CYCLOIDEA gene activity, local growth and curvature in the dorsal petal of Lathyrus odoratus (Fabaceae)

ABSTRACT

The hooded (hdd) floral mutant of sweet pea (Lathyrus odoratus L.) is apparently caused by loss of function of the floral developmental gene CYCLOIDEA (CYC). It has a concavely folded dorsal petal (standard) compared to the more or less flat standard of the wild type. To examine localised growth differences in wild type and hdd flowers, we printed fine-scale grids on the surfaces of sweet pea buds using inkjet technology. Wild-type standard petals have a more uniform rate of growth, whereas hdd standard petals show increased growth at their margins. The resultant lamina/margin growth differential leads to negative Gaussian curvature and can account for the differences in curvature between wild-type and hdd petals. We conclude that CYC has a role in the negative regulation of marginal petal growth in Lathyrus in order to maintain dorsal petal flatness. Differences in CYC expression and activity could possibly contribute to the range of dorsal petal form seen throughout the Fabaceae.

KEYWORDS:

• Lathyrus odoratus
• CYCLOIDEA2
• hooded (hdd)
• dynamic morphometrics
• landmark analysis

Acknowledgments

We thank David Kaplan, Seane Trehearne, Farnaz Pournia and Evelyn Carpenter for assistance in growing and maintaining the Lathyrus odoratus F2 population.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We gratefully acknowledge the support of an NSERC discovery grant to QC and the support of UBC’s Martha Piper Research Fund to KW and QC.

Notes on contributors

C. Woollacott

C. Woollacott is a botanist and jeweller.Contribution: She carried out the experimental work on Lathyrus and wrote the initial manuscript.

L. Wang

L. Wang is an electrical engineer.Contribution: He is responsible for the development of the advanced microprinting technology.

S. T. Beyer

S. T. Beyer is an electrical engineer.Contribution: He assisted the development of the tissue printing technology.

K. Walus

K. Walus is an Associate Professor in the Department of Electrical and Computer Engineering at the University of British Columbia.Contribution: He oversaw the development of the advanced microprinting technology and obtained funding.

Q. C. B. Cronk

Q. C. B. Cronk is Professor of Botany at the University of British Columbia.Contribution: He oversaw the experimental work on Lathyrus, co-wrote the manuscript and obtained funding.