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Tocopherol deficiency reduces sucrose export from salt-stressed potato leaves independently of oxidative stress and symplastic obstruction by callose.

Asensi-Fabado MA, Ammon A, Sonnewald U, Munné-Bosch S, Voll LM - J. Exp. Bot. (2014)

Bottom Line: Based on comprehensive gene expression analyses, we propose that enhanced responsiveness of SnRK1 target genes in mesophyll cells and altered redox regulation of phloem loading by SUT1 contribute to the attenuation of sucrose export from salt-stressed SXD:RNAi source leaves.In leaves of the SXD1:RNAi plants, sodium accumulation was diminished, while proline accumulation and pools of soluble antioxidants were increased.As supported by phytohormone contents, these differences seem to increase longevity and prevent senescence of SXD:RNAi leaves under salt stress.

View Article: PubMed Central - PubMed

Affiliation: University of Barcelona, Faculty of Biology, Department of Plant Biology, Diagonal Avenue 643, E-08028 Barcelona, Spain.

No MeSH data available.


Related in: MedlinePlus

Effects of salt treatment on sodium and calcium content in source leaves. Sodium (top panels) and calcium contents (bottom panels) are depicted on a dry weight (DW) basis. Left panels represent middle leaves (leaf 8); right panels represent bottom leaves (leaf 11). Samples were collected 19 days after the onset of treatments (salt stress, black bars; control, white bars) and data represent the mean ± SE of four individual plants. Data were analysed by t-test; significant differences between the transgenic lines and the wild type (WT) within a treatment are indicated by a black asterisk (control treatment) or a white asterisk (stress treatment), while diamonds indicate significant differences between control and salt stress within a genotype (P < 0.05).
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Figure 6: Effects of salt treatment on sodium and calcium content in source leaves. Sodium (top panels) and calcium contents (bottom panels) are depicted on a dry weight (DW) basis. Left panels represent middle leaves (leaf 8); right panels represent bottom leaves (leaf 11). Samples were collected 19 days after the onset of treatments (salt stress, black bars; control, white bars) and data represent the mean ± SE of four individual plants. Data were analysed by t-test; significant differences between the transgenic lines and the wild type (WT) within a treatment are indicated by a black asterisk (control treatment) or a white asterisk (stress treatment), while diamonds indicate significant differences between control and salt stress within a genotype (P < 0.05).

Mentions: Since the negative impact of tocopherol deficiency on sugar export and tuber yield was exacerbated under salt treatment, we assessed whether the physiology of tocopherol-deficient leaves was more sensitive to salt challenge and whether an elevated degree of oxidative stress might explain the altered sugar response of transgenic leaves. The CO2 assimilation rate of SXD1:RNAi source leaves was significantly reduced by 40–60% in the transgenic plants under salt-stress conditions (Table 2). The transpiration rate was diminished in salt-stressed transgenic plants in comparison to stressed wild-type plants (Table 2), and concomitantly the contents of xylem-mobile Na+ and Ca2+ were 2- to 3-fold reduced in SXD1:RNAi source leaves (Fig. 6). Consequently, the K+/Na+ ratio was higher in both middle and bottom leaves of salt-stressed transgenic plants, indicating that the foliar ionic balance was less disturbed in SXD1:RNAi leaves compared to the wild type (Supplementary Figure S2). However, leaf osmolality in middle and bottom source leaves did not exhibit significant changes across genotypes and treatments (Supplementary Figure S3).


Tocopherol deficiency reduces sucrose export from salt-stressed potato leaves independently of oxidative stress and symplastic obstruction by callose.

Asensi-Fabado MA, Ammon A, Sonnewald U, Munné-Bosch S, Voll LM - J. Exp. Bot. (2014)

Effects of salt treatment on sodium and calcium content in source leaves. Sodium (top panels) and calcium contents (bottom panels) are depicted on a dry weight (DW) basis. Left panels represent middle leaves (leaf 8); right panels represent bottom leaves (leaf 11). Samples were collected 19 days after the onset of treatments (salt stress, black bars; control, white bars) and data represent the mean ± SE of four individual plants. Data were analysed by t-test; significant differences between the transgenic lines and the wild type (WT) within a treatment are indicated by a black asterisk (control treatment) or a white asterisk (stress treatment), while diamonds indicate significant differences between control and salt stress within a genotype (P < 0.05).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4321552&req=5

Figure 6: Effects of salt treatment on sodium and calcium content in source leaves. Sodium (top panels) and calcium contents (bottom panels) are depicted on a dry weight (DW) basis. Left panels represent middle leaves (leaf 8); right panels represent bottom leaves (leaf 11). Samples were collected 19 days after the onset of treatments (salt stress, black bars; control, white bars) and data represent the mean ± SE of four individual plants. Data were analysed by t-test; significant differences between the transgenic lines and the wild type (WT) within a treatment are indicated by a black asterisk (control treatment) or a white asterisk (stress treatment), while diamonds indicate significant differences between control and salt stress within a genotype (P < 0.05).
Mentions: Since the negative impact of tocopherol deficiency on sugar export and tuber yield was exacerbated under salt treatment, we assessed whether the physiology of tocopherol-deficient leaves was more sensitive to salt challenge and whether an elevated degree of oxidative stress might explain the altered sugar response of transgenic leaves. The CO2 assimilation rate of SXD1:RNAi source leaves was significantly reduced by 40–60% in the transgenic plants under salt-stress conditions (Table 2). The transpiration rate was diminished in salt-stressed transgenic plants in comparison to stressed wild-type plants (Table 2), and concomitantly the contents of xylem-mobile Na+ and Ca2+ were 2- to 3-fold reduced in SXD1:RNAi source leaves (Fig. 6). Consequently, the K+/Na+ ratio was higher in both middle and bottom leaves of salt-stressed transgenic plants, indicating that the foliar ionic balance was less disturbed in SXD1:RNAi leaves compared to the wild type (Supplementary Figure S2). However, leaf osmolality in middle and bottom source leaves did not exhibit significant changes across genotypes and treatments (Supplementary Figure S3).

Bottom Line: Based on comprehensive gene expression analyses, we propose that enhanced responsiveness of SnRK1 target genes in mesophyll cells and altered redox regulation of phloem loading by SUT1 contribute to the attenuation of sucrose export from salt-stressed SXD:RNAi source leaves.In leaves of the SXD1:RNAi plants, sodium accumulation was diminished, while proline accumulation and pools of soluble antioxidants were increased.As supported by phytohormone contents, these differences seem to increase longevity and prevent senescence of SXD:RNAi leaves under salt stress.

View Article: PubMed Central - PubMed

Affiliation: University of Barcelona, Faculty of Biology, Department of Plant Biology, Diagonal Avenue 643, E-08028 Barcelona, Spain.

No MeSH data available.


Related in: MedlinePlus