Association between Elemental Content and Fruit Ripening in rin and Normal Tomatoes

Abstract

Analysis of Ca and other inorganic ions in the pericarp of rin, a nonripening mutant, and normal tomato (Lycopersicon esculentum Mill) fruits revealed significant differences in their accumulations at advanced stages of fruit development. During early stages of fruit development, soluble Ca was higher in Rutgers and there were no detectable changes in the accumulation patterns of the other inorganic ions. In the mutant rin, bound Ca continued to increase with age and it was twice as high as compared to earlier stages. In the normal tomato, bound Ca decreased about 3-fold at later stages of development. Mg and Mn also showed some changes similar to Ca. K continued to increase with age and the mutant in had lower levels than Rutgers throughout development. Other ions such as P, Zn, Cu, and Co were similar in the mutant and normal fruits. These results are interpreted as indicating that high levels of bound divalent cations in the mutant inn may be associated with an altered membrane and cell wall and play a role in fruit ripening.Rin was first described as a spontaneous mutation in 1968 (21). Since then, the mutant has been used as a tool for the study of fruit ripening and ethylene biosynthesis (7,18 Mill) were grown in greenhouses in a mixture of soil, Vermiculite, and peat moss in the ratio of 2: 1:1 (v/v), respectively. Plants were drip-irrigated for 5 min daily, using a complete Hoagland nutrient solution (full strength) alternated with plain water throughout the growing season. Day (25 C) and night temperatures (19 C) were also maintained. Plants were trained to one stem, and fruits tagged at the time of anthesis allowing for two to three fruits/flower cluster and a maximum of seven to 10 fruits/plant.Composite samples of three fruits each representing the two varieties at four different ages (30, 40, 50, and 60 days) after anthesis were picked at random. Fruits were cleaned with deionized water. The pericarp was separated from the jelly and the seeds, blotted dry, and homogenized in a Waring Blendor in a cold room (4 C). Representative samples were freeze-dried and finely pulverized to pass through a 40-mesh screen. Pulverized samples were shaken after addition of distilled H20 for I hr and centrifuged at 15,000g for 15 min. The supernatant was filtered using Whatman No. 541 ashless filter paper and the filtrates were analyzed for soluble Ca, K, Mg, and P. The pellet was washed three times with distilled H20 and the supernatant was discarded. The pellet was ashed at 550 C overnight, dissolved in 5% HCI, and used to determine the bound Ca, P, and Mg. For the determination of Cu, Zn, Mn, and Co, freeze-dried samples were ashed directly.Ca and K were analyzed by flame photometry, and Mg, Zn, Cu, and Mn were determined by flame atomic absorption. Flameless atomic absorption was used for Co determination. P was determined by colorimetry (1) using ammonium molybdate and hydroquinone. Results are presented on dry wt basis with the standard deviations.

The Use of Nonaqueous Fractionation to Assess the Ionic Composition of the Apoplast during Fruit Ripening

“…Where a simple distinction is made between soluble and bound ions after dispersing the material in water (Suwwan and Poovaiah, 1978;Tieman and Handa, 1994), the data are unreliable because organic acids in the extract may leach cations from the cell wall (Ferguson et al, 1980). Table I1 supports this contention, showing that during the period between 5 and 60 min after tissue disruption losses are occurring from the insoluble material.…”

“…Whereas this is the first time an attempt has been made to estimate the level of organic acids in the cell wall space, there have been numerous attempts to measure cell wall calcium. To make a comparison with other methods of estimating cell wall calcium and magnesium, we determined the relative amounts of soluble and bound calcium in aqueous extracts of unripe and ripe fruit (Table 11) following a procedure similar to Suwwan and Poovaiah (1978).…”

Influência do cálcio nas características físicas e no teor de cálcio durante desenvolvimento e maturação da uva 'Itália'

“…Este processo, conforme Suwwan & Poovaiah (1978), pode ter um papel no início do amolecimento dos frutos em amadurecimento.…”

45Ca mobility and distribution during ripening and maturation of Rutgers and RIN tomatoes

“…Representative samples were finely ground to pass through a 60 mesh screen. The samples were analyzed for soluble and bound 45 Ca by a modified method of Suwaan and Poovaiah (1978 Samples (1.0 ml) from soluble and bound 45 Ca fractions were placed into vials which contained 10 ml of PCS liquid scintillation cocktail (Amersham). Radioactivity was measured with a liquid scintillation counter (LKB Wallac Rackbeta 1215).…”

“…Incorporation of calcium into the cell wall results in enhanced tissue resistance to PG, although the ecaxt chemical nature of resistance is unresolved (Wills and Tirmazi, 1979; Buescher and Hobson, 1982). Several studies have reported that cell wall bound calcium declines prior to, or simultaneously with the initiation of ripening (Suwaan and Poovaiah, 1978;Rigney and Wills, 1981). Rigney and Wills, (1981) have suggested that mobility of cell wall bound calcium might initiate ripening and precede PG activity which has also been postulated to initiate tomato ripening (No and Tigchelaar, 1977;Tigchelaar et al, 1978;Poovaiah and Nukaya, 1979 Buescher and Tigchelaar, 1975).…”