content in ( C ) Expt. 1 and ( D ) Expt. 2. Spermine content in ( E ) Expt. 1 and ( F ) Expt. 2. Treatment means were separated using Fisher’s least significant difference at P ≤ 0.05 (n = 4), which is represented by the vertical bar. Day 0 for Expts. 1
Abbreviations: CI, chilling injury; PG, endopolygalacturonase; PUT, putrescine; SPD, spermidine; SPN, spermine. We express our gratitude to Frank Liu and Dave for their assistance in obtaining the apples and to Hilarine Repace and George Brown for
Effects of low temperature and chilling injury (CI) on jasmonic acid (JA) and methyl jasmonate (MeJA) concentrations were investigated in mangosteens (Garcinia mangostana L.). JA concentrations in the skin of fruit stored at 7 °C increased significantly compared with that of those stored at 13 °C, but JA decreased with the occurrence of visible symptoms of CI. Neither an increase in JA nor CI was detected in pulp of fruit stored at 7 °C. JA concentrations in the skin of fruit treated with spermine (Spm) and stored at 7 °C also increased, but at a lesser extent than in untreated fruit. Thus, the response of JA to low temperatures appears to be limited to chill-susceptible parts of the fruit. The decrease of JA and the onset of CI was delayed in fruit treated with Spm kept at 7 °C compared with untreated control fruit. Exogenous application of n-propyl dihydrojasmonate, which is a jasmonic acid derivative, effectively decreased CI. These results suggest that low temperature-induced JA accumulation may play a protective role against CI. The application of jasmonates may increase chill-resistance in fruit.
Polyamines [putrescine (put), spermidine (spd), and spermine (spm)] are aliphatic amines that are implicated in the regulation of many basic physiological processes such as cell growth, proliferation and stress responses in organisms including plants (Walden et al. 1997). Put is metabolized to spd and spm through the successive enzymatic reactions of spd synthase (SPDS) and spm synthase (SPMS) with the use of decarboxylated S-adenosylmethionine (dcSAM) as an aminopropyl donor, which is generated by SAM decarboxylase (SAMDC). So far, two MdSAMDC (MdSAMDC1 and MdSAMDC2) homologous to SAMDC and two MdACL5 (MdACL5-1 and MdACL5-2) homologous to ACL5 encoding SPMS in Arabidopsis (Hanzawa et al. 2000) were isolated from `Orin' apple. To investigate the function of these genes, complementation analyses were carried out using yeast mutants. Each of the MdSAMDCs consists of three ORFs; tiny- and small-ORFs in the 5' regions, and main ORF like other plant SAMDC genes. Both constructs for MdSAMDC containing all ORFs (SAM-DCall) or containing only main ORF (SAMDCorf) were capable of recovering the growth of yeast SAMDC-deficient mutants (delta spe2) without supplement of spd, although the SAMDCall constructs always showed the lower growth speed than the SAMDCorf constructs. On the other hand, yeast SPMS-deficient mutant (delta spe4) introduced by MdACL5 cDNA produced significantly higher amount of spm than the delta spe4 with control vector by HPLC. Collectively, these results suggest that both MdSAMDCs are functional as a SAMDC and the tiny- and small-ORFs are negative-regulatory factor for the translation efficiency of SAMDC, and also that MdACL5 encodes a functional SPMS like as ACL5 in Arabidopsis. The first and second authors contributed equally to this work.
). The PAs, for example, putrescine (PUT), spermidine, and spermine (SPM), constitute a group of cell components that are precisely regulated. The biosynthesis and metabolism of PAs in plants have been well clarified. The oxidation of PAs can produce
Polyamine, putrescine, spermidine, and spermine contents were determined during endodormancy in the buds of low-chilling-requiring `Anna' apples (Malus domestics Borkh.). Putrescine, spermidine, and spermine contents increased greatly in buds when their chilling requirement was satisfied. Polyamine biosynthetic inhibitors α -difluoromethylarginine (DFMA) or α -difluoromethylornithine (DFMO) reduced bud break and bud growth in concert with decreased polyamine titers. DFMO or DFMA did not inhibit bud break when it was applied to buds after they received the full chilling requirement. DFMO was more inhibitory than DFMA. The polyamine requirement was much higher for bud growth and bud development than during differentiation and bud break.
A DNA extraction protocol was developed for tissues from woody species. DNA was extracted successfully from 11 species and five different types of tissues and was suitable for RAPD and restriction analysis. Spermine precipitation was used to further purify DNA. The protocol can be used for large-scale analysis and mini-preparations.
The effects of silver thiosulfate (STS) on stored and freshly made cuttings of `Royalty' rose (Rosa hybrids) were examined in relation to rooting and subsequent budbreak. STS pretreatment at 0.5 mm during storage stimulated budbreak but decreased the percentage of cuttings that rooted and the number of roots. IBA at 4.9 to 9.8 mm inhibited budbreak but this effect was partially reversed by STS. Spraying the cuttings with 1.0 mm STS once daily during the first 5 days of the rooting period also reduced rooting but prevented IBA-induced leaf senescence. Ethephon and spermine, each applied at 0.5 mm before rooting, had no effect on rooting or budbreak. Chemical names used: (2-chloroethyl)-phosphonic acid (ethephon); indole butyric acid (IBA); N,N'-bis(3-aminopropyl) -l,4-buanediamine (spermine).
Plant cells contain long-chain amine compounds called polyamines, of which the most common are spermidine, spermine, and putrescine. These compounds are considered phytohormone-like because they play various regulatory roles in plant cells. They are
Abstract
Polyamines acted as antisenescence agents (2, 5), increased membrane stability of beet root, rose petal, and spinach leaf tissue (8, 9), and decreased the rate of chlorophyll degradation in radish cotyledons (2). Ozone is a major air pollutant causing economic losses to crops in agricultural areas (1). One approach to controlling the damage caused by ozone has been the use of chemical protectants (7), but consistent responses have been difficult to achieve. The antisenescence properties of polyamines may confer protectant properties that will reduce or prevent ozone-induced injury to plants. Previous studies have shown increased membrane permeability by ozone at 0.15 μl·liter−1 (4) and increased senescence with ozone at 0.15 μl·liter−1 (3). The objective of this study was to determine if the polyamines—spermine, spermidine, and putrescine—could act as protectants in tomato (Lycopersicon esculentum Mill.).