Developmental phase-dependent photosynthetic responses to ultraviolet-B radiation: damage, defence, and adaptation of primary leaves of wheat seedlings

• Published in: Photosynthetica 2008-09, Vol.46 (3), p.370-377
• Main Authors: Pradhan, M. K, Nayak, L, Joshi, P. N, Mohapatra, P. K, Patro, L, Biswal, B, Biswal, U. C
• Format: Article
• Language: English
• Subjects: anthocyanin; Biomedical and Life Sciences; carotenoids; chlorophyll; flavonoids; Life Sciences; Original Papers; O₂ evolution; phases of leaf development; photosynthetically active radiation; Plant Physiology; senescence; thylakoids
• ISSN: 0300-3604; 1573-9058
• DOI: 10.1007/s11099-008-0067-z

Alterations in photosynthetic capacity of primary leaves of wheat seedlings in response to ultraviolet-B (UV-B; 280-320 nm; 60 μmol m⁻² s⁻¹) exposure alone and in combination with photosynthetically active radiation (PAR; 400-800 nm; 200 μmol m⁻² s⁻¹) during different phases of leaf growth and development were assessed. UV-B exposure resulted in a phase-dependent differential loss in photosynthetic pigments, photochemical potential, photosystem 2 (PS2) quantum yield, and in vivo O₂ evolution. UV-B exposure induced maximum damage to the photosynthetic apparatus during senescence phase of development. The damages were partially alleviated when UV-B exposure was accompanied by PAR. UV-B induced an enhancement in accumulation of flavonoids during all phases of development while it caused a decline in anthocyanin content during senescence. The differential changes in these parameters demonstrated the adaptation ability of leaves to UV-B stress during all phases of development and the ability was modified in UV-B+ PAR exposed samples.