Altering the Sex Pheromone Cyclo(l-Pro-l-Pro) of the Diatom Seminavis robusta towards a Chemical Probe

Abstract

As a major group of algae, diatoms are responsible for a substantial part of the primary production on the planet. Pennate diatoms have a predominantly benthic lifestyle and are the most species-rich diatom group, with members of the raphid clades being motile and generally having heterothallic sexual reproduction. It was recently shown that the model species Seminavis robusta uses multiple sexual cues during mating, including cyclo(l-Pro-l-Pro) as an attraction pheromone. Elaboration of the pheromone-detection system is a key aspect in elucidating pennate diatom life-cycle regulation that could yield novel fundamental insights into diatom speciation. This study reports the synthesis and bio-evaluation of seven novel pheromone analogs containing small structural alterations to the cyclo(l-Pro-l-Pro) pheromone. Toxicity, attraction, and interference assays were applied to assess their potential activity as a pheromone. Most of our analogs show a moderate-to-good bioactivity and low-to-no phytotoxicity. The pheromone activity of azide- and diazirine-containing analogs was unaffected and induced a similar mating behavior as the natural pheromone. These results demonstrate that the introduction of confined structural modifications can be used to develop a chemical probe based on the diazirine- and/or azide-containing analogs to study the pheromone-detection system of S. robusta.

Diproline-induced resistance to parasitic nematodes in the same and subsequent rice generations: Roles of iron, nitric oxide and ethylene

“…In case of priming, the defense genes are faster or more strongly activated only when the plants are under attack ( De Kesel et al., 2021 ). Diproline is known to act as attraction pheromone for the diatom Seminavis robusta and has been detected in various other species ( Bonneure et al., 2021 ). Possibly, diproline-synthesizing species act as nutritional competitors for rice plants and therefore their presence needs to be detected.…”

“…The diketopiperazine diproline ( cyclo ( l -Pro- l -Pro)) is known to act as attraction pheromone for the diatom Seminavis robusta and has been detected in various other species, often as constituent of pheromonal secretions ( Bonneure et al., 2021 ). Recently, we demonstrated that foliar diproline treatment leads to systemic IR against Mg in rice grown under aerobic conditions ( De Kesel et al., 2020 ).…”

Cyclic Dipeptides: The Biological and Structural Landscape with Special Focus on the Anti-Cancer Proline-Based Scaffold

“…Diatoms, an important ecological group of phytoplankton, an extremely diverse group of microalgae, offer possibilities for biotechnological applications, e.g., sustainable pest control in agriculture [363,364]. The proline derived DKP, cyclo(L-Pro-L-Pro), has been recently reported as the first molecular structure of sex-inducing pheromone from marine diatom, Seminavis robusta sp., with moderate to good bioactivity, and low to no phytotoxicity [365].…”

Diketopiperazine Gels: New Horizons from the Self-Assembly of Cyclic Dipeptides

“…All these features make CDPs an attractive choice as biocompatible, green, functionalizable, and cheap building blocks for smart materials with a wide scope of applications from industry to medicine. The basic design is very simple: two amino acids bound together in a cyclic structure with a defined stereochemistry (i.e., LL, LD/DL, or DD) and the possibility to further derivatize the side chains [ 42 , 43 , 44 , 45 , 46 ] of selected amino acids [ 47 , 48 , 49 , 50 ], as widely applied in nature [ 51 , 52 , 53 , 54 , 55 , 56 ].…”