Researchers solving the riddle of biosynthesis of strigolactone in plants Strigolactones (SLs) are a class of compounds in plants that have attracted attention in the rhizosphere because of their role as plant hormones and signaling molecules.
They play an important role in regulating plant architecture and in promoting the germination of parasitic weeds to the roots (* 1), which have major adverse effects on plant growth and production.
They discovered orobanchol synthase, which is responsible for the conversion of SL-carlactonic acid, which promotes a symbiotic relationship with fungi, in SL-Orobanchol, which causes the development of root-parasitic weeds. By turning off (* 3) the orobanchol synthase gene using genome editing, they are able to artificially regulate SL production.
This finding will lead to a better understanding of individual SL functions and practical applications of SL to improve the system. solving the riddle of biosynthesis of strigolactone in plants.
It is known that strigolactone has a variety of functions, such as the development of plant architecture, the promotion of a mutually beneficial mycorrhizal relationship with fungi, and the signaling effect for germination of root-parasitic weeds.
Strigolactone is classified into canonical and non-canonical SL based on its chemical structure.
The canonical SL has an ABC ring, while the non-canonical SL has an unopened BC ring.
The study found the synthase gene responsible for converting non-canonical SL-carlactonic acid into canonical SL-Orobanchol.
This group is able to produce tomatoes with the growth of the Carlactic Acid (CLA) synthase gene and prevent the production of Orobanchol.
Root parasitic weed germination rates are lower in these cut plants.
Strigolactones (SL) are a class of compounds that were originally marked as sprouts for root parasitic weeds.
SL has also received attention for other functions. They play an important role in controlling shoot growth and promoting the symbiosis of mycorrhizae in many terrestrial plants, where plants and fungi exchange nutrients.
So far, around 20 SL have been isolated. with stereochemical differences in ring C and modification in rings A and / or B. SL with closed BC rings have been discovered in recent years. At present, SL with closed ABC rings are referred to as canonical SL, whereas SL with closed BC rings is non-canonical SL. Now the researchers solving the riddle of biosynthesis of strigolactone in plants.
However, it is unclear which compounds act as hormones and which act as rhizosphere signals.
If SL production can be suppressed, plants will cause fewer weeds to germinate and their adverse effects on crop production will be reduced.
On the other hand, increasing SL production will improve plant nutrition by promoting connections to the mycorrhizal fungus. In addition, manipulation of endogenous SL mirrors will control the system architecture above ground.
However, the route of orobanchol biosynthesis in other plants is still unknown. The study found new orobanchol synthase that was converted by CLA in orobanchol to cherry and tomato plants.
This working group separates Orobanchol from pea exudate and determines its structure. Metabolic experiments using peas predict that cytochrome P450 (* 4) will be involved in the conversion of CLA to Orobanchol.
In this study, grapes were planted under low and high phosphate conditions, with orbanchol production restricted and promoted accordingly.
The genes expressed in plant roots in both conditions are compared in detail. This group searched for the CYP gene whose expression correlated with the production of orobanchol, expressed it as a recombinant protein and conducted an enzyme response analysis.
From these results it became clear that the enzyme VuCYP722C catalyzed the conversion of CLA to Orobanchol.
In addition, the SlCYP722C gene, homologous (* 5) from VuCYP722C in tomatoes, was confirmed as the orobanchol synthase gene. The SlCYP722C gene was eliminated in tomato plants using genome editing (KO). Unlike wild-type tomato plants (control plants), Orobanchol was not detected in the excretion of the roots of KO plants, but rather CLA was detected.
The research team was able to show that SlCYP722C is an orobanchol synthase in tomatoes that converts non-canonical SL-CLA into canonical SL-Orobanchol.
The architecture of CO and wild plants is comparable (Figure 1). This shows that Orobanchol does not affect the architecture of plants in tomatoes. It is believed that these KO tomato plants can still benefit from mycorrhizal fungi because CLA activity against fungal hyphal branching is comparable to Canonical SL activity.
This study shows that it is possible to limit the damage done by these weed parasites to tomato production by killing the orobanchol synthase gene.