Differential expression of plastidic aldolase genes in Nicotiana plants under salt stress

Abstract Two homologous genes of plastidic fructose-1,6-bisphosphate aldolase (AldP) isozymes were isolated from green leaves of a salt stress-tolerant Nicotiana species, Nicotiana paniculata , by differential screening. The products of the corresponding genes, NpAldP1 and NpAldP2 , were 91% identical to each other and 70–85% identical to the other known plant plastidic aldolases. Although these two genes showed similar organ-specific expression and daily cycles, their responses to salt stress differed: mRNA accumulation of NpAldP2 increased, but that of NpAldP1 slightly decreased. The mRNA accumulations of their counterparts of two other Nicotiana species, NeAldP1 and NeAldP2 ( Nicotiana excelsior ), and NaAldP1 and NaAldP2 ( Nicotiana arentsii ) were studied under the same stress condition. N. arentsii conserved accumulation profiles similar to N. paniculata , but N. excelsior did not. In N. excelsior , accumulation of NeAldP1 decreased to 50% of the control after stress and gradually recovered thereafter, whereas accumulation of NeAldP2 temporarily decreased and reached 250% of the control by the third day of stress. Southern blot analysis indicated that NpAldP1 , NpAldP2 , NaAldP1 , and NaAldP2 include one or two closely related genes and NeAldP1 and NeAldP2 several.