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Starch phosphorylase 2 is essential for cellular carbohydrate partitioning in maize
Yao Qin1, Ziyi Xiao1, Hailiang Zhao1
1National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
Journal of Integrative Plant Biology
|July 7, 2022
Summary
The study identifies ZmPHOH as crucial for carbohydrate partitioning in maize (Zea mays L.). Its mutation leads to starch accumulation and impaired growth by affecting transitory starch remobilization.
Area of Science:
- Plant Biology
- Molecular Genetics
- Biochemistry
Background:
- Carbohydrate partitioning is vital for plant growth, with disruptions causing excess carbohydrate accumulation in source tissues.
- While sucrose transport defects are known in maize mutants, other carbohydrate partitioning mechanisms are less understood.
Purpose of the Study:
- To investigate novel mechanisms of carbohydrate partitioning in maize.
- To characterize the chlorotic leaf3 (chl3) mutant and identify the gene responsible for its phenotype.
Main Methods:
- Positional cloning to identify the mutated gene in the chl3 mutant.
- Allelism tests to confirm gene function.
- RNA-sequencing (RNA-seq) to analyze gene expression changes.
- Biochemical analysis of starch content and carbohydrate metabolism.
Main Results:
- The chl3 mutation was mapped to ZmPHOH, encoding starch phosphorylase 2, crucial for transitory starch conversion.
- ZmPHOH inactivation led to excessive starch accumulation in bundle sheath chloroplasts and altered carbohydrate metabolism.
- Transcriptional analysis revealed downregulation of photosynthesis and carbohydrate metabolism genes in chl3 mutants.
Conclusions:
- ZmPHOH is indispensable for transitory starch remobilization in maize.
- Efficient starch remobilization is critical for cellular carbohydrate partitioning and overall plant development.
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