Alpha-glucosidase inhibition from a Chinese medical herb (Ramulus mori) in normal and diabetic rats and mice

Alpha-glucosidase inhibitors are oral antidiabetic drugs. A traditional Chinese medical herb, Sangzhi (Ramulus mori), appears to have properties similar to those of alpha-glucosidase inhibitors. The effects of an aqueous extract of Shangzhi (SZ) were studied in normal and alloxan diabetic rats and mice, and these results compared with those for acarbose, an alpha-glucosidase inhibitor. In our grade-dose studies, SZ was found to lower and prolong the zenith of blood glucose concentration (ZBG) after sucrose or starch loading and stabilize blood glucose levels in fasting normal and alloxan diabetic mice. After 2 weeks of SZ administration with high-calorie chow or a normal diet, the fasting and non-fasting blood glucose concentrations in alloxan diabetic mice and rats were decreased. In alloxan rats, the blood fructosamine concentration was lowered. Results for acarbose and SZ were similar. These indicate that SZ has alpha-glucosidase inhibitory effects.     

Two related low-temperature-inducible genes of Arabidopsis encode proteins showing high homology to 14-3-3 proteins,a family of putative kinase regulators

We have isolated two Rare Cold-Inducible (RCI1 and RCI2) cDNAs by screening a cDNA library prepared from cold-acclimated etiolated seedlings of Arabidopsis thaliana with a subtracted probe. RNA-blot hybridizations revealed that the expression of both RCI1 and RCI2 genes is induced by low temperature independently of the plant organ or the developmental stage considered. However, RCI1 mRNA accumulates faster and at higher levels than the RCI2 one indicating that these genes have differential responsiveness to cold stress. Additionally, when plants are returned to room temperature, RCI1 mRNA decreases faster than RCI2. In contrast to most of the cold-inducible plant genes characterized, the expression of RCI1 and RCI2 is not induced by ABA or water stress. The nucleotide sequences of RCI1 and RCI2 cDNAs predict two acidic polypeptides of 255 and 251 amino acids with molecular weights of 29 and 28 kDa respectively. The alignment of these polypeptides indicates that they have 181 identical amino acids suggesting that the corresponding genes have a common origin. Sequence comparisons reveal no similarities between the RCI proteins and any other cold-regulated plant protein so far described. Instead, they demonstrate that the RCI proteins are highly homologous to a family of proteins, known as 14-3-3 proteins, which are thought to be involved in the regulation of multifunctional protein kinases.     

Somaclonal variation and chilling tolerance improvement in rice: Changes in fatty acid composition

The relationship between chilling tolerance of six rice cultivars – Facagro 57, Facagro 76, Fujisaka 5, Kirundo 3, Kirundo 9 and IR64 -and the fatty acid composition in total lipids, phospholipids, galactolipids and neutral lipids from leaves was studied. Higher double bond index and proportions of linolenic acid in the phospholipid and galactolipid classes were related to cultivar chilling tolerance, but this was not so for the total lipids nor the neutral lipid class. The somaclonal families derived from Facagro 76, Kirundo 3 and Kirundo 9 that showed enhanced chilling tolerance as compared to their original parental cultivar were analyzed for fatty acid composition in phospholipids and galactolipids from leaves. Altered proportions in fatty acid composition in phospholipids, galactolipids or both were found in the somaclonal families derived from Facagro 76 and Kirundo 9, but not from Kirundo 3. These changes most usually resulted in higher double bond index and higher proportions in linoleic and linolenic acids which were related either to lower ratio of C16 to C18 fatty acids or to higher unsaturation in the C18 fatty acid fraction. Different mechanisms thus seem to be implicated in the altered fatty acid composition of somaclones, which may be related to the chilling tolerance improvement of some somaclonal families.     

