How do plants cope with oxidative stress in nature? A study on the dwarf bearded iris (Iris pumila)
2015
Тип документа:
Чланак у часопису (Објављена верзија)
Метаподаци
Приказ свих података о документуАпстракт:
Oxidative stress results from incongruity between the generation of
toxic reactive oxygen species (ROS) and the availability of their
scavengers-antioxidants. Although the short-term effects of this
phenomenon are attracting much scientific attention, oxidative stress
may influence an organism's metabolism over the long (evolutionary) time
scale as well. To disentangle the impact of strong light intensity from
co-occurring abiotic stresses in creating adaptive responses in
antioxidants and heat shock proteins (Hsps), an environment manipulation
experiment was performed using a xerophyte clonal monocot, Iris pumila,
native to semi-arid grasslands at the Deliblato Sands. This species is
very tolerant to the combined effect of extreme abiotic stressors such
as high light intensity, elevated soil surface temperatures, and
scarcity of water, which commonly takes place in its natural habitats
during the summer. By shading half of each selected clone, leaving the
other half sun-exposed, we contrasted short-term effects of reduced
daylight intensity with long-term effects of photo-oxidative stress. In
both light treatments, the enzymatic activities of SOD and APX
antioxidants were similar in magnitude, whereas those of CAT and POD
significantly decreased in exposed compared to shaded leaves. Moreover,
exposed leaves expressed a unique CAT isoform that differed
biochemically from two CAT isoforms observed in shaded leaves. The
content of non-enzymatic antioxidants, carotenoids (Car), remained
constant with the reduction of light intensity, but their ratio to total
chlorophylls (Chl) significantly decreased compared to that expressed in
full sunlight. The abundance of Hsps was considerably greater in exposed
than in shaded leaves, especially regarding the inducible isoforms,
Hsp70 and Hsp90a, as were their proportions in relation to the
constitutively expressed Hsp90b isoform. The presented results, thus,
indicate that adaptive metabolic responses of I. pumila leaves to
photo-oxidative stress entailed the high activity of two key enzymatic
antioxidants, SOD and APX and the expression of a light-resistant CAT-to
counteract the stress-mediated ROS accumulation, the increased Car to
Chl ratio-to adjust the photosynthetic apparatus to the high light
conditions, as well as the accelerated biosynthesis of heat shock
proteins Hsp70 and Hsp90-to preserve the cellular proteostasis.
Кључне речи:
Photo-oxidative stress; Enzymatic antioxidants; Carotenoids; Hsp70; Hsp90; Iris pumilaИзвор:
Acta Physiologiae Plantarum, 2015, 37, 1711
DOI: 10.1007/s11738-014-1711-9
ISSN: 1861-1664