Higher amounts of anthocyanins and UV‐absorbing compounds effectively lowered CPD photorepair in purple rice (Oryza sativa L.)

• Published in: Plant, cell and environment Vol. 26; no. 10; pp. 1691 - 1701
• Main Authors: HADA, H., HIDEMA, J., MAEKAWA, M., KUMAGAI, T.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.10.2003; Wiley Subscription Services, Inc
• Subjects: blue; challenge exposure; chronic exposure; cyclobutane pyrimidine dimer (CPD)‐photolyase; DNA damage; near‐isogenic line; photoreactivation; UV‐A radiation
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1046/j.1365-3040.2003.01087.x

ABSTRACT Growth of a near‐isogenic line (NIL) for the purple leaf gene Pl of rice with a genetic background of Taichung 65 (T‐65) rice was significantly retarded by supplementary ultraviolet‐B radiation (UV‐B), despite the fact that the amounts of UV‐absorbing compounds and anthocyanins in NIL were significantly higher than those in T‐65. In order to understand the role of flavonoids in UV‐B induced damage protection in T‐65 and the NIL, both the (1) relationships between changes in the steady state of cyclobutane pyrimidine dimer (CPD) levels and changes in accumulation of anthocyanins and UV‐absorbing compounds in leaves with leaf age, and (2) the susceptibility to CPD induction by UV‐B radiation and the ability to photorepair CPD were examined. Although supplementary UV‐B elevated the steady state of CPD levels in leaves in both strains, the level in the leaf of the NIL was higher than that in T‐65 at any time. The susceptibility to CPD induction by short‐term (challenge) UV‐B exposure was lower in the NIL than in T‐65. On the other hand, the CPD photorepair was also lower in the leaves of the NIL than in those of T‐65. The decrease in CPD‐photorepair in the NIL was due to a lowering of the leaf‐penetrating blue/UV‐A radiation, which is effective for photoreactivation by photolyase, by anthocyanins. Thus, accumulation of anthocyanins and UV‐absorbing compounds did not effectively function as screening against damage caused by elevated UV‐B radiation in the NIL, and the retardation of growth in the NIL resulted from its lower ability to photorepair CPD by higher amounts of anthocyanins.