Int. J. Plant Biol., Volume 4, Issue 1 (September 2013) – 6 articles

The potential to enhance growth of cold stressed wheat by seed treatment (priming) with the beneficial bacteria Bacillus amyloliquefaciens 5113 and Azospirillum brasilense NO40 were tested. Results showed an improved ability of bacteria-treated seedlings to survive at −5 °C up to 12 h. Cold stress increased transcript levels of three stress marker genes and increased activity for the ascorbate-glutathione redox enzymes. However, primed and stressed seedlings generally showed smaller effects on the stress markers correlating with better growth and improved stress tolerance. Bacterial priming to improve crop plant performance at low temperature seems a useful strategy to explore further. Full article

During fall leaf senescence in deciduous species, photosynthesis nears completion due to chlorophyll breakdown and re-assimilation. However, several other processes such as leaf nutrient uptake, re-translocation, and storage, or tissue dehydration to avoid frost damage, may be important and dependent upon stomatal opening. We report here on measured changes in photosynthesis (A), leaf conductance to water vapor (g), and WUE (estimated by A/g) in three deciduous tree species (Acer saccharum, Cornus florida, and Ginkgo biloba) during the weeks of leaf senescence preceding abscission. Substantial decreases in A of 60 up to 80% were not matched quantitatively by similar declines in g (40 to 70%), resulting in corresponding decreases in WUE (estimated by A/g) from near 50% to over 300% among the three species. This shift to a lower WUE may reflect adaptive value in maintaining a higher g relative to A during the fall leaf senescence period. Full article

Prune dwarf virus (PDV) is one of the major positive RNA viruses which cause economical damages in stone fruit trees. The symptoms of PDV vary between different stone fruits namely sour and sweet cherry, almond, peach, apricot and plum including leaf narrowing, leaf chlorosis, vein clearing, mosaic, leaf whitening, leathery leaf, bushy branches and stunt trees. During the years 2011 and 2012, 251 leaf samples were collected for detection of PDV in stone fruit orchards of Charmahal-va-Bakhtiari province. DAS-ELISA test proved PDV presence serologically. Then, total RNA were extracted and tested by two-step RT-PCR which replicated partial and full coat protein sequence of PDV. One hundred and eighty one out of total samples (251 samples) showed PDV infection using serological and two-step RT-PCR assays, hence, incidence of PDV in Charmahal-va-Bakhtiari province was confirmed. This is the first report of PDV in stone fruit orchards of Charmahal-va-Bakhtiari province and in Iran. Full article

Allelopathy is an important mechanism of interference competition in some plants, but little is known about whether compounds exuded from seeds influence the germination of neighbors. We treated seeds of multiple lines of Brassica rapa (field mustard) with aqueous extracts of Brassica rapa Fast Plant seeds and extracts of seeds of the invasive, allelopathic plant Alliaria petiolata (garlic mustard). Germination patterns differed significantly among populations, with Fast Plants germinating earliest. As predicted, Alliaria seed extracts significantly delayed germination compared to controls. Surprisingly, Fast Plant extracts reduced germination probability and delayed germination more than both controls and Alliaria extract-treated seeds. These results suggest that compounds in the seeds of both species appear to be allelopathic, and indicate a potentially important and unrecognized role for allelopathy in intra- and inter- specific competition at the seed stage. Full article

DREB transcription factors (TF) belong to the superfamily of AP2/ERF and their involvement in protein-protein interactions and DNA binding has been proposed. AP2/ERF proteins have important functions in the transcriptional regulation of a variety of biological processes related to growth and development, as well as various responses to environmental stimuli, regulating expression of plant biotic and abiotic stress-responsive genes. In this study an AP2/ERF TF gene (named RcDREB1) was isolated from castor bean (Ricinus communis L.) and its expression was analyzed in developing seeds, leaves, ovules, stems and petals of plants cultivated under field conditions. Transcripts were only observed in pollen grains, peaking during anthesis. The RcDREB1 deduced amino acid sequence was compared to other AP2/ERF TF proteins and presented 38–78% identity. Phylogenetic analysis classified it as a member of the CBF/DREB subfamily, rooting with the subgroup A-5. The RcDREB1 promoter was fused to the gus reporter gene and used to transform tobacco. Transgenic plants were exposed to various abiotic stress treatments (low and high tempera- tures, drought, salinity and exogenous ABA) and no detectable GUS expression was observed, suggesting that the RcDREB1 promoter is not active under tested conditions. In silico analyses revealed the presence of three copies of the regulatory late pollen-specific element (AGAAA) in the RcDREB1 5′-region. Interestingly, GUS expression was only observed in pollen grains, starting when the flower opened and initiating the senescence process; at this point, desiccated mature pollen grains are released from anthers. In addition, dehydrated developing pollen grains also expressed the gus gene. This is the first study on a DREB gene presenting pollen-specific expression. Full article

The use of flaxseed flours in the diets of poultry and broilers may be limited by the presence of antinutritive compounds. The content of cyanogenic glycosides, phytic acid, condensed tannins and trypsin inhibitors was evaluated in seven varieties of Linum usitatissimum. Phytic acid, condensed tannins and trypsin inhibitors showed significant differences among varieties. Only the concentration of cyanogenic glycosides and phytic acid in the flour deserves attention, while the content of condensed tannins and trypsin inhibitors are to acceptable levels. Since the flax meal is an important source of omega-3 for poultry and broilers, the cyanogenic glycoside and phytic acid contents in linseed has to be reduced to increase the ration to be included in the diet. Full article