Inhibition of shoot branching in Arabidopsis by the artificially produced canonical-strigolactone.

Strigolactones (SLs) are apocarotenoid plant hormones that regulate shoot branching. The natural SLs can be divided into two groups, canonical and non-canonical SLs according to those chemical structures. In a model plant, Arabidopsis thaliana, it has been thought to produce only non-canonical SLs.

Highly Sensitive Strigolactone Perception by a Divergent Clade KAI2 Receptor in a Facultative Root Parasitic Plant, Phtheirospermum japonicum.

Phtheirospermum japonicum, a member of the Orobanchaceae family, is a facultative root parasitic plant that can survive without parasitizing the host. In contrast, obligate root parasitic plants, such as Striga and Orobanche, which are also members of the Orobanchaceae family, cannot survive in the absence of the host. The germination of obligate root parasitic plants is typically induced by host root-derived strigolactones (SLs) at very low concentrations.

Radicle Growth Regulation of Root Parasitic Plants by Auxin-related Compounds.

Root parasitic plants in the Orobanchaceae, such as Striga and Orobanche, cause significant damage to crop production. The germination step of these root parasitic plants is induced by host-root-derived strigolactones. After germination, the radicles elongate toward the host and invade the host root.

Latest knowledge on strigolactone biosynthesis and perception.

Strigolactones (SLs) are a class of terpenoid lactones initially identified as seed germination stimulants for root parasitic plants more than 50 years ago. Long after this initial discovery, SLs were re-characterized as the symbiotic signals for arbuscular mycorrhizal fungi that supply inorganic nutrients, such as phosphate, to their host plants. In 2008, SLs were found to be endogenous plant hormones that regulate shoot branching in plants.

Unveiling the complexity of strigolactones: exploring structural diversity, biosynthesis pathways, and signaling mechanisms.

Strigolactone is the collective name for compounds containing a butenolide as a part of their structure, first discovered as compounds that induce seed germination of root parasitic plants. They were later found to be rhizosphere signaling molecules that induce hyphal branching of arbuscular mycorrhizal fungi, and, finally, they emerged as a class of plant hormones. Strigolactones are found in root exudates, where they display a great variability in their chemical structure.

Activation of Strigolactone Biosynthesis by the DWARF14-LIKE/KARRIKIN-INSENSITIVE2 Pathway in Mycorrhizal Angiosperms, but Not in Arabidopsis, a Non-mycorrhizal Plant.

Strigolactones (SLs) are a class of plant hormones that regulate many aspects of plant growth and development. SLs also improve symbiosis with arbuscular mycorrhizal fungi (AMF) in the rhizosphere. Recent studies have shown that the DWARF14-LIKE (D14L)/KARRIKIN-INSENSITIVE2 (KAI2) family, paralogs of the SL receptor D14, are required for AMF colonization in several flowering plants, including rice.

Synthesis of Carlactone Derivatives to Develop a Novel Inhibitor of Strigolactone Biosynthesis.

Strigolactones (SLs), phytohormones that inhibit shoot branching in plants, promote the germination of root-parasitic plants, such as spp. and spp., which drastically reduces the crop yield.

A Divergent Clade KAI2 Protein in the Root Parasitic Plant Orobanche minor Is a Highly Sensitive Strigolactone Receptor and Is Involved in the Perception of Sesquiterpene Lactones.

Strigolactones (SLs) were initially discovered as germination inducers for root parasitic plants. In 2015, three groups independently reported the characterization of the SL receptor in the root parasitic plant Striga hermonthica, which causes significant damage to crop production, particularly in sub-Saharan Africa. The characterized receptors belong to HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE2 (HTL/KAI2), which is a member of the α/β-hydrolase protein superfamily.

A carlactonoic acid methyltransferase that contributes to the inhibition of shoot branching in .

SignificanceStrigolactones (SLs) are a group of apocarotenoid hormones, which regulates shoot branching and other diverse developmental processes in plants. The major bioactive form(s) of SLs as endogenous hormones has not yet been clarified. Here, we identify an methyltransferase, CLAMT, responsible for the conversion of an inactive precursor to a biologically active SL that can interact with the SL receptor in vitro.

Tryptophan derivatives regulate the seed germination and radicle growth of a root parasitic plant, Orobanche minor.

Root parasitic plant germination is induced by the host-derived chemical, strigolactone (SL). We found that a major microbial culture broth component, tryptone, inhibits the SL-inducible germination of a root parasitic plant, Orobanche minor. l-tryptophan (l-Trp) was isolated as the active compound from tryptone.