Uniconazole-induced thermotolerance in soybean seedling root tissue

Soybean [Glycine max(L.) Merr. cv. A2] seeds were germinated in 0 or 1 mg 1¹ (3.4 uM) uniconazole, after which seedling roots were excised and exposed to 22 or 48°C for 90 min. Prior to the temperature treatments there were few ultrastructural differences between uniconazole-treated seedling roots and the controls. Following exposure to 48°C, electron micrographs revealed near complete loss of normal ultrastructure in control epidermal root cells, whereas cellular integrity was maintained in treated roots, indicating that uniconazole conferred tolerance to high temperature. Total electrolyte, sugar and K⁺ leakage were all greater from control roots than treated roots during exposure to 48°C. Proline content in the roots was unaffected by uniconazole at 22°C but was 25–30% greater in treated tissue than in controls following exposure to 48°C. Malondialdehyde content was unaffected by uniconazole at 22°C but was nearly 20% less in treated tissue than in controls following high temperature exposure. This indicates that uniconazole decreased high-temperature-induced lipid peroxidation. Uniconazole elevated several antiox-idant systems in the roots, including water-soluble sulfhydryl concentration and catalase, peroxidase and superoxide dismutase activities. These findings are consistent with the hypothesis that uniconazole-induced stress tolerance is due, at least in part, to enhanced antioxidant activity which reduces stress-related oxidative damage to cell membranes.     

Screening of rice cultivars for Cr-stress response by using the parameters of seed germination,morpho-physiological and antioxidant analysis

Rice is the most important crop for the majority of population across the world with sensitive behavior toward heavy metals such as chromium (Cr) in polluted regions. Although, there is no information on the Cr resistance phenotyping in rice. Herein, two different groups of rice cultivars (normal, and hybrid) were used, each group with 14 different rice cultivars. Firstly, seed germination analysis was conducted by evaluating various seed germination indices to identify the rice cultivars with greatest seed germination vigor. Furthermore, exposure of chromium (Cr) toxicity to 28 different rice varieties (NV1-NV14, HV1-HV14) caused noticeable plant biomass reduction. Subsequently, NV2, NV6, NV10, NV12, NV13 (normal type), HV1, HV4, HV8, and HV9 (hybrid types) were pragmatic as moderately sensitive varieties, while NV3, NV4, NV9, and NV14 (normal type), HV3, HV6, HV7, and HV13 were observed as moderately tolerant. Although, NV7, and HV10 were ranked most sensitive cultivars, and NV11, and HV14 were considered as most tolerant varieties as compared to the other rice (both groups) genotypes. Afterward, Cr induced reduction in chlorophyll pigments were significantly lesser in HV14 relative to NV11, NV7, and especially HV10, and as a result HV14 modulated the total soluble sugar level as well as reduced ROS accumulation, and MDA contents production by stimulating the antioxidant defense mechanism conspicuously which further reduced the electrolyte leakage as well. Our outcomes provide support to explore the Cr tolerance mechanism in cereal crops as well as knowledge about rice breeding with increased tolerance against Cr stress.     

Gene flow from transgenic rice to red rice (Oryza sativa L.) in the field

In this study, we simulate a transgenic rice crop highly infested with red rice to examine transgene transfer from a transgenic line (A2504) resistant to glufosinate ammonium to cohabitant red rice. The red rice was sown along with the transgenic line at the highest density found in naturally infested crops in the region. Agricultural practices similar to those used to control red rice infestation in northern Italy rice fields were used to reproduce the local rice production system. During the first 2 years, the field was treated with herbicide at the appropriate time; in the first year the dosage of herbicide was three times the recommended amount. In this first year, detectable red rice plants that escaped herbicide treatment were manually removed. Nevertheless, two herbicide‐resistant hybrid plants (named 101 and 104) were identified in the experimental field during the second year of cultivation. Phenotypic and molecular characterisation suggests the hybrid nature of these two plants, deriving from crossing events involving A2504, respectively, with red rice (plant 101) and the buffer cultivar Gladio (plant 104). The progeny of two subsequent generations of the two plants were examined and the presence of the transgene detected, indicating stable transfer of the transgene across generations. In conclusion, despite control methods, red rice progeny tolerant to the herbicide can be expected following use of transgenic rice and, consequently, difficulties in controlling this weed with chemicals will emerge in a relatively short time.     

