-related sequences involved in resistance to abioticstress in Triticeae. Plant Mol. Biol. , 48 , 649-665.
Chromosome regions and stress-related sequences involved in resistance to abioticstress in
Authors:Q. Xu, W.J. Feng, H.R. Peng, Z.F. Ni and Q.X. Sun
Members of WRKY gene family encode transcription factors involved in plant developmental processes and response to biotic and abiotic stresses. In order to understand the function of the TaWRKY71 gene, a homologue gene was isolated and characterised in wheat (Triticum aestivum L.) genotype TAM107. Tissue-specific gene expression profiles indicated that TaWRKY71 was constitutively expressed in roots, stems, leaves, stamen and pistil. The relative expression of TaWRKY71 was elucidated under ABA treatment and other abiotic stresses. In agreement with this, several putative cis-acting elements involved in ABA-response, drought-inducibility, low-temperature and heat response were detected in the promoter region of TaWRKY71. The function of TaWRKY71 was further determined by transforming Arabidopsis thaliana. Transgenic plants over-expressing TaWRKY71 displayed enhanced seed germination under ABA treatment and were tolerant to salt and drought stresses. These results indicate that TaWRKY71 gene might play important roles in seed germination and abiotic stress response.
Authors:A. Mohana Priya, S. Karutha Pandian and M. Ramesh
A simple and efficient protocol has been developed for high frequency plant regeneration through callus cultures derived from leaf bases of abiotic stress sensitive Asian indica rice variety IR 64. Leaf base segments (4–5 mm diameter) were obtained from 6-day-old dark grown seedlings germinated on halfstrength Murashige and Skoog medium and cultured on MS medium supplemented with different concentrations of 2,4-Dichlorophenoxyacetic acid (2.2–18 μM) and Kinetin (0.2–1.7 μM). Among the various combinations, 13.5 μM 2,4-D and 1.3 μM Kn resulted in high callus induction frequency (87.5%) with a maximum fresh weight of 0.22 g per segment. The regeneration frequency was 75.5% with multiple shoots within 3 weeks of transfer on MS medium supplemented with 13.3 μM 6-benzylamino purine and 8 μM Naphthaleneacetic acid. The shoots readily rooted on half-strength MS medium without any hormonal supplements. In vitro regenerated plantlets with multiple shoots and roots were transferred to sterile soil and vermiculite mix and maintained in shade house for 30 days. Complete plantlets were then transferred to nursery and acclimatized to the external environment until seed set. RAPD profile reveals monomorphism and thus confirming the genetic stability of the regenerated plants. This method has the potential for both direct as well as indirect method of transformation for the production of genetically modified plants.
Authors:N. Sinha, V. Priyanka, K.T. Ramya, T. Leena, J.A. Bhat, Harikrishna, N. Jain, P.K. Singh, G.P. Singh and K.V. Prabhu
Abiotic stresses are major constraints to wheat productivity in many parts of the world. Tolerance to abiotic stresses can be achieved indirectly by selection for morpho-physiological traits. Physiological trait based breeding has been associated with improved performance under stress; and hence can combat and adapt wheat to drought and heat stress. Therefore, in the present study, phenotyping was carried out for agro-physiological traits in 52 diverse wheat germplasm lines under timely sown, rainfed and late sown environments for two years. Mean yield of the genotypes over the six environments were positively correlated with NDVI, days to maturity and negatively correlated with canopy temperature. The phenotypic data validated marker-trait associations of a number of meta-QTLs identified earlier for different physiological and agronomic traits. Six and seven meta-QTL genomic regions were found to be consistent in their expression for two years under rainfed/restricted irrigation and late sown environments, respectively. Expression analysis of the underlying candidate gene AK248593.1 in meta-QTL26 region revealed two folds higher expression in the NILs carrying the co-localized SSR markers. The linked markers of the thirteen meta-QTL regions associated with different traits can be used for effective transfer of the QTLs through marker assisted selection in wheat breeding programmes.
Authors:Zoltán Mayer, Nguyen Hong Duc, Zita Sasvári and Katalin Posta
The association between terrestrial plants and arbuscular mycorrhizal (AM) fungi is one of the most common and widespread mutualistic plant-fungi interaction. AM fungi are of beneficial effects on the water and nutrient uptake of plants and increase plant defense mechanisms to alleviate different stresses. The aim of this study was to determine the level of polyphenol oxidase (PPO), guaiacol peroxidase (POX) and glutathione S-transferase (GST) enzyme activities and to track the expression of glutathione S-transferase (GST) gene in plant-arbuscular mycorrhizal system under temperature- and mechanical stress conditions. Our results suggest that induced tolerance of mycorrhizal sunflower to high temperature may be attributed to the induction of GST, POX and PPO enzyme activities as well as to the elevated expression of GST. However, the degree of tolerance of the plant is significantly influenced by the age which is probably justified by the energy considerations.