Optimal temperature drop for the growth and development of young cucumber plants

The thermomorphological responses of young cucumber plants to a temperature drop lasting 2, 4 and 6 hours applied at the beginning, in the middle and at the end of the night were examined. Plant height, leaf petiole length and plant dry weight were measured and, based on the experimental data, the regression dependences of growth variables on the temperature drop were fitted. A method to determine the optimal temperature drop (the duration and time of exposure) which results in shortened plant height and leaf petiole length without a decrease in plant dry weight is proposed.     

Slow wave potentials in cucumber differ in form and growth effect from those in pea seedlings

A positive hydraulic signal in the form of a xylem pressure step was applied to the roots of intact seedlings of Cucumis sativus L. and Pisum sativum L. Surface electrodes at three positions along the epicotyl/hypocotyl recorded a propagating depolarization which appeared first in the basal, then the central and sometimes the apical electrode positions and fitted the characteristics of a slow wave potential (SWP). This depolarization differed between pea and cucumber. It was transient in cells of pea epicotyls but sustained in cucumber hypocotyls. It was not associated with a change in cell input resistance in pea epicotyls but preceded an increase in the input resistance of cucumber hypocotyl cells. With the increased xylem pressure the growth rate (GR) of cucumber hypocotyls and pea epicotyls underwent a transient increase, peaking after 5 min. If the depolarization reached the growing upper region, it preceded a sustained decrease in the GR of cucumber hypocotyls but only a transient decrease in the GR of pea epicotyls. A temperature jump in the root medium (heat treatment) induced a steep pressure spike in the xylem of the cucumber hypocotyl which showed similar electric and growth effects as the previously applied, non-injurious pressure steps. We suggest that the observed differences in the electric and growth responses between the species were caused by the closure of ion channels in depolarized cells of cucumber but not pea seedlings.     

Purification of NADPH-specific indole-3-acetaldehyde reductase from Cucumis sativus by two-dimensional native polyacrylamide gel electrophoresis

NADPH-specific indole-3-acetaldehyde (IAAId) reductase from cucumber ( Cucumis sativus L. 相似文献   

Characterization of repeat arrays in ultra‐long nanopore reads reveals frequent origin of satellite DNA from retrotransposon‐derived tandem repeats

Amplification of monomer sequences into long contiguous arrays is the main feature distinguishing satellite DNA from other tandem repeats, yet it is also the main obstacle in its investigation because these arrays are in principle difficult to assemble. Here we explore an alternative, assembly‐free approach that utilizes ultra‐long Oxford Nanopore reads to infer the length distribution of satellite repeat arrays, their association with other repeats and the prevailing sequence periodicities. Using the satellite DNA‐rich legume plant Lathyrus sativus as a model, we demonstrated this approach by analyzing 11 major satellite repeats using a set of nanopore reads ranging from 30 to over 200 kb in length and representing 0.73× genome coverage. We found surprising differences between the analyzed repeats because only two of them were predominantly organized in long arrays typical for satellite DNA. The remaining nine satellites were found to be derived from short tandem arrays located within LTR‐retrotransposons that occasionally expanded in length. While the corresponding LTR‐retrotransposons were dispersed across the genome, this array expansion occurred mainly in the primary constrictions of the L. sativus chromosomes, which suggests that these genome regions are favourable for satellite DNA accumulation.     

Influence of bicarbonate and metal ions on the development of root Fe(III) reducing capacity by Fe-deficient cucumber (Cucumis sativus) plants

