The double staining of plant peroxidase and other proteins in the same polyacrylamide gel

We present a simple and rapid technique for the double staining of plant peroxidase and other proteins in the same polyacrylamide gel using the principle of iodide oxidation followed by Coomassie Blue counterstain. The colored bands of peroxidase isozymes and proteins are easily distinguishable. An additional benefit of the method is the use of the low cost chemicals, as well as it eliminates the need for a potentially hazardous reagents frequently used in the detection of peroxidase isozymes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Immunohistochemical localization of the stress-related anionic peroxidase in germinating cucumber seeds

The distribution of the stress-related anionic peroxidase in the course of cucumber (Cucumis sativus L.) seed germination was determined by tissue printing and immunoblotting. Of the three molecular forms of cucumber stress-related anionic peroxidase, the form PRX 1 was temporally accumulated in developing seedlings. Up to 6 d of germination PRX 1 was localized mainly in roots. As germination progressed, the immunoreactive PRX 1 signal was found in the transition zone between roots and stem, as well as in the lower epidermis of expanding cotyledons at the midrib. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cytokinin-like effects of caffeine in bioassays

Cytokinin-like effects of pure caffeine were tested in bioassays specific for this hormonal activity [radish cotyledon growth and chlorophyll (Chl) biosynthesis in cucumber cotyledon and tobacco cell suspension] and in cell elongation bioassays [elongation of segments from soybean internode and internode elongation in dwarf cultivars of guandu (Cajanus cajan) and mucuna (Mucuna deeringiana)]. 6-Benzyl-aminopurine and kinetin (KIN) were used for comparison with caffeine. Although weaker than those given by cytokinins, positive responses were observed in all specific bioassays and in elongation of soybean internodes. A remarkable synergistic effect between caffeine and KIN was observed for the synthesis of Chl in the tobacco cell suspension bioassay, in which different concentrations of the alkaloid were combined with a single concentration of KIN. The hormone-like effect of caffeine might be related to the resemblance between caffeine and adenine derivatives. This revised version was published online in August 2006 with corrections to the Cover Date.     

Field observations on nitrogen catch crops. I. Potential and actual growth and nitrogen accumulation in relation to sowing date and crop species

In temperate climates with a precipitation surplus during autumn and winter, nitrogen catch crops can help to reduce nitrogen losses from cropping systems by absorbing nitrogen from the soil and transfer it to a following main crop. The actual and potential accumulation of dry matter and nitrogen in catch crops were studied in the field during four seasons with winter rye (Secale cereale) and forage rape (Brassica napus ssp. oleifera (Metzg.) Sinsk) or oil radish (Raphanus sativus spp. oleiferus (DC.) Metzg.). Sowing dates were end of August and three and six weeks later. Potential nitrogen accumulation, Y (g m^-2), could be summarized with Y = 96 –0.34 X, where X is the day number in the year of the sowing date (range: late August till end of September). Species were compared in their performance, looking at differences in specific leaf area, leaf weight ratio, leaf area ratio, light extinction and persistence during frost. The rate of dry matter accumulation in intervals of 14 days appeared to be determined primarily by the amount of radiation intercepted. A regression, forced through the origin, gave as a common slope 1.12 g dry matter accumulated per MJ intercepted global radiation, irrespective of season, species, sowing date or nitrogen treatment (period from ca. day 250 to day 310). From this result the inference is made that leaf expansion is a key process, determining the performance of catch crop species under varying environmental conditions.     

Multiple alleles for zucchini yellow mosaic virus resistance at the zym locus in cucumber

 Sources of resistance to several potyviruses have been identified and characterized within the cucumber (Cucumis sativus L.) germplasm. Resistance to zucchini yellow mosaic virus (ZYMV) is present in inbred lines derived from the Dutch hybrid Dina (Dina-1) and from the Chinese cultivar ‘Taichung Mou Gua’ (TMG-1). Tests of allelism indicated that the genes for resistance to ZYMV in TMG-1 and Dina-1 are at the same locus; however, the two genotypes exhibited different phenotypes in response to cotyledon inoculation with ZYMV. Dina-1 exhibited a distinct veinal chlorosis and accumulation of virus limited to the first and/or second true leaves, while TMG-1 remained symptom-free and did not accumulate virus. The distinct veinal chlorosis phenotype in Dina-1 was dominant to the symptom-free phenotype in TMG-1 and was shown not to be due to a separate gene. These results indicate that a series of alleles differing in effectiveness and dominance relationships occurs at the zym locus such that Zym>zym ^Dina>zym ^TMG-1. In addition to ZYMV resistance, TMG-1 is also resistant to watermelon mosaic virus (WMV), the watermelon strain of papaya ringspot virus (PRSV-W) and the Moroccan watermelon mosaic virus (MWMV); the WMV and MWMV resistances are at the same locus, or tightly linked to the zym locus. Dina-1 also was found to be resistant to PRSV-W and MWMV. The gene for MWMV resistance in Dina-1 appeared to be at the same locus or tightly linked (<1% recombination) to the gene for ZYMV resistance. In contrast to the response to ZYMV inoculation, Dina-1 does not exhibit distinct veinal chlorosis when inoculated with PRSV-W or MWMV. Collectively, these observations suggest that the gene(s) conferring resistance to ZYMV, WMV, and MWMV may be part of a gene cluster for potyvirus resistance in cucumber. Received: 12 November 1996 / Accepted: 25 April 1997     

