Using RAD-seq to develop sex-linked markers in a haplodiplontic alga

Area of Science:

• Marine Biology
• Genetics
• Phycology

Background:

• Determining sex and ploidy is difficult in many taxa, particularly isomorphic haplodiplontic macroalgae.
• This limitation hinders population genetics and demographic studies.

Purpose of the Study:

• To identify sex-linked molecular markers in Agarophyton vermiculophyllum using double-digest restriction site-associated DNA sequencing (ddRAD-seq).
• To develop a practical assay for sex and ploidy determination in this ecologically significant red alga.

Main Methods:

• Utilized ddRAD-seq on female, male, and tetrasporophyte life stages of A. vermiculophyllum from native and non-native populations.
• Identified putatively sex-linked sequences and developed sex-specific markers.
• Created a duplex PCR assay and validated it on sampled thalli, confirming ploidy through visual and genetic methods.

Main Results:

• Discovered seven putatively female-linked and 19 putatively male-linked sequences.
• Validated four female- and eight male-linked markers across all life stages.
• Successfully assigned sex and confirmed ploidy for 32 vegetative thalli using the developed duplex PCR assay.

Conclusions:

• The developed sex-linked markers and duplex PCR assay are effective for determining sex and ploidy in A. vermiculophyllum.
• ddRAD-seq offers advantages over previous methods like RAPDs for marker development in macroalgae.
• These tools are crucial for ongoing research into A. vermiculophyllum invasion dynamics.