Ohtsuki, Tatsuo , Mori, Izumi , Katsuhara, Maki , Setoguchi, Hiroaki .
Physiological divergence of the freshwater and coastal ecotypes of the beach pea, Lathyrus japonicus (Fabaceae), to salinity stress, involving differential uptake Na+ to shoot.
Ecological divergence between populations often generates divergent natural selection, shaping “ecotype” in local environment. Salt stress, which could cause plants hyperosmolality (water deficit) and ion disequilibrium, is a key factor affecting plant abundance and distribution. Some plants, called salt-tolerant plants, have evolved various protective mechanisms allowing them to survive and grow in this harsh environment. Coastal plant is a representative example of salt-tolerant plants, possessing high heterogeneity of environmental salinity. Some species adapted to fresh, intermediate and saline conditons for salt stress variation. Thus, adaptation to salinity stress plays an important role in their persistence. Lathyrus japonicus is a typical coastal species and also inhabits in Lake Biwa, a freshwater lake. This species was reported to show physiological and genetic differentiations between freshwater and coastal ecotypes (FW and CS), which suggested its adaptive response to original habitat. Given that the two different types of habitat provide fresh and saline conditions, intraspecific differentiation between the two ecotypes provides a valuable experimental system for exploring divergent natural selection and local adaptation. This study was conducted to assess the different response to salinity between FW and CS through both reciprocal transplant and growth cabinet experiments. The results of reciprocal transplant experiment showed that both ecotypes represented adaptive response to original habitat in growth rate. The CS from coastal site accumulated less amount of Na+ in the shoot than FW at higher salt levels. The findings of growth cabinet experiments also displayed the physiological divergence between FW and CS, involving differential accumulation of Na+ ions, but not osmotic stress tolerance associated with salt stress. These physiological results are consistent with sensitiveness of FW to salt stress. Physiological assays in this study suggested a major role for uptaking Na+ to shoot. While growth rate of CS in control (0 mmol NaCl) exhibited no significant difference from that of FW, suggesting that CS can adapt to the freshwater condition.
1 - Kyoto University, Graduate School of Human and Environmental Studies, Nihonmatsu-cho,, Sakyo-ku, Kyoto, 606-8501, Japan
2 - Institute of Plant Science and Resources (IPSR) Okayama University, 2-20-1, Chuo, Kurashiki, 710-0046, JAPAN
3 - Institute of Plant Science and Resources (IPSR) Okayama University, Adress: 2-20-1, Chuo, Kurashiki, 710-0046, JAPAN
4 - Kyoto University, DEPT OF NATRL ENVIRON SCIENCES, Yoshida Nihonmatsu-cho, Kyoto, N/A, 606-8501, Japan
Presentation Type: Poster:Posters for Topics
Candidate for Awards:None