Plants use Circadian rhytms to prepare for battle with insects

ScienceDaily (Feb. 13, 2012) — In a study of the molecular underpinnings
of plants' pest resistance, Rice University biologists have shown that
plants both anticipate daytime raids by hungry insects and make sophisticated
preparations to fend them off.

"When you walk past plants, they don't look like they're doing anything,"
said Janet Braam, an investigator on the new study, which appears this week
in the Proceedings of the National Academy of Sciences. "It's intriguing
to see all of this activity down at the genetic level. It's like watching a
besieged fortress go on full alert."
Braam, professor and chair of Rice's Department of Biochemistry and Cell
Biology, said scientists have long known that plants have an internal clock
that allows them to measure time regardless of light conditions. For
example, some plants that track the sun with their leaves during the day are known
to "reset" their leaves at night and move them back toward the east in
anticipation of sunrise.
In recent years, scientists have begun to apply powerful genetic tools to
the study of plant circadian rhythms. Researchers have found that as many as
one-third of the genes in Arabidopsis thaliana -- a widely studied species
in plant biology -- are activated by the circadian cycle. Rice biochemist
Michael Covington found that some of these circadian-regulated genes were
also connected to wounding responses.
"We wondered whether some of these circadian-regulated genes might allow
plants to anticipate attacks from insects, in much the same way that they
anticipate the sunrise," said Covington, now at the University of California,
Davis.
Danielle Goodspeed, a graduate student in biochemistry and cell biology,
designed a clever experiment to answer the question. She used 12-hour light
cycles to entrain the circadian clocks of both Arabidopsis plants and
cabbage loopers, a type of caterpillar that eats Arabidopsis. Half of the plants
were placed with caterpillars on a regular day-night cycle, and the other
half were placed with "out-of-phase" caterpillars whose internal clocks were
set to daytime mode during the hours that the plants were in nighttime
mode.
"We found that the plants whose clocks were in phase with the insects were
relatively resistant, whereas the plants whose clocks were out of phase
were decimated by the insects feeding on them," Goodspeed said.
Wassim Chehab, a Rice faculty fellow in biochemistry and cell biology,
helped Goodspeed design a follow-up experiment to understand how plants used
their internal clocks to resist insect attacks. Chehab and Goodspeed examined
the accumulation of the hormone jasmonate, which plants use to regulate
the production of metabolites that interfere with insect digestion.
They found that Arabidopsis uses its circadian clock to increase jasmonate
production during the day, when insects like cabbage loopers feed the most.
They also found that the plants used their internal clocks to regulate the
production of other chemical defenses, including those that protect
against bacterial infections.
"Jasmonate defenses are employed by virtually all plants, including
tomatoes, rice and corn," Chehab said. "Understanding how plants regulate these
hormones could be important for understanding why some pests are more
damaging than others, and it could help suggest new strategies for insect
resistance."

In a message dated 2/14/2012 9:14:20 A.M. Pacific Standard Time,
pbs-request@lists.ibiblio.org writes:

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Today's Topics:

1. Need identification (Joseph Kraatz)
2. Re: Need identification (Alberto Castillo)
3. OT/ PBS contributor's tragic loss (Youngs)
4. Re: OT/ PBS contributor's tragic loss (The Silent Seed)
5. Need identification (AW)
6. Winter Projects (Richard)
7. Lily Stratification (Richard)

----------------------------------------------------------------------

Message: 1
Date: Mon, 13 Feb 2012 13:16:25 -0800
From: Joseph Kraatz <plantnut@cox.net>
Subject: [pbs] Need identification
To: pbs@lists.ibiblio.org
Message-ID: <5C712669-FC8E-420A-ACF8-1A89736609A5@cox.net>
Content-Type: text/plain; charset=us-ascii

A friend gave me a handful of Oxalis bulbs of which she didn't know the
species. They are now blooming but need help in identifying the species.
Thanks, Joe, Oceanside, CA.

http://flickr.com/photos/oceanside2012/…

------------------------------

Message: 2
Date: Mon, 13 Feb 2012 21:30:38 +0000
From: Alberto Castillo <ezeizabotgard@hotmail.com>
Subject: Re: [pbs] Need identification
To: Pacific Bulb Society <pbs@lists.ibiblio.org>
Message-ID: <BAY156-W5155DCDDD53C5236B3CA72AE7F0@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"

You have obtusa and brasiliensis there so far.

