Beta-Cyclocitral Root Growth Stimulation
A Plant Hormone that Speeds Root Growth
Could Be a New Agricultural Tool
Scientists have identified a plant hormone, beta-cyclocitral,
that makes tomato and rice plant roots grow faster and branch
more. The hormone could help farmers enhance crop plant growth.
A molecule sold as a food additive has an underground role, too:
helping roots grow faster.
When added to soil, the molecule, called beta-cyclocitral, speeds
root growth in rice and tomato plants, scientists report May 8,
2019, in the journal Proceedings of the National Academy of
Sciences. It also makes rice plants resistant to salty soil, which
usually turns plants sickly and stunted. The molecule, a hormone
found naturally in plants, could be a useful tool for farmers
seeking healthier and more drought-resistant crops.
For centuries, plants have been bred for vigorous foliage and
other easily visible traits. Because roots are hidden underground,
“they’ve been largely ignored,” says developmental biologist
Philip Benfey, a Howard Hughes Medical Institute investigator at
And yet, roots make up half the plant, points out coauthor Jazz
Dickinson, also at Duke. She and Benfey wanted to find plant
hormones that affected root development. Their previous research
had hinted that some molecule chemically related to carotenoids –
the pigments that give carrots their vibrant orange hue – might be
important. But the researchers weren’t sure exactly which one,
Many of these carotenoid relatives have been repurposed and are
available commercially as food additives or dietary supplements.
Dickinson rounded up about 20 and tested their effects on a common
lab plant, Arabidopsis. She added each compound to the clear agar
gel in which the plants were growing – a setup that let her easily
see the roots – and monitored what happened over 10 days.
“Beta-cyclocitral stood out,” she says. It made the roots grow
faster and also branch out more. And it had the same effect in
rice and tomato plants, follow-up tests showed.
In rice plants, the team noticed an even more striking effect: the
plants could also withstand salty soil. Irrigation of farm fields
can make soil saltier, especially near the top. The team mimicked
those conditions in the lab, and then watched how rice plants
grew. “Untreated rice plants were very unhappy with that level of
salt,” Benfey says. But with beta-cyclocitral added, the plants
didn’t seem perturbed.
It’s possible that the compound helped the roots push down through
the salty topsoil to reach the deeper, less-salty soil more
quickly, Dickinson proposes.
The researchers hope that beta-cyclocitral will be useful
agriculturally, either added to soil or sprayed onto crops. And
since the molecule worked in both rice and tomatoes – two very
different plants – it may boost root growth in crops more broadly.
These racing roots show the effects of beta-cyclocitrical, a plant
hormone that boosts root growth. The rice plants on the left are
growing in a gel that contains the hormone, but the ones on the
right aren’t getting any help.
May 8, 2019
ß-Cyclocitral is a conserved root growth
Alexandra J. Dickinson, Kevin Lehner, Jianing Mi, Kun-Peng
Jia, Medhavinee Mijar, José Dinneny, Salim Al-Babili, and
Philip N. Benfey
Roots produce hundreds to thousands of small molecules with
unknown functions. We targeted the apocarotenoid pathway, which
has been linked to numerous developmental processes in
Arabidopsis, for a sensitized chemical genetic screen to identify
regulators of root development. ß-Cyclocitral, a small molecule
derived from ß-carotene, was identified as a regulator of root
stem cell behavior in Arabidopsis as well as in rice and tomato.
ß-Cyclocitral promotes root stem cell divisions to enhance root
growth and branching. In rice, ß-cyclocitral enhanced both root
and shoot growth during salt stress, which has important
implications for agriculture.
Natural compounds capable of increasing root depth and
branching are desirable tools for enhancing stress tolerance in
crops. We devised a sensitized screen to identify natural
metabolites capable of regulating root traits in Arabidopsis.
ß-Cyclocitral, an endogenous root compound, was found to promote
cell divisions in root meristems and stimulate lateral root
branching. ß-Cyclocitral rescued meristematic cell divisions in
ccd1ccd4 biosynthesis mutants, and ß-cyclocitral–driven root
growth was found to be independent of auxin, brassinosteroid, and
reactive oxygen species signaling pathways. ß-Cyclocitral had a
conserved effect on root growth in tomato and rice and generated
significantly more compact crown root systems in rice. Moreover,
ß-cyclocitral treatment enhanced plant vigor in rice plants
exposed to salt-contaminated soil. These results indicate that
ß-cyclocitral is a broadly effective root growth promoter in both
monocots and eudicots and could be a valuable tool to enhance crop
vigor under environmental stress.
