Phosphate deficiency-dependent upregulation of UDP-glucose pyrophosphorylase genes is insensitive to ABA and ethylene status in Arabidopsis leavesCiereszko, Iwona; Kleczkowski, Leszek
doi: 10.1007/BF02706620pmid: N/A
The effects of inorganic phosphate (Pi) deficiency and ABA/ethylene status on expression of UDP-glucose pyrophosphorylase (UGPase) genes (Ugp), involved in sucrose/polysaccharide metabolism, were investigated. Both wild-type (wt), aba and abi mutants (ABA-deficient and -in-sensitive), etr, ein and eto (ethylene resistant and overproducing) grown on Pi-deficient and complete nutrient solution, as well as phol (Pi-deficient) mutants of Arabidopsis thaliana were used for experiments. Generally, Pi-deficiency conditions (including mannose feeding to decrease cytosolic Pi pool) resulted in an increase of Ugp expression in the leaves, under all experimental conditions. Mutant backgrounds reflecting differences in ABA or ethylene status/ sensitivity had no effect on the level of Ugp up-regulation by Pi-stress. Furthermore, feeding ABA to the leaves of wt and pho1 plants had no effect on Ugp expression, regardless of the sucrose status in the leaves. The data suggest that Pi deficiency leading to up-regulation of Ugp acts independently of ABA and ethylene status.
Effect of abscisic acid and ontogenic phases of the host alga on the infection process in the pathosystem Scenedesmus acutus — Phlyctidium scenenedesmiPouneva, Irina
doi: 10.1007/BF02706621pmid: N/A
The parasite contamination make difficult laboratory cultivation of green algae and decrease significantly the production of microalgal biomass during industrial cultivation. In the present study the influence of the endogenous abscisic acid content (determinate by gas chromatography) on the host-parasite relationship in different ontogenetic phases of the host Scenedesmus as well as resistance induction after treatment of synchronous algal culture with ABA were studied. Synchronization of algae was carried out by alteration of light and dark periods. The age groups under study were: autospores (at the beginning of the light period), growing cells, mature cells (belonging to in the end of the light period) and mature cells, starting to release autospore at the beginning of dark phases. The higher levels of endogenous ABA during the algal autospore formation as well as exogenous ABA supply of (10−5 M) inhibited the infection process in the pathosystem green microalga Scenedesmus acutus and unicellular fungal parasite Phlyctidium scenedesmi. The treatment with fluridone 10−7 M (an inhibitor of ABA biosynthesis) increased the host susceptibility during all ontogenetic phases. The susceptibility of S. acutus to the chytridial infection depended on the endogenous ABA level during different ontogenetic stages of the alga.
Responses in ion leakage of wild sugarcane (Saccharum spontaneum L.) clones to enhanced ultraviolet-B radiation under field conditionsLi, Yuan; Zu, Yanqun; He, Yongmei; Chen, Haiyan; Chen, Jianjun; Li, Fusheng; He, Lilian
doi: 10.1007/BF02706622pmid: N/A
Field studies were conducted to determine the potential for alterations in ion leakage and the intraspecific variation in ion leakage sensitivity of 20 wild sugarcane clones (Saccharum spontaneum L.) to enhanced ultraviolet-B (UV-B, 280–315nm) radiation in two consecutive years. The clones were collected from original sites with different altitude (from 0 to 1650 m) and latitude (from 18–37 °N). The supplemental UV-B radiation was 5.00 kJ m−2, simulating a depletion of 20 % stratospheric ozone. Across all clones tested in the present study, a significant change (P<0.01 or 0.05) in ion leakage for 11 in tillering, 14 in elongation and 15 in flowering in 2003, and for 9 in tillering, 5 in elongation and 5 in floweing in 2004 were observed. In general, intraspecific responses of ion leakage of wild sugarcane clones to enhanced UV-B radiation existed under field conditions for two consecutive years, although intraspecific difference in 2003 was more obvious than that in 2004. Wild sugarcane clones originating from lower latitude or high elevation were not necessarily the more tolerant to enhanced UV-B radiation.
