Prof. Zhang Fan and his research team published a paper titled “DcWRKY75 promotes ethylene induced petal senescence in carnation (Dianthus caryophyllus L.)” in The Plant Journal. They work in HZAU’s Key Laboratory of Horticultural Plant Biology, affiliated to College of Horticulture and Forestry Sciences. Zhang and his team screened out some candidate genes related to ethylene induced postharvest senescence in carnation, and unveiled relavant molecular mechanisms. The study helps people better understand the molecular mechanisms of ethylene induced postharvest senescence in carnation, and lays a theoretical foundation for prolonging the shelf life and vase life of cut carnation.

As an important part of horticultural crops, flowers can be seen everywhere, and they are also of vital importance to build a beautiful China and realize rural revitalization. Cut flower is an important circulation form of flowers, which plays a key role in human activities such as holiday greetings and home gardening. The shelf life and vase life of cut flowers are greatly shortened because they cannot absorb nutrients and water effectively after being taken from their parent plants, and pathogens and other harmful substances breed in them. Therefore, to develop effective, fast, convenient and green preservatives and technology, has become a bottleneck to be solved in cut flower industry chain, which requires basic research on molecular mechanisms of postharvest petal senescence of cut flowers. Previous studies indicated that plant hormones, especially ethylene, play a crucial role in regulating the postharvest petal senescence of most cut flowers, but its specific molecular mechanisms are unknown, which greatly limits people's understanding of ethylene induced postharvest senescence of cut flowers.

Carnation (Dianthus caryophyllus L.) is one of the most important and typical ethylene sensitive cut flowers worldwide, so it is generally served as a model plant for studying ethylene induced flower senescence, especially petal senescence. Decades of research has made it clear that ethylene plays a crucial role regulating petal senescence in carnation, but its regulation networks and mechanisms remain largely unknown.

In order to analyze in detail the molecular mechanisms of ethylene induced postharvest petal senescence in carnation, the transcriptome analysis of petal senescence in carnation treated wth ethylene at different time was conducted. The study found that WRKY family transcription factor DcWRKY75 can show a quick induction by ethylene treatment and significantly up-regulate the expression. By using virus induced gene silencing (VIGS) technique, silencing of DcWRKY75 delays ethylene induced petal senescence in carnation and inhibits ethylene biosynthesis. Meanwhile, the expression levels of key ethylene biosynthetic genes and senescence associated genes (SAGs) are down-regulated. Molecular evidences indicated that DcWRKY75 promotes expression of key ethylene biosynthetic genes and senescence associated genes (SAGs) by binding to their promoters.

Silencing of DcWRKY75 delays ethylene induced petal senescence in carnation

The molecular experiments further indicated that DcEIL3-1, the ethylene signaling core transcription factor, indeed can bind to the promoter of DcWRKY75, and activate the expression of DcWRKY75. Silencing of DcEIL3-1 also delays ethylene induced petal senescence in carnation and inhibits ethylene biosynthesis. The expression levels of DcWRKY75 and its target genes are down-regulated. Meanwhile, the study found that DcEIL3-1 can directly interact with DcWRKY75 to form protein complex, so as to co-regulate the expression of downstream genes.

Silencing of DcEIL3-1 delays ethylene induced petal senescence in carnation

The study indicated that DcEIL3-1-DcWRKY75 transcription complex module plays a key role in regulating the ethylene induced postharvest petal senescence in carnation. The finding may not only help extend the vase life of cut carnation, but also shed some light on the postharvest preservation of other species of cut flowers.

Source: http://m.hzau.edu.cn/article/15949

Translated by: Duan Jun

Supervised by: Jin Bei