关键词: 砷超积累植物, 生态型, 生理生化响应, 低温胁迫, 耐寒机制

Abstract: Pteris vittata (PV) is the first known arsenic (As) hyperaccumulating plant and an ideal material for As-contaminated environment remediation. However, low temperature is an important factor affecting the growth and geographical distribution of P. vittata. Here, seven ecotypes of P. vittata (Guangzhou, Wenshan, Kunming, Tengchong, Xiamen, Zhaotong, and Fuzhou) and two As-hyperaccumulators Pteris cretica (PC) and Pteris multifida (PM) from the same genera were used to examine their physico-biochemical responses to cold stress. Plants were cultivated for 24, 72 and 120 h in an artificial intelligence incubator at 4 ℃. After treatment, malondialdehyde (MDA) content in cell membrane, proline (Pro) content for osmoticregulation, peroxidase (POD) and catalase (CAT) activities in protective enzyme system and relative conductivity were analyzed. Membership function method was used to evaluate the cold tolerance ability of plants. The results showed that: (1) The MDA content and the activities of Pro, POD and CAT increased with the increasing treatment duration, with increments of 11.9%-1720%, 0.5%-115%, 98.9%-946% and 10.7%-220% respectively after 120 h of cultivation. The largest increases occurred in PC, PM, and Xiamen PV, which were 3.79-144, 1.14-2.43, 1.99-2.54 and 1.94-20.6 folds that of Kunming, Fuzhou and Guangzhou PV, respectively. Specifically, MDA in PC, Pro in PM, and POD and CAT in Xiamen PV were increased by 17.2, 11.5, 9.46, and 2.2 times respectively, indicating the three species are sensitive to cold stress. The relative conductivity was increased by 17.7%-82.6% at 72 h then decreased by 9.7%-51.7% at 120 h, with the largest increase occurring in PC, reaching 74.8%. Two principal components (PC1 and PC2) were extracted by principal component analysis, with a total contribution reaching 62.1%. The contribution of indicators was in an order of: relative conductivity (26.8%) > Pro (25.5%) > POD (21.7%) > MDA (16.6%) > CAT (9.5%). (2) Results of fuzzy membership function method, comprehensive evaluation and cluster analysis showed that plants can be divided into three groups based on their cold tolerance ability: high tolerance (Fuzhou > Kunming > Guangzhou > Wenshan), medium tolerance (PC > Tengchong > Xiamen > PM), and low tolerance (Zhaotong). This indicated that PC, PM, and PV ecotypes evolved different adaptabilities and responses to cold stresses. Under cold stress, plants can increase Pro content and POD and CAT activity to regulate cell metabolism to adapt to cold environment. The information helps to better understand the regulatory mechanisms of plants’ cold stresses responses and provide theoretical supports to breed cold-resistant species and genotypes.

Key words: arsenic hyperaccumulator, ecotype, physico-biochemical response, cold stress, cold tolerance mechanism