Different growth sensitivity to enhanced UV-B radiation between male and female Populus cathayana.
We investigated sex-related morphological and physiological responses to enhanced UV-B radiation in the dioecious species Populus cathayana Rehd. Cuttings were subjected to two UV-B radiation regimes: ambient (4.5 kJ m⁻² day⁻¹) and enhanced (12.5 kJ m⁻² day⁻¹) biologically effective UV-B radiation for one growing season. Enhanced UV-B radiation was found to significantly decrease the shoot height and basal diameter and to reduce the leaf area, dry matter accumulation, net photosynthesis rate (P(n)), chlorophyll a/b ratio (Chl a/b) and anthocyanin content. Enhanced UV-B radiation also increased chlorophyll pigment, leaf nitrogen, malondialdehyde and abscisic acid (ABA) content, superoxide dismutase and peroxidase activities and UV-B-absorbing compounds. No significant effects of enhanced UV-B radiation were found on biomass allocation, gas exchange (except for P(n)), photochemical efficiency of photosystem II or water use efficiency. Moreover, different sensitivity to enhanced UV-B radiation between males and females was detected. Under enhanced UV-B radiation, males exhibited significantly higher basal diameter and leaf nitrogen, and lower Chl a/b, ABA content, UV-B-absorbing compounds, as well as less decrement of leaf area and dry matter accumulation than did females. However, no significant sexual differences in these traits were found under ambient UV-B radiation. Our results suggest that males may possess a greater UV-B resistance than do females, with males having a more efficient antioxidant system and higher anthocyanin content to alleviate UV-B penetration stress than females.
Chengdu Institute of Biology, Chinese Academy of Sciences, PO Box 416, Chengdu 610041, China.
Xiao
X
Xu
Hongxia
H
Zhao
Xiaolu
X
Zhang
Heikki
H
Hänninen
Helena
H
Korpelainen
Chunyang
C
Li
D000040:Abscisic Acid / Q000378:metabolism; D018533:Biomass; D002734:Chlorophyll / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D018526:Plant Transpiration; D032107:Populus / Q000254:growth & development* / Q000528:radiation effects*; D013482:Superoxide Dismutase / Q000378:metabolism; D014466:Ultraviolet Rays; D014867:Water / Q000378:metabolism
D014867:Water; D002734:Chlorophyll; D008315:Malondialdehyde; D000040:Abscisic Acid; D010544:Peroxidases; D013482:Superoxide Dismutase