Red rice (Oryza sativa L.) and barnyardgrass (Echinochloa spp.) biotype susceptibility to postemergence-applied imazamox

Pot experiments were conducted to evaluate the level of imazamox tolerance in five red rice ( Oryza sativa L.) and four barnyardgrass (three Echinochloa crus-galli (L.) Beauv. and one Echinochloa oryzoides (Ard.) Fritch) morphologically distinct biotypes collected from rice fields in northern Greece. The susceptibility of barnyardgrass biotypes to propanil was also studied. Red rice biotypes were not controlled by imazamox applied at 40 g ha⁻¹. In contrast, 80 g imazamox ha⁻¹ provided 56–84% red rice control (averaged across shoot number and fresh weight reduction). Not all barnyardgrass biotypes were susceptible to imazamox applied postemergence. However, propanil applied at 2.6 kg ha ⁻¹ controlled the E. crus-galli biotypes well, but propanil applied at rates of 2.6 and 5.2 kg ha ⁻¹ was not effective in reducing the shoot number and fresh weight of the E. oryzoides biotype. Propanil applied at 10.4 kg ha ⁻¹ reduced the shoot number and fresh weight of this biotype by 78 and 85%, respectively. In most cases, a linear equation ( y  = % of control, x  = g ha⁻¹) provided the best fit for regressions between red rice or barnyardgrass shoot number or fresh weight and imazamox rates. The results of this study suggest that postemergence application of imazamox is not effective against all red rice and barnyardgrass biotypes found in the rice fields of Greece and that significant variability regarding herbicide efficacy among biotypes might exist.     

水稻旱作对其生长量和经济产量的影响

1998～1999年，研究了水稻旱作条件下，不同生育时期受水分胁迫后对作物生长量的影响。结果表明：不同指标对水分胁迫时期的敏感性不一，植株高度对抽穗期水分胁迫最敏感；单株绿叶面积和单株地上部干重对幼穗分化后期水分胁迫最敏感；根系干重和根冠比对幼穗分化前期水分胁迫最敏感；幼穗分化后期水分胁迫对经济产量影响程度最大，无效分蘖期水分胁迫对产量影响程度最小。     

天然芸苔素内酯缓解胺苯磺隆对后茬水稻药害的作用机理初探

通过测定天然芸苔素内酯对水稻幼苗谷胱甘肽(GSH)含量、谷胱甘肽-S-转移酶(GST)活性以及在离体和活体条件下对水稻幼苗乙酰乳酸合成酶(ALS)活力的影响,研究天然芸苔素内酯减轻胺苯磺隆对水稻药害的作用机理。结果表明,其作用机理与水稻幼苗GSH含量、GST活性变化没有太大相关性,可能与其能间接激活水稻幼苗ALS活力有较大相关。     

Biological characteristics of long passaging rat mesenchymal stem cells

AIM:To investigate multi-potential of rat bone marrow mesenchymal stem cells (rBMMSC) and mutation inclination, the rBMMSC were long passaged in vitro. METHODS:Cellular cycles of different passages were assayed by FACSan flow cytometry and karyotypes of passage 6, passage 25 and passage 45 were compared by G-binding analysis. RESULTS:The early passages and long-term passages all showed strong proliferation; passage 6, passage 25 and passage 45 all showed normal karyotype. CONCLUSION:Long-term culture and passage of rBMMSC still remains strong proliferation. With this capability, the mutation inclination is not enhanced.     

Effects of TGF-β1 and TNF-α antisense PS-ODNS on ex vivo expansion of hematopoietic stem/progenitor cells(HSPC)

AIM:To study the effect of TGF-β₁ and TNF-α antisense PS-ODNS on ex vivo expansion of hematopoietic stem/progenitor cells (HSPC). METHODS:CD₃₄⁺cells were purified from fresh umbilical cord blood by immunomagnetic beads, and mononuclear cells were purified from bone marrow by Ficoll-hypaque. The effects of TGF-β₁ and /or TNF-α antisense PS-ODNS on ex vivo expansion of CD₃₄⁺ cells、CFU-GEMM、CFU-GM、CFU-E and BFU-E were detected by using liquid and semi-solid culture systems.RESULTS:TGF-β₁ antisense PS-ODNS cooperated with cytokines increased the number of CD₃₄⁺ cells, CFU-GEMM, CFU-GM, CFU-E and BFU-E, which was as 4, 2.6, 2.7, 1.8, 2.1 times as that of the control (the cytokines combination), respectively. TNF-α antisense PS-ODNS cooperated with cytokines respectively increased the number of CD₃₄⁺ cells, CFU-GEMM, CFU-GM, CFU-E and BFU-E by 4, 2.9, 2.6, 1.7, 1.8 times as that of the control. The above two antisense PS-ODNS cooperated with cytokines could respectively increased the number of CD₃₄⁺ cells, CFU-GEMM, CFU-GM, CFU-E and BFU-E by 5.3, 2.1, 2.7, 1.9, 1.8 times as that of the control.CONCLUSION:Inhibition of endogenous TGF-β₁ and TNF-α by antisense PS-ODNS will be one of the effective methods to expand HSPC ex vivo.     

