Retrograde signaling by the plastidial metabolite MEcPP regulates expression of nuclear stress-response genes

Plastid-derived signals are known to coordinate expression of nuclear genes encoding plastid-localized proteins in a process termed retrograde signaling. To date, the identity of retrograde-signaling molecules has remained elusive. Here, we show that methylerythritol cyclodiphosphate (MEcPP), a precursor of isoprenoids produced by the plastidial methylerythritol phosphate (MEP) pathway, elicits the expression of selected stress-responsive nuclear-encoded plastidial proteins. Genetic and pharmacological manipulations of the individual MEP pathway metabolite levels demonstrate the high specificity of MEcPP as an inducer of these targeted stress-responsive genes. We further demonstrate that abiotic stresses elevate MEcPP levels, eliciting the expression of the aforementioned genes. We propose that the MEP pathway, in addition to producing isoprenoids, functions as a stress sensor and a coordinator of expression of targeted stress-responsive nuclear genes via modulation of the levels of MEcPP, a specific and critical retrograde-signaling metabolite.     

Sublethal effects of Beauveria bassiana on life table parameters of two–spotted spider mite,Tetranychus urticae (Acari: Tetranychidae)

Effects of the entomopathogenic fungus Beauveria bassiana were studied on life table parameters of two-spotted spider mite, Tetranychus urticae feeding on bean and cucumber under laboratory conditions. The developmental periods for all immature stages were not affected by fungal infection on each host plant but the duration of larval stage was significantly longer on bean. The female and male longevity, oviposition period and fecundity were significantly lower on fungus-treated mites but were not different between two host plants. Significant reductions were found on the intrinsic rate of increase (r _m ), the net reproductive rate (R ₀), the finite rate of increase (λ), the mean generation time (T _c ) and the population doubling time (D _t ) as a result of mycosis. Only the mean generation time (T _c ) was influenced considering the effect of host plant, which was shorter on cucumber.     

锈褐原花蝽在不同温度下的发育与积温必需条件

阿月浑子树木虱Agonoscena pistaciae Burckhardt and Lauterer （半翅目: 木虱总科）是伊朗园林树木阿月浑子树上常见的最具破坏性的害虫,其捕食性天敌锈褐原花蝽Anthocoris minki pistaciae Wagner在伊朗阿月浑子树种植区为该害虫的生防因子。本研究在17.5~35℃的8个恒温以及相对湿度55%±5%,光照周期16L∶8D的控制条件下,在A. pistaciae若虫上饲养这种捕食性花蝽的同时,调查温度对其发育的影响。结果表明：这种捕食性花蝽在17.5~32℃下可成功发育;然而在35℃下,卵不能孵化,且只有10%的若虫进入成虫阶段。30℃下从卵至成虫羽化的发育历期最短。据测算估计,这种捕食性花蝽的卵、若虫发育以及整个发育（卵至成虫）的积温分别为77,200和263度·日;卵、若虫和整个发育的低温度阈值分别为8.53, 9.2 和9.47℃。这些结果为建立阿月浑子树木虱的综合防治计划提供了宝贵的信息。     

Understanding Plant Development and Stress Responses through Integrative Approaches

As the name reflects, integrative plant biology is the core topic of JIPB. In the past few years JIPB has been pursuing the development of this area, to assist the scientific community to bring together all possible research tools to understand plant growth, development and stress responses in micro- and macro-scales. As part of these efforts, JIPB and Yantai University organized the 1st International Symposium on Integrative Plant Biology in the seaside town of Yantai during August 10-12,2009 (Figure 1). The symposium was co-sponsored by Botanical Society of China, Chinese Society for Cell Biology, Genetics Society of China, and Chinese Society for Plant Physiology.     

Overexpression of 3-ketoacyl-acyl-carrier protein synthase IIIs in plants reduces the rate of lipid synthesis

A cDNA coding for 3-ketoacyl-acyl-carrier protein (ACP) synthase III (KAS III) from spinach (Spinacia oleracea; So KAS III) was used to isolate two closely related KAS III clones (Ch KAS III-1 and Ch KAS III-2) from Cuphea hookeriana. Both Ch KAS IIIs are expressed constitutively in all tissues examined. An increase in the levels of 16:0 was observed in tobacco (Nicotiana tabacum, WT-SR) leaves overexpressing So KAS III when under the control of the cauliflower mosaic virus-35S promoter and in Arabidopsis and rapeseed (Brassica napus) seeds overexpressing either of the Ch KAS IIIs driven by napin. These data indicate that this enzyme has a universal role in fatty acid biosynthesis, irrespective of the plant species from which it is derived or the tissue in which it is expressed. The transgenic rapeseed seeds also contained lower levels of oil as compared with the wild-type levels. In addition, the rate of lipid synthesis in transgenic rapeseed seeds was notably slower than that of the wild-type seeds. The results of the measurements of the levels of the acyl-ACP intermediates as well as any changes in levels of other fatty acid synthase enzymes suggest that malonyl-ACP, the carbon donor utilized by all the 3- ketoacyl-ACP synthases, is limiting in the transgenic plants. This further suggests that malonyl-coenzyme A is a potential limiting factor impacting the final oil content as well as further extension of 16:0.     

Rapid Adsorption of Copper(II) and Lead(II) by Rice Straw/Fe3O4 Nanocomposite: Optimization,Equilibrium Isotherms,and Adsorption Kinetics Study

Rice straw/magnetic nanocomposites (RS/Fe₃O₄-NCs) were prepared via co-precipitation method for removal of Pb(II) and Cu(II) from aqueous solutions. Response surface methodology (RSM) was utilized to find the optimum conditions for removal of ions. The effects of three independent variables including initial ion concentration, removal time, and adsorbent dosage were investigated on the maximum adsorption of Pb (II) and Cu (II). The optimum conditions for the adsorption of Pb(II) and Cu(II) were obtained (100 and 60 mg/L) of initial ion concentration, (41.96 and 59.35 s) of removal time and 0.13 g of adsorbent for both ions, respectively. The maximum removal efficiencies of Pb(II) and Cu(II) were obtained 96.25% and 75.54%, respectively. In the equilibrium isotherm study, the adsorption data fitted well with the Langmuir isotherm model. The adsorption kinetics was best depicted by the pseudo-second order model. Desorption experiments showed adsorbent can be reused successfully for three adsorption-desorption cycles.