Characterization of a stearoyl-acyl carrier protein desaturase gene from potential biofuel plant, Pongamia pinnata L.

A new full length cDNA clone encoding stearoyl-ACP desaturase (SAD) was isolated from seeds of Pongamia pinnata, an oil yielding legume plant. The cDNA clone (PpSAD) contained a single open reading frame of 1182-bp coding for 393 amino acids with a predicted molecular mass of 45.04 kDa, and shares similarity with SAD from other plants. Characteristics of the deduced protein were predicted and analyzed using molecular homology modeling; its three dimensional structure strongly resembled the crystal structure of Ricinus communis (RcSAD). Southern blot analysis indicated that ‘sad’ is a multiple copy gene and was a member of a small gene family. Expression analysis using quantitative real-time PCR revealed that the gene showed marked distinct expression during different stages of seed developments. The results of the expression analysis in this study, combined with existing research, suggest that ‘sad’ gene may be involved in the regulation of plant seed growth and development.     

Overexpression of the betaine aldehyde dehydrogenase gene from Atriplex hortensis enhances salt tolerance in the transgenic trifoliate orange (Poncirus trifoliata L. Raf.)

Trifoliate orange (Poncirus trifoliata L. Raf.), a rootstock widely used for citrus species, is salt-sensitive. Worldwide, salinity is a major abiotic stress affecting citrus growth and yield. Glycinebetaine (GB) is an important osmoprotectant involved in responses to salt stress. However, current evidence regarding the effect of salt stress on GB accumulation in trifoliate orange is limited, and the GB synthesis gene has not yet been shown to confer enhanced salt stress tolerance to this species in a transgenic context. In the current study, we first examined the change in GB level of trifoliate orange seedlings exposed to salt stress, and found that salt increased endogenous GB level in a concentration-dependent manner. A betaine aldehyde dehydrogenase gene (AhBADH) cloned from Atriplex hortensis was introduced into the trifoliate orange by means of Agrobacterium-mediated transformation. RT-PCR analysis on three selected transgenic lines showed that the AhBADH gene was overexpressed in each of them. GB levels in these lines were also higher than those in untransformed wild-type (WT) plants. In the transgenic lines, exposure to 200 mM NaCl resulted in significantly less serious leaf burning and defoliation, lower MDA accumulation, and higher chlorophyll contents than those in the WT plants. Moreover, when exposed to salt, shoots of transgenic plants contained lower levels of Na⁺ and Cl⁻, higher levels of K⁺, and a higher K/Na ratio, while the same was true for the roots in most cases. Taken together, the data suggest that overexpression of the AhBADH gene in transgenic trifoliate orange enhanced salt stress tolerance. This may be correlated with the low levels of lipid peroxidation, protection of the photosynthetic machinery, and increase in K⁺ uptake.     

Overexpression of two cold-responsive ATAF-like NAC transcription factors from fine-stem stylo (<Emphasis Type="Italic">Stylosanthes guianensis</Emphasis> var. <Emphasis Type="Italic">intermedia</Emphasis>) enhances cold tolerance in tobacco plants

Tissue culture data is non-linear in nature. Decision tree algorithms stand out in revealing the non-linear interactions and relationships between the predictors and responses. Classification and regression tree (CART), chi squared automatic interaction detector (CHAID) and exhaustive CHAID are the common decision tree algorithms. These three models were employed to predict and optimize the effect of minor mineral nutrients on shoot cultures of Corylus avellana L. cultivars. H₃BO₃, CuSO₄·5H₂O, MnSO₄·H₂O, Na₂MoO₄·2H₂O and Zn(NO₃)₂·6H₂O were tested in a range of 0.5?×?to 4?×?Driver and Kuniyuki (DKW) medium within a RSM optimal design. NiSO₄·6H₂O was also an input within the design with varying levels of 0 to 6 µM. Shoot quality and length were affected by genotype, B and Mo amounts. Multiplication rate depended on genotype, B, Zn and Cu levels. Callus formation was affected by genotype and B. Leaf size depended on genotype, Zn and Mn concentrations. Cu was a significant predictor of leaf color and Ni slightly improved SPAD readings (chlorophyll content). CART in general outperformed CHAID and exhaustive CHAID in terms of the predictive performance. Both CHAID and exhaustive CHAID failed to generate a tree model for a leaf size response. The optimal minor nutrients for hazelnuts based on the predictions of the CART algorithm were suggested to be: B 2.3?×?DKW, Cu 0.5×, Mn 0.5×, 2?×?Mo and Zn 2×.     

Overexpression of <Emphasis Type="Italic">OsiSAP8</Emphasis>, a member of stress associated protein (SAP) gene family of rice confers tolerance to salt,drought and cold stress in transgenic tobacco and rice

We describe here the isolation and characterization of OsiSAP8, a member of stress Associated protein (SAP) gene family from rice characterized by the presence of A20 and AN1 type Zinc finger domains. OsiSAP8 is a multiple stress inducible gene, induced by various stresses, namely heat, cold, salt, desiccation, submergence, wounding, heavy metals as well as stress hormone Abscisic acid. OsiSAP8 protein fused to GFP was localized towards the periphery of the cells in the epidermal cells of infiltrated Nicotiana benthamiana leaves. Yeast two hybrid analysis revealed that A20 and AN1 type zinc-finger domains of OsiSAP8 interact with each other. Overexpression of the gene in both transgenic tobacco and rice conferred tolerance to salt, drought and cold stress at seed germination/seedling stage as reflected by percentage of germination and gain in fresh weight after stress recovery. Transgenic rice plants were tolerant to salt and drought during anthesis stage without any yield penalty as compared to unstressed transgenic plants. OsiSAP8 is deposited in the Genbank with the Accession number AY345599.     

Overexpression of <Emphasis Type="Italic">PtrABF</Emphasis> gene,a bZIP transcription factor isolated from <Emphasis Type="Italic">Poncirus trifoliata</Emphasis>, enhances dehydration and drought tolerance in tobacco via scavenging ROS and modulating expression of stress-responsive genes

Background  

Drought is one of the major abiotic stresses affecting plant growth, development and crop productivity. ABA responsive element binding factor (ABF) plays an important role in stress responses via regulating the expression of stress-responsive genes.     

Isolation and characterization of a novel glycogen synthase kinase-3 gene, <Emphasis Type="Italic">GmGSK</Emphasis>, in <Emphasis Type="Italic">Glycine max</Emphasis> L. that enhances abiotic stress tolerance in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

A novel glycogen synthase kinase-3 gene, GmGSK, was isolated from Glycine max. It is 1,596 bp in length with one ORF of 410 amino acids. Southern blot analysis revealed that it has at least two copies in the G. max genome. GmGSK, when transiently expressed in Nicotiana tabacum leaves, was localized in both cell membrane and cytoplasm. Northern blot analysis indicated that GmGSK is expressed in all tissues, with highest expression in the root. GmGSK can be induced by various abiotic stresses. When transformed with GmGSK, Saccharomyces cerevisiae exhibited enhanced resistance to salt and drought stress.