Plants use Circadian rhytms to prepare for battle with insects
Tue, 14 Feb 2012 09:51:52 PST

This is intriguing. 
Janet McGarry
Plants Use Circadian Rhythms 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,  
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 
"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  

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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  <>
Subject: [pbs] Need identification
Message-ID:  <>
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.…


Message:  2
Date: Mon, 13 Feb 2012 21:30:38 +0000
From: Alberto Castillo  <>
Subject: Re: [pbs] Need  identification
To: Pacific Bulb Society  <>
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"  <>
Subject: [pbs] OT/ PBS contributor's  tragic loss
To: <>
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 :…
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  <>
Subject: Re: [pbs] OT/ PBS contributor's tragic  loss
Message-ID:   &<>
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.  


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


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.  

San  Diego


Message: 6
Date:  Mon, 13 Feb 2012 21:05:58 -0800
From: Richard  <>
Subject: [pbs] Winter Projects
To: Pacific Bulb  Society <>
Message-ID:  <>
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  

rinsing presoaked seed
setting up tray, paper lined, peat bottom
fungicide dip (optional)
spreading seed inside sandwiched layer
placing seed inside sandwich
covering seed layer with peat
stacking trays inside cooler. Note warm incubator  on right
recording all data in a filemaker  relational database 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  <>
Subject: [pbs] Lily Stratification
To: Pacific  Bulb Society <>
Message-ID:  <>
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?…

Rich  Haard
Bellingham,  Washington


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