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ULTRAVIOLET‐RADIATION‐ACCELERATED LEAF CHLOROSIS: PREVENTION OF CHLOROSIS BY REMOVAL OF EPIDERMIS OR BY FLOATING LEAF DISCS ON WATER *
Author(s) -
Wu J. H.,
Skokut T.,
Hartman M.
Publication year - 1973
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1973.tb06394.x
Subject(s) - chlorosis , epidermis (zoology) , irradiation , incubation , biology , botany , horticulture , ultraviolet radiation , chemistry , anatomy , biochemistry , radiochemistry , physics , nuclear physics
— Low doses (1800–7200 ergs/mm 2 ) of ultraviolet (U V) radiation accelerated chlorosis in the mesophyll of Nicotiana glutinosa leaves when the lower epidermis of the leaves was irradiated. This occurred in either a subsequent light or dark incubation. However, within 12 h after irradiation, peeling of the lower epidermis prevented this accelerated chlorosis. The accelerated chlorosis was also prevented by floating irradiated leaf discs on water during the incubation period without removal of the epidermis. These results suggest that accelerated chlorosis in mesophyll tissue caused by low doses of UV is due to an indirect effect of the UV‐damaged epidermis, possibly mediated by some toxic substance released from the epidermal cells. High UV doses (36,000–108,000 ergs/mm 2 ) prevented normal yellowing of the leaf. The irradiated portion of the leaf remained green, while the nonirradiated area turned yellow upon dark incubation. However, if the irradiated leaf was incubated in continuous light, bleaching of the irradiated area took place, and the irradiated area became yellow faster than the nonirradiated area. Peeling of the epidermis did not affect the outcome of these experiments. These results suggest that high UV doses directly damage the mesophyll tissue.