Double-fluorescent proteins enable robust maternal haploid identification in wheat

This study is led by Professor Long Mao (Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China). The authors used red fluorescence from dsRED driven by an endosperm-specific promoter and enhanced green fluorescent protein (eGFP) driven by an embryo-specific promoter to develop an efficient method for identifying and selecting haploid seeds in wheat. The authors first expressed the double-fluorescent protein (DFP) cassette in wheat variety Fielder via Agrobacterium-mediated transformation, and demonstrate that the dual tissue-specific DFP construct was functionally expressed in the expected tissues of transgenic wheat plants. Subsequently, the authors crossed these MTL mutant lines with a T3-generation DFP line to develop DFP mediated haploid inducer lines (DHILs), using MTL mutant plants as the maternal parent and DFP plants as pollen donors.

To test the accuracy of DHILs, the authors determined the accuracy rate for haploid detection in self-pollinated seeds and outcross-pollinated seeds. The results showed that DHILs were an efficient HID system for wheat by integrating a dual-fluorescent protein-based haploid identification toolbox with MTL mutant haploid inducer lines. Specially, this study selected lines with large-fragment deletions in TaMTL-A and TaMTL-D for integration into DHILs. Molecular markers based on these large-fragment deletions were developed to complement the fluorescence-based identification system, which showed clear polymorphisms via agarose gel electrophoresis, thereby providing an optional low-cost dual-insurance strategy for haploid induction and identification.

In summary, this work established an efficient HID system for wheat by integrating a dual-fluorescent protein-based haploid identification toolbox with MTL mutant haploid inducer lines. This system utilizes dual fluorescent signals to enhance the phenotypic contrast between the dual tissues (embryo and endosperm), thereby achieving efficient haploid induction and screening independent of the recipient's genetic background, and could lead to the development of a commercially viable pipeline for efficient haploid production to accelerate wheat breeding.

See the article:

Double-fluorescent proteins enable robust maternal haploid identification in wheat

https://www.sciencedirect.com/science/article/pii/S2662173825002231