A rapid method to quantify vein density in C4 plants using starch staining

Abstract

Abstract C 4 photosynthesis has evolved multiple times in the angiosperms and typically involves alterations to the biochemistry, cell biology and development of leaves. One common modification found in C 4 plants compared with the ancestral C 3 state is an increase in vein density such that the leaf contains a larger proportion of bundle sheath cells. Recent findings indicate that there may be significant intra-specific variation in traits such as vein density in C 4 plants but to use such natural variation for trait-mapping, rapid phenotyping would be required. Here we report a high-throughput method to quantify vein density that leverages the bundle sheath specific accumulation of starch found in C 4 species. Starch staining allowed high-contrast images to be acquired that permitted image analysis using a MATLAB-based program. The method works for the dicotyledon Gynandropsis gynandra where significant variation in vein density was detected between natural accessions, and the monocotyledon Zea mays where no variation was apparent in the genotypically diverse lines assessed. We anticipate this approach will be useful to map genes controlling vein density in C 4 species demonstrating natural variation for this trait. One sentence summary Preferential accumulation of starch in bundle sheath cells of C 4 plants allows high-throughput phenotyping of vein density.

Plant phenotyping relevance

C4植物の葉脈密度を定量する高スループット染色・画像解析法の開発と適用が研究の中心であり、植物形質の取得手法を扱っている。

Code and data availability

The paper's Starch4Kranz MATLAB pipeline for quantifying vein density in C4 plants is explicitly stated to be publicly available on GitHub at the authors' repository.