Isolation and Characterisation of Thionin Genes in Rice (Oryza Sativa)
Thionins are cysteine rich, basic and toxic proteins that are assumed to be involved in the defense against pathogens. Two partial cDNA clones encoding for putative thionin in rice were isolated from endosperm (Rth-l) and shoots (Rth-2). The nucleotide sequences encoding for thionin precursor wer...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
2001
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/8461/1/FSMB_2001_37_IR.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Thionins are cysteine rich, basic and toxic proteins that are assumed to be involved in
the defense against pathogens. Two partial cDNA clones encoding for putative
thionin in rice were isolated from endosperm (Rth-l) and shoots (Rth-2). The
nucleotide sequences encoding for thionin precursor were further identified from the
amplification of the 3' -end of the cDNA. The amino acid sequence for JRth-l
isolated from endosperm showed 72% homology to barley leaf thionins DB4
(Bohlmann and Apel, 1987), 68% to pKG1940 (Gausing, 1987), 51% to
hordothionin Hth-1 (Rodriguez-Palenzuela et 01., 1988), 50% to purothionin Pur-AI
(Ohtani et 01., 1977), 33% to crambin Thi2Ca1 (Teeter et 01., 1981) and viscotoxin
Vis A3 (Samuelsson et 01., 1974).
The homologies for JRth-2 at the amino acid level were 83% to barley leaf thionins
DB4 (Bohlmann and Apel, 1987), 71% to pKG1940 (Gausing, 1987), 46% to the
hordothionin Hth-l (Rodriguez-Palenzuela et 01., 1988) and purothionin Pur-AI
(Ohtani et 01., 1977), 41% to crambin Thi2CaI (Teeter et 01., 1981) and 33% to the
viscotoxin Vis A3 (Samuelsson et 01., 1974). Like other thionin precursors, the
putative rice thionin has an N-terminal domain characteristic of a signal peptide and an acidic C-terminal extension. In the expression studies, rice thionins mRNA were
found to accumulate abundantly in endosperm and shoots only with a transcript size
of around 600-700 bp. In both of these tissues, the expression of the thionin genes
was strongly repressed by the exposure to light. Southern analysis showed that the
rice thionin seemed to be coded by 1-2 genes. |
|---|