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Photochemical and antioxidative responses of the glume and flag leaf to seasonal senescence in wheat.

Kong L, Sun M, Xie Y, Wang F, Zhao Z - Front Plant Sci (2015)

Bottom Line: In the present study, an experiment was conducted to investigate the anatomy, chloroplast temporal changes, chlorophyll fluorescence, xanthophyll cycle and antioxidative defense system in glumes of field-grown wheat during grain filling compared with flag leaves.In addition, the glumes exhibited a higher antioxidant enzyme activity and a lower accumulation of reactive oxygen species.These results suggest that the glumes are photosynthetically active and senesce later than the flag leaves; the advantages may have been achieved by coordinated contributions of the structural features, higher NPQ levels, greater de-epoxidation of the xanthophyll cycle components and antioxidative defense metabolism.

View Article: PubMed Central - PubMed

Affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences , Jinan, China.

ABSTRACT
The non-leaf photosynthetic organs have recently attracted much attention for the breeding and screening of varieties of cereal crops to achieve a high grain yield. However, the glume photosynthetic characteristics and responses to high temperature at the late stages of grain filling are not well known in winter wheat (Triticum aestivum L.). In the present study, an experiment was conducted to investigate the anatomy, chloroplast temporal changes, chlorophyll fluorescence, xanthophyll cycle and antioxidative defense system in glumes of field-grown wheat during grain filling compared with flag leaves. Observations using a light microscope revealed that the glumes developed a solid structural base for performing photosynthesis. Compared with the flag leaves, the glumes preserved a more integral ultrastructure, as observed under transmission electron microscopy, and had higher values of Fv/Fm and ΦPSII at the maturity stage. Further analysis of the chlorophyll fluorescence demonstrated that the glumes experienced high non-photochemical quenching (NPQ) at the late stages. Determination of the pool size of the xanthophyll cycle suggested that the (A+Z)/(V+A+Z) ratio was consistently higher in glumes than in flag leaves and that the V+A+Z content was considerably higher in glumes at the maturity stage. In addition, the glumes exhibited a higher antioxidant enzyme activity and a lower accumulation of reactive oxygen species. These results suggest that the glumes are photosynthetically active and senesce later than the flag leaves; the advantages may have been achieved by coordinated contributions of the structural features, higher NPQ levels, greater de-epoxidation of the xanthophyll cycle components and antioxidative defense metabolism.

No MeSH data available.


Related in: MedlinePlus

Comparison of the activities of POD (A), CAT (B) and SOD (C) and of the relative DCFH-DA fluorescence intensity between the glumes and flag leaves (D). The ROS concentration was measured using DCFH-DA, which is oxidized by ROS to DCF. The fluorescence was determined at 20 min after the incubation of glumes or flag leaf cross-sections with DCFH-DA. Each value represents the mean ± SD from four independent samples. The columns labeled with different letters are significantly different at P < 0.05 according to Duncan’s multiple range test using DPS software. The P value for comparison between flag leaf and glume at each stage is presented over the top of column.
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Figure 6: Comparison of the activities of POD (A), CAT (B) and SOD (C) and of the relative DCFH-DA fluorescence intensity between the glumes and flag leaves (D). The ROS concentration was measured using DCFH-DA, which is oxidized by ROS to DCF. The fluorescence was determined at 20 min after the incubation of glumes or flag leaf cross-sections with DCFH-DA. Each value represents the mean ± SD from four independent samples. The columns labeled with different letters are significantly different at P < 0.05 according to Duncan’s multiple range test using DPS software. The P value for comparison between flag leaf and glume at each stage is presented over the top of column.

Mentions: Figure 6 shows the changes in the activities of POD, CAT and SOD in the glumes and flag leaves. At 0 DAA, the POD activity of the glumes was similar to that of the flag leaves (Figure 6A); whereas the CAT and SOD activities of the glumes were lower than those of the flag leaves (Figures 6B,C). At 8 DAA, the activity of these enzymes increased to different extents in both organs; therefore, the glumes presented higher POD and SOD activity and lower CAT activity. At subsequent stages, the glumes showed consistently higher activities of these enzymes, particularly POD (Figure 6). Effects of the organ (glume and flag leaf) and the date of sampling on the activities of these antioxidative enzymes was significant (Table 2).


