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Volume 7 Number 1 2013 
CONTENTS AND ABSTRACTS
Gisele Cristina Dedemo, Fabiana Aparecida Rodrigues, Patricia Garnica Roberto, Cyro Bueno Neto, Suzelei de Castro França, Sonia M. Zingaretti (Brazil) Osmoprotection in Sugarcane under Water Deficit Conditions (pp 1-7)
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ABSTRACT
Invited Mini-Review: Drought has become a limiting factor for expansion of agricultural areas. Plant stress caused by water deficit is a major abiotic agent that affects many crops throughout the world, causing decrease in productivity and consequently economic losses. Development of more tolerant cultivars seems to be the right way to overcome adverse environmental conditions and increase productivity. Plant adaptive response to unfavorable conditions occurs via distinct mechanism such as salinity, drought, or high temperatures. This review covers some of the biochemical and genetic mechanisms which are related to plant tolerance and how they may interact to induce plant tolerance to drought. The role of signaling molecules, osmoregulators and Reactive Oxygen Species (ROS) in plant response mechanisms are discussed. In addition modifications at the transcriptional level are pointed out with the characterization of sugarcane gene expression profile under water stress conditions. Understanding how sugarcane gene expression is regulated and how its biochemical machinery is mobilized in response to drought will promote the development of tolerant cultivars. Based on the overall results already reported and in our findings on the differential expression of genes related to water stress cell response a coordinated mechanism of tolerance and sensitivity is proposed.
Qazi Fariduddin, Priyanka Varshney, Mohammad Yusuf, Ahmad Ali, Aqil Ahmad (India) Dissecting the Role of Glycine Betaine in Plants under Abiotic Stress (pp 8-18)
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ABSTRACT
Review: Among the compatible solutes, glycine betaine (GB) is particularly an effective osmolyte against abiotic stress. Metabolic acclimation of GB is regarded as a basic strategy for the protection and survival of plants in harsh environmental conditions. Plant species vary in their capacity to synthesize GB. Some plants, such as spinach and barley, accumulate relatively higher levels of GB in their chloroplasts while others, like Arabidopsis and tobacco, lack this compound. The accumulation of GB is induced under stress conditions and the level of GB is correlated with the degree of tolerance to stress. Genetic engineering has allowed the introduction of genes of its biosynthetic pathway into GB-deficient species from both microorganisms and higher plants. This approach has facilitated investigation of the importance of GB in stress protection. However, the level of GB in transgenic plants is relatively low. An alternative approach of exogenous application of GB to plants under stress has gained some attention. In this review, the protective role of GB in conferring tolerance to plants against various abiotic stresses through both exogenous application and genetic engineering has been summarized.
Manvir Kaur, Priyanka Bhagi, Anil Kumar Gupta, Vikramjit Kaur Zhawar (India) Antioxidant Potential and Expression of Lea genes under Heat Stress in Two Wheat Cultivars Differing in Heat Tolerance (pp 19-29)
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ABSTRACT
Original Research Paper: Two wheat (Triticum aestivum L.) cultivars differing in heat tolerance, ‘C306’ (heat tolerant) and ‘PBW343’ (heat susceptible) were compared for their growth, antioxidant response and expression of late embryogenesis abundant (LEA) genes under heat stress (37°C) given to 4-day old seedlings. Dry biomasses and water contents in shoots and roots of ‘C306’ were comparatively less affected under heat stress than of ‘PBW343’. Root dry mass to shoot dry mass ratios were improved by higher amount in ‘C306’ than in ‘PBW343’ under stress. Decline in proteins contents of roots under heat stress was higher in ‘PBW343’ than ‘C306’. Ascorbate contents and ascorbate to dehydroascorbate ratios were comparatively less affected in shoots and roots of ‘C306’ than of ‘PBW343’ under stress. ‘PBW343’ roots showed higher levels of malondialdehyde (MDA) under prolonged stress. Dehydroascorbate and proline contents did not increase during heat stress in shoots and roots of both cultivars. Activities of antioxidant enzymes were maintained in shoots of ‘C306’ but affected in shoots of ‘PBW343’ during the stress period. In roots of both cultivars, levels of antioxidant enzymes were decreased under heat stress. Glutathione-S-transferase-F (GST-F, member of phi class) was induced only in C306, GST-µ (member of tau class) was not induced in both cultivars, glutathione-peroxidase (GPX) was induced by same amount in both cultivars, peroxisomal-ascorbate peroxidase was induced only in PBW343 under heat stress. Some of LEA group 2 and group 4 genes were induced while of group 3 genes were not induced under heat stress. Among group 2, Wcor410c was induced mainly in C306, Td16 was induced mainly in PBW343, Td27e was induced higher in ‘C306’, Wdhn13 was not induced in both cultivars under heat stress. LEA group4 Td29 was induced higher in ‘C306’ than in ‘PBW343’ under heat stress.
