Available online at www.sciencedirect.com Environmental and Experimental Botany 61 (2007) 237–245 Principal component analysis of intraspecific responses of tartary buckwheat to UV-B radiation under field conditions Yinan Yao a,b , Zuying Xuan a , Yongmei He c , Stanley Lutts d , Helena Korpelainen e , Chunyang Li a,∗ a Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu 610041, China b College of Agronomy, Guizhou University, Guiyang 550025, China c College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China d Unit of Plant Biology, Catholic University of Louvain, 5 (bte 13) Place Croix du Sud, B-1348 Louvain-la-Neuve, Belgium e Department of Applied Biology, P.O. Box 27, University of Helsinki, FI-00014 Helsinki, Finland Received 13 May 2007; accepted 8 June 2007 Abstract Fifteen populations of tartary buckwheat (Fagopyrum tataricum Gaertn.) occurring in habitats with different natural UV-B levels were sampled, and the plants were exposed to enhanced UV-B radiation under field conditions simulating 25% depletion of the stratospheric ozone layer. The experimental design was a 2 × 15 factorial, with two levels of UV-B radiation (ambient and enhanced UV-B radiation) and plants from 15 populations. The responses of plants in growth, morphology, productivity and in the composition of photosynthetic pigments were measured. The results demonstrated that there were significant differences among populations in responses to UV-B radiation: some populations exhibited a positive effect while others were negatively affected. The UV-B effects on plant traits were correlated with the constitutive values. A principal component analysis (PCA) was used to evaluate the overall sensitivity of responses to UV-B radiation. Our results suggest that the sensitivity of plants to UV-B radiation is not only associated with the ambient UV-B level in natural habitats but also with the relative growth rate and other factors. © 2007 Elsevier B.V. All rights reserved. Keywords: Plant responses; Population differences; Principal component analysis; Tartary buckwheat (Fagopyrum tataricum Gaertn.); UV-B radiation 1. Introduction Reductions in the ozone column primarily due to anthro- pogenic discharge of chlorofluorocarbons (CFCs) have led to a substantial increase in UV-B radiation on the Earth’s surface (Madronich et al., 1998; WMO, 1999). As CFCs can remain in the upper atmosphere with a half-life ranging from 50 to 150 years, decreased ozone levels will not be recovered to the pre- 1970 levels until 2050 (Dentener et al., 2001; UNEP, 2002). During the last few decades, numerous investigations concern- ing the influence of enhanced UV-B radiation on different plant species have been conducted. The majority of plant species are affected negatively (Kakani et al., 2003; Yang et al., 2005; Ren et al., 2007; Lu et al., in press), although neutral and positive effects ∗ Corresponding author. Tel.: +86 28 85221347; fax: +86 28 85222753. E-mail address: licy@cib.ac.cn (C. Li). have also been reported in some species (Papadopoulos et al., 1995). Great intraspecific variation in the responses of plants to UV-B radiation has been observed in different species, e.g., wheat (Li et al., 2000), maize (Correia et al., 1998), cucumber (Murali and Teramura, 1986), soybean (Li et al., 2002) and rice (Dai et al., 1994). However, the basis of intraspecific responses and the mechanisms of plant adaptation need to be further elu- cidated. Nowadays, due to a reborn-interest, buckwheat is becom- ing one of the most important alternative crops for health food (Halbrecq et al., 2005). Tartary buckwheat (Fagopyrum tatar- icum Gaertn.) is mainly cultivated in the alpine regions and on the high plateau of Asia, and also in some countries of Central Europe (Bonafaccia et al., 2003; Fabjan et al., 2003). In some regions, it suffers from high doses of UV-B radiation during the growth season. Previous studies have shown that tartary buck- wheat is sensitive to ambient and enhanced UV-B radiation (Yao et al., 2006a). Therefore, there is an urgent need to improve the 0098-8472/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.envexpbot.2007.06.003