Clara A. Croci

Changes in peroxidases associated with radiation-induced sprout inhibition in garlic (Allium sativum L.)

The effects of an acute dose of gamma-rays (10 Gy) to post-dormant garlic cloves on inner sprout growth and changes in peroxidases and soluble proteins were evaluated up to 100 days of storage in darkness at 19 +/- 1 degree C and 42 +/- 2% relative humidity. Radiation-induced inhibition of sprout growth became evident after 25 days of treatment and was synchronous with a marked increase in peroxidase activity. Thin-layer isoelectric focusing revealed that radiation induced an increase in the number of anodic peroxidase isoenzymes at 100 days, suggesting modifications in the vascularization process. Neither the soluble protein content nor the protein pattern were affected by irradiation. These results are discussed in terms of a possible mediating effect of peroxidase on radiation-induced sprout inhibition in garlic.

Effect of gamma-irradiation and extended storage on chemical quality in onion (Allium cepa L.)

The effects of gamma-irradiation and long-term storage on the chemical quality of the Valenciana sintetica 14 onion variety were determined under warehouse conditions in two sets of bulbs grown consecutively in 1988 and 1989. In both years irradiated and non-irradiated bulbs showed similar behaviour in terms of carbohydrate and ascorbic acid contents throughout the 300 days of storage. It was found that the carbohydrate content significantly decreased in irradiated and non-irradiated samples up to 180 days of storage. The storage time was found not to have a significant effect on the ascorbic acid content of bulbs. The carbohydrate and ascorbic acid contents were found to be higher in the irradiated and non-irradiated bulbs grown in 1988. Neither storage time nor gamma-irradiation nor the specific year significantly affected dry matter or acidity. Gamma-irradiation did not significantly affect flavour strength in terms of total pyruvate content.

Biochemical changes in garlic (Allium sativum L.) during storage following gamma-irradiation

The aim of this paper was to evaluate an acute dose of gamma-rays (10 Gy) on post-dormant garlic seed cloves in terms of total DNA, total RNA, total protein and soluble carbohydrates in order to correlate these levels with sprouting inhibition induced by gamma-irradiation. Decreases in total DNA content were found in inner sprouts immediately and 100 days after irradiation. The total RNA and protein contents and the carbohydrate content of the storage leaf or the inner sprout were not affected by gamma-irradiation. The results support the notion that in post-dormant garlic seed cloves, DNA content and its behaviour seem to be among the sensitive cellular responses to radiation.

Effect of gamma rays on seed cloves of garlic (Allium sativum L.) at post-harvest: Reversion by exogenous growth regulators

Abstract The aims of this work were to analyze the effect of (1) acute doses of gamma rays (1.0–10.0 Gy) on dormant and post-dormant garlic seed cloves, and (2) exogenous applications of growth regulators in reversing the effect produced by irradiation. The results indicated that a 10.0-Gy dose applied in post-dormancy significantly decreased sprouting; sprouts were modified in size (length), color and peroxidase activity. No changes were observed for the dormancy period treatments. The storage leaf showed no modifications. Application of some growth regulators was effective in modifying the effectiveness of the gammarays exposure. Indole acetic acid was the most effective, followed by gibberellic acid; benzyl-adenine gave no evidence of reversal of sprout growth inhibition in in vitro conditions.

Morphological changes induced by different doses of gamma irradiation in garlic sprouts

Abstract The objective of this work was to evaluate the effects of different doses of gamma rays applied in dormancy and post-dormancy on garlic bulbs in relation with some morphophysiological parameters. High (commercial) doses cause the complete inhibition of sprouting and mitosis (due to nuclear aberrations). Relatively low doses show no effects on bulbs but doses of 10 Gy applied in post-dormancy reduce sprouting and stop mitosis. This inhibition becomes noticeable from 150 days post-harvest onwards. Exogenous growth regulators can reverse these effects. Results may reinforce the good practice of radioinhibition processes in garlic.

Effect of gamma rays on sprouting of seed cloves of garlic (Allium sativum L.): levels of auxin-like substances and growth inhibitors.

Abstract The aims of this research were (1) to analyze the effect of an acute dose of gamma rays (10.0 Gy) on post-dormant garlic seed cloves in terms of the endogenous levels of auxin-like substances and growth inhibitors, and (2) to correlate these levels with sprouting inhibition induced by gamma irradiation. The results indicated that the gamma ray exposure had no effect on sprout longitudinal growth during pre-emergence (up to 100 days), but changes in the endogenous growth regulators were found in the irradiated seed cloves by the wheat coleoptile straight growth test. At 25 and 100 days the irradiated seed clove extracts contained different growth inhibitors and relatively more active auxin-like substances than non-irradiated cloves. The presence of indole acetic acid was confirmed. The sprout growth interruption became evident at emergence (after 100 days), promoting a significant decreased sprouting and an inability to reach the seedling stage. The results suggests that auxins are involved in a long-term mechanism of radiation-induced sprouting inhibition in garlic.

Effects of γ-irradiation on the lipid composition of inner sprout of garlic

Abstract The aim of this work was to evaluate the effects of a dose of 60.0 Gy of 60Co γ-rays on the concentration and composition of lipids from the inner sprout of garlic cloves. 210 days after treatment, the levels of phospholipids, triacylglycerols and glycolipids were significantly reduced as a result of radiation. Levels of polyunsaturated fatty acids from these lipid fractions such as linoleic acids showed a similar trend of decrease. Irradiation also brought about an increase in diacylglycerols. Results are correlated with sprouting inhibition induced by γ-irradiation in garlic.