Adaptive response to salt involving carbohydrate metabolism in leaves of a salt-sensitive tomato cultivar.
A salt-sensitive genotype of Solanum lycopersicum cv. Volgogradskij was submitted to a 6-day treatment with high salt (100, 200 mM NaCl), allowed to recover for 6 days and then submitted to a second period of salt stress in order to study changes in carbohydrate metabolism related to salt adaptation. The ion, soluble sugar and starch contents, as well as sucrose biosynthetic and sugar mobilizing enzyme activities and transcript levels were determined during the salt stress/recovery/stress cycle. Sodium ions were found to accumulate preferentially in old leaves. Young leaves accumulated lower levels of sodium ions but maintained control levels of potassium ions. Hexoses accumulated to higher levels and starch was better maintained in young compared to old leaves during the two salt treatments. Sucrose accumulated dramatically only in old leaves during the initial salt treatment. Sugar accumulation was not related to decreases in the activities of sugar mobilizing enzymes, acid (EC 3.2.1.25) and neutral (EC 3.2.1.26) invertases, sucrose synthase (EC 2.4.1.13) and hexokinase (EC 2.7.1.1). The activity of the biosynthetic enzyme sucrose phosphate synthase (EC 2.3.1.14) was linked to changes in sucrose levels but not with transcript levels. These results point to the importance of post-transcriptional regulation. Transcriptional regulation could nevertheless be seen in the down-regulation of ribulose bisphosphate carboxylase small subunit (EC 4.1.1.39) in old compared to young leaves, but this was not related to sugar levels.
Khelil
Aminata
A
Equipe Osmoadaptation et Métabolismes de Stress, UMR CNRS 6026, Université de Rennes I, Rennes, France. ricard@bordeaux.inra.fr
Menu
Thierry
T
Ricard
Bérénice
B
D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry*; D007477:Ions; D018551:Solanum lycopersicum / Q000187:drug effects / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D010944:Plants / Q000378:metabolism; D011188:Potassium / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D012492:Salts / Q000494:pharmacology*; D012964:Sodium / Q000737:chemistry; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000737:chemistry; D013997:Time Factors
D002241:Carbohydrates; D007477:Ions; D012333:RNA, Messenger; D012492:Salts; D012965:Sodium Chloride; D013395:Sucrose; D012964:Sodium; D012273:Ribulose-Bisphosphate Carboxylase; D011188:Potassium