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Mechanisms of salt tolerance in habanero pepper plants (Capsicum chinense Jacq.): Proline accumulation, ions dynamics and sodium root-shoot partition and compartmentation.

Bojórquez-Quintal E, Velarde-Buendía A, Ku-González A, Carillo-Pech M, Ortega-Camacho D, Echevarría-Machado I, Pottosin I, Martínez-Estévez M - Front Plant Sci (2014)

Bottom Line: To address this question, we compared differences in responses to NaCl in two Capsicum chinense varieties: Rex (tolerant) and Chichen-Itza (sensitive).Under salt stress (150 mM NaCl over 7 days) roots of Rex variety accumulated 50 times more compatible solutes such as proline compared to Chichen-Itza.Furthermore, Na(+) extrusion to apoplast does not appear to be an efficient strategy for salt tolerance in pepper plants.

View Article: PubMed Central - PubMed

Affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Yucatán, México.

ABSTRACT
Despite its economic relevance, little is known about salt tolerance mechanisms in pepper plants. To address this question, we compared differences in responses to NaCl in two Capsicum chinense varieties: Rex (tolerant) and Chichen-Itza (sensitive). Under salt stress (150 mM NaCl over 7 days) roots of Rex variety accumulated 50 times more compatible solutes such as proline compared to Chichen-Itza. Mineral analysis indicated that Na(+) is restricted to roots by preventing its transport to leaves. Fluorescence analysis suggested an efficient Na(+) compartmentalization in vacuole-like structures and in small intracellular compartments in roots of Rex variety. At the same time, Na(+) in Chichen-Itza plants was compartmentalized in the apoplast, suggesting substantial Na(+) extrusion. Rex variety was found to retain more K(+) in its roots under salt stress according to a mineral analysis and microelectrode ion flux estimation (MIFE). Vanadate-sensitive H(+) efflux was higher in Chichen-Itza variety plants, suggesting a higher activity of the plasma membrane H(+)-ATPase, which fuels the extrusion of Na(+), and, possibly, also the re-uptake of K(+). Our results suggest a combination of stress tolerance mechanisms, in order to alleviate the salt-induced injury. Furthermore, Na(+) extrusion to apoplast does not appear to be an efficient strategy for salt tolerance in pepper plants.

No MeSH data available.


Related in: MedlinePlus

Effect of vanadate pre-treatment on NaCl-induced H+ efflux in roots of C. chinense. (A) Kinetics of net H+ flux measured in the mature root zone of the Rex variety and (B) of the Chichen-Itza variety. 10-day-old roots of the two strains were pre-treated with 1 mM vanadate for 45–60 min before adding of 150 mM NaCl (marked by an arrow). Open circles and squares indicate pre-treatment with vanadate. Closed circles and squares indicate no pre-treatment. (C) Average effect of vanadate pre-treatment on the net flow of H+ from the root of each variety in the first 10 min after the application of 150 mM NaCl, ME ± SD (n = 3–4). The asterisk indicates statistically significant differences between varieties by treatment (P < 0.001, Tukey's test).
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Figure 7: Effect of vanadate pre-treatment on NaCl-induced H+ efflux in roots of C. chinense. (A) Kinetics of net H+ flux measured in the mature root zone of the Rex variety and (B) of the Chichen-Itza variety. 10-day-old roots of the two strains were pre-treated with 1 mM vanadate for 45–60 min before adding of 150 mM NaCl (marked by an arrow). Open circles and squares indicate pre-treatment with vanadate. Closed circles and squares indicate no pre-treatment. (C) Average effect of vanadate pre-treatment on the net flow of H+ from the root of each variety in the first 10 min after the application of 150 mM NaCl, ME ± SD (n = 3–4). The asterisk indicates statistically significant differences between varieties by treatment (P < 0.001, Tukey's test).

Mentions: In the roots of habanero pepper, NaCl stress caused significant changes in the net flux of H+ (Figure 6). Before starting the salt treatment (first 5 min), the net flux of H+ was zero in both varieties. Application of 150 mM NaCl induced a substantial H+ efflux (Figure 6A). In the roots of the Rex variety, NaCl induced H+ efflux was much lower as compared the Chichen-Itza variety (Figure 6B). Furthermore, a pre-treatment of seedlings with 1 mM sodium orthovanadate (an inhibitor of P-type H+-ATPases) strongly suppressed the H+ efflux from the mature root zone of both genotypes (Figure 7). Thus, the NaCl- induced H+ efflux was mediated by P-type H+-ATPases.


