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Foliar Abscisic Acid-To-Ethylene Accumulation and Response Regulate Shoot Growth Sensitivity to Mild Drought in Wheat.

Valluru R, Davies WJ, Reynolds MP, Dodd IC - Front Plant Sci (2016)

Bottom Line: We concluded that SDW of the DT and DS groups might be distinctly regulated by specific ABA:ethylene ratio.Furthermore, the DT group accumulated a significantly higher galactose while a significantly lower maltose in the shoot compared to the DS group.Taken all together, these results suggest an impact of ABA, ethylene, and ABA:ethylene ratio on SDW of wheat seedlings that may partly underlie a genotypic variability of different shoot growth sensitivities to drought among crop species under field conditions.

View Article: PubMed Central - PubMed

Affiliation: Global Wheat Program, International Maize and Wheat Improvement Center (CIMMYT)El Batan, Mexico; Plant Biology Department, Lancaster Environmental Center, Lancaster UniversityLancaster, UK.

ABSTRACT
Although, plant hormones play an important role in adjusting growth in response to environmental perturbation, the relative contributions of abscisic acid (ABA) and ethylene remain elusive. Using six spring wheat genotypes differing for stress tolerance, we show that young seedlings of the drought-tolerant (DT) group maintained or increased shoot dry weight (SDW) while the drought-susceptible (DS) group decreased SDW in response to mild drought. Both the DT and DS groups increased endogenous ABA and ethylene concentrations under mild drought compared to control. The DT and DS groups exhibited different SDW response trends, whereby the DS group decreased while the DT group increased SDW, to increased concentrations of ABA and ethylene under mild drought, although both groups decreased ABA/ethylene ratio under mild drought albeit at different levels. We concluded that SDW of the DT and DS groups might be distinctly regulated by specific ABA:ethylene ratio. Further, a foliar-spray of low concentrations (0.1 μM) of ABA increased shoot relative growth rate (RGR) in the DS group while ACC (1-aminocyclopropane-1-carboxylic acid, ethylene precursor) spray increased RGR in both groups compared to control. Furthermore, the DT group accumulated a significantly higher galactose while a significantly lower maltose in the shoot compared to the DS group. Taken all together, these results suggest an impact of ABA, ethylene, and ABA:ethylene ratio on SDW of wheat seedlings that may partly underlie a genotypic variability of different shoot growth sensitivities to drought among crop species under field conditions. We propose that phenotyping based on hormone accumulation, response and hormonal ratio would be a viable, rapid, and an early-stage selection tool aiding genotype selection for stress tolerance.

No MeSH data available.


Related in: MedlinePlus

Shoot relative growth rate (RGR) of six wheat genotypes at 3rd leaf stage that were either sprayed with water (controls), abscisic acid (ABA, 0.1 μM), or the ethylene-precursor, 1-aminocyclopropane-1-carboxylic acid (ACC, 0.1 μM) with four replications for each genotype. **, *** indicate p < 0.01, and < 0.05, respectively.
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Figure 5: Shoot relative growth rate (RGR) of six wheat genotypes at 3rd leaf stage that were either sprayed with water (controls), abscisic acid (ABA, 0.1 μM), or the ethylene-precursor, 1-aminocyclopropane-1-carboxylic acid (ACC, 0.1 μM) with four replications for each genotype. **, *** indicate p < 0.01, and < 0.05, respectively.

Mentions: Previous studies have often shown that very mild concentrations of exogenous ABA (Takahashi, 1972; Watanabe and Takahashi, 1997) and ethylene (Burg and Burg, 1966, 1968) stimulated growth of various organs of a range of plant species. We, therefore, examined whether low concentrations of exogenous ABA and ethylene could stimulate growth of DT and DS genotypes under WW condition. Both the DT and DS groups showed a significantly different shoot relative growth rate (RGR) response to exogenous ABA and ACC spray (Figure 5). ABA and ACC strongly promoted RGR of DS genotypes (131 and 130% respectively; P = 0.01) but had modest effect on RGR of DT genotypes (5 and 32% respectively; P = 0.03). Across all groups, ABA had an increased RGR by 50% (P = 0.04), while ACC was slightly more effective in stimulating shoot RGR (78%, P = 0.002). Such growth stimulation responses to exogenous ABA and ACC sprayed at the three-leaf stage were not significantly different from control at the 6th leaf-stage (Supplementary Figure S4), suggesting that low concentrations of ABA and ACC stimulated growth response may be dependent on the developmental stages.


