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Asymmetric transcriptomic signatures between the cob and florets in the maize ear under optimal- and low-nitrogen conditions at silking, and functional characterization of amino acid transporters ZmAAP4 and ZmVAAT3.

Pan X, Hasan MM, Li Y, Liao C, Zheng H, Liu R, Li X - J. Exp. Bot. (2015)

Bottom Line: Fourteen genes responsive specifically to LN provided potential molecular markers for N-efficient maize breeding.We further functionally characterized two newly identified broad-spectrum amino acid transporters, ZmAAP4 and ZmVAAT3, that showed distinct expression patterns in the cob and florets and potentially important roles in amino-N mobilization in the ear.While both proteins could transport various amino acids into yeast or Arabidopsis cells, ZmAAP4 appeared to have higher efficiencies than ZmVAAT3 in transporting seven out of 22 examined amino acids.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Nutrition, China Agricultural University, Beijing 100193, China.

No MeSH data available.


Related in: MedlinePlus

Heat maps showing the expression levels of tissue-specific genes in the cob and florets under sufficient N supply.
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Figure 3: Heat maps showing the expression levels of tissue-specific genes in the cob and florets under sufficient N supply.

Mentions: Of particular interest were genes only detected in the cob or florets. In total, 63 out of 161 cob-specific genes (Supplementary Table S6) and 45 out of 108 floret-specific genes are functionally unknown genes (Supplementary Table S7), indicating that DGE may identify previously uncharacterized transcripts. We analysed tissue-specific genes with proper annotation using manual functional classification and heat map illustration (Supplementary Tables S6, S7; Fig. 3). First, 18 genes involved in transport facilitation were only detected in the cob, including two carbohydrate transporters, four amino acid transporters, four nutrient transporters and eight other transporters, suggesting the cob’s unique function to transport carbohydrates, amino acids and nutrients for bearing florets (Fig. 3A). Second, 21 genes involved in metabolism also showed cob-specific expression pattern. Third, certain cytokinin and ethylene signalling components, such as cytokinin dehydrogenase (CKX) and ethylene-insensitive 3 (EIN 3), were only detected in the cob (Fig. 3B). Fourth, 14 transcription factors were only expressed in the cob. In addition, genes involved in cell rescue, signal transduction and proteolytic degradation were also preferentially expressed in the cob during this phase. In sharp contrast, only a few floret-specific genes were related to transport facilitation; three major groups of floret-specific genes were involved in development, transcription and metabolism (Fig. 3). Thirteen development related genes, 21 transcription factors, and 15 metabolism related genes (such as hydrolyzing O-glycosyl compounds, crinkly 4 related 4 (CR4), pectate lyase family protein and subtilase family protein) co-modulated floret development (Fig. 3). 3-ketoacyl-coa synthase 6 and strictosidine synthase family proteins were essential for protein synthesis during floret growth. As expected, hormone signalling components isopentenyl transferase 5, gibberellin 2-oxidase 6, gibberellin 20 oxidase 2, and auxin response factor 16 were specifically expressed in florets (Fig. 3). In summary, the cob and florets showed contrasting gene expression profiles, underpinning their tissue identities and distinct biological functions at a critical developmental stage in maize.


Asymmetric transcriptomic signatures between the cob and florets in the maize ear under optimal- and low-nitrogen conditions at silking, and functional characterization of amino acid transporters ZmAAP4 and ZmVAAT3.

Pan X, Hasan MM, Li Y, Liao C, Zheng H, Liu R, Li X - J. Exp. Bot. (2015)

Heat maps showing the expression levels of tissue-specific genes in the cob and florets under sufficient N supply.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4588875&req=5

Figure 3: Heat maps showing the expression levels of tissue-specific genes in the cob and florets under sufficient N supply.
Mentions: Of particular interest were genes only detected in the cob or florets. In total, 63 out of 161 cob-specific genes (Supplementary Table S6) and 45 out of 108 floret-specific genes are functionally unknown genes (Supplementary Table S7), indicating that DGE may identify previously uncharacterized transcripts. We analysed tissue-specific genes with proper annotation using manual functional classification and heat map illustration (Supplementary Tables S6, S7; Fig. 3). First, 18 genes involved in transport facilitation were only detected in the cob, including two carbohydrate transporters, four amino acid transporters, four nutrient transporters and eight other transporters, suggesting the cob’s unique function to transport carbohydrates, amino acids and nutrients for bearing florets (Fig. 3A). Second, 21 genes involved in metabolism also showed cob-specific expression pattern. Third, certain cytokinin and ethylene signalling components, such as cytokinin dehydrogenase (CKX) and ethylene-insensitive 3 (EIN 3), were only detected in the cob (Fig. 3B). Fourth, 14 transcription factors were only expressed in the cob. In addition, genes involved in cell rescue, signal transduction and proteolytic degradation were also preferentially expressed in the cob during this phase. In sharp contrast, only a few floret-specific genes were related to transport facilitation; three major groups of floret-specific genes were involved in development, transcription and metabolism (Fig. 3). Thirteen development related genes, 21 transcription factors, and 15 metabolism related genes (such as hydrolyzing O-glycosyl compounds, crinkly 4 related 4 (CR4), pectate lyase family protein and subtilase family protein) co-modulated floret development (Fig. 3). 3-ketoacyl-coa synthase 6 and strictosidine synthase family proteins were essential for protein synthesis during floret growth. As expected, hormone signalling components isopentenyl transferase 5, gibberellin 2-oxidase 6, gibberellin 20 oxidase 2, and auxin response factor 16 were specifically expressed in florets (Fig. 3). In summary, the cob and florets showed contrasting gene expression profiles, underpinning their tissue identities and distinct biological functions at a critical developmental stage in maize.

Bottom Line: Fourteen genes responsive specifically to LN provided potential molecular markers for N-efficient maize breeding.We further functionally characterized two newly identified broad-spectrum amino acid transporters, ZmAAP4 and ZmVAAT3, that showed distinct expression patterns in the cob and florets and potentially important roles in amino-N mobilization in the ear.While both proteins could transport various amino acids into yeast or Arabidopsis cells, ZmAAP4 appeared to have higher efficiencies than ZmVAAT3 in transporting seven out of 22 examined amino acids.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Nutrition, China Agricultural University, Beijing 100193, China.

No MeSH data available.


Related in: MedlinePlus