The RUBY reporter enables efficient haploid identification in maize and tomato

Area of Science:

• Plant Science
• Genetics
• Agricultural Biotechnology

Background:

• Haploid induction is vital for doubled haploid technology in various crops.
• Current haploid identification methods (e.g., R1-nj, RFP, eGFP) have limitations in species specificity or equipment requirements.
• An efficient, broadly applicable visual marker for haploid identification is needed.

Purpose of the Study:

• To introduce and evaluate the RUBY reporter system as a novel visual marker for haploid identification in maize and tomato.
• To assess the efficiency and accuracy of the RUBY reporter across different crop species.

Main Methods:

• The RUBY reporter, a betalain biosynthesis system, was integrated into maize and tomato haploid inducers.
• Expression of the RUBY reporter was analyzed for pigmentation in haploid embryos and seedlings.
• Identification accuracy and timing were evaluated.

Main Results:

• RUBY expression resulted in deep betalain pigmentation in maize embryos by 10 days post-pollination, enabling 100% accurate identification.
• In tomato, RUBY induced deep red pigmentation in radicles, allowing easy and accurate haploid identification.
• The RUBY marker demonstrated background independence.

Conclusions:

• The RUBY reporter is an efficient and broadly applicable visual marker for haploid identification.
• This marker system is promising for advancing doubled haploid breeding programs in diverse crop species.