marker-free and tissue-specific platform for molecular farming applications

Tissue-specific expression of recombinant proteins in transgenic plants is of particular importance. Production of tissue-specific transplastomic plants is challenging due to lack of tissue-specific promoter in the plastome. The objective of the present study was to produce a transgenic platform enhancing tissue-specific transgene expression in the green organs of Nicotiana tabacum Cv. Jafarabadi. A bacteria/plant hybrid sigma factor sequence (hsig) under control of the PEP Carboxylase promoter (PEPC) was designed and cloned in a plasmid construct without selectable marker gene and finally transformed into the nucleus genome by Agrobacterium. Transformation was confirmed by PCR, RT-PCR, southern blot and real-time PCR analysis. The resulted platform was re-transformed using a plastid construct pFNGi containing gfp (reporter gene) and neo genes (a kanamycin resistance selectable marker gene). Expression of GFP was assayed under Epifluorescence microscopy. The results showed that the constructed platform was functional, and the GFP was expressed. Finally, it can be concluded that application of the hybrid sigma factor (hsig) under control of a tissue-specific promoter could be a suitable platform for tissue-specific expression of plastome integrated transgenes, and also it is proposed to use other more safer marker genes for plastid transformation instead of the antibiotic resistance gene.