Alternative Route of Infection for Bacterial Seedling Blight of Rice Caused by Burkholderia plantarii

Burkholderia plantarii , the pathogen of bacterial seedling blight of rice, was detected in paddy water. Its concentration rose in July and August. The bacterial concentration in the paddy water was always higher along levees than at distances more than 5 m from levees. Confirmed to be released into water when graminaceous weeds were immersed, B. plantarii survived for at least 4 days at 30°C. B. plantarii was splashed at least 30 cm upward by rain splash in the field. Harvested seeds, which had been sprayed with B. plantarii released from graminaceous weeds at the flowering stage, retained the bacteria. Bacterial seedling blight occurred when the seeds were then sown in nursery boxes. These results indicated that graminaceous weeds growing on levees of paddy fields are a source of infection of the disease and that rice seeds are infected through the paddy water. Received 23 May 2002/ Accepted in revised form 1 September 2002     

Detection of Colletotrichum coccodes from soil and potato tubers by conventional and quantitative real-time PCR

Colletotrichum coccodes is the causal agent of the potato blemish disease black dot. Two PCR primer sets were designed to sequences of the ribosomal internal transcribed spacer (ITS1 and ITS2) regions for use in a nested PCR. The genus-specific outer primers (Cc1F1/Cc2R1) were designed to regions common to Colletotrichum spp., and the species-specific nested primers (Cc1NF1/Cc2NR1) were designed to sequences unique to C . coccodes . The primer sets amplified single products of 447 bp (Cc1F1/Cc2R1) and 349 bp (Cc1NF1/Cc2NR1) with DNA extracted from 33 European and North American isolates of C. coccodes. The specificity of primers Cc1NF1/Cc2NR1 was confirmed by the absence of amplified product with DNA of other species representing the six phylogenetic groups of the genus Colletotrichum and 46 other eukaryotic and prokaryotic plant pathogenic species. A rapid procedure for the direct extraction of DNA from soil and potato tubers was used to verify the PCR assay for detecting C. coccodes in environmental samples. The limit of sensitivity of PCR for the specific detection of C. coccodes when inoculum was added to soils was 3·0 spores per g, or the equivalent of 0·06 microsclerotia per g soil, the lowest level of inoculum tested. Colletotrichum coccodes was also detected by PCR in naturally infested soil and from both potato peel and peel extract from infected and apparently healthy tubers. Specific primers and a TaqMan fluorogenic probe were designed to perform quantitative real-time (TaqMan) PCR to obtain the same levels of sensitivity for detection of C. coccodes in soil and tubers during a first-round PCR as with conventional nested PCR and gel electrophoresis. This rapid and quantitative PCR diagnostic assay allows an accurate estimation of tuber and soil contamination by C. coccodes .     

Growth and development of Cuscuta chinensis Lam. and its impact on selected crops

The growth and development of Cuscuta chinensis Lam., and the effects of the holoparasite on the growth and yield of tomato ( Lycopersicon esculentum ), chilli ( Capsicum annuum ) and rice ( Oryza sativa ) were investigated in pot experiments under glasshouse conditions. 'Mature' and 'immature' seeds of C. chinensis showed 15 and 47% germination, respectively. The independent life duration of seedlings from 'immature' seeds was 6 days shorter than 'mature' seeds (19 days). Cuscuta chinensis formed haustoria on chilli and tomato, but not on rice seedlings. Infection with three C. chinensis seedlings per host plant reduced leaf area, dry weight, carbon and nitrogen content by 78–84% and 27–44% in tomato and chilli plants, respectively. Dry weight of C. chinensis was 0.63 g per pot in tomato, and 0.24 g per pot in chilli. Carbon and nitrogen content of C. chinensis was 0.189 and 0.028 g per pot, respectively, when grown with tomato. When it was grown with chilli, the carbon and nitrogen content of C. chinensis was 0.001 and 0.007 g per pot, respectively. Cuscuta chinensis reduced the fruit yield of tomato and chilli by 72 and 29%, respectively. The results indicated that tomato is a preferred host of C. chinensis compared with chilli, and rice is not preferred. In the host–parasite associations, C. chinensis suppressed growth and yield of chilli and tomato by diverting the elaborated products of metabolism of the hosts.