Hydrocotyle ranunculoides (floating pennywort).

H. ranunculoides is a perennial, aquatic plant native to the Americas. It was introduced outside of its native range through the aquatic nursery trade and has since naturalized in many countries around the world. Like many aquatic weeds, H. ranunculoides possesses a number of characteristics which contributes to its invasiveness: high growth rates, adaptability to prevailing nutrient conditions, very effective vegetative propagation, plasticity in growth response, overwintering to avoid low temperature stress, resistance to herbivory, resistance to chemical control, and absence of specific pests and diseases in introduced environments. Its rapid growth means that H. ranunculoides can produce dense, interwoven floating mats across slow-flowing waters. These mats restrict the light available for submerged macrophytes, decreases oxygen levels and therefore decrease the overall biodiversity of an area. It can also increase the risk of flooding and block channels. H. ranunuloides is considered a serious invader in Belgium, the Netherlands, and the UK in particular and was added to the EPPO alert list in 2004 (EPPO, 2004) and Schedule 9 of the Wildlife and Countryside Act in the UK. It is also banned from sale in the Netherlands. It has spread into water bodies in a number of other European countries including France, Belgium, Germany and Italy. In 2016, the European Commission's Implementing Regulation (2016/1141) was published, which includes H. ranunculoides among the list of 14 invasive alien plant species of Union concern.

Novel Crosstalks between Circadian Clock and Jasmonic Acid Pathway Finely Coordinate the Tradeoff among Plant Growth, Senescence and Defense

Circadian clock not only functions as a cellular time-keeping mechanism, but also acts as a master regulator to coordinate the tradeoff between plant growth and defense in higher plants by timing a few kinds of phytohormone biosynthesis and signaling, including jasmonic acid (JA). Notably, circadian clock and JA pathway have recently been shown to intertwine with each other to ensure and optimize the plant fitness in an ever-changing environment. It has clearly demonstrated that there are multiple crosstalk pathways between circadian clock and JA at both transcriptional and post-transcriptional levels. In this scenario, circadian clock temporally modulates JA-mediated plant development events, herbivory resistance and susceptibility to pathogen. By contrast, the JA signaling regulates clock activity in a feedback manner. In this review, we summarized the cross networks between circadian clock and JA pathway at both transcriptional and post-transcriptional levels. We proposed that the novel crosstalks between circadian clock and JA pathway not only benefit for the understanding the JA-associated circadian outputs including leaf senescence, biotic, and abiotic defenses, but also put timing as a new key factor to investigate JA pathway in the future.