Is quantity of protein in barley forms determined by proteins localized in the subaleurone layer?Macewicz, Jerzy; Orzechowski, Sławomir; Dobrzy ska, Urszula; Haebel, Sophie
doi: 10.1007/BF02706623pmid: N/A
Barley biotypes from the world collection differ in their storage protein content even till 200 %. This is the first report including results of the research, in which the structure of grains containing different amount of protein was tested to explain this difference. The endosperm was investigated using scanning electron microscopy. The structure of the aleurone layer, storing large quantities of protein, did not differ between the high- and low-protein forms of barley. It has been proven that the large quantities of kernel protein may be stored in some cells of the zone adjacent to the aleurone layer, defined as the subaleurone cells. It has been shown that morphologically uniform kernels of the same plant and even of the same ear can vary greatly with respect to the number of these subaleurone cells. The purpose of the study was an examination of variation in protein structure in single kernels of a fodder, a brewery and in an extra high-protein form of barley as well. Moreover the studies were aimed to detect qualitative differences in the subaleurone protein. Application of mass spectrometry made possible the identification of several kinds of proteins which were present in subaleurne layer of kernels. In the granule-bound protein fraction isolated from the subaleurone type kernels, a much stronger representation of some protein was found, with the molecular mass between 29 and 45 kDa, in comparison with the low-protein kernels. It is supposed, that these protein are isoforms of z-type serpin and B3-hordein.
Evidence for a role of Ethylene-Insensitive 2 gene in the regulation of the oxidative stress response in ArabidopsisCao, Shuqing; Jiang, Shaotong; Zhang, Rongxian
doi: 10.1007/BF02706624pmid: N/A
The Arabidopsis Ethylene-Insensitive 2 (EIN2) gene has been shown to be involved in mediating the oxidative stress response; however, little is known about the underlying mechanisms involved. In this study, we found that the ethylene-insensitive mutant ein2-1 showed enhanced tolerance to oxidative stresses caused by both paraquat (PQ) and hydrogen peroxide as well as alleviated oxidative damage. Moreover, higher transcript levels of a choroplast Cu/Zn superoxide dismutase gene CSD2 and a catalase gene CAT3 and, consequently, higher activities of superoxide dismutase (SOD) and catalase (CAT), were detected in ein2-1 plants than in wild-type plants in the absence or presence of PQ. These results suggest that the ein2-1 mutation results in constitutive activation of CSD2 and CAT3 genes and increases in the activities of SOD and CAT and, consequently, enhanced oxidative stress tolerance.
Responsive regions for direct organogenesis in sunflower cotyledonsVega, Tatiana; Nestares, Graciela; Zorzoli, Roxana; Picardi, Liliana
doi: 10.1007/BF02706625pmid: N/A
Regeneration efficiency from three different regions of cotyledonary explants was examined in six sunflower inbred lines. Proximal, middle and distal regions from seedling cotyledons were cultured on regeneration medium supplemented with growth regulators. Plant regeneration by direct organogenesis was observed after four weeks. Significant differences among inbred lines were found for regeneration percentage and average number of shoots per total explants. Also a decreasing regeneration capacity was observed from proximal to distal sections for all inbred lines. Regeneration ability from cotyledonary explants in this species is strongly influenced by the genotype and by the region from which the explant was obtained. The distance to the cotyledonary node plays a preponderant role in the expression of shoot forming capacity. Shoot differentiation via seedling cotyledons depends upon the presence of the proximal region of cotyledon regardless of the genotype.
Influence of different temperatures on bud break and 1-aminocyclopropane-1-carboxylic acid content of young peach treesEl-Shereif, Ali; Mizutani, Fusao; Onguso, Justus; Sharif Hossain, A.
doi: 10.1007/BF02706629pmid: N/A
Effects of different temperatures on bud break and 1-aminocyclopropane-1-carboxylic acid (ACC) content were determined by using potted two-year-old ‘Akatsuki’ peach trees. One group of trees were subjected to 1°C for four weeks and then transferred to a growth chamber at 24°C, while the other was kept at 24 °C throughout the experiment. After four-week temperature treatments floral and vegetative bud break were evaluated weekly and bud break percentage was calculated. Bud break was greater under 1 °C than 24 °C in both November and December. The time required to release buds from dormancy was shorter in December than November. In November ACC content in peach buds increased after one and two weeks, then decreased in the forth week under both treatments. However, in December ACC content after two and four weeks showed a similar trend under 1 °C and a reverse trend under 24 °C. It was higher under low temperature treatment. These data indicate that chilling requirements for bud break of peach seems to be associated with the promotion of ethylene biosynthesis caused by low temperature stress.