{'fraction_non_alphanumeric': 0.04271548436308162, 'fraction_numerical': 0.004576659038901602, 'mean_word_length': 5.527363184079602, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Action of the Non-ripening (nor) Mutant on Fruit Ripening of Tomato1


Changes in respiration, ethylene production, firmness, pectolytic enzyme activity and carotenoid accumulation during ripening were monitored in fruit of a segregating population of the non-ripening (nor) mutant of tomato (Lycopersicon esculentum Mill.). In fruit from mutant (nor/nor) plants, no respiratory or ethylene climacteric was observed, firmness declined very slowly with only trace levels of polygalacturonase present in mature fruit and phytoene, β-carotene and neurosporene were the major carotenes. In very old fruit (120 days’ post-anthesis), lycopene and β-carotene were the predominant carotenoids, however lycopene content was less than 10% of normal.
Ripening of fruit from heterozygous (nor+/nor) plants was delayed and occurred more slowly than for normal (nor+/nor+) fruit. The respiratory climacteric was partially suppressed, peak ethylene production was one-sixth of normal, fruit softening was retarded, and polygalacturonase activity was lower at comparable maturity stages. Fruit from heterozygous (nor+nor) plants accumulated lycopene, gamma-carotene, phytofluene, and phytoene at a slower rate, but β-carotene accumulation was similar to normal. A mechanism for action of nor in control of ripening is proposed.