------------------------------

Message: 3
Date: Mon, 13 Feb 2012 23:02:56 -0000
From: "Youngs" <youngs.aberdeen@btinternet.com>
Subject: [pbs] OT/ PBS contributor's tragic loss
To: <pbs@lists.ibiblio.org>
Message-ID: <44AE7AADF91D45FC9A7E1059CF95836E@userfba71dce46>
Content-Type: text/plain; charset="windows-1252"

PBS members must be greatly saddened to hear, as we have been in the UK,
of the death of Michelle Avent, wife of PBS stalwart Tony Avent of Plant
Delights Nursery Inc.

A touching tribute to his wife and partner by Tony is paid here :
http://plantdelights.com/February/products/…
Our thoughts are with Tony at this sad time.

M & I
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Message: 4
Date: Mon, 13 Feb 2012 18:13:07 -0500 (EST)
From: The Silent Seed <santoury@aol.com>
Subject: Re: [pbs] OT/ PBS contributor's tragic loss
To: pbs@lists.ibiblio.org
Message-ID: &<8CEB8BC2DF0A74C-1F74-15463@webmail-d036.sysops.aol.com>
Content-Type: text/plain; charset="us-ascii"

I just learned of this this evening - very sad indeed. My heart goes out
to Tony and his family.
Jude

------------------------------

Message: 5
Date: Mon, 13 Feb 2012 19:42:09 -0800
From: "AW" <awilson@avonia.com>
Subject: [pbs] Need identification
To: <pbs@lists.ibiblio.org>
Message-ID: <E59842C712E54E7ABED05B5F2C70317B@Desktop>
Content-Type: text/plain; charset="us-ascii"

Joe,

I think you have two forms of O. obtusa. That species is blooming all over
in these parts right now. Check the Wiki page on this species to see the
number of color variants there are. You have a nice combination there.

Andrew
San Diego

------------------------------

Message: 6
Date: Mon, 13 Feb 2012 21:05:58 -0800
From: Richard <richrd@nas.com>
Subject: [pbs] Winter Projects
To: Pacific Bulb Society <pbs@lists.ibiblio.org>
Message-ID: <B479A048-FDAA-458B-9656-BEF5AA5FB7E3@nas.com>
Content-Type: text/plain; charset=us-ascii

Nursery scale stratification

This is what we are working on now at our nursery, preparing mostly tree
and shrub seeds for a 90 day cold stratification and planting in May. There
are many ways to accomplish this task this is just my own twist on the job.
Earlier we used open top plastic bags but this gives us better aeration
and ease of inspection. Here is a series of pictures that illustrates our
process.

rinsing presoaked seed http://flic.kr/p/btpKEK/
setting up tray, paper lined, peat bottom http://flic.kr/p/btpJaP/
fungicide dip (optional) http://flic.kr/p/btpLnK/
spreading seed inside sandwiched layer http://flic.kr/p/btpNSF/
placing seed inside sandwich http://flic.kr/p/btpM76/
covering seed layer with peat http://flic.kr/p/btpJWH/
stacking trays inside cooler. Note warm incubator on right
http://flic.kr/p/btpMMp/
recording all data in a filemaker relational database
http://flic.kr/p/btpMYe/ In this screen shot from left is our field map, propagation and seed
inventory databases

Working with Lily seed is new for me and I have a question in my following
post for lily savy stratifiers.

Rich Haard
Bellingham Washington

------------------------------

Message: 7
Date: Mon, 13 Feb 2012 21:08:02 -0800
From: Richard <richrd@nas.com>
Subject: [pbs] Lily Stratification
To: Pacific Bulb Society <pbs@lists.ibiblio.org>
Message-ID: <9FA5584B-B614-4A58-BE6C-6355780D3D7C@nas.com>
Content-Type: text/plain; charset=us-ascii

Question for lily stratifiers

All three are fresh collections of L. columbianum and L. washingtonianum.
These are 'immediate cool hypogeal' species and were warm stratified 30
days at 50 deg f then the last 2 weeks at 40 deg F. All have begun putting out
a radical some reaching considerable length with signs of leaf shoot on a
few. They're growing now in mesh bags buried in moist peat. Otherwise their
condition is very nice, no mold.

Earlier this fall in October I field planted the same collections and this
is a test to try stratification and tray planting. These radicals seem
rather fragile. Is it time to move them to flats and continue chilling for
another 60 days before placing outside?

http://flic.kr/p/btoASZ/
http://flic.kr/p/btoBoZ/
http://flic.kr/p/btoBTR/

http://pacificbulbsociety.org/pbswiki/index.php/…

Rich Haard
Bellingham, Washington

------------------------------

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