Polyamine Metabolism in Ripening Tomato Fruit

Abstract

The fruit of the Alcobaca landrace of tomato (Lycopersicon esculentum Mill.) have prolonged keeping qualities (determined by the allele aic) and contain three times as much putrescine as the standard Rutgers variety (Aic) The fruit of Alcobaca landrace of tomato (Lycopersicon esculentum Mill.) ripen more slowly than the standard commercial varieties and if picked ripe they can be kept four times longer (9). The delayed overripening feature is conferred by a single recessive gene a/c, whose inheritance, linkage, and effects on ripening-related mRNAs have been described (8,10).In an earlier paper (3), we reported on the levels of free PAs3 in the fruit pericarp tissues of Alcobaca (alc), its spontaneous revertant Alcobaca-red, and the standard variety Rut-' Supported by grants from the Herman Frasch Foundation and the Cornell University Biotechnology Program. 2Current address: Department of Molecular Biology and Genetics, University of Guelph, Guelph, Ontario, N 1G 2W 1, Canada. 3Abbreviations: PA(s), polyamine(s); Ptc, putrescine; Spd, spermidine; Spm, spermine; SAM, S-adenosylmethionine; PCA, perchloric acid; ODC, ornithine decarboxylase; ADC, arginine decarboxylase; GABA, -y-aminobutyric acid. gers (both Alc) during the process of ripening. In all the lines, the levels of Ptc were high at the immature green stage and then declined at the mature green stage. Thereafter, Ptc levels in the fruit of Alc lines remained low but in fruit of alc they rose to levels similar to that of immature green fruit (3). The level of Spd, however, was not significantly different either during ripening or in different genotypes. The Spm content was always very low. Similar changes in Ptc content were recently documented in the ripening fruit of another long keeping variety of tomato (14).The increase in Ptc level in the alc fruit may be due to either decreased Ptc metabolism or increased biosynthesis.We, therefore, examined PA metabolism, i.e. PA conjugate levels and Ptc and Spd breakdown, and Ptc biosynthesis in the fruit ofalc and A/c genotypes at different stages ofripening. In a companion paper (1 1), we characterized the pathways of Ptc and Spd metabolism in tomato pericarp tissues. MATERIALS AND METHODS Plant Material and Cultivation MethodsThe fruit of tomato (Lvcopersicon esculentum Mill.) isogenic lines Alcobaca (alc) versus Alcobaca-red (Alc-red: a revertant of alc) and near isogenic lines Rutgers versus Rutgers-alc (a/c backcrossed into cv Rutgers) were used for experiments. Seed was originally obtained from Dr. M. A. Mutschler (Plant Breeding Department, Cornell University, Ithaca, NY). Plant cultivation methods were similar to those described previously (1 1). Ripening stages used were immature green, mature green, breaker (streaks of orange at the distal end), and ripe. For experiments on storage in light and in dark, fruit of different lines were excised at mature green stage and stored at 22 ± 2°C in darkness or under fluorescent lights. The Alc fruit (Rutgers and A/c-red) were analyzed after 12 to ...

Abscisic acid induced stress-like polyamine pattern in wheat seedlings, and its reversal by potassium ions

“…Crude extracts for Om decarboxylase (ODC) and ADC assays were prepared according to Rastogi and Davies (1991). TBq mol"'; Amersham).…”

“…TBq mol"'; Amersham). The ODC assay was according to Rastogi and Davies (1991) and the ADC assay as previously reported (Reggiani et al 1989). Enzyme activity data are the means of 2 independent experiments and the reactions were performed twice.…”

The Arabidopsis thaliana gene annotated by the locus tag At3g08860 encodes alanine aminotransferase

“…Moreover, in plants the metabolism of L‐alanine and the non‐proteinogenic amino acid β‐alanine are linked. β‐Alanine biosynthesis can be initiated from four different precursors: (a) the polyamines spermine and spermidine (Galston & Sawhney, ; Rastogi & Davies, ; Terano & Suzuki, ), (b) the nucleotide base uracil (Barnes & Naylor, ; Campbell, ; Traut & Loechel, ), (c) propionate (Hayaishi, Nishizuka, Tatibana, Takeshita, & Kuno, ; Stinson & Spencer, , ), and (d) L‐aspartate (Ottenhof et al, ; Shi, Blundell, & Mizuguchi, ). L‐alanine enters the propionate pathway of β‐alanine synthesis via the reverse reaction of the β‐alanine‐pyruvate aminotransferase [http://www.chem.qmul.ac.uk/iubmb/enzyme/EC:2/6/1/18.html], exchanging an amino group with malonate semialdehyde, and generating pyruvate and β‐alanine (Figure b).…”

Transcriptome and Metabolite Profiling Show That APETALA2a Is a Major Regulator of Tomato Fruit Ripening

“…Interestingly, in the Sl AP2i fruits, both ethylene and putrescine levels are elevated. In general, putrescine is the predominant polyamine during tomato ripening, and its levels are high at the immature-green stage and decline throughout the ripening process (Rastogi and Davies, 1991), which coincides with the accumulation of AP2a transcript. Together, our data suggest that AP2a is a negative regulator of both ethylene and putrescine synthesis in wild-type fruits.…”