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Isolation and Characterization of Two Persimmon Xyloglucan Endotransglycosylase/Hydrolase (XTH) Genes That Have Divergent Functions in Cell Wall Modification and Fruit Postharvest Softening.

Han Y, Ban Q, Hou Y, Meng K, Suo J, Rao J - Front Plant Sci (2016)

Bottom Line: We found that DkXTH6 protein was localized in cell wall by its signal peptide, while cytoplasmic DkXTH7 protein contained no signal peptide.When expressed in vitro, the recombinant proteins of both DkXTH6 and DkXTH7 exhibited strict xyloglucan endotransglycosylase (XET) activity but no xyloglucan endohydrolase (XEH) activity.The recombinant protein of DkXTH6 showed a higher affinity with small acceptor molecules than the recombinant DkXTH7.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University Yangling, China.

ABSTRACT
Fruit cell wall modification is the primary factor affecting fruit softening. Xyloglucan endotransglycosylase/hydrolase (XTH), a cell wall-modifying enzyme, is involved in fruit softening. In this study, two novel XTH genes (DkXTH6 and DkXTH7) were identified from persimmon fruit. Transcriptional profiles of both of the two genes were analyzed in different tissues of persimmon, and in response to multiple hormonal and environmental treatments [gibberellic acid (GA3), abscisic acid (ABA), propylene, and low temperature]. Expression of DkXTH6 was positively up-regulated during ethylene production and by propylene and ABA treatments, and suppressed by GA3 and cold treatment. In contrast, DkXTH7 exhibited its highest transcript levels in GA3-treated fruit and cold-treated fruit, which had higher fruit firmness. We found that DkXTH6 protein was localized in cell wall by its signal peptide, while cytoplasmic DkXTH7 protein contained no signal peptide. When expressed in vitro, the recombinant proteins of both DkXTH6 and DkXTH7 exhibited strict xyloglucan endotransglycosylase (XET) activity but no xyloglucan endohydrolase (XEH) activity. The recombinant protein of DkXTH6 showed a higher affinity with small acceptor molecules than the recombinant DkXTH7. Taken together with their opposing expression patterns and subcellular localizations, these results suggested that DkXTH6 might take part in cell wall restructuring and DkXTH7 was likely to be involved in cell wall assembly, indicating their special roles in persimmon fruit softening.

No MeSH data available.


Related in: MedlinePlus

Expression pattern of DkXTH6 and DkXTH7 in various tissues of persimmon fruits. The DkXTH mRNA levels are relative to those of Actin mRNA. “F” and “S” are indicated the flowers and stems picked at anthesis, respectively. Young leaves (“YL”) were picked while rapidly expanding (at ~4 × 6 cm in size), whereas ripe leaves (“RL”) were picked when fully expanded (~10 × 15 cm). Young fruits (“YF”) were picked at 40 days after full bloom, whereas ripe fruits (“RF”) were picked at 150 days after full bloom. Expression of gene at “RF” was used as the control with a nominal value of 1. Vertical bars indicate the standard error of three replicate assays. Columns with different letters at each time point are significantly different (LSD, P = 0.05).
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Figure 4: Expression pattern of DkXTH6 and DkXTH7 in various tissues of persimmon fruits. The DkXTH mRNA levels are relative to those of Actin mRNA. “F” and “S” are indicated the flowers and stems picked at anthesis, respectively. Young leaves (“YL”) were picked while rapidly expanding (at ~4 × 6 cm in size), whereas ripe leaves (“RL”) were picked when fully expanded (~10 × 15 cm). Young fruits (“YF”) were picked at 40 days after full bloom, whereas ripe fruits (“RF”) were picked at 150 days after full bloom. Expression of gene at “RF” was used as the control with a nominal value of 1. Vertical bars indicate the standard error of three replicate assays. Columns with different letters at each time point are significantly different (LSD, P = 0.05).

Mentions: A quantitative RT-PCR analysis was performed to reveal the expression pattern of persimmon DkXTH6 and DkXTH7 genes in various tissues (Figure 4). The transcripts of the two genes could be detected in all of the tested tissues, including leaf, stem, flower, and fruit. Interestingly, the expression level of DkXTH6 in mature tissues was evidently higher than that in fast growing tissues. By contrast, the DkXTH7 mRNA was expressed at an extremely high level in both leaf and fruit fast growing tissues.


