The lateral root initiation index: an integrative measure of primordium formation

Authors: Dubrovsky, J. G.; Soukup, A.; Napsucialy-Mendivil, S.; Jekni, Z.; Ivanchenko, M. G.

Source: Annals of Botany, Volume 103, Number 5, 6 March 2009 , pp. 807-817(11)

Publisher: Oxford University Press

Abstract:

Background and Aims

Lateral root initiation is an essential and continuous process in the formation of root systems; therefore, its quantitative analysis is indispensable. In this study a new measure of lateral root initiation is proposed and analysed, namely the lateral root initiation index (I_LRI), which defines how many lateral roots and/or primordia are formed along a parent-root portion corresponding to 100 cortical cells in a file.

Methods

For data collection, a commonly used root clearing procedure was employed, and a new simple root clearing procedure is also proposed. The I_LRI was determined as 100dl, where d is the density of lateral root initiation events (number mm¹) and l is the average fully elongated cortical cell length (mm).

Key Results

Analyses of different Arabidopsis thaliana genotypes and of a crop plant, tomato (Solanum lycopersicum), showed that I_LRI is a more precise parameter than others commonly used as it normalizes root growth for variations in cell length. Lateral root primordium density varied in the A. thaliana accessions Col, Ler, Ws, and C24; however, in all accessions except Ws, I_LRI was similar under the same growth conditions. The nitrogen/carbon ratio in the growth medium did not change the lateral root primordium density but did affect I_LRI. The I_LRI was also modified in a number of auxin-related mutants, revealing new root branching phenotypes in some of these mutants. The rate of lateral root initiation increased with Arabidopsis seedling age; however, I_LRI was not changed in plants between 8 and 14 d post-germination.

Conclusions

The I_LRI allows for a more precise comparison of lateral root initiation under different growth conditions, treatments, genotypes and plant species than other comparable methods