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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.


Na+content and H+flux of Nipponbare-2x and -4x under salt stress. (A) Na+ content in Nipponbare-2x and -4x. (B) H+ flux in Nipponbare-2x and -4x.
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Figure 7: Na+content and H+flux of Nipponbare-2x and -4x under salt stress. (A) Na+ content in Nipponbare-2x and -4x. (B) H+ flux in Nipponbare-2x and -4x.

Mentions: The Na+ content in the whole plant including the root and shoot was measured using inductively coupled plasma emission spectroscopy (ICP-AES)( Figure 7A). The results clearly indicated that Na+ accumulation in Nipponbare-2x and Nipponbare-4x did not differ from control conditions, whereas Na+ content in Nipponbare-2x increased significantly compared to Nipponbare-4x under salt stress. This low level of Na+ content suggested that Nipponbare-4x had a better protective effect against deleterious ions, leading to higher salt tolerance. H+ efflux and influx were detected in the roots of Nipponbare-2x and Nipponbare-4x, which was demonstrated 500 μm from the root tip (Figure 7B). We observed that H+ efflux or influx in Nipponbare-2x and Nipponbare-4x did not differ between control and treated conditions. At 500–1000 μm from the root tip, H+ influx was dominant, which was similar in diploid and tetraploid rice. However, H+ efflux increased gradually as distance increased to 1000–2000 μm from the root tip, which was higher in Nipponbare-4x than in Nipponbare-2x under both control conditions and salt stress. Subsequently, H+ efflux entered into the stable stage beyond 2000 μm from the root tip, and a striking difference was observed between H+ efflux in Nipponbare-4x and Nipponbare-2x under salt treatment. The high H+ efflux was indicative of low pH in Nipponbare-4x.


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)

Na+content and H+flux of Nipponbare-2x and -4x under salt stress. (A) Na+ content in Nipponbare-2x and -4x. (B) H+ flux in Nipponbare-2x and -4x.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Na+content and H+flux of Nipponbare-2x and -4x under salt stress. (A) Na+ content in Nipponbare-2x and -4x. (B) H+ flux in Nipponbare-2x and -4x.
Mentions: The Na+ content in the whole plant including the root and shoot was measured using inductively coupled plasma emission spectroscopy (ICP-AES)( Figure 7A). The results clearly indicated that Na+ accumulation in Nipponbare-2x and Nipponbare-4x did not differ from control conditions, whereas Na+ content in Nipponbare-2x increased significantly compared to Nipponbare-4x under salt stress. This low level of Na+ content suggested that Nipponbare-4x had a better protective effect against deleterious ions, leading to higher salt tolerance. H+ efflux and influx were detected in the roots of Nipponbare-2x and Nipponbare-4x, which was demonstrated 500 μm from the root tip (Figure 7B). We observed that H+ efflux or influx in Nipponbare-2x and Nipponbare-4x did not differ between control and treated conditions. At 500–1000 μm from the root tip, H+ influx was dominant, which was similar in diploid and tetraploid rice. However, H+ efflux increased gradually as distance increased to 1000–2000 μm from the root tip, which was higher in Nipponbare-4x than in Nipponbare-2x under both control conditions and salt stress. Subsequently, H+ efflux entered into the stable stage beyond 2000 μm from the root tip, and a striking difference was observed between H+ efflux in Nipponbare-4x and Nipponbare-2x under salt treatment. The high H+ efflux was indicative of low pH in Nipponbare-4x.

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.