Nodal root instances (crown and seminal roots)

[Vincent, Leszek]

Hi Marty (& colleagues),

Comments on your last paragraph first (copy just below):  Kiesselbach
(1949) in "The Structure and Reproduction of Corn" provides something of
a 'definition' of "crown" in the following: 

"The term adventitious roots has come to apply to all of those roots
that arise in the basal intercalary meristem of the lower internodes of
the stem. Through common usage this is synonymous with crown roots, so
designated because of origin in the basal portion of the growing stem
known as the crown. Following the seedling stage, they constitute the
principal part of the root system. Any aerial brace roots are included
in this category." (p. 21). 

Elsewhere in this section one can further glean the following: The first
whorl of crown roots (nodal/adventitious roots) appears from the base of
the 2nd internode which is just above the mesocotyl. The underground
internodes, immediately above the mesocotyl, don't elongate. This region
with several nodes & very short internodes is the region from which the
nodal roots (crown/adventitious roots) emerge - from the base of most of
these very short internodes. This short, multiple node region is
considered the crown. The crown region is considered to extend to above
the soil surface, where further nodal roots are produced (brace/prop
roots)

So the "crown" is the region which produces adventitious roots (syn.:
crown/nodal roots) at and near the base of the maize culm (stem).

Feldman (1993) in 'The Maize Handbook', provides the following:
"Permanent, adventitious roots originate from the nodes on the
belowground portion of the stem. Usually many whorls of roots arise from
these nodes. Because underground internodes fail to elongate, and hence
are very short, close inspection is often necessary to ascertain the
node of origin of each root. Collectively, the whorls comprise the root
crown." (p. 31)

In wheat nodal roots (syn.: adventitious or crown roots) emerge from the
lower 3-7 nodes (presumably those just above the non-elongating
mesocotyl. Nodal roots from at least the 7th node are typically above
the soil surface. 

Comparing maize with wheat - while it appears that the crown in maize is
a more contracted region than in wheat, the term "crown" seems to be
used similarly (?).

The terminology of crown roots & nodal roots is used rather differently
in rice. Crown roots (mat roots) emerge from nodes below the soil
surface. Nodal roots emerge from nodes above the soil surface. However,
the 'crown roots' (mat roots) do emerge from a fairly compact region at
the base of the culm - seemingly similar to the occurrence in maize (I
haven't checked this carefully - others are welcome to correct me).

While one might be tempted to use the terms 'crown roots' & 'nodal
roots' as synonyms of 'adventitious roots' it should be noted that
'adventitious' is used atypically in maize & wheat with respect to the
internationally recognized definition for the term. The typical
definition of 'adventitious' is "structures or organs developing in an
unusual position, as roots originating on the stem."  Notwithstanding
this, my inclination is to use 'crown roots' & 'nodal roots' as synonyms
of 'adventitious roots' (well, that's what I 'root' for ;-) ).
 
>From Marty: " I'm not sure what the origin of the term 'crown roots' is,
but I'm 
guessing it comes from the triticeae where the structure looks 
somewhat like a 'crown' and the name is apparently used by some 
(e.g.,  in the links given above) in maize and other cereals as a 
synonym of adventitious roots (unless I'm missing something).  It's 
not completely clear to me that maize has a true 'crown' as in the 
sense one sees it in the triticeae.  I would suggest that we find out 
exactly what the origin of the term 'crown' is in this regard, before 
including it as a term in the database."

Comments?

- Leszek
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
P. Leszek D. Vincent Ph.D., FLS
Division of Plant Sciences
Res. Prof. Dept. of Horticulture
215 Curtis Hall
University of Missouri-Columbia
Columbia
MO 65211-7020
USA
Ph: (573) 884-3716; Fax:(573) 884-7850;
Email: Leszek at missouri.edu
Associate Curator, Dunn-Palmer Herbarium (UMO);
Research Associate, Missouri Botanical Garden (MO), USA;
Plant Systematist on The Plant Ontology Consortium - NSF award 0321666
(www.plantontology.org)
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
 

