The Rhizobium-Legume Symbiosis: Co-opting Successful Stress Management

The interaction of bacteria with plants can result in either a positive, negative, or neutral association. The rhizobium-legume interaction is a well-studied model system of a process that is considered a positive interaction. This process has evolved to require a complex signal exchange between the host and the symbiont. During this process, rhizobia are subject to several stresses, including low pH, oxidative stress, osmotic stress, as well as growth inhibiting plant peptides. A great deal of work has been carried out to characterize the bacterial response to these stresses. Many of the responses to stress are also observed to have key roles in symbiotic signaling. We propose that stress tolerance responses have been co-opted by the plant and bacterial partners to play a role in the complex signal exchange that occurs between rhizobia and legumes to establish functional symbiosis. This review will cover how rhizobia tolerate stresses, and how aspects of these tolerance mechanisms play a role in signal exchange between rhizobia and legumes.

In vitro Assessment of Cytotoxic Activity of Bioactive Peptides from Momordica dioica and Solanum trilobatum against Human Colon Cancer Cells

Plant peptides have gained attention in the medicinal field due to their high anti-microbial and anti-cancer properties. Various plant sources are being used to extract proteins and peptides to be used as a cure for a variety of diseases. The latest studies show that plant peptides are effective in the treatment of cancer due to their ability to preferentially bind to the receptors or membranes of cancer cells leading to tumour growth inhibition, cytotoxicity, decreased proliferation, and apoptosis. The peptides get internalized into the cells causing cancer cell agglutination and aggregation. In addition to acting as therapeutic agents, plant peptides are also used for the targeting of drugs specific to cancer cells. In this study, bioactive peptides were isolated from the seeds of Momordica dioica and leaves of Solanum trilobatum. They were screened and identified using HPLC and MALDI-TOF techniques. In this study, apoptosis was analyzed by the Hoechst 33342 staining method which detected the presence of condensed pycnotic nuclei in apoptotic COLO320DM and COLO205 colon cancer cellsat the maximum concentrations of 150 and 175 µg/mL of plant peptides.Further DCFH-DA staining indicated the intracellular ROS production in the treated COLO320DM and COLO205 colon cancer cells. Thus, the isolated bioactive plant peptides can be formulated towards the development of effective anticancer drugs for the treatment of colon cancer in humans.

Function of Small Peptides During Male-Female Crosstalk in Plants

Plant peptides secreted as signal molecular to trigger cell-to-cell signaling are indispensable for plant growth and development. Successful sexual reproduction in plants requires extensive communication between male and female gametophytes, their gametes, and with the surrounding sporophytic tissues. In the past decade, it has been well-documented that small peptides participate in many important reproductive processes such as self-incompatibility, pollen tube growth, pollen tube guidance, and gamete interaction. Here, we provide a comprehensive overview of the peptides regulating the processes of male-female crosstalk in plant, aiming at systematizing the knowledge on the sexual reproduction, and signaling of plant peptides in future.

Solution NMR and racemic crystallography provide insights into a novel structural class of cyclic plant peptides

Head-to-tail cyclic and disulfide-rich peptides are natural products with applications in drug design. Among these are the PawS-Derived Peptides (PDPs) produced in seeds of the daisy plant family. PDP-23 is...

Plant Bioactive Peptides: Current Status and Prospects Towards Use on Human Health

Large numbers of bioactive peptides with potential applications in protecting against human diseases have been identified from plant sources. In this review, we summarized recent progress in the research of plant-derived bioactive peptides, encompassing their production, biological effects, and mechanisms. This review focuses on antioxidant, antimicrobial, antidiabetic, and anticancer peptides, giving special attention to evidence derived from cellular and animal models. Studies investigating peptides with known sequences and well-characterized peptidic fractions or protein hydrolysates will be discussed. The use of molecular docking tools to elucidate inter-molecular interactions between bioactive peptides and target proteins is highlighted. In conclusion, the accumulating evidence from in silico, in vitro and in vivo studies to date supports the envisioned applications of plant peptides as natural antioxidants as well as health-promoting agents. Notwithstanding, much work is still required before the envisioned applications of plant peptides can be realized. To this end, future researches for addressing current gaps were proposed.