Abstract
Xerophyta humilis (Bak.) Dur and Schinz is an indigenous Southern African resurrection plant which is able to protect itself from the stresses associated with extreme dehydration. For the purpose of analysing global patterns of gene expression in response to desiccation and recovery on rehydration, we have generated a normalized 10 900 library, representing genes from root and leaf tissue that are expressed during the dehydration‐rehydration cycle. For the small‐scale microarray analysis described here, 424 cDNAs were sequenced, annotated, arrayed and hybridized with hydrated and dehydrated, leaf‐specific RNA. Reverse Northern blots were used as an alternative method to compare the expression results. A total of 55 dehydration‐inducible cDNAs were identified combining the results of both methods. Northern blot analysis of 14 of the 55 the dehydration‐upregulated cDNAs verified the expression status of all 14 genes. Dehydration‐upregulated cDNAs included those homologous to known dehydration stress‐responsive genes encoding metallothioneins, galactinol synthases, an aldose reductase and a glyoxalase. A large number of genes encoding late embryonic abundant proteins (LEAs), dehydrins and desiccation‐related proteins were also identified, suggesting that proteins that provide mechanical and antioxidant protection against water loss dominate the mRNA population in desiccated X . humilis leaf tissue. Dehydration‐upregulated genes identified in this study, and not previously implicated in the dehydration response, include cDNAs encoding a putative chloroplast RNA‐binding protein and a protein containing SNF2/helicase domains. Comparisons with microarray data, which profile the dehydration response in desiccation‐sensitive plants, reveal differences in expression patterns between X . humilis and Arabidopsis and rice that could provide clues as to the mechanisms underlying desiccation‐tolerant and ‐sensitive phenotypes. The X . humilis library promises to be a useful resource for transcript profiling the dehydration and rehydration response in a desiccation‐tolerant plant.
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Claims 8
Claim · model-written summary
A normalized library representing root and leaf genes expressed during dehydration and rehydration was generated.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Organ / stage
- root and leaf tissuee0
- Outcome
- normalized 10 900 librarye0
- Value
- 10 900e0
Verbatim
e0“we have generated a normalized 10 900 library, representing genes from root and leaf tissue that are expressed during the dehydration‐rehydration cycle”
t0“Xerophyta humilis”
Claim · model-written summary
Combined methods identified 55 dehydration-inducible cDNAs.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Outcome
- dehydration‐inducible cDNAse0
- Value
- 55e0
Verbatim
e0“A total of 55 dehydration‐inducible cDNAs were identified combining the results of both methods.”
t0“Xerophyta humilis”
Claim · model-written summary
Northern blot analysis verified the expression status of all 14 tested dehydration-upregulated genes.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Outcome
- verified the expression statuse0
- Value
- 14e0
Verbatim
e0“Northern blot analysis of 14 of the 55 the dehydration‐upregulated cDNAs verified the expression status of all 14 genes.”
t0“Xerophyta humilis”
Claim · model-written summary
Dehydration-upregulated cDNAs included homologs encoding metallothioneins, galactinol synthases, and an aldose reductase.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Gene
- metallothioneins, galactinol synthases, an aldose reductasee0
- Outcome
- Dehydration‐upregulated cDNAse0
Verbatim
e0“Dehydration‐upregulated cDNAs included those homologous to known dehydration stress‐responsive genes encoding metallothioneins, galactinol synthases, an aldose reductase and a glyoxalase.”
t0“Xerophyta humilis”
Claim · model-written summary
A glyoxalase homolog was among the dehydration-upregulated cDNAs.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Gene
- a glyoxalasee0
- Outcome
- Dehydration‐upregulated cDNAse0
Verbatim
e0“Dehydration‐upregulated cDNAs included those homologous to known dehydration stress‐responsive genes encoding metallothioneins, galactinol synthases, an aldose reductase and a glyoxalase.”
t0“Xerophyta humilis”
Claim · model-written summary
Many identified genes encoded LEAs, dehydrins, and desiccation-related proteins.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Outcome
- genes encoding late embryonic abundant proteins (LEAs), dehydrins and desiccation‐related proteinse0
Verbatim
e0“A large number of genes encoding late embryonic abundant proteins (LEAs), dehydrins and desiccation‐related proteins were also identified”
t0“Xerophyta humilis”
Claim · model-written summary
Previously unimplicated dehydration-upregulated genes included a putative chloroplast RNA-binding protein and a protein with SNF2/helicase domains.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Gene
- a putative chloroplast RNA‐binding protein and a protein containing SNF2/helicase domainse0
- Outcome
- Dehydration‐upregulated genese0
Verbatim
e0“Dehydration‐upregulated genes identified in this study, and not previously implicated in the dehydration response, include cDNAs encoding a putative chloroplast RNA‐binding protein and a protein containing SNF2/helicase domains.”
t0“Xerophyta humilis”
Claim · model-written summary
Dehydration expression patterns differed between X. humilis and Arabidopsis and rice.
- Taxon
- Xerophyta humilisXerophyta humilist0
- Outcome
- expression patternse0
- Direction
- differencese0
- Comparator
- Arabidopsis and ricee0
Verbatim
e0“reveal differences in expression patterns between X . humilis and Arabidopsis and rice”
t0“Xerophyta humilis”