Limits...
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

Fluorescence imaging of the maximal efficiency of PSII photochemistry (Fv/Fm, A, D), actual PSII efficiency (ΦPSII, B, E) and non-photochemical quenching (NPQ, C, F) of flag leaves and glumes in wheat (Triticum aestivum var. Jimai 22) during grain filling. The measurements were performed at 0, 8, 16, 24, and 32 DAA. The data were determined in the year 2013. Each value is the mean ± SD from at least six leaves or 30 glumes. The columns labeled with different letters differed significantly at P < 0.05 according to Duncan’s multiple range test using DPS software.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4440901&req=5

Figure 4: Fluorescence imaging of the maximal efficiency of PSII photochemistry (Fv/Fm, A, D), actual PSII efficiency (ΦPSII, B, E) and non-photochemical quenching (NPQ, C, F) of flag leaves and glumes in wheat (Triticum aestivum var. Jimai 22) during grain filling. The measurements were performed at 0, 8, 16, 24, and 32 DAA. The data were determined in the year 2013. Each value is the mean ± SD from at least six leaves or 30 glumes. The columns labeled with different letters differed significantly at P < 0.05 according to Duncan’s multiple range test using DPS software.

Mentions: The PSII photochemistry in the flag leaves and glumes in the dark-adapted state was investigated during grain filling. Figure 4 demonstrates the changes in Fv/Fm (Figures 4A,D), ΦPSII (Figures 4B,E) and NPQ (Figures 4C,F) in the flag leaves and glumes during grain filling. After anthesis, the values of Fv/Fm and ΦPSII in the flag leaves and glumes gradually decreased, and no difference was observed between both organs at 0, 8, and 16 DAA. In subsequent stages, the decline was much greater in flag leaves than in glumes. As a result, the values of Fv/Fm and ΦPSII in the glumes were significantly higher at 24 and 32 DAA compared with those found for the flag leaves (P < 0.05). In addition, the differences in Fv/Fm and ΦPSII between both organs were significant during the grain filling phrase (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)

Fluorescence imaging of the maximal efficiency of PSII photochemistry (Fv/Fm, A, D), actual PSII efficiency (ΦPSII, B, E) and non-photochemical quenching (NPQ, C, F) of flag leaves and glumes in wheat (Triticum aestivum var. Jimai 22) during grain filling. The measurements were performed at 0, 8, 16, 24, and 32 DAA. The data were determined in the year 2013. Each value is the mean ± SD from at least six leaves or 30 glumes. The columns labeled with different letters differed significantly at P < 0.05 according to Duncan’s multiple range test using DPS software.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Fluorescence imaging of the maximal efficiency of PSII photochemistry (Fv/Fm, A, D), actual PSII efficiency (ΦPSII, B, E) and non-photochemical quenching (NPQ, C, F) of flag leaves and glumes in wheat (Triticum aestivum var. Jimai 22) during grain filling. The measurements were performed at 0, 8, 16, 24, and 32 DAA. The data were determined in the year 2013. Each value is the mean ± SD from at least six leaves or 30 glumes. The columns labeled with different letters differed significantly at P < 0.05 according to Duncan’s multiple range test using DPS software.
Mentions: The PSII photochemistry in the flag leaves and glumes in the dark-adapted state was investigated during grain filling. Figure 4 demonstrates the changes in Fv/Fm (Figures 4A,D), ΦPSII (Figures 4B,E) and NPQ (Figures 4C,F) in the flag leaves and glumes during grain filling. After anthesis, the values of Fv/Fm and ΦPSII in the flag leaves and glumes gradually decreased, and no difference was observed between both organs at 0, 8, and 16 DAA. In subsequent stages, the decline was much greater in flag leaves than in glumes. As a result, the values of Fv/Fm and ΦPSII in the glumes were significantly higher at 24 and 32 DAA compared with those found for the flag leaves (P < 0.05). In addition, the differences in Fv/Fm and ΦPSII between both organs were significant during the grain filling phrase (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