Researchers Identify Candidate Gene for Compact Plant Architecture in Cucumber

The dwarf or compact plant architecture is an important trait in plant breeding. A number of genes controlling plant height have been identified, which were often involved in synthesis or signaling of plant hormones such as brassinosteroids (BR). However, no genes for plant architecture have been identified in cucurbits. From a mutant population, researchers from the Northwest A&F University and the University of Wisconsin identified a super compact (SCP) cucumber (Cucumis sativus L.) mutant, C257, with practically no internode elongation.

Under dark growing conditions, C257 did not undergo skotomorphogenesis, rapid hypocotyl growth to seek sunlight, and its mutant could be rescued with exogenous application of brassinolide, suggesting that it might be a BR-deficient mutant. The team identified CsCYP85A1, a member of the plant cytochrome P450 monooxygenase gene family, as a possible candidate gene. It encodes a BR-C6-oxidase in the BR biosynthesis pathway.

Three copies of the CsCYP85A gene are present in the cucumber genome, however, only the scp-1/CsCYP85A1 gene seemed active. Its expression was higher in flowers than in the leaves and stem and its expression is reduced in C257 compared to wildtypes.

This study is the first report of map-based cloning of a plant architecture gene in cucurbits.

For more on the study, read the article in Frontiers in Plant Science.