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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.


Root growth in diploid and tetraploid rice cultivars under salt stress for 5 days. 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. Note: (A) Length of the longest root; (B) The number of roots; (C) Fresh weight of the total roots; (D) Dry weight of the total roots.
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Figure 1: Root growth in diploid and tetraploid rice cultivars under salt stress for 5 days. 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. Note: (A) Length of the longest root; (B) The number of roots; (C) Fresh weight of the total roots; (D) Dry weight of the total roots.

Mentions: The length, fresh weight, dry weight, and number of roots of polyploid rice cultivars were investigated to characterize the effects of genome duplication under salt stress. Our results demonstrated that salt stress significantly restricted rice root growth, irrespective of being diploid or tetraploid rice, and genome duplication improved root resistance in tetraploid rice by contributing to faster and better root growth in the presence of 150 mM NaCl (Figure 1). Root length was restricted in all species. Salt stress significantly decreased the length of the longest root, irrespective of being diploid or tetraploid rice. Moreover, compared with roots under normal conditions, the restriction degree of root length in the diploid was much stronger than that in the tetraploid. The fresh weight of total roots in tetraploid rice showed a more significant increase than in diploid rice under salt conditions. However, the fresh weight of total roots decreased in all rice tested after salt treatment, and no significant difference in the dry weight of total roots was observed, excluding HN2026-4x. In addition, the results suggested that the total number of roots existed no evident difference in both HN2026-4x and Nipponbare-4x under salt stress, but significant differences were found in the two diploid rice materials with salt treatment (Figure 1).


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)

Root growth in diploid and tetraploid rice cultivars under salt stress for 5 days. 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. Note: (A) Length of the longest root; (B) The number of roots; (C) Fresh weight of the total roots; (D) Dry weight of the total roots.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Root growth in diploid and tetraploid rice cultivars under salt stress for 5 days. 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. Note: (A) Length of the longest root; (B) The number of roots; (C) Fresh weight of the total roots; (D) Dry weight of the total roots.
Mentions: The length, fresh weight, dry weight, and number of roots of polyploid rice cultivars were investigated to characterize the effects of genome duplication under salt stress. Our results demonstrated that salt stress significantly restricted rice root growth, irrespective of being diploid or tetraploid rice, and genome duplication improved root resistance in tetraploid rice by contributing to faster and better root growth in the presence of 150 mM NaCl (Figure 1). Root length was restricted in all species. Salt stress significantly decreased the length of the longest root, irrespective of being diploid or tetraploid rice. Moreover, compared with roots under normal conditions, the restriction degree of root length in the diploid was much stronger than that in the tetraploid. The fresh weight of total roots in tetraploid rice showed a more significant increase than in diploid rice under salt conditions. However, the fresh weight of total roots decreased in all rice tested after salt treatment, and no significant difference in the dry weight of total roots was observed, excluding HN2026-4x. In addition, the results suggested that the total number of roots existed no evident difference in both HN2026-4x and Nipponbare-4x under salt stress, but significant differences were found in the two diploid rice materials with salt treatment (Figure 1).

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.