Т.Г. Шибаева, А.Ф. Титов.
Влияние круглосуточного освещения на пигментный комплекс растений семейства Solanacea
// Труды КарНЦ РАН. No 5. Сер. Экспериментальная биология. 2017. C. 111-118
T.G. Shibaeva, A.F. Titov. Effect of continuous light on photosynthetic pigments in Solonacea species // Transactions of Karelian Research Centre of Russian Academy of Science. No 5. Experimental biology. 2017. Pp. 111-118
Key words: Solanum lycopersicum L.; Solanum melongena L.; Capsicum annuum L.; continuous lighting; photosynthetic pigments; chlorosis; necrosis
Photosynthetic pigments and photosynthetic activity of three Solanacea species –Solanum lycopersicum L., Solanum melongena L. and Capsicum annuum L. in response to continuous lighting (CL) during pre-reproductive period were studied. It is shown that CL resulted in decreased chlorophyll content, increased chlorophyll a/b ratios, reduced light-harvesting complex II in tomato and eggplant. These changes were aimed to reduce light absorption efficiency per unit leaf area. CL-induced leaf injuries were seen as interveinal chlorosis in tomato and necrotic spots in eggplant. Sweet pepper plants did not show a reduction in chlorophyll content. On the contrary, some increase in chlorophyll content was observed, although pepper leaves had some deformations (wrinkles). A higher concentration of carotenoids possessing photoprotective properties in pepper leaves probably protects the photosynthetic apparatus of this species from adverse excessive lighting. Possible reasons of CL-induced leaf injuries are discussed, among them are the continuous energy supply for photosynthesis, continuous photooxidative stress, continuous signalling to the photoreceptors and a mismatch between the internal circadian clock frequency and the external light/dark cycle known as circadian asynchrony. We suppose that another possible cause of leaf depigmentation under unfavorable light conditions may be of genetic nature. Some species (ecotypes, genotypes) may have a photosensitive mutant gene, which is normally suppressed and does not manifest itself, wherefore mutant plants phenotypically do not differ from normal (wild type) plants. In such plants, excessive lighting may cause inactivation of the suppressor protein controlledby suppressor gene and, consequently, de-repression of the mutant gene, resulting in leaf depigmentation. In this case, CL-induced chlorosis and possibly necrosis in CL-sensitive plant species (ecotypes, genotypes) can be considered as a manifestation of suppressed light-dependent chlorophyll deficiency.
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