Polyamine Content of Long-Keeping Alcobaca Tomato Fruit

Abstract

Fruit of tomato landrace Alcobaca, containing the recessive allele alc, ripen more slowly, with a reduced level of ethylene production, and have prolonged keeping qualities. The levels of polyamines in pericarp tissues of alc and 'wild type' Alc (cv Rutgers and Alcobaca-red) fruit were measured by HPLC in relation to ripening. Putrescine was the predominant polyamine with a lower content of spermidine, while spermine was just detectable. The level of putrescine was high at the immature green stage and declined in the mature green stage. In Alc fruit the decline persisted but in alc fruit the putrescine level increased during ripening to a level smilar to that present at the immature green stage. There was no pronounced change or difference in spermidine levels. The enhanced polyamine level in ale fruit may account for their ripening and storage characteristics.member of the polyamine sequence, the diamine PTC,3 is synthesized in most plant systems from arginine via ADC, though in tomato fruit the principal pathway appears to be similar to that in animals and microorganisms, namely from ornithine via ODC (4,5,8,9). The level of ODC is highest shortly after pollination and declines to a low level of maturity (9), while inhibitors of ODC activity inhibit fruit development (4). Actual levels of polyamines have not been recorded through development and ripening, nor have ODC or ADC been followed through ripening in any tomato line. As the conversion of PTC to the other polyamines, SPD and SPM, involves SAM, which is also the precursor of ethylene (7), it follows that the synthesis of polyamines and ethylene are competitive.In view of the reduced ethylene production and delayed senescence of alc fruit, the polyamine content of these fruit was analyzed to determine whether it might vary from normal tomato fruit.Alcobaca is a landrace oftomato in which the fruit ripen more slowly than standard horticultural varieties (60 versus 50 d from anthesis) and have prolonged keeping qualities. If picked ripe, fruit can be kept at 20C for four times longer than standard varieties (33 versus 9 d) (13,15). This characteristic is determined by a single recessive gene, designated alc, whose inheritance and linkage have been described (13,14). The storability of alc fruit is not due to extreme firmness of the harvested fruit, but to an attenuation of the overripening process, including a slower rate of softening possibly because of lower polygalacturonase levels (12; MA Mutschler, in preparation). alc Fruit lack a climacteric pattern of CO2 and ethylene production and produce less than 25% of the ethylene produced by cv Rutgers (15).A spontaneous mutant in Alcobaca has given rise to a plant with normal ripening fruit but with all the other characteristics of the original Alcobaca landrace. The fruit of this line, which has been named Alcobaca-red, ripen to a crimson red as compared to the medium orange color of the original Alcobaca fruits and do not possess prolonged keeping qualities. Genetic analysis has shown that the al...

Involvement of Polyamine in Floral and Fruit Development

“…The inverse relationship between ethylene and polyamine is primarily illustrated by their opposite synthesis patterns during fruit development and/or delay or inhibition of ethylene production by free polyamine. In long-keeping tomato fruits, less ethylene and more polyamines were produced in comparison with short-keeping ones 21 . In addition, blocking of ethylene production by an ethylene inhibitor, aminoethoxyvinylglycine (AVG), could promote polyamine production 4 .…”

Polyamine Metabolism in Ripening Tomato Fruit

“…The identity of the PAs was determined by mixing the radioactive peaks with a mixture of danysl PAs and running the resulting mixture on HPLC using the same column and solvent gradient. The peaks were detected by an attached fluorescence spectrophotometer as described in Dibble et al (5).…”

“…Samples (3)(4)(5) ,uL) were injected in split mode (50-1) onto a bonded methyl silicone capillary column (HP-1, 25 m x 0.2 mm).…”

“…S-adenosylmethionine for their biosynthesis (24). Earlier, we (5) reported that fruit of the Alcobaca landrace of tomato, which ripen slowly and have prolonged keeping qualities, contain three times as much Ptc as the normal variety at the ripe stage. It was suggested that the enhanced Ptc level in this line may be responsible for the ripening and storage features.…”

Polyamine Metabolism in Ripening Tomato Fruit

“…The pericarp discs were treated with the radioactive PAs for 24 h, and the metabolites purified by HPLC as described previously (1 1 (3). In the jelly, free PA levels were comparable to that in the pericarp, and like the pericarp Ptc was the predominant free amine (Table I).…”