The effect of bicarbonate and selected metal ions on the development of enhanced root Fe(III) reducing capacity (a response to Fe deficiency of dicotyledons) was studied in young plants of cucumber ( Cucumis sativus L. cv. Ashley) grown in nutrient solution. Pretreatment of 11-day-old Fe-deficient cucumber plants with 20 m M NaHCO₃, for at least 23 h prior to determination of root Fe(III) reducing capacity, markedly inhibited this response. The inhibitory effect of bicarbonate could be partly reversed by a 4- to 8-h treatment with either 10 μ M MnSO₄, 10 μ M FeEDDHA, 2 μ M ZnSO₄, 0.5 μ M NiCl₂, or 0.25 μ M , or CoSO₄ (final concentrations), added to the nutrient solution. By contrast, the addition of other salts of metal ions, like CuSO₄ and Cd(NO₃)₂, at 0.25, 0.5 or 1 μ M , or MgSO₄, at 0.5, 1 or 2 m M (final concentrations), had no beneficial effect. The results suggest that bicarbonate may inhibit the development of root Fe(III) reducing capacity by diminishing the availability of certain metal ions required for this response.     

Interactions of drought and low temperature stress on lipid and fatty acid composition of cucumber genotypes differing in growth response at suboptimal temperature

The effects of drought stress and/or low temperature stress on total lipid and phospholipid content and fatty acid composition of leaves of cucumber ( Cucumis sativus L.) genotypes differing in growth response at suboptimal temperature were studied. Both drought and low temperature resulted in reduced growth, especially in cv. Farbio, the genotype least tolerant to low temperature. Drought resulted in an increase in total lipid and phospholipid per g fresh weight. On a lipid basis no change in phospholipids or fatty acid content was observed. The fatty acid composition was changed by drought and low temperature, resulting in an increase in the degree of unsaturation. The genotype-specific reaction to treatment for total lipid content and the degree of unsaturation point to the possibility of a genetic origin for drought-induced lipid changes, which may be used in a breeding program for improved growth at suboptimal temperature.     

Re-examination of the localization of Mg-chelatase within the chloroplast

In a plastid-free assay, Mg-chelatase from pea ( Pisum sativum L. cv. Spring) and cucumber ( Cucumis sativus L. cv. Sumter) chloroplasts is inhibited to equal extents by the mercurial reagents. p -chloromercuribenzoate (PCMB) and p -chloromercuribenzene sulfonate (PCMBS). However, in intact chloroplasts PCMB inhibits Mg-chelatase fourfold more strongly than does PCMBS. Since PCMBS cannot penetrate membranes as readily as PCMB, Mg-chelatase may be localized interior to the inner chloroplast envelope. When Mg-chelatase is assayed with photosynthetically generated ATP, the presence of an external ATP trap does not inhibit activity, suggesting that the enzyme is not located in the interenvelope space. None of the components of Mg-chelatase are integral membrane proteins: Mg-chelatase activity is readily solubilized by washing the total chloroplast membranes in buffers of low MgCl₂ content. This precludes localization by purifying individual thylakoid and envelope membranes which requires low MgCl₂ concentrations.     

Induction of 2-cyanoethyl-isoxazolin-5-one as an antifeedant against the tobacco cutworm (Spodoptera litura) by jasmonic acid in sweet pea leaf

ABSTRACT

Although sweet pea (Lathyrus odoratus) beans contain toxic β-aminopropionitrile, the plant itself is readily attacked by insects and is, therefore, protected through the use of pesticides. Consequently, the induction of L. odoratus resistance to insect attack via exogenous treatment is promising for pest control development. Screening of inducible elicitor effects showed that treatment of sweet pea foliage with jasmonic acid (JA) can induce antifeeding-based resistance to tobacco cutworm (Spodoptera litura) larvae. Spectroscopic analysis identified 2-cyanoethyl-isoxazolin-5-one (2-CEIX) as the antifeedant with a half-maximal effective concentration of 33.6 µmol/g fr. wt., i.e., exogenous JA treatment induced antifeeding activity due to the accumulation of 2-CEIX. Moreover, 2-CEIX-induced mortality of S. litura larvae was evaluated by a dipping test and the half-maximal lethal dose was determined to be 5.9 mg/mL. Therefore, 2-CEIX was concluded to be a suitable induced resistance target for elicitors or a lead compound for insecticide development.