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Dihydroxyacid dehydratase is important for gametophyte development and disruption causes increased susceptibility to salinity stress in Arabidopsis.

Zhang C, Pang Q, Jiang L, Wang S, Yan X, Chen S, He Y - J. Exp. Bot. (2014)

Bottom Line: In addition, reduced expression of DHAD in knockdown mutants resulted in a reduction in the accumulation of all three BCAAs in roots and, as a consequence, led to a shorter root phenotype, which could be restored by an exogenous supplement of free BCAAs.This would be the second amino acid shown to confer such a function in addition to the well-documented proline.Our results provide evidence that BCAA biosynthesis plays important roles in gametophyte and root development, and BCAA homeostasis contributes to the adaptation of Arabidopsis to salinity stress.

View Article: PubMed Central - PubMed

Affiliation: National Maize Improvement Centre of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China.

No MeSH data available.


Related in: MedlinePlus

dhad-1 and dhad-2 are hypersensitive to salt stress. (A–F) 10-day-old WT, dhad-1, and dhad-2 seedlings grown on half MS medium supplemented with different levels of NaCl (A–C) and 0.1mM Ile (A–F). Bar, 10mm. (G) Root length in the mutants was measured and shown as a percentage relative to that in the WT grown in the same conditions. Error bars indicate standard error. This figure is available in colour at JXB online.
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Figure 4: dhad-1 and dhad-2 are hypersensitive to salt stress. (A–F) 10-day-old WT, dhad-1, and dhad-2 seedlings grown on half MS medium supplemented with different levels of NaCl (A–C) and 0.1mM Ile (A–F). Bar, 10mm. (G) Root length in the mutants was measured and shown as a percentage relative to that in the WT grown in the same conditions. Error bars indicate standard error. This figure is available in colour at JXB online.

Mentions: Previous studies have shown that the accumulation of BCAAs was greatly elevated under abiotic stresses (Joshi and Jander, 2009; Joshi et al., 2010), suggesting that BCAA homeostasis may contribute to the multifaceted stress tolerance systems in plants. To test the possibility that reduction in BCAA abundance may lead to hypersensitivity to abiotic stress, the effects of salt stress on root growth were investigated. As shown in Fig. 4A, with a low concentration of Na+ (50mM), the root length of dhad knockdown mutants was 62–64% of that in the WT (Fig. 4G), which is lower than the 68–71% without salt treatment (Fig. 3A and 3I). When Na+ concentration increased to 75mM, the ratio of the root length between the mutant and WT became 53–55% (Fig. 4B and 4G), and further decreased to 39–41% after treatment with 100mM Na+. This indicates that dhad knockdown mutants exhibited greater sensitivity compared to the WT towards increasing concentration of Na+. More importantly, the sensitivity to Na+ treatment under different concentrations could be restored to similar levels as in the WT when 0.1mM Ile was supplied exogenously. These results suggest that the high sensitivity of dhad to Na+ stress can be attributed to the reduced level of Ile (Fig. 4D–G).


Dihydroxyacid dehydratase is important for gametophyte development and disruption causes increased susceptibility to salinity stress in Arabidopsis.

Zhang C, Pang Q, Jiang L, Wang S, Yan X, Chen S, He Y - J. Exp. Bot. (2014)

dhad-1 and dhad-2 are hypersensitive to salt stress. (A–F) 10-day-old WT, dhad-1, and dhad-2 seedlings grown on half MS medium supplemented with different levels of NaCl (A–C) and 0.1mM Ile (A–F). Bar, 10mm. (G) Root length in the mutants was measured and shown as a percentage relative to that in the WT grown in the same conditions. Error bars indicate standard error. This figure is available in colour at JXB online.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4321549&req=5

Figure 4: dhad-1 and dhad-2 are hypersensitive to salt stress. (A–F) 10-day-old WT, dhad-1, and dhad-2 seedlings grown on half MS medium supplemented with different levels of NaCl (A–C) and 0.1mM Ile (A–F). Bar, 10mm. (G) Root length in the mutants was measured and shown as a percentage relative to that in the WT grown in the same conditions. Error bars indicate standard error. This figure is available in colour at JXB online.
Mentions: Previous studies have shown that the accumulation of BCAAs was greatly elevated under abiotic stresses (Joshi and Jander, 2009; Joshi et al., 2010), suggesting that BCAA homeostasis may contribute to the multifaceted stress tolerance systems in plants. To test the possibility that reduction in BCAA abundance may lead to hypersensitivity to abiotic stress, the effects of salt stress on root growth were investigated. As shown in Fig. 4A, with a low concentration of Na+ (50mM), the root length of dhad knockdown mutants was 62–64% of that in the WT (Fig. 4G), which is lower than the 68–71% without salt treatment (Fig. 3A and 3I). When Na+ concentration increased to 75mM, the ratio of the root length between the mutant and WT became 53–55% (Fig. 4B and 4G), and further decreased to 39–41% after treatment with 100mM Na+. This indicates that dhad knockdown mutants exhibited greater sensitivity compared to the WT towards increasing concentration of Na+. More importantly, the sensitivity to Na+ treatment under different concentrations could be restored to similar levels as in the WT when 0.1mM Ile was supplied exogenously. These results suggest that the high sensitivity of dhad to Na+ stress can be attributed to the reduced level of Ile (Fig. 4D–G).

Bottom Line: In addition, reduced expression of DHAD in knockdown mutants resulted in a reduction in the accumulation of all three BCAAs in roots and, as a consequence, led to a shorter root phenotype, which could be restored by an exogenous supplement of free BCAAs.This would be the second amino acid shown to confer such a function in addition to the well-documented proline.Our results provide evidence that BCAA biosynthesis plays important roles in gametophyte and root development, and BCAA homeostasis contributes to the adaptation of Arabidopsis to salinity stress.

View Article: PubMed Central - PubMed

Affiliation: National Maize Improvement Centre of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, China.

No MeSH data available.


Related in: MedlinePlus