Dehydrins associated with the development of frost resistance of Asian white birch

Seasonal changes in the content of dehydrins in Asian white birch (Betula platyphylla Sukacz.) growing under extreme cold conditions of Eastern Siberia (Central Yakutia) were studied for the first time by SDS-PAGE and immunoblotting. Several polypeptides, including putative storage proteins, which content was higher in winter than in other periods, were observed. Intraspecies polymorphism of dehydrins was detected during plant dormancy. The two groups of dehydrins were found: dehydrins with mol wts of 56-73 kD, which were present year-round, and dehydrins with mol wts of 15–21 kD, evidently related to the development of frost resistance because they were absent in summer but present in large amounts in winter. Under low winter temperatures, the highest level of dehydrins coincided with the lowest content of water in buds, which was accompanied by increased plant frost resistance to the highest values.     

Characterization of the mitochondrial genome of the MAX1 type of cytoplasmic male-sterile sunflower

Background

More than 70 cytoplasmic male sterility (CMS) types have been identified in Helianthus, but only for less than half of them, research of mitochondrial organization has been conducted. Moreover, complete mitochondrion sequences have only been published for two CMS sources – PET1 and PET2. It has been demonstrated that other sunflower CMS sources like MAX1, significantly differ from the PET1 and PET2 types. However, possible molecular causes for the CMS induction by MAX1 have not yet been proposed. In the present study, we have investigated structural changes in the mitochondrial genome of HA89 (MAX1) CMS sunflower line in comparison to the fertile mitochondrial genome.

Results

Eight significant major reorganization events have been determined in HA89 (MAX1) mtDNA: one 110 kb inverted region, four deletions of 439 bp, 978 bp, 3183 bp and 14,296 bp, respectively, and three insertions of 1999 bp, 5272 bp and 6583 bp. The rearrangements have led to functional changes in the mitochondrial genome of HA89 (MAX1) resulting in the complete elimination of orf777 and the appearance of new ORFs - orf306, orf480, orf645 and orf1287. Aligning the mtDNA of the CMS sources PET1 and PET2 with MAX1 we found some common reorganization features in their mitochondrial genome sequences.

Conclusion

The new open reading frame orf1287, representing a chimeric atp6 gene, may play a key role in MAX1 CMS phenotype formation in sunflower, while the contribution of other mitochondrial reorganizations seems to appear negligible for the CMS development.

     

Effect of Chitosan on Systemic Viral Infection and Some Defense Responses in Potato Plants

The development and the possible mechanism of the chitosan-induced resistance to viral infection were investigated in potato plants. The plants were sprayed with a solution of chitosans (1 mg/ml) with the mol wt of 3, 36, and 120 kD. After 1, 2, 3, or 4 days, the treated leaves were cut off and mechanically infected with the potato virus X (PVX). The disks cut out from the inoculated leaves were used for determining virus accumulation, callose content, and ribonuclease and -1,3-glucanase activities. In another set of experiments, the plants were infected with PVX within 1, 4, or 8 days after chitosan treatment, and the number of systemically infected plants was determined. It was found that, a day after treatment, the plants acquired a resistance to viral infection. The disks from the chitosan-treated leaves, as compared to the control, accumulated less amount of virus. The chitosan treatment also significantly decreased the number of systemically infected plants as compared to the control. After 2–3 days, the resistance disappeared or even gave way to an increased susceptibility to the infection; subsequently, the resistance increased again. The extent of the resistance correlated with the callose content and the level of ribonuclease activity observed on the infection day. The resistance towards the infection with PVX is probably mediated by the callose and ribonuclease induction. The cultivation of test-tube potato plants from the cuttings previously infected with PVX on the chitosan-containing nutrient medium did not eradicate the viral infection from the plants.     

DNA barcoding the native flowering plants and conifers of Wales

We present the first national DNA barcode resource that covers the native flowering plants and conifers for the nation of Wales (1143 species). Using the plant DNA barcode markers rbcL and matK, we have assembled 97.7% coverage for rbcL, 90.2% for matK, and a dual-locus barcode for 89.7% of the native Welsh flora. We have sampled multiple individuals for each species, resulting in 3304 rbcL and 2419 matK sequences. The majority of our samples (85%) are from DNA extracted from herbarium specimens. Recoverability of DNA barcodes is lower using herbarium specimens, compared to freshly collected material, mostly due to lower amplification success, but this is balanced by the increased efficiency of sampling species that have already been collected, identified, and verified by taxonomic experts. The effectiveness of the DNA barcodes for identification (level of discrimination) is assessed using four approaches: the presence of a barcode gap (using pairwise and multiple alignments), formation of monophyletic groups using Neighbour-Joining trees, and sequence similarity in BLASTn searches. These approaches yield similar results, providing relative discrimination levels of 69.4 to 74.9% of all species and 98.6 to 99.8% of genera using both markers. Species discrimination can be further improved using spatially explicit sampling. Mean species discrimination using barcode gap analysis (with a multiple alignment) is 81.6% within 10×10 km squares and 93.3% for 2×2 km squares. Our database of DNA barcodes for Welsh native flowering plants and conifers represents the most complete coverage of any national flora, and offers a valuable platform for a wide range of applications that require accurate species identification.     

Immunochemical determination of placenta-specific and interorganic antigens in placental extract and blood serum in pregnant rats

It has been demonstrated that placenta extract of rats contains up to 14 antigens. Moreover, 11 of them are interorgan proteins of wide and limited specificity, two antigens (alpha 1- and alpha 2-globulins) are attributed to acute-phase proteins typical for pregnancy. beta 1-Globulin is a specific protein of rat placenta. The content of these antigens in blood serum increases with pregnancy and reaches a maximum toward the delivery; 3-4 days after delivery beta 1-globulin disappears completely from maternal blood, whereas the concentration of acute-phase proteins drops to the initial level.     

Dehydrin stress proteins in <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. needles under conditions of extreme climate of Yakutia

This is the first study to investigate stress proteins dehydrins with the use of specific antibodies in the Scots pine (Pinus sylvestris L.) needles and their changes in the annual cycle under extreme climate of Yakutia. No pronounced polymorphism of major dehydrins (14–15 and 66 kDa) has been found during the winter dormancy period of P. sylvestris. A clear correlation between the seasonal variations in dehydrins and changes in the water content in needles was revealed. Consistently high levels of dehydrins was retained throughout the period of low negative temperatures. It is assumed that dehydrins can participate in the formation of P. sylvestris L. resistance to the permafrost conditions.