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Physiological and biochemical responses of fruit exocarp of tomato (Lycopersicon esculentum Mill.) mutants to natural photo-oxidative conditions.

Abstract：

:Photo-oxidative stress was imposed under natural solar radiation on exposed and shaded sections of detached fruit of immature green tomato (Lycopersicon esculentum Miller = Solanum lycopersicum L.) mutants (anthocyanin absent, beta-carotene, Delta, and high pigment-1) and their nearly isogenic parents ('Ailsa Craig' and 'Rutgers'). After 5 h exposure to high solar irradiance, either with or without ultraviolet (UV) radiation, surface colour changes, pigment composition, photosynthetic efficiency, antioxidant metabolites and enzyme activities, and selected flavonoids and antioxidant proteins in exocarp tissue were evaluated. The imposed photo-oxidative stress reproduced the symptoms observed on attached fruit. Both high temperature and solar irradiance caused fruit surface discoloration with faster degradation of chlorophyll (Chl) than carotenoids (Car), leading to an increase in the Car/Chl ratio. Surface bleaching was mostly caused by visible light, whereas elevated temperatures were mostly responsible for the inactivation of photosynthesis, measured as decreased F(v)/F(m). Ascorbate, glutathione, and total soluble protein concentrations decreased in the exocarp as the duration of exposure increased. Specific activities of superoxide dismutase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase (MDHAR), glutathione reductase (GR), and catalase increased with exposure, suggesting that these proteins were conserved during the imposed stress. GR protein expression remained stable during the imposed stress, whereas, MDHAR protein expression increased. Quercetin and kaempferol concentrations increased rapidly upon exposure, but not to UV radiation, suggesting rapid photo-protection in response to visible light; however, naringenin synthesis was not induced. The apparent increased tolerance of hp-1 fruit is discussed.

journal_name

J Exp Bot

journal_title

Journal of experimental botany

authors

Torres CA,Andrews PK,Davies NM

doi

10.1093/jxb/erj136

subject

Has Abstract

pub_date

2006-01-01 00:00:00

pages

1933-47

issue

eissn

0022-0957

issn

1460-2431

pii

erj136

journal_volume

pub_type

杂志文章

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Physiological and biochemical responses of fruit exocarp of tomato (Lycopersicon esculentum Mill.) mutants to natural photo-oxidative conditions.