Donald R. Baud, S. Reza Pezeshki (USA) Response of Quercus phellos L. Seedlings to Increased Root-zone Temperature and Simulated Herbivory (pp 30-33)
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ABSTRACT
Original Research Paper: Quercus phellos increased mean foliage production (F(2,33) = 58.56, P < 0.0001) three leaves per plant in response to increasing root-zone temperature and eight leaves per plant in response to a concomitant increase in herbivory (F(2,23) = 33.62, P < 0.0001) at the expense of the root system. A decrease in shoot biomass (F(2,33) = 88.47, P < 0.0001) and stomatal conductance, in response to increasing temperature (F(2,33) = 85.8, P < 0.0001) and herbivory (F(2,33) = 443.8, P < 0.0001), translated into a decrease in transpiration rate (F(2, 33) = 60.06, P < 0.0001) and a concomitant decrease in net photosynthesis in response to temperature (F(2,33) = 170.07, P < 0.0001) and herbivory (F(2, 33) = 259.85, P < 0.0001) while internal C concentration increased in response to temperature (F(2,33) = 4.39, P = 0.015 and herbivory (F(2,33) = 26.19, P < 0.0001). The findings of this study imply this wetland tree species will experience losses across its range in response to global warming, and the associated increase in insect herbivores, due allocating resources away from the root system and decreases in photosynthesis.
Taek-Ryoun Kwon, Seung-Kon Lee, Sang Ryeol Park (Korea), Zamin Shaheed Siddiqui (Pakistan), Seok-Jun Moon, Soo-Chul Park, Myung-Ok Byun (Korea) Atcbf1 Gene Enhances Salt Tolerance in Potato (Solanum tuberosum L.) (pp 34-38)
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ABSTRACT
Original Research Paper: CBF1 (C-repeat/DRE Binding Factor 1), isolated from Arabidopsis thaliana, was transformed into potato plants (Solanum tuberosum L.) using the CaMV 35S promoter to test for salt tolerance. Two transgenic lines were selected using genomic PCR and northern hybridization. The plants showed normal vegetative growth in in vitro culture. To examine CBF1 gene (AtCBF1) function, transgenic lines and a null-transgenic line were planted in a continuously aerated water culture system in a controlled environment. Plant growth and physiological traits contributing to the tolerance were observed in saline (50 mM NaCl) and non-saline (distilled water) environments. Growth performance of transgenic and null-transgenic plants in the control environment did not differ significantly. However, the transgenic plants showed better growth and osmotic adjustment than null-transgenic plants in the saline environment. The transgenic plants accumulated more than 20% biomass and 2-fold higher osmotic adjustment than null-transgenic plants. The results are discussed in relation to the possible role of the AtCBF1 gene with respect to salt tolerance of potato plants with some unique physiological traits.
Mina Kolahdouz Mohammadi, Dariush Minai-Tehrani (Iran), Jaime A. Teixeira da Silva (Japan), Leila Lotfi (Iran) Biochemical and Cellular Changes in the Root of Lens culinaris Grown on Crude Oil-Contaminated Soil (pp 39-44)
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ABSTRACT
Original Research Paper: Catalase (CAT) is an enzyme that decomposes hydrogen peroxide with high velocity. Under environmental stress, CAT plays an important role in the disposal of hydrogen peroxide. Spillage of crude oil into the soil can damage plants and microorganisms. Oil contamination in soil may act as a stressful element and cause damage to plants. In this experiment, the effect of crude oil-contaminated soil (5% w/w) on root of lentil (Lens culinaris) CAT activity and subcellular changes was studied. CAT activity was measured at different pHs and temperatures. The optimum pH was 10 and maximum activity was observed at 30°C in treated and control samples. Both Km and Vmax changed in treated samples. The Km of the enzyme was 1.13 and 1.5 mM and Vmax was 1.16 and 2 mM/min/mg protein in the treatment and control, respectively. After purification of CAT, SDS-PAGE of purified enzyme revealed a minor difference between the molecular weight of the enzyme in treated samples and the control, suggesting that a CAT isoenzyme was induced in treated samples relative to the control.
