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Genome duplication improves rice root resistance to salt stress.

Tu Y, Jiang A, Gan L, Hossain M, Zhang J, Peng B, Xiong Y, Song Z, Cai D, Xu W, Zhang J, He Y - Rice (N Y) (2014)

Bottom Line: We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice.Furthermore, Na(+) in tetraploid rice roots significantly decreased while root tip H(+) efflux in tetraploid rice significantly increased.Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na(+) entrance into the roots.

View Article: PubMed Central - HTML - PubMed

Affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.

ABSTRACT

Background: Salinity is a stressful environmental factor that limits the productivity of crop plants, and roots form the major interface between plants and various abiotic stresses. Rice is a salt-sensitive crop and its polyploid shows advantages in terms of stress resistance. The objective of this study was to investigate the effects of genome duplication on rice root resistance to salt stress.

Results: Both diploid rice (HN2026-2x and Nipponbare-2x) and their corresponding tetraploid rice (HN2026-4x and Nipponbare-4x) were cultured in half-strength Murashige and Skoog medium with 150 mM NaCl for 3 and 5 days. Accumulations of proline, soluble sugar, malondialdehyde (MDA), Na(+) content, H(+) (proton) flux at root tips, and the microstructure and ultrastructure in rice roots were examined. We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice. In addition, a protective gap appeared between the cortex and pericycle cells in tetraploid rice. Next, ultrastructural analysis showed that genome duplication improved membrane, organelle, and nuclei stability. Furthermore, Na(+) in tetraploid rice roots significantly decreased while root tip H(+) efflux in tetraploid rice significantly increased.

Conclusions: Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na(+) entrance into the roots.

No MeSH data available.


The accumulation of MDA in roots of diploid and tetraploid rice under salt stress. Data represent the mean ± SD (n = 30 × 3 independent biological replicates: all samples were tested in three independent experiments with each included thirty rice plants). Means followed by common letters are not significantly different at P = 0.05 using a protected least-significant difference.
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Figure 4: The accumulation of MDA in roots of diploid and tetraploid rice under salt stress. Data represent the mean ± SD (n = 30 × 3 independent biological replicates: all samples were tested in three independent experiments with each included thirty rice plants). Means followed by common letters are not significantly different at P = 0.05 using a protected least-significant difference.

Mentions: Malondialdehyde (MDA) accumulated to similar levels in all rice cultivars tested, and no significant difference was detected between diploid and tetraploid rice cultivars without salt stress. However, the amount of MDA in the roots of various rice cultivars under salt stress was significantly greater than in the control (Figure 4). In contrast, the amount of MDA in the roots of tetraploid rice under salt stress was significantly lower than that in diploid cultivars, suggesting that membrane integrity was higher in tetraploid cultivars than in diploid rice (Figure 4). Genotypes Nipponbare-4x (55.58 μmol g–1) and HN2026-4x (60.10 μmol g–1) accumulated less MDA in their roots compared to the corresponding diploid cultivars under normal condition. Under salt stress, the amount of MDA in HN2026-4x conditioned with salt was lowest among all cultivars (Figure 4).


Genome duplication improves rice root resistance to salt stress.

Tu Y, Jiang A, Gan L, Hossain M, Zhang J, Peng B, Xiong Y, Song Z, Cai D, Xu W, Zhang J, He Y - Rice (N Y) (2014)

The accumulation of MDA in roots of diploid and tetraploid rice under salt stress. Data represent the mean ± SD (n = 30 × 3 independent biological replicates: all samples were tested in three independent experiments with each included thirty rice plants). Means followed by common letters are not significantly different at P = 0.05 using a protected least-significant difference.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4151024&req=5

Figure 4: The accumulation of MDA in roots of diploid and tetraploid rice under salt stress. Data represent the mean ± SD (n = 30 × 3 independent biological replicates: all samples were tested in three independent experiments with each included thirty rice plants). Means followed by common letters are not significantly different at P = 0.05 using a protected least-significant difference.
Mentions: Malondialdehyde (MDA) accumulated to similar levels in all rice cultivars tested, and no significant difference was detected between diploid and tetraploid rice cultivars without salt stress. However, the amount of MDA in the roots of various rice cultivars under salt stress was significantly greater than in the control (Figure 4). In contrast, the amount of MDA in the roots of tetraploid rice under salt stress was significantly lower than that in diploid cultivars, suggesting that membrane integrity was higher in tetraploid cultivars than in diploid rice (Figure 4). Genotypes Nipponbare-4x (55.58 μmol g–1) and HN2026-4x (60.10 μmol g–1) accumulated less MDA in their roots compared to the corresponding diploid cultivars under normal condition. Under salt stress, the amount of MDA in HN2026-4x conditioned with salt was lowest among all cultivars (Figure 4).

Bottom Line: We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice.Furthermore, Na(+) in tetraploid rice roots significantly decreased while root tip H(+) efflux in tetraploid rice significantly increased.Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na(+) entrance into the roots.

View Article: PubMed Central - HTML - PubMed

Affiliation: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, P.R. China.

ABSTRACT

Background: Salinity is a stressful environmental factor that limits the productivity of crop plants, and roots form the major interface between plants and various abiotic stresses. Rice is a salt-sensitive crop and its polyploid shows advantages in terms of stress resistance. The objective of this study was to investigate the effects of genome duplication on rice root resistance to salt stress.

Results: Both diploid rice (HN2026-2x and Nipponbare-2x) and their corresponding tetraploid rice (HN2026-4x and Nipponbare-4x) were cultured in half-strength Murashige and Skoog medium with 150 mM NaCl for 3 and 5 days. Accumulations of proline, soluble sugar, malondialdehyde (MDA), Na(+) content, H(+) (proton) flux at root tips, and the microstructure and ultrastructure in rice roots were examined. We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice. In addition, a protective gap appeared between the cortex and pericycle cells in tetraploid rice. Next, ultrastructural analysis showed that genome duplication improved membrane, organelle, and nuclei stability. Furthermore, Na(+) in tetraploid rice roots significantly decreased while root tip H(+) efflux in tetraploid rice significantly increased.

Conclusions: Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na(+) entrance into the roots.

No MeSH data available.