Isolation and Characterization of Two Persimmon Xyloglucan Endotransglycosylase/Hydrolase (XTH) Genes That Have Divergent Functions in Cell Wall Modification and Fruit Postharvest Softening.

Han Y, Ban Q, Hou Y, Meng K, Suo J, Rao J - Front Plant Sci (2016)

Expression pattern of DkXTH6 and DkXTH7 in various tissues of persimmon fruits. The DkXTH mRNA levels are relative to those of Actin mRNA. “F” and “S” are indicated the flowers and stems picked at anthesis, respectively. Young leaves (“YL”) were picked while rapidly expanding (at ~4 × 6 cm in size), whereas ripe leaves (“RL”) were picked when fully expanded (~10 × 15 cm). Young fruits (“YF”) were picked at 40 days after full bloom, whereas ripe fruits (“RF”) were picked at 150 days after full bloom. Expression of gene at “RF” was used as the control with a nominal value of 1. Vertical bars indicate the standard error of three replicate assays. Columns with different letters at each time point are significantly different (LSD, P = 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4863071&req=5

Figure 4: Expression pattern of DkXTH6 and DkXTH7 in various tissues of persimmon fruits. The DkXTH mRNA levels are relative to those of Actin mRNA. “F” and “S” are indicated the flowers and stems picked at anthesis, respectively. Young leaves (“YL”) were picked while rapidly expanding (at ~4 × 6 cm in size), whereas ripe leaves (“RL”) were picked when fully expanded (~10 × 15 cm). Young fruits (“YF”) were picked at 40 days after full bloom, whereas ripe fruits (“RF”) were picked at 150 days after full bloom. Expression of gene at “RF” was used as the control with a nominal value of 1. Vertical bars indicate the standard error of three replicate assays. Columns with different letters at each time point are significantly different (LSD, P = 0.05).
Mentions: A quantitative RT-PCR analysis was performed to reveal the expression pattern of persimmon DkXTH6 and DkXTH7 genes in various tissues (Figure 4). The transcripts of the two genes could be detected in all of the tested tissues, including leaf, stem, flower, and fruit. Interestingly, the expression level of DkXTH6 in mature tissues was evidently higher than that in fast growing tissues. By contrast, the DkXTH7 mRNA was expressed at an extremely high level in both leaf and fruit fast growing tissues.

Bottom Line: We found that DkXTH6 protein was localized in cell wall by its signal peptide, while cytoplasmic DkXTH7 protein contained no signal peptide.When expressed in vitro, the recombinant proteins of both DkXTH6 and DkXTH7 exhibited strict xyloglucan endotransglycosylase (XET) activity but no xyloglucan endohydrolase (XEH) activity.The recombinant protein of DkXTH6 showed a higher affinity with small acceptor molecules than the recombinant DkXTH7.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University Yangling, China.

ABSTRACT
Fruit cell wall modification is the primary factor affecting fruit softening. Xyloglucan endotransglycosylase/hydrolase (XTH), a cell wall-modifying enzyme, is involved in fruit softening. In this study, two novel XTH genes (DkXTH6 and DkXTH7) were identified from persimmon fruit. Transcriptional profiles of both of the two genes were analyzed in different tissues of persimmon, and in response to multiple hormonal and environmental treatments [gibberellic acid (GA3), abscisic acid (ABA), propylene, and low temperature]. Expression of DkXTH6 was positively up-regulated during ethylene production and by propylene and ABA treatments, and suppressed by GA3 and cold treatment. In contrast, DkXTH7 exhibited its highest transcript levels in GA3-treated fruit and cold-treated fruit, which had higher fruit firmness. We found that DkXTH6 protein was localized in cell wall by its signal peptide, while cytoplasmic DkXTH7 protein contained no signal peptide. When expressed in vitro, the recombinant proteins of both DkXTH6 and DkXTH7 exhibited strict xyloglucan endotransglycosylase (XET) activity but no xyloglucan endohydrolase (XEH) activity. The recombinant protein of DkXTH6 showed a higher affinity with small acceptor molecules than the recombinant DkXTH7. Taken together with their opposing expression patterns and subcellular localizations, these results suggested that DkXTH6 might take part in cell wall restructuring and DkXTH7 was likely to be involved in cell wall assembly, indicating their special roles in persimmon fruit softening.

No MeSH data available.


Related in: MedlinePlus