Open AccessMode of Action of the Massively Accumulated β-Carotene of Dunaliella bardawil in Protecting the Alga against Damage by Excess Irradiation
Author(s) -
Ami BenAmotz,
Aviv Shaish,
Mordhay Avron
Publication year - 1989
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.91.3.1040
Subject(s) - photoinhibition , dunaliella salina , dunaliella , photosynthesis , carotene , beta carotene , irradiation , biology , oxygen , photochemistry , botany , biophysics , chemistry , algae , carotenoid , photosystem ii , physics , organic chemistry , nuclear physics
When grown under defined conditions Dunaliella bardawil accumulates a high concentration of beta-carotene, which is composed primarily of two isomers, all-trans and 9-cis beta-carotene. The high beta-carotene alga is substantially resistant to photoinhibition of photosynthetic oxygen evolution when compared with low beta-carotene D. bardawil or with Dunaliella salina which is incapable of accumulating beta-carotene. Protection against photoinhibition in the high beta-carotene D. bardawil is very strong when blue light is used as the photoinhibitory agent, intermediate with white light, and nonexistent with red light. These observations suggest that the massively accumulated beta-carotene in D. bardawil protects the alga against damage by high irradiation by screening through absorption of the blue region of the spectrum. Irradiation of D. bardawil by high intensity blue light results in the following temporal sequence of events: photoinhibition of oxygen evolution, photodestruction of 9-cis beta-carotene, photodestruction of all-trans beta-carotene, photodestruction of chlorophyll and cell death.