Affiliation:
1. Bioscience, Wageningen University & Research, 6700 AA Wageningen, The Netherlands
2. Laboratory of Molecular Biology, Wageningen University & Research, 6700 AA Wageningen, The Netherlands
3. Dekker Chrysanten, 1711 RP Hensbroek, The Netherlands
Abstract
Chrysanthemum is a genus in the Asteraceae family containing numerous cut flower varieties with high ornamental value. It owes its beauty to the composite flower head, which resembles a compact inflorescence. This structure is also known as a capitulum, in which many ray and disc florets are densely packed. The ray florets are localized at the rim, are male sterile, and have large colorful petals. The centrally localized disc florets develop only a small petal tube but produce fertile stamens and a functional pistil. Nowadays, varieties with more ray florets are bred because of their high ornamental value, but, unfortunately, this is at the expense of their seed setting. In this study, we confirmed that the disc:ray floret ratio is highly correlated to seed set efficiency, and therefore, we further investigated the mechanisms that underlie the regulation of the disc:ray floret ratio. To this end, a comprehensive transcriptomics analysis was performed in two acquired mutants with a higher disc:ray floret ratio. Among the differentially regulated genes, various potential brassinosteroid (BR) signaling genes and HD-ZIP class IV homeodomain transcription factors stood out. Detailed follow-up functional studies confirmed that reduced BR levels and downregulation of HD-ZIP IV gene Chrysanthemum morifolium PROTODERMAL FACTOR 2 (CmPDF2) result in an increased disc:ray floret ratio, thereby providing ways to improve seed set in decorative chrysanthemum varieties in the future.
Subject
Inorganic Chemistry,Organic Chemistry,Physical and Theoretical Chemistry,Computer Science Applications,Spectroscopy,Molecular Biology,General Medicine,Catalysis
Reference67 articles.
1. Cronk, Q.C.B., Bateman, R.M., and Hawkins, J.A. (2002). Developmental Genetics and Plant Evolution, CRC Press.
2. Inflorescence and floral ontogeny in asteraceae: A synthesis of historical and current concepts;Harris;Bot. Rev.,1995
3. Regulatory genes control a key morphological and ecological trait transferred between species;Kim;Science,2008
4. Anderson, N.O. (2006). Flower Breeding and Genetics: Issues, Challenges and Opportunities for the 21st Century, Springer.
5. Chapter ten—Molecular control of inflorescence development in Asteraceae;Fornara;Advances in Botanical Research,2014