Foliar Abscisic Acid-To-Ethylene Accumulation and Response Regulate Shoot Growth Sensitivity to Mild Drought in Wheat.

Valluru R, Davies WJ, Reynolds MP, Dodd IC - Front Plant Sci (2016)

Shoot relative growth rate (RGR) of six wheat genotypes at 3rd leaf stage that were either sprayed with water (controls), abscisic acid (ABA, 0.1 μM), or the ethylene-precursor, 1-aminocyclopropane-1-carboxylic acid (ACC, 0.1 μM) with four replications for each genotype. **, *** indicate p < 0.01, and < 0.05, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834443&req=5

Figure 5: Shoot relative growth rate (RGR) of six wheat genotypes at 3rd leaf stage that were either sprayed with water (controls), abscisic acid (ABA, 0.1 μM), or the ethylene-precursor, 1-aminocyclopropane-1-carboxylic acid (ACC, 0.1 μM) with four replications for each genotype. **, *** indicate p < 0.01, and < 0.05, respectively.
Mentions: Previous studies have often shown that very mild concentrations of exogenous ABA (Takahashi, 1972; Watanabe and Takahashi, 1997) and ethylene (Burg and Burg, 1966, 1968) stimulated growth of various organs of a range of plant species. We, therefore, examined whether low concentrations of exogenous ABA and ethylene could stimulate growth of DT and DS genotypes under WW condition. Both the DT and DS groups showed a significantly different shoot relative growth rate (RGR) response to exogenous ABA and ACC spray (Figure 5). ABA and ACC strongly promoted RGR of DS genotypes (131 and 130% respectively; P = 0.01) but had modest effect on RGR of DT genotypes (5 and 32% respectively; P = 0.03). Across all groups, ABA had an increased RGR by 50% (P = 0.04), while ACC was slightly more effective in stimulating shoot RGR (78%, P = 0.002). Such growth stimulation responses to exogenous ABA and ACC sprayed at the three-leaf stage were not significantly different from control at the 6th leaf-stage (Supplementary Figure S4), suggesting that low concentrations of ABA and ACC stimulated growth response may be dependent on the developmental stages.

Bottom Line: We concluded that SDW of the DT and DS groups might be distinctly regulated by specific ABA:ethylene ratio.Furthermore, the DT group accumulated a significantly higher galactose while a significantly lower maltose in the shoot compared to the DS group.Taken all together, these results suggest an impact of ABA, ethylene, and ABA:ethylene ratio on SDW of wheat seedlings that may partly underlie a genotypic variability of different shoot growth sensitivities to drought among crop species under field conditions.

View Article: PubMed Central - PubMed

Affiliation: Global Wheat Program, International Maize and Wheat Improvement Center (CIMMYT)El Batan, Mexico; Plant Biology Department, Lancaster Environmental Center, Lancaster UniversityLancaster, UK.

ABSTRACT
Although, plant hormones play an important role in adjusting growth in response to environmental perturbation, the relative contributions of abscisic acid (ABA) and ethylene remain elusive. Using six spring wheat genotypes differing for stress tolerance, we show that young seedlings of the drought-tolerant (DT) group maintained or increased shoot dry weight (SDW) while the drought-susceptible (DS) group decreased SDW in response to mild drought. Both the DT and DS groups increased endogenous ABA and ethylene concentrations under mild drought compared to control. The DT and DS groups exhibited different SDW response trends, whereby the DS group decreased while the DT group increased SDW, to increased concentrations of ABA and ethylene under mild drought, although both groups decreased ABA/ethylene ratio under mild drought albeit at different levels. We concluded that SDW of the DT and DS groups might be distinctly regulated by specific ABA:ethylene ratio. Further, a foliar-spray of low concentrations (0.1 μM) of ABA increased shoot relative growth rate (RGR) in the DS group while ACC (1-aminocyclopropane-1-carboxylic acid, ethylene precursor) spray increased RGR in both groups compared to control. Furthermore, the DT group accumulated a significantly higher galactose while a significantly lower maltose in the shoot compared to the DS group. Taken all together, these results suggest an impact of ABA, ethylene, and ABA:ethylene ratio on SDW of wheat seedlings that may partly underlie a genotypic variability of different shoot growth sensitivities to drought among crop species under field conditions. We propose that phenotyping based on hormone accumulation, response and hormonal ratio would be a viable, rapid, and an early-stage selection tool aiding genotype selection for stress tolerance.

No MeSH data available.


Related in: MedlinePlus