Strigolactone biosynthesis, transport and perception.

Strigolactones (SLs) are plant hormones that regulate diverse developmental processes and environmental responses. They are also known to be root-derived chemical signals that regulate symbiotic and parasitic interactions with arbuscular mycorrhizal fungi and root parasitic plants, respectively. Since the discovery of the hormonal function of SLs in 2008, there has been much progress in the SL research field.

Chemical identification of 18-hydroxycarlactonoic acid as an LjMAX1 product and in planta conversion of its methyl ester to canonical and non-canonical strigolactones in Lotus japonicus.

Strigolactones (SLs) are a group of plant apocarotenoids that act as rhizosphere signaling molecules for both arbuscular mycorrhizal fungi and root parasitic plants. They also regulate plant architecture as phytohormones. The model legume Lotus japonicus (synonym of Lotus corniculatus) produces canonical 5-deoxystrigol (5DS) and non-canonical lotuslactone (LL).

Genome Sequence of Striga asiatica Provides Insight into the Evolution of Plant Parasitism.

Parasitic plants in the genus Striga, commonly known as witchweeds, cause major crop losses in sub-Saharan Africa and pose a threat to agriculture worldwide. An understanding of Striga parasite biology, which could lead to agricultural solutions, has been hampered by the lack of genome information. Here, we report the draft genome sequence of Striga asiatica with 34,577 predicted protein-coding genes, which reflects gene family contractions and expansions that are consistent with a three-phase model of parasitic plant genome evolution.

Chemical screening of novel strigolactone agonists that specifically interact with DWARF14 protein.

Strigolactones (SLs) are a class of plant hormones that regulate shoot branching as well as being known as root-derived signals for parasitic and symbiotic interactions. The physical interaction between SLs and the DWARF14 (D14) receptor family can be examined by differential scanning fluorimetry (DSF) that monitors the changes in protein melting temperature (Tm). The Tm of D14 is lowered by bioactive SLs in DSF analysis.

Structural Basis of Karrikin and Non-natural Strigolactone Perception in Physcomitrella patens.

In plants, strigolactones are perceived by the dual receptor-hydrolase DWARF14 (D14). D14 belongs to the superfamily of α/β hydrolases and is structurally similar to the karrikin receptor KARRIKIN INSENSITIVE 2 (KAI2). The moss Physcomitrella patens is an ideal model system for studying this receptor family, because it includes 11 highly related family members with unknown ligand specificity.

Strigolactone perception and deactivation by a hydrolase receptor DWARF14.

The perception mechanism for the strigolactone (SL) class of plant hormones has been a subject of debate because their receptor, DWARF14 (D14), is an α/β-hydrolase that can cleave SLs. Here we show via time-course analyses of SL binding and hydrolysis by Arabidopsis thaliana D14, that the level of uncleaved SL strongly correlates with the induction of the active signaling state. In addition, we show that an AtD14 catalytic mutant that lacks enzymatic activity is still able to complement the atd14 mutant phenotype in an SL-dependent manner.

Ethylene-gibberellin signaling underlies adaptation of rice to periodic flooding.

Most plants do poorly when flooded. Certain rice varieties, known as deepwater rice, survive periodic flooding and consequent oxygen deficiency by activating internode growth of stems to keep above the water. Here, we identify the gibberellin biosynthesis gene, (), whose loss-of-function allele catapulted the rice Green Revolution, as being responsible for submergence-induced internode elongation.

An allelic series at the KARRIKIN INSENSITIVE 2 locus of Arabidopsis thaliana decouples ligand hydrolysis and receptor degradation from downstream signalling.

Karrikins are butenolide compounds present in post-fire environments that can stimulate seed germination in many species, including Arabidopsis thaliana. Plants also produce endogenous butenolide compounds that serve as hormones, namely strigolactones (SLs). The receptor for karrikins (KARRIKIN INSENSITIVE 2; KAI2) and the receptor for SLs (DWARF14; D14) are homologous proteins that share many similarities.

Unveiling the functional diversity of the alpha/beta hydrolase superfamily in the plant kingdom.

The alpha/beta hydrolase (ABH) superfamily is a widespread and functionally malleable protein fold recognized for its diverse biochemical activities across all three domains of life. ABH enzymes possess unexpected catalytic activity in the green plant lineage through selective alterations in active site architecture and chemistry. Furthermore, the ABH fold serves as the core structure for phytohormone and ligand receptors in the gibberellin, strigolactone, and karrikin signaling pathways in plants.