Nodal root innstances (crown and seminal roots)

[Marty Sachs]

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/y4011e05.htm

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


Also the corn development sections of:

http://web.extension.uiuc.edu/RockfordCenter/newsletters/morrisonj/Issue3Vol4.htm

http://web.extension.uiuc.edu/RockfordCenter/newsletters/morrisonj/Issue4Vol4.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