ACCUMULATION OF ORGANIC AND INORGANIC SOLUTES IN THE SUB-ANTARCTIC CRUCIFEROUS SPECIES PRINGLEA-ANTISCORBUTICA IN RESPONSE TO SALINE AND COLD STRESSES

Pringlea antiscorbutica R. Br., a subantarctic endemic cruciferous spe cies, is endangered in its natural sites by several ecological changes . This species is tolerant to salinity and a permanent cold temperatur e on Kerguelen and Crozet Islands. We attempted the investigation of r egulating mechanisms of osmotic adjustment in this species. C-13 NMR a nalyses of water-soluble compounds from leaves collected from the fiel d revealed glucose and proline to be the main accumulated organic solu tes. Colorimetric determinations in these samples showed that proline and soluble carbohydrates were present at remarkably high levels. When young giants were cultivated in growth chambers they showed a good re sistance to cold and medium resistance to saline conditions. High leve ls of soluble carbohydrates were present in all situations. Proline wa s accumulated in response to a saline and a cold treatment. The quanti tative variations of the pool of proline in response to saline treatme nts were rapid and important. The adaptive value of these responses of organic solutes in the tolerance of Pringlea antiscorbutica to variou s stresses is discussed.