PT  - JOURNAL ARTICLE
AU  - Samuel W.H. Koh
AU  - Carlisle S. Bascom
AU  - Eduardo Berenguer
AU  - Gwyneth Ingram
AU  - Mark Estelle
AU  - Christian S. Hardtke
TI  - Heterologous expression of a lycophyte protein enhances angiosperm seedling vigor
AID  - 10.1101/2022.05.06.490942
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.05.06.490942
4099  - http://biorxiv.org/content/early/2022/05/06/2022.05.06.490942.short
4100  - http://biorxiv.org/content/early/2022/05/06/2022.05.06.490942.full
AB  - Seedling vigor is a key agronomic trait that determines juvenile plant performance. Angiosperm seeds develop inside fruits and are connected to the mother plant through vascular tissues. Their formation requires plant-specific genes, such as BREVIS RADIX (BRX) in Arabidopsis thaliana roots. BRX family proteins are found throughout the angiosperms but also occur in non-vascular bryophytes and non-seed lycophytes. They consist of four conserved domains, including the tandem “BRX-domains”. We found that bryophyte or lycophyte BRX homologs can only partially substitute for Arabidopsis BRX (AtBRX) because they miss key features in the linker between the BRX-domains. Intriguingly however, expression of a BRX homolog from the lycophyte Selaginella moellendorffii (SmBRX) in A. thaliana wildtype background confers robustly enhanced root growth vigor that persists throughout the life cycle. This effect can be traced back to a substantial increase in seed and embryo size, and can be reproduced with a modified, “SmBRX-like” variant of AtBRX. Our results thus suggest that BRX variants could serve as biotechnological tools to boost seedling vigor and shed light on the activity of ancient, non-angiosperm BRX family proteins.Competing Interest StatementThe authors have declared no competing interest.