Organic solvent tolerance of halophilic α-amylase from a Haloarchaeon, Haloarcula sp. strain S-1

A halophilic archaeon, Haloarcula sp. strain S-1, produced extracellular organic solvent-tolerant -amylase. Molecular mass of the enzyme was estimated to be 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This amylase exhibited maximal activity at 50°C in buffer containing 4.3 M NaCl, pH 7.0. Moreover, the enzyme was active and stable in various organic solvents (benzene, toluene, and chloroform, etc.). Activity was not detected at low ionic strengths, but it was detected in the presence of chloroform at low salt concentrations. On the other hand, no activity was detected in the presence of ethyl alcohol and acetone.     

The miR156‐SPL9‐DFR pathway coordinates the relationship between development and abiotic stress tolerance in plants

Young organisms have relatively strong resistance to diseases and adverse conditions. When confronted with adversity, the process of development is delayed in plants. This phenomenon is thought to result from the rebalancing of energy, which helps plants to coordinate the relationship between development and stress tolerance; however, the molecular mechanism underlying this phenomenon remains mysterious. In this study, we found that miR156 integrates environmental signals to ensure timely flowering, thus enabling the completion of breeding. Under stress conditions, miR156 is induced to maintain the plant in the juvenile state for a relatively long period of time, whereas under favorable conditions, miR156 is suppressed to accelerate the developmental transition. Blocking the miR156 signaling pathway in Arabidopsis thaliana with 35S::MIM156 (via target mimicry) increased the sensitivity of the plant to stress treatment, whereas overexpression of miR156 increased stress tolerance. In fact, this mechanism is also conserved in Oryza sativa (rice). We also identified downstream genes of miR156, i.e. SQUAMOSA PROMOTER BINDING PROTEIN‐LIKE 9 (SPL9) and DIHYDROFLAVONOL‐4‐REDUCTASE (DFR), which take part in this process by influencing the metabolism of anthocyanin. Our results uncover a molecular mechanism for plant adaptation to the environment through the miR156‐SPLs‐DFR pathway, which coordinates development and abiotic stress tolerance.     

Genetic basis of pre-harvest sprouting tolerance using single-locus and two-locus QTL analyses in bread wheat

Quantitative trait loci (QTL) analysis for pre-harvest sprouting tolerance (PHST) in bread wheat was conducted following single-locus and two-locus analyses, using data on a set of 110 recombinant inbred lines (RILs) of the International Triticeae Mapping Initiative population grown in four different environments. Single-locus analysis following composite interval mapping (CIM) resolved a total of five QTLs with one to four QTLs in each of the four individual environments. Four of these five QTLs were also detected following two-locus analysis, which resolved a total of 14 QTLs including 8 main effect QTLs (M-QTLs), 8 epistatic QTLs (E-QTLs) and 5 QTLs involved in QTL × environment (QE) or QTL × QTL × environment (QQE) interactions, some of these QTLs being common. The analysis revealed that a major fraction (76.68%) of the total phenotypic variation explained for PHST is due to M-QTLs (47.95%) and E-QTLs (28.73%), and that only a very small fraction of variation (3.24%) is due to QE and QQE interactions. Thus, more than three-quarters of the genetic variation for PHST is fixable and would contribute directly to gains under selection. Two QTLs that were detected in more than one environment and at LOD scores above the threshold values were located on 3BL and 3DL presumably in the vicinity of the dormancy gene TaVp1. Another QTL was found to be located on 3B, perhaps in close proximity to the R gene for red grain colour. However, these associations of QTLs for PHST with genes for dormancy and grain colour are only suggestive. The results obtained in the present study suggest that PHST is a complex trait controlled by large number of QTLs, some of them interacting among themselves or with the environment. These QTLs can be brought together through marker-aided selection, leading to enhanced PHST.