Beta-Cyclocitral Synthesis Patents
Method for preparing cyclocitral by micro-structural
The invention discloses a method for preparing cyclocitral by
micro-structural reactors. The method comprises steps as follows:
a liquid raw material citral and organic amine in a mole ratio
being 1: (0.8-1.5) are simultaneously pumped into a tubular
reactor or one micro-structural reactor for an amination reaction,
the reaction temperature of the reactor is controlled in a range
of 10-20 DEG C, a flow velocity of a reaction liquid is
controlled, the reaction liquid is enabled to totally stay in the
reactor for 0.1-25 min, and obtained aldimine and concentrated
sulfuric acid are injected into another micro-structural reactor
and subjected to a ring closing reaction; a reaction product is
neutralized by a sodium hydroxide solution and is subjected to
acidic hydrolysis, liquid separation, reduced pressure
distillation and drying, and a pale yellow oily product, namely,
cyclocitral, is obtained. According to the method, the reaction
time is short, the reaction temperature is accurate and
controllable, and product select
PROCESS FOR PREPARING CYCLOCITRAL
A process for preparing cyclocitral by expoxidizing a
Preparation of alpha - and beta -cyclocitral, and the
N-methylaldimines of these compounds
An improved process for the preparation of cyclocitrals of the
general formula I (I) via the novel N-methylaldimines of the
general formula II (II) and the novel N-methylaldimines of the
formula II. The cyclocitrals of the formula I are obtained in
yields of 80-90%, based on citral employed. The compounds I and II
are important intermediates for the preparation of fragrances and
carotinoids, such as vitamin A, and products related thereto.
Manufacture of Ionone from Citral and Acetone and of
Cyclocitral as Intermediate Product.
Ionone is prepared from citral and acetone by the following
operations :-(1) Cyclocitral is first produced. For this purpose
citral is condensed with cyanacetic acid, or a salt or ether
thereof, in the presence of caustic soda' and alcohol, whereby
citralidene cyanacetic acid melting at 124 -122 C., or a
derivative thereof, is produced ; then this product is converted
into its cyclic isomeride by boiling it at a reflux-cooler with
diluted sulphuric acid for twelve hours, after the manner
described in Specification No. 22,114, A.D. 1893; and, finally,
the cyclic compound, which after removal of bye-products is
obtained as a syrup, is distilled in a powerful current of steam
in presence of caustic alkali, and the distillate is fractionated
to obtain crude cyclocitral as a yellowish liquid boiling at 80
-110 C. under a pressure of 15 mm. The cyclocitralidene cyanacetio
acid may also be hydrolysed by boiling it with caustic potash
solution and xylene, and then separating and fractionating the
xylene layer. A small quantity of a gentle oxidizing- agent, such
as lead peroxide or the like, may advantageously be used in these
hydrolysing operations. (2) Cyclocitral is condensed with acetone
by means of alkaline reagents, for example, a solution of sodium
in alcohol, at the ordinary temperature. The mixture is then
neutralized by tartaric or other acid, and is distilled in a
strong current of steam. On redistillation the fraction which
boils at 130 -140 C., under a pressure of 16 mm., is collected as
ionone. It is rich in #-ionone, and yields a semi-earbazone
melting at 148 C., and a p-bromophenyl-hydrazone melting at 116 C.
MANUFACTURE OF CYCLOCITRAL
Compounds of the formula where R is H or CH 3 are prepared by
passing a stream of gas consisting of O 2 and O 3 into a solution
of #-ionone or #-isone in a solvent for ozonolysis reactions in an
amount to provide 1 to 2 moles 03 per mole of #-ionone or #-isone
and the resulting reaction mixture is worked up hydrolytically or
Tomato products enriched in beta-cyclocitral
The invention relates to processing tomatoes into paste, sauce
or related products, in which the processed products have an
improved flavour. More in particular, the processed products have
increased amounts of fruity flavour compounds. This is achieved by
co-oxidation of carotenoids and polyunsaturated fatty acids, using
an enzyme having lipoxygenase activity.
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