Role of Vacuolar H+-inorganic pyrophosphatase in tomato fruit development.
cDNA corresponding to two type-I vacuolar H(+)-inorganic pyrophosphatases (V-PPases) (SlVP1, SlVP2) and one type-II V-PPase (SlVP3) was isolated from tomato fruit to investigate their role in fruit development. Southern analysis revealed that type-I V-PPase genes form a multigene family, whereas there is only one type-II V-PPase gene in the tomato genome. Although SlVP1 and SlVP2 were differentially expressed in leaves and mature fruit, the highest levels of both SlVP1 and SlVP2 mRNA were observed in fruit at 2-4 days after anthesis. The expression pattern of type-II SlVP3 was similar to that of SlVP2, and the highest levels of SlVP3 mRNA were also observed in fruit at 2-4 days after anthesis, thus suggesting that SlVP3 plays a role in early fruit development. Because SlVP1 and SlVP2 mRNA was more abundant than SlVP3 mRNA, expression of type-I V-PPases was analysed further. Type-I V-PPase mRNA was localized in ovules and their vicinities and in vascular tissue at an early stage of fruit development. Tomato RNAi lines in which the expression of type-I V-PPase genes was repressed using the fruit-specific promoter TPRP-F1 exhibited fruit growth retardation at an early stage of development. Although the major function of V-PPases in fruit has been believed to be the accumulation of materials such as sugars and organic acids in the vacuole during cell expansion and ripening, these results show that specific localization of V-PPase mRNA induced by pollination has a novel role in the cell division stage.
Graduate School of Life Sciences, Tohoku University Sendai 980-8577  Japan.
Seedahmed A
SA
Mohammed
Sogo
S
Nishio
Hideyuki
H
Takahashi
Katsuhiro
K
Shiratake
Hiroki
H
Ikeda
Koki
K
Kanahama
Yoshinori
Y
Kanayama
D000595:Amino Acid Sequence; D002455:Cell Division; D018076:DNA, Complementary / Q000235:genetics; D005638:Fruit / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D043564:Inorganic Pyrophosphatase / Q000235:genetics / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010641:Phenotype; D010802:Phylogeny; D054817:Pollination; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D016415:Sequence Alignment; D014617:Vacuoles / Q000201:enzymology*
D018076:DNA, Complementary; D012333:RNA, Messenger; D018749:RNA, Plant; D043564:Inorganic Pyrophosphatase