Nodal root instances (crown and seminal roots)

[Marty Sachs]

Leszek,

In maize is there any difference between the roots that form between 
the coleoptile and mesocotyl and those that form in above ground 
nodes (a.k.a. prop roots)?

It seems to me that these root types are the same in the triticeae 
where roots will form in any nodes that are below soil surface (the 
deeper the seed is planted, the more nodes that have roots).

In maize, the mesocotyl elogates so that the roots forming below the 
coleoptile are just below soil surface.  Prop roots form in nodes 
above soil surface.

My question about the origin of the term 'crown'  is still open.  Is 
this term used by some in maize, simply to give a similar name to the 
place in maize where adventicious roots form, to the structure in the 
triticeae that looks like a 'crown'?

Concerning your question on the use of 'adventitious' to describe 
these roots.  They are indeed structures or organs developing in an 
unusual position; they are indeed roots originating on the stem.

I agree that crown roots' & 'nodal roots' should be used as synonyms 
of 'adventitious roots'.

	-Marty

At 2:23 PM -0500 5/5/05, Vincent, Leszek wrote:
>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