Differential expression of wheat aspartic proteinases, WAP1 and WAP2, in germinating and maturing seeds.
Two aspartic proteinase (AP) cDNA clones, WAP1 and WAP2, were obtained from wheat seeds. Proteins encoded by these clones shared 61% amino acid sequence identity. RNA blotting analysis showed that WAP1 and WAP2 were expressed in both germinating and maturing seeds. The level of WAP2 mRNA expression was clearly weaker than that of WAP1 in all tissues of seeds during germination and maturation. APs purified from germinating seeds were enzymatically active and digested the wheat storage protein, gluten. To elucidate the physiological functions of WAP1 and WAP2 in seeds, we investigated the localisation of WAP1 and WAP2 by in situ hybridisation. In germinating seeds investigated 24h after imbibition, both WAP1 and WAP2 were expressed in embryos, especially in radicles and shoots, scutellum, and the aleurone layer. In maturing seeds, WAP1 was expressed in the whole embryo, with slightly stronger expression in radicles and shoots. WAP1 was also expressed in the aleurone layer 3 weeks after flowering. Strong signals of WAP1 mRNA were detected in the whole embryo and aleurone layer 6 weeks after flowering. On the other hand, WAP2 was scarcely detected in seeds 3 weeks after flowering, and thereafter weak signals began to appear in the whole embryo. WAP1 and WAP2 were expressed widely in germinating and maturing seeds. Such diversity in site- and stage-specific expression of the two enzymes suggests their differential functions in wheat seeds.
Tamura
Tomoko
T
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Terauchi
Kaede
K
Kiyosaki
Toshihiro
T
Asakura
Tomiko
T
Funaki
Junko
J
Matsumoto
Ichiro
I
Misaka
Takumi
T
Abe
Keiko
K
D016282:Aspartic Acid Endopeptidases / Q000235:genetics*; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018525:Germination; D017403:In Situ Hybridization; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000201:enzymology / Q000254:growth & development; D014908:Triticum / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development
D017931:DNA Primers; D012333:RNA, Messenger; D018749:RNA, Plant; D016282:Aspartic Acid Endopeptidases