Abstract
Background: During wheat senescence, leaf components are degraded in a coordinated manner, releasing amino acids and micronutrients which are subsequently transported to the developing grain. We have previously shown that the simultaneous downregulation of Grain Protein Content (GPC) transcription factors, GPC1 and GPC2, greatly delays senescence and disrupts nutrient remobilization, and therefore provide a valuable entry point to identify genes involved in micronutrient transport to the wheat grain. Results: We generated loss-of-function mutations for GPC1 and GPC2 in tetraploid wheat and showed in field trials that gpc1 mutants exhibit significant delays in senescence and reductions in grain Zn and Fe content, but that mutations in GPC2 had no significant effect on these traits. An RNA-seq study of these mutants at different time points showed a larger proportion of senescence-regulated genes among the GPC1 (64%) than among the GPC2 (37%) regulated genes. Combined, the two GPC genes regulate a subset (21.2%) of the senescence-regulated genes, 76.1% of which are upregulated at 12 days after anthesis, before the appearance of any visible signs of senescence. Taken together, these results demonstrate that GPC1 is a key regulator of nutrient remobilization which acts predominantly during the early stages of senescence. Genes upregulated at this stage include transporters from the ZIP and YSL gene families, which facilitate Zn and Fe export from the cytoplasm to the phloem, and genes involved in the biosynthesis of chelators that facilitate the phloem-based transport of these nutrients to the grains. Conclusions: This study provides an overview of the transport mechanisms activated in the wheat flag leaf during monocarpic senescence. It also identifies promising targets to improve nutrient remobilization to the wheat grain, which can help mitigate Zn and Fe deficiencies that afflict many regions of the developing world.
| Original language | English |
|---|---|
| Article number | 368 |
| Journal | BMC Plant Biology |
| Volume | 14 |
| Issue number | 1 |
| DOIs | |
| State | Published - 2014 |
| Externally published | Yes |
Bibliographical note
Funding Information:The authors would like to thank Henny O'Geen for help and advice during RNA-seq library construction and sequencing and to Guillermo Santamaría for advice relating to wheat physiology. This project was supported by the National Research Initiative Competitive Grants 2008-35318-18654 and 2011-68002-30029 (Triticeae-CAP) from the USDA National Institute of Food and Agriculture, the United States – Israel Binational Science Foundation (BSF) grant number 2007194, by the Marie Curie International Reintegration Grant number PIRG08-GA-2010-277036 and by the Howard Hughes Medical Institute and the Gordon and Betty Moore Foundation grant GBMF3031. Facundo Tabbita was the recipient of a four-month "René Hugo Thalmann" fellowship from Universidad de Buenos Aires for financial support while working at UC Davis (EXP-UBA: 31.621/2010).
Funding Information:
Acknowledgements The authors would like to thank Henny O'Geen for help and advice during RNA-seq library construction and sequencing and to Guillermo Santamaría for advice relating to wheat physiology. This project was supported by the National Research Initiative Competitive Grants 2008-35318-18654 and 2011-68002-30029 (Triticeae-CAP) from the USDA National Institute of Food and Agriculture, the United States-Israel Binational Science Foundation (BSF) grant number 2007194, by the Marie Curie International Reintegration Grant number PIRG08-GA-2010-277036 and by the Howard Hughes Medical Institute and the Gordon and Betty Moore Foundation grant GBMF3031. Facundo Tabbita was the recipient of a four-month "René Hugo Thalmann" fellowship from Universidad de Buenos Aires for financial support while working at UC Davis (EXP-UBA: 31.621/2010).
Keywords
- GPC
- Iron transport
- Senescence
- Wheat
- ZIP
- Zinc transport
ASJC Scopus subject areas
- Plant Science
