The Maize Leaf Starch Mutation agps-m1 Has Diminished Field Growth and Productivity
- Alanna J. Schlossera,
- John M. Martina,
- L. Curtis Hannahb and
- Michael J. Giroux *a
Modification of enzymes involved in sink or source strength has been one common method used in attempts to improve cereal yield. In this regard, ADP-glucose pyrophosphorylase (AGPase) has received considerable attention because it controls the rate-limiting step in starch biosynthesis in both leaves and seeds. Previous studies, focused on increasing AGPase activity in seeds, indicate that productivity increases occur only when environmental resources are nonlimiting. The objective of this study was to determine the importance of leaf starch on the productivity and growth of maize. Field trials of BC4F2:3 plants segregating for the agps-m1 mutation and leaf starch were conducted. The results clearly demonstrate the importance of normal leaf starch levels to maize productivity. The starchless agps-m1 plants were 6 to 15 cm shorter, flowered 2 to 6 d later, and were 30% lower yielding than their wild-type sister lines. Photosynthetic rates were not significantly different between wild-type and agps-m1 plants. However, agps-m1 leaves were significantly lower in the levels of major photosynthetic proteins such as phosphoenolpyruvate carboxylase, pyruvate phosphate dikinase, and RuBisCO until the end of the photoperiod. The results demonstrate a link between leaf starch and whole plant productivity under agronomic conditions. Further study would help to define how leaf starch regulates the production of leaf photosynthetic proteins.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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