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| Title: The Arabidopsis ABA-deficient mutant aba4 demonstrates that the major route for stress-induced ABA accumulation is via neoxanthin isomers .
| | Author: North HM De Almeida A Boutin JP Frey A To A Botran L Sotta B Marion-Poll A | | Journal: Plant J Citation: V : 50 P : 810-24 Year: 2007 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub17470058 Accession (PMID): 17470058 | | Abstract: A novel abscisic acid ( ABA ) -deficient mutant , aba4 , was identified in a screen for paclobutrazol-resistant germination .
Compared with wild-type , the mutant showed reduced endogenous ABA levels in both dehydrated rosettes and seeds .
Carotenoid composition analysis demonstrated that the defective locus affects neoxanthin synthesis .
The ABA4 gene was identified by map-based cloning , and found to be a unique gene in the Arabidopsis genome .
The predicted protein has four putative helical transmembrane domains and shows significant similarity to predicted proteins from tomato , rice and cyanobacteria .
Constitutive expression of the ABA4 gene in Arabidopsis transgenic plants led to increased accumulation of trans-neoxanthin , indicating that the ABA4 protein has a direct role in neoxanthin synthesis . aba4 mutant phenotypes were mild compared with previously identified ABA-deficient mutants that exhibit vegetative it issue phenotypes .
Indeed , ABA levels in seeds of aba4 mutants were higher than those of aba1 mutants .
As aba1 mutants are also affected in a unique gene , this suggests that ABA can be produced in the aba4 mutant by an alternative pathway using violaxanthin as a substrate .
It appears , therefore , that in Arabidopsis both violaxanthin and neoxanthin are in vivo substrates for 9-cis-epoxycarotenoid dioxygenases .
Furthermore , significantly reduced levels of ABA were synthesized in the aba4 mutant on dehydration , demonstrating that ABA biosynthesis in response to stress must occur mainly via neoxanthin isomer precursors .
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[ Sen. 7, subscore: 1.00 ]: Indeed , ABA levels in seeds of aba4 mutants were higher than those of aba1 mutants .
[ Sen. 8, subscore: 1.00 ]: As aba1 mutants are also affected in a unique gene , this suggests that ABA can be produced in the aba4 mutant by an alternative pathway using violaxanthin as a substrate .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
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| Title: Novel bifunctional nucleases , OmBBD and AtBBD1 , are involved in abscisic acid-mediated callose deposition in Arabidopsis .
| | Author: You MK Shin HY Kim YJ Ok SH Cho SK Jeung JU Yoo SD Kim JK Shin JS | | Journal: Plant Physiol Citation: V : 152 P : 1015-29 Year: 2010 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub20018603 Accession (PMID): 20018603 | | Abstract: Screening of the expressed sequence tag library of the wild rice species Oryza minuta revealed an unknown gene that was rapidly and strongly induced in response to attack by a rice fungal pathogen ( Magnaporthe oryzae ) and an insect ( Nilaparvata lugens ) and by wounding , abscisic acid ( ABA ) , and methyl jasmonate treatments .
Its recombinant protein was identified as a bifunctional nuclease with both RNase and DNase activities in vitro .
This gene was designated OmBBD ( for O minuta bifunctional nuclease in basal defense response ) .
Overexpression of OmBBD in an Arabidopsis ( Arabidopsis thaliana ) model system caused the constitutive expression of the PDF1 . 2 , ABA1 , and AtSAC1 genes , which are involved in priming ABA-mediated callose deposition .
This activation of defense responses led to an increased resistance against Botrytis cinerea . atbbd1 , the knockout mutant of the Arabidopsis ortholog AtBBD1 , was susceptible to attack by B cinerea and had deficient callose deposition .
Overexpression of either OmBBD or AtBBD1 in atbbd1 plants complemented the susceptible phenotype of atbbd1 against B cinerea as well as the deficiency of callose deposition .
We suggest that OmBBD and AtBBD1 have a novel regulatory role in ABA-mediated callose deposition .
| Matching Sentences:
[ Sen. 4, subscore: 1.00 ]: Overexpression of OmBBD in an Arabidopsis ( Arabidopsis thaliana ) model system caused the constitutive expression of the PDF1 . 2 , ABA1 , and AtSAC1 genes , which are involved in priming ABA-mediated callose deposition .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
