-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: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.
Authors:P. Bónis, T. Árendás, I. Jócsák, C. Mikecz, G. Micskei and L. Marton
Inbred maize lines were treated with normal and double rates of post-emergence herbicides in a small-plot field experiment in one dry and one wet year. The chlorophyll a + b content of symptom-free ear-leaves was determined using a spectrophotometer after 50% silking in order to determine whether various rates of post-emergence herbicides had any effect on the chlorophyll content at flowering and how this was influenced by the type of year. The chlorophyll a + b content of the inbred lines was greatly dependent on the year, with values twice as high in the wet year as in the dry year. Treatment with tembotrione + isoxadifen-ethyl had no effect on the chlorophyll content in either year. Both rates of mesotrione + terbutylazine reduced the chlorophyll a + b content of one stress-sensitive inbred line in the dry year, but not in the wet year. In the wet year bentazone + dicamba increased the chlorophyll content, but only for one line was this effect significant irrespective of the dose. In the dry year the double dose caused a significant increase in this genotype, but the chlorophyll contents of the other lines did not differ significantly from the control.