-----Original Message-----
From: owner-po-dev at brie4.cshl.org [mailto:owner-po-dev at brie4.cshl.org]
On Behalf Of Marty Sachs
Sent: Wednesday, May 04, 2005 10:21 PM
To: po-dev at plantontology.org; Pankaj Jaiswal
Subject: Re: Nodal root innstances (crown and seminal roots)

At 2:35 PM -0400 5/3/05, Pankaj Jaiswal wrote:
>Vincent, Leszek wrote:
>
>>Hi Toby, Pankaj (& others),
>>
>>
>>It would seem essential that these terms be brought back. I provide 
>>the detailed definitions for these terms from the Zea mays 
>>ontology. If you'd like me to offer tweaked definitions for the 
>>definitions offered by Toby, based on my Zea definitions, I could 
>>attempt those.
>>
>>
>>Crown roots - The crown roots are the predominant component of the 
>>adventitious root system. They are termed crown roots because they 
>>originate from the basal portion of the growing stem known as the 
>>crown. The crown roots are subterranean in origin. The first crown 
>>roots (4-5), arranged in a whorl, appear at the base of the second 
>>internode about as soon as the tip of the coleoptile reaches the 
>>soil surface. A few of the subsequent higher internodes may have a 
>>similar number of crown roots (in whorls), after which the 
>>successive internodes have more and larger crown roots. The crown 
>>roots are usually extensively branched, via the production of 
>>numerous lateral adventitious roots. Note that the adventitious 
>>roots which arise from 2-3 internodes immediately above the soil 
>>surface (aerial in origin) are a separate component of the 
>>adventitious root system, called 'prop' or 'brace roots'. (Feldman 
>>in Freeling & Walbot (eds), 1994. The Maize Handbook, ID#60920; 
>>Kiesselbach, ID#59445; Poethig in Sheridan, WF (ed), 1982. Maize 
>>for Biological Research, ID#25744; Vincent, ID#165572, 2002)
>>
>
>Most part of this definition can actually go to the comments 
>section. However, this raises a question about
>
># adding new term "brace roots, synonym: prop roots". These are 
>different from "crown roots", if I go with Leszek's definition.
>
># What is "crown"  or "seedling crown" [not the crown of tree]? We 
>need to define it somewhere in ontology or add it as synonym to 
>multiple terms suggesting that X-plant_part is grouped to form 
>seedling crown. Or create a new term "seedling crown" which we all 
>know is not a biologically correct term, but can be treated as a 
>bin/grouping term. It's children with part of relationships will 
>more precisely tell what region is called as "crown".
>
>-Pankaj

What is being called the crown seems (at least to me) to be really 
different in the triticeae (e.g., wheat, barley) vs. maize (and 
apparently oats and rice).  In maize the mesocotyl elongates during 
germination (especially when the kernel is deeply sown).  In maize, 
there is a separation between the seminal roots (formed below the 
germinating kernel) and adventitious roots (forming at the base of 
the coleoptile near the soil surface).

In wheat and barely, unlike oats and maize, the internode between the 
scutellum and coleoptile (the mesocotyl) does not elongate. In the 
case of very deeply sown seeds (more than 100 mm), the internode 
between leaves 1 and 2 and sometimes between leaves 2 and 3 may also 
elongate.

See:

http://www.fao.org/documents/show_cdr.asp?url_file=/DOCREP/006/Y4011E/y4
011e05.htm

http://www.ikisan.com/links/ap_ricemorp.shtml


Also the corn development sections of:

http://web.extension.uiuc.edu/RockfordCenter/newsletters/morrisonj/Issue
3Vol4.htm

http://web.extension.uiuc.edu/RockfordCenter/newsletters/morrisonj/Issue
4Vol4.htm

I'm not sure what the origin of the term 'crown roots' is, but I'm 
guessing it comes from the triticeae where the structure looks 
somewhat like a 'crown' and the name is apparently used by some 
(e.g.,  in the links given above) in maize and other cereals as a 
synonym of adventitious roots (unless I'm missing something).  It's 
not completely clear to me that maize has a true 'crown' as in the 
sense one sees it in the triticeae.  I would suggest that we find out 
exactly what the origin of the term 'crown' is in this regard, before 
including it as a term in the database.

	-Marty