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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

Firmness (A), respiration rate (B) and ethylene production (C) of persimmon fruits during storage. “propylene” “ABA,” and “GA3” indicated Fuping Jianshi fruit treated with propylene (5000 μl L−1, 24 h), ABA (50 mg L−1, 2 min), and GA3(60 mg L−1, 2 min), respectively, and stored at 25°C. The fruit without any treatment and stored at 25 and 0°C was served as the “CK” and “cold,” respectively. The vertical bars indicate the standard errors of three biological replicate assays.
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Figure 3: Firmness (A), respiration rate (B) and ethylene production (C) of persimmon fruits during storage. “propylene” “ABA,” and “GA3” indicated Fuping Jianshi fruit treated with propylene (5000 μl L−1, 24 h), ABA (50 mg L−1, 2 min), and GA3(60 mg L−1, 2 min), respectively, and stored at 25°C. The fruit without any treatment and stored at 25 and 0°C was served as the “CK” and “cold,” respectively. The vertical bars indicate the standard errors of three biological replicate assays.

Mentions: Fruit firmness was recorded for all postharvest samples at 4-day intervals starting from the day after harvest. The firmness of CK fruit (“Fuping jianshi” fruit without any treatment stored at 25°C) showed an obvious decrease at 12 days after harvest and decreased from 121.5 to 20.7 N on day 20 (Figure 3A), whereas the propylene and ABA fruit (Fuping jianshi fruit treated with propylene and ABA, respectively, and stored at 25°C) exhibited a higher rate of softening. When tested for firmness, CK fruit was 19 and 77% more firm than propylene fruit at 4 and 12 days of storage, respectively. Meanwhile, CK fruit was 22 and 58% more firm than ABA fruit at 8 and 16 days of storage, respectively. By contrast, the GA3 fruit (Fuping jianshi' fruit treated with GA3 and stored at 25°C), and cooling fruit (Fuping jianshi fruit without any treatment stored at 0°C) showed a strong suppression of softening, which were 68 and 78% firmer than CK fruit at 20 days of storage, respectively.


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)

Firmness (A), respiration rate (B) and ethylene production (C) of persimmon fruits during storage. “propylene” “ABA,” and “GA3” indicated Fuping Jianshi fruit treated with propylene (5000 μl L−1, 24 h), ABA (50 mg L−1, 2 min), and GA3(60 mg L−1, 2 min), respectively, and stored at 25°C. The fruit without any treatment and stored at 25 and 0°C was served as the “CK” and “cold,” respectively. The vertical bars indicate the standard errors of three biological replicate assays.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Firmness (A), respiration rate (B) and ethylene production (C) of persimmon fruits during storage. “propylene” “ABA,” and “GA3” indicated Fuping Jianshi fruit treated with propylene (5000 μl L−1, 24 h), ABA (50 mg L−1, 2 min), and GA3(60 mg L−1, 2 min), respectively, and stored at 25°C. The fruit without any treatment and stored at 25 and 0°C was served as the “CK” and “cold,” respectively. The vertical bars indicate the standard errors of three biological replicate assays.
Mentions: Fruit firmness was recorded for all postharvest samples at 4-day intervals starting from the day after harvest. The firmness of CK fruit (“Fuping jianshi” fruit without any treatment stored at 25°C) showed an obvious decrease at 12 days after harvest and decreased from 121.5 to 20.7 N on day 20 (Figure 3A), whereas the propylene and ABA fruit (Fuping jianshi fruit treated with propylene and ABA, respectively, and stored at 25°C) exhibited a higher rate of softening. When tested for firmness, CK fruit was 19 and 77% more firm than propylene fruit at 4 and 12 days of storage, respectively. Meanwhile, CK fruit was 22 and 58% more firm than ABA fruit at 8 and 16 days of storage, respectively. By contrast, the GA3 fruit (Fuping jianshi' fruit treated with GA3 and stored at 25°C), and cooling fruit (Fuping jianshi fruit without any treatment stored at 0°C) showed a strong suppression of softening, which were 68 and 78% firmer than CK fruit at 20 days of storage, respectively.

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