Differential expression of two calmodulin genes in response to physical and chemical stimuli.
Two different calmodulin (CaM) cDNAs (MBCaM-1 and MBCaM-2) were isolated from a vigna radiata lambda gt11 library by screening with a heterologous Arabidopsis cDNA probe (TCH-1). Both cDNAs are 85% homologous inside the coding region but are highly divergent outside this region. The polypeptides encoded by MBCaM-1 and MBCaM-2 are identical except for two conservative substitutions at positions 7 and 10. Southern analysis revealed that both cDNAs are encoded by different genes. Expression studies revealed different patterns of expression of both genes. MBCaM-1 mRNA exhibited a dramatic transient increase in response to touch, while MBCaM-2 expression showed a steady but small increase as compared to MBCaM-1. When plants were grown in complete darkness MBCaM-1 was undetectable and MBCaM-2 exhibited very low levels of expression. One hour after exposure of etiolated seedlings to light MBCaM-1 showed no change, while MBCaM-2 expression was increased. After a 6 h exposure to light there was an induction of both MBCaM-1 and MBCaM-2; however, the magnitude of this increase was much greater for MBCaM-2. When plants were grown under a 16 h light/8 h dark cycle the mRNA levels for MBCaM-1 were lower during the light period and increased during the beginning of the night cycle, while MBCaM-2 showed no change. Plants treated with indole-3-acetic acid had a peak in MBCaM-1 expression 6 h after treatment initiation with a slight decline 3 h after the peak, while MBCaM-2 showed a steady but small increase over time as compared to MBCaM-1. When plants were subjected to salt stress they showed an increase in MBCaM-1 expression 2 h after treatment initiation reaching a maximum after 4 h with no further increase after 6 h, while MBCaM-2 remained unchanged over the time course.
Botella
J R
JR
Department of Horticulture, Pennsylvania State University, University Park 16802.
Arteca
R N
RN
D000595:Amino Acid Sequence; D001483:Base Sequence; D002147:Calmodulin / Q000235:genetics*; D003001:Cloning, Molecular; D007887:Fabaceae / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics*; D007210:Indoleacetic Acids / Q000494:pharmacology; D008027:Light; D008969:Molecular Sequence Data; D010812:Physical Stimulation; D010946:Plants, Medicinal; D012333:RNA, Messenger / Q000032:analysis; D017422:Sequence Analysis, DNA; D013268:Stimulation, Chemical
D002147:Calmodulin; D007210:Indoleacetic Acids; D012333:RNA, Messenger; C030737:indoleacetic acid