Involvement of Ca2+-calmodulin in Cd2+ toxicity during the early phases of radish (Raphanus sativus L.) seed germination

The toxicity of Cd²⁺in vivo during the early phases of radish (Raphanus sativus L.) seed germination and the in vitro Cd²⁺ effect on radish calmodulin (CaM) were studied. Cd²⁺ was taken up in the embryo axes of radish seeds; the increase in fresh weight of embryo axes after 24 h of incubation was inhibited significantly in the presence of 10 mmol m^?3 Cd²⁺ in the external medium, when the Cd²⁺ content in the embryo axes was c. 1.1 μmol g^?1 FW. The reabsorption of K⁺, which characterizes germination, was inhibited by Cd²⁺, suggesting that Cd²⁺ affected metabolic reactivation. The slight effect of Cd²⁺ on the transmembrane electric potential of the cortical cells of the embryo axes excluded a generalized toxicity of Cd²⁺ at the plasma membrane level. After 24 h of incubation, Cd²⁺ induced no increase in total acid-soluble thiols and Cd²⁺-binding peptides able to reduce Cd²⁺ toxicity. Ca²⁺ added to the incubation medium partially reversed the Cd²⁺-induced inhibition of the increase in fresh weight of embryo axes and concomitantly reduced Cd²⁺ uptake. Equilibrium dialysis experiments indicated that Cd²⁺ bound to CaM and competed with Ca²⁺ in this binding. Cd²⁺ inhibited the activation of Ca²⁺-CaM-dependent calf-brain phosphodiesterase, inhibiting the Ca²⁺-CaM active complex. Cd²⁺ reduced the binding of CaM to the Ca²⁺-CaM binding enzymes present in the soluble fraction of the embryo axes of radish seeds. The possibility that Cd²⁺ toxicity in radish seed germination is mediated by the action of Cd²⁺ on Ca²⁺-CaM is discussed in relation to the in vivo and in vitro effects of Cd²⁺.     

热胁迫下萝卜不同耐热性品种细胞组织结构比较

利用显微及扫描电镜方法,研究热胁迫下萝卜不同耐热性品种外部形态,叶片及叶柄组织细胞结构的差异,耐热性品种比感热性品种叶表皮气孔密度大,体积小和开度小,部分呈关闭状态,叶片厚,叶肉细胞排列紧密,叶肉细胞很少出现质壁分离;耐热品种叶柄内维管束总面积是感热性品种的１．５倍以上,具发达的形成层及厚壁组织。     

酚酸物质对黄瓜幼苗及枯萎病菌菌丝生长的影响

研究了不同连作年限大棚土壤中酚酸物质的种类、含量及其对黄瓜幼苗和枯萎病菌菌丝生长的影响。结果表明:土壤中香草酸、对羟基苯甲酸及阿魏酸随黄瓜连作年限增加而呈现积累趋势;在连作7年的大棚土壤中3种酚酸类物质总量达29.8mg.kg-1干土,显著高于连作1年和3年土壤中的含量;酚酸物质可使黄瓜幼苗根长及茎粗显著降低,使株高及干物质量略有下降。与对照相比,酚酸物质使黄瓜幼苗体内过氧化物酶(POD)活性在短期内升高,5d后又呈下降趋势;对超氧化物歧化酶(SOD)活性的影响也表现出先升高后下降的变化趋势。高浓度酚酸使黄瓜幼苗丙二醛(MDA)含量持续升高。枯萎病菌菌丝生长测定表明:42h内,低浓度(≤50mg.L-1)酚酸对枯萎病菌丝生长有刺激作用;酚酸浓度高于50mg.L-1时,对菌丝生长有抑制作用;随酚酸处理时间延长,枯萎病菌对酚酸物质的耐受性增强,对高浓度酚酸的生长抑制作用表现不明显。     

The use of image analysis to monitor the germination of seeds of broccoli (Brassica oleracea) and radish (Raphanus sativus)

To study broccoli and radish seed germination under different temperature regimes the germination test has been used to assess final germination percentage, start and rate. This method has been integrated with a computer‐aided image analysis test which is more accurate in monitoring the extent of imbibition phases through the assessment of seed area increase and timing of radicle emergence detected on single seeds. In addition, seed area increase has been used also to establish a close relationship with radicle elongation rate in the time range when ‘visible germination’ is scored by a classical germination test. The results suggest that this image analysis parameter may be considered as a reliable seed imbibition marker to integrate the germination parameters obtained by a germination test.