Photochemical and antioxidative responses of the glume and flag leaf to seasonal senescence in wheat.

Kong L, Sun M, Xie Y, Wang F, Zhao Z - Front Plant Sci (2015)

Comparison of the activities of POD (A), CAT (B) and SOD (C) and of the relative DCFH-DA fluorescence intensity between the glumes and flag leaves (D). The ROS concentration was measured using DCFH-DA, which is oxidized by ROS to DCF. The fluorescence was determined at 20 min after the incubation of glumes or flag leaf cross-sections with DCFH-DA. Each value represents the mean ± SD from four independent samples. The columns labeled with different letters are significantly different at P < 0.05 according to Duncan’s multiple range test using DPS software. The P value for comparison between flag leaf and glume at each stage is presented over the top of column.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440901&req=5

Figure 6: Comparison of the activities of POD (A), CAT (B) and SOD (C) and of the relative DCFH-DA fluorescence intensity between the glumes and flag leaves (D). The ROS concentration was measured using DCFH-DA, which is oxidized by ROS to DCF. The fluorescence was determined at 20 min after the incubation of glumes or flag leaf cross-sections with DCFH-DA. Each value represents the mean ± SD from four independent samples. The columns labeled with different letters are significantly different at P < 0.05 according to Duncan’s multiple range test using DPS software. The P value for comparison between flag leaf and glume at each stage is presented over the top of column.
Mentions: Figure 6 shows the changes in the activities of POD, CAT and SOD in the glumes and flag leaves. At 0 DAA, the POD activity of the glumes was similar to that of the flag leaves (Figure 6A); whereas the CAT and SOD activities of the glumes were lower than those of the flag leaves (Figures 6B,C). At 8 DAA, the activity of these enzymes increased to different extents in both organs; therefore, the glumes presented higher POD and SOD activity and lower CAT activity. At subsequent stages, the glumes showed consistently higher activities of these enzymes, particularly POD (Figure 6). Effects of the organ (glume and flag leaf) and the date of sampling on the activities of these antioxidative enzymes was significant (Table 2).

Bottom Line: In the present study, an experiment was conducted to investigate the anatomy, chloroplast temporal changes, chlorophyll fluorescence, xanthophyll cycle and antioxidative defense system in glumes of field-grown wheat during grain filling compared with flag leaves.In addition, the glumes exhibited a higher antioxidant enzyme activity and a lower accumulation of reactive oxygen species.These results suggest that the glumes are photosynthetically active and senesce later than the flag leaves; the advantages may have been achieved by coordinated contributions of the structural features, higher NPQ levels, greater de-epoxidation of the xanthophyll cycle components and antioxidative defense metabolism.

View Article: PubMed Central - PubMed

Affiliation: Crop Research Institute, Shandong Academy of Agricultural Sciences , Jinan, China.

ABSTRACT
The non-leaf photosynthetic organs have recently attracted much attention for the breeding and screening of varieties of cereal crops to achieve a high grain yield. However, the glume photosynthetic characteristics and responses to high temperature at the late stages of grain filling are not well known in winter wheat (Triticum aestivum L.). In the present study, an experiment was conducted to investigate the anatomy, chloroplast temporal changes, chlorophyll fluorescence, xanthophyll cycle and antioxidative defense system in glumes of field-grown wheat during grain filling compared with flag leaves. Observations using a light microscope revealed that the glumes developed a solid structural base for performing photosynthesis. Compared with the flag leaves, the glumes preserved a more integral ultrastructure, as observed under transmission electron microscopy, and had higher values of Fv/Fm and ΦPSII at the maturity stage. Further analysis of the chlorophyll fluorescence demonstrated that the glumes experienced high non-photochemical quenching (NPQ) at the late stages. Determination of the pool size of the xanthophyll cycle suggested that the (A+Z)/(V+A+Z) ratio was consistently higher in glumes than in flag leaves and that the V+A+Z content was considerably higher in glumes at the maturity stage. In addition, the glumes exhibited a higher antioxidant enzyme activity and a lower accumulation of reactive oxygen species. These results suggest that the glumes are photosynthetically active and senesce later than the flag leaves; the advantages may have been achieved by coordinated contributions of the structural features, higher NPQ levels, greater de-epoxidation of the xanthophyll cycle components and antioxidative defense metabolism.

No MeSH data available.


Related in: MedlinePlus