Applied acetaldehyde is known to lead to sugar accumulation in fruit including tomatoes (Lycopersicon esculentum) (O Paz, HW Janes, BA Prevost, C Frenkel [1982] presumably due to stimulation of gluconeogenesis. This conjecture was examined using tomato fruit pencarp discs as a test system and applied -[U-14C]malic acid as the source for gluconeogenic carbon mobilization. The label from malate was recovered in respiratory C02, in other organic acids, in ethanol insoluble material, and an appreciable amount in the ethanol soluble sugar fraction. In Rutgers tomatoes, the label recovery in the sugar fraction and an attendant label reduction in the organic acids fraction intensified with fruit ripening. In both Rutgers and in the nonripening tomato rin, these processes were markedly stimulated by 4000 ppm acetaldehyde. The onset of label apportioning from malic acids to sugars coincided with decreased levels of fructose-2,6-biphosphate, the gluconeogenesis inhibitor.In acetaldehyde-treated tissues, with enhanced label mobilization, this decline reached one-half to one third of the initial fructose-2,6-biphosphate levels. Application of 30 micromolar fructose-2,6-biphosphate or 2,5-anhydro-d-mannitol in tum led to a precipitous reduction in the label flow to sugars presumably due to inhibition of fructose-1,6-biphosphatase by the compounds. We conclude that malic and perhaps other organic acids are carbon sources for gluconeogenesis occurring normally in ripening tomatoes. The process is stimulated by acetaldehyde apparently by attenuating the fructose-2,6-biphosphate levels. The mode of the acetaldehyde regulation of fructose-2,6-biphosphate metabolism awaits clarification.AA4 is a common volatile in plants that accumulate during physiological disorders (25) and in ripening fruit (7,14).

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Halińska, A. and Lewak, St. 1987. Free and conjugated gibberellins in dormancy and germination of apple seeds.The presence of gibberellin A4 (GA4) was confirmed in partly stratified seeds of apple (Malus domestica Borb., cv. Antonówka) by mass spectrometry of the methyl ester. Levels of free and conjugated gibberellins A4+7 and A9 changed during drying of mature seeds, during cold and warm stratification, as well as during germination of dormant and non‐dormant embryos. The temporary rise in GA4+7 during cold stratification and during the culture of dormant embryos as well as the lack of it under conditions of warm stratification, allowed us to postulate a role for GA4+7 in the removal of dormancy. In addition, GA9 was absent in dormant embryos and increased during cold stratification and during the culture of non‐dormant embryos. This suggests the involvement of GA9, in induction of normal development of the seedling. The equivalence between changes in free and conjugated GAs suggests that formation and hydrolysis of conjugates are involved in the control of the physiologically active levels of free GA4+7 and GA9.

Metabolism of [14C]gibberellin (GA) A12 (GA12) and [14C]gibberellin A12-aldehyde (GA12-aldehyde) was examined in cotyledons and seed coats from developing seeds of pea (Pisum sativum L.). Both were metabolized to only 13-hydroxylated GAs in cotyledons but to 13-hydroxylated and non-13-hydroxylated GAs in seed coats. appropriate markers for the recovery of endogenous GAs from seed coats or cotyledons. These GAs were purified by HPLC and identified and quantified by gas chromatography-mass spectrometry. GA15, GA24, GA9, GA51, GA51-catabolite, GA20, GA29, and GA29-catabolite were detected in seed coats, whereas GA9, GA53, GA44, GA19, GA20, and GA29 were found in cotyledons. The highest GA levels were for GA20 and GA29 in cotyledons (783 and 912 nanograms per gram fresh weight, respectively) and for GA29 and GA29-catabolite in seed coats (1940 and >1940 nanograms per gram fresh weight, respectively).The identification, quantitation, and metabolism of GAs4 in developing seeds of garden pea (Pisum sativlum L.) have '