Mechanisms of salt tolerance in habanero pepper plants (Capsicum chinense Jacq.): Proline accumulation, ions dynamics and sodium root-shoot partition and compartmentation.

Bojórquez-Quintal E, Velarde-Buendía A, Ku-González A, Carillo-Pech M, Ortega-Camacho D, Echevarría-Machado I, Pottosin I, Martínez-Estévez M - Front Plant Sci (2014)

Effect of vanadate pre-treatment on NaCl-induced H+ efflux in roots of C. chinense. (A) Kinetics of net H+ flux measured in the mature root zone of the Rex variety and (B) of the Chichen-Itza variety. 10-day-old roots of the two strains were pre-treated with 1 mM vanadate for 45–60 min before adding of 150 mM NaCl (marked by an arrow). Open circles and squares indicate pre-treatment with vanadate. Closed circles and squares indicate no pre-treatment. (C) Average effect of vanadate pre-treatment on the net flow of H+ from the root of each variety in the first 10 min after the application of 150 mM NaCl, ME ± SD (n = 3–4). The asterisk indicates statistically significant differences between varieties by treatment (P < 0.001, Tukey's test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4228851&req=5

Figure 7: Effect of vanadate pre-treatment on NaCl-induced H+ efflux in roots of C. chinense. (A) Kinetics of net H+ flux measured in the mature root zone of the Rex variety and (B) of the Chichen-Itza variety. 10-day-old roots of the two strains were pre-treated with 1 mM vanadate for 45–60 min before adding of 150 mM NaCl (marked by an arrow). Open circles and squares indicate pre-treatment with vanadate. Closed circles and squares indicate no pre-treatment. (C) Average effect of vanadate pre-treatment on the net flow of H+ from the root of each variety in the first 10 min after the application of 150 mM NaCl, ME ± SD (n = 3–4). The asterisk indicates statistically significant differences between varieties by treatment (P < 0.001, Tukey's test).
Mentions: In the roots of habanero pepper, NaCl stress caused significant changes in the net flux of H+ (Figure 6). Before starting the salt treatment (first 5 min), the net flux of H+ was zero in both varieties. Application of 150 mM NaCl induced a substantial H+ efflux (Figure 6A). In the roots of the Rex variety, NaCl induced H+ efflux was much lower as compared the Chichen-Itza variety (Figure 6B). Furthermore, a pre-treatment of seedlings with 1 mM sodium orthovanadate (an inhibitor of P-type H+-ATPases) strongly suppressed the H+ efflux from the mature root zone of both genotypes (Figure 7). Thus, the NaCl- induced H+ efflux was mediated by P-type H+-ATPases.

Bottom Line: To address this question, we compared differences in responses to NaCl in two Capsicum chinense varieties: Rex (tolerant) and Chichen-Itza (sensitive).Under salt stress (150 mM NaCl over 7 days) roots of Rex variety accumulated 50 times more compatible solutes such as proline compared to Chichen-Itza.Furthermore, Na(+) extrusion to apoplast does not appear to be an efficient strategy for salt tolerance in pepper plants.

View Article: PubMed Central - PubMed

Affiliation: Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán Yucatán, México.

ABSTRACT
Despite its economic relevance, little is known about salt tolerance mechanisms in pepper plants. To address this question, we compared differences in responses to NaCl in two Capsicum chinense varieties: Rex (tolerant) and Chichen-Itza (sensitive). Under salt stress (150 mM NaCl over 7 days) roots of Rex variety accumulated 50 times more compatible solutes such as proline compared to Chichen-Itza. Mineral analysis indicated that Na(+) is restricted to roots by preventing its transport to leaves. Fluorescence analysis suggested an efficient Na(+) compartmentalization in vacuole-like structures and in small intracellular compartments in roots of Rex variety. At the same time, Na(+) in Chichen-Itza plants was compartmentalized in the apoplast, suggesting substantial Na(+) extrusion. Rex variety was found to retain more K(+) in its roots under salt stress according to a mineral analysis and microelectrode ion flux estimation (MIFE). Vanadate-sensitive H(+) efflux was higher in Chichen-Itza variety plants, suggesting a higher activity of the plasma membrane H(+)-ATPase, which fuels the extrusion of Na(+), and, possibly, also the re-uptake of K(+). Our results suggest a combination of stress tolerance mechanisms, in order to alleviate the salt-induced injury. Furthermore, Na(+) extrusion to apoplast does not appear to be an efficient strategy for salt tolerance in pepper plants.

No MeSH data available.


Related in: MedlinePlus