Nalini Pandey, Archana (India) Membrane Damage in an Oxygen-Free Radical-Dependant Manner induced via Boron Deficiency and Toxicity in Maize (pp 45-51)
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ABSTRACT
Original Research Paper: Maize (Zea mays var. ‘32-A09’) plants grown with variable boron (B) supply ranging from deficiency to toxicity (0.033, 0.33, 0.66, 3.3, 33 mg B L-1), were investigated for the concentration of antioxidants and activities of antioxidative enzymes in leaves. Plants subjected to deficiency and excess B supply showed retarded growth and characteristic B stress symptoms. Chlorophyll a, b and carotenoids decreased under B stress at both stages i.e., 26 and 38 days after treatment. There was lipid peroxidation as indicated by the high MDA content and accumulation of H2O2 under B stress. The activities of SOD, APX, GR, CAT and POX increased both under deficiency and toxicity. The concentration of total non-protein thiols increased under B stress and ascorbate decreased under B deficiency. DHA concentration decreased under B deficiency and increased under B toxicity in leaves at both treatment stages. There was also an accumulation of phenols with enhanced PPO activity under B deficiency and toxicity.
Ehab AbouKheir (Syria), Trichy Ganesh Prasad, Madavalam Sreeman Sheshshayee, Makarla Udayakumar (India) Root Biomass and Water Use Efficiency Determine Biomass Accumulation under Drought Stress: Implications for Identifying Donor Parents for Breeding for Abiotic Stress Tolerance in Cotton (pp 52-58)
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ABSTRACT
Original Research Paper: Water stress is the most yield limiting factor in field crops, including cotton. This study aimed to determine drought-tolerant genotypes. 158 cotton (Gossypium hirsutum L.) germplasm accessions were grown in a "field root phenotyping structure". Our results showed significant genotypic variability in root dry weight (RW), root volume (RV), root length (RL) and carbon isotope discrimination (∆13C) among cotton accessions. Based on differing root dry weight and carbon isotope discrimination, cotton accessions were classified into four groups. We found that different groups had different biomass accumulated and group-I with high RW and low ∆13C showed highest biomass produced compared with other groups. Therefore, genotypes belonging to group-I might be better than other genotypes belonging to other groups under drought stress. To assess this hypothesis, six genotypes were selected from group-I (three) and group-II (three) and raised in containers under well-watered (100% field capacity) and water limited (55% field capacity) conditions. Drought stress reduced root traits, leaf area, total dry matter in both groups. However, genotypes belong to group-I accumulated high total dry matter under water stress, mainly due to maintain high photosynthetic rate, transpiration rate and carboxylation efficiency. Results emphasize the relevance of selecting drought-tolerant genotypes by choosing genotypes with a large root system coupled with a low ∆13C.
Ramzi Murshed, Safaa Najla, Fahed Albiski (Syria) Screening of Some Syrian Potato Lines Based on the Morphological Responses to Water Stress (pp 59-63)
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ABSTRACT
Original Research Paper: In order to screen 21 in vitro local lines of potato for water stress, the morphological responses of aerial and radical parts were studied. Water stress was mediated by adding 2, 4, 6, 8 and 10% (w/v) of sorbitol to Murashige and Skoog (MS) medium against 0% for the control. Plant length and diameter, leaf area, root number, length and diameter, as well as plant fresh and dry weight and plant water content, were measured. Water stress induced a decrease in several growth parameters. Using cluster analysis, based on the sum of relative values of water stress responses, three groups could be distinguished: (1) a tolerant group consisting of six lines (SY-C.09 > SY-C.32 > SY-C.42 > SY-C.49 > SY-C.48 > SY-C.08), (2) a moderately tolerant group consisting of eight lines (SY-C.10 > SY-C.51 > SY-C.16 > SY-C.06 > SY-C.30 > SY-C.37 > SY-C.41 > SY-C.50) and (3) a sensitive group consisting of seven lines (SY-C.36 > SY-C.44 > SY-C.33 > SY-C.45 > SY-C.40 > SY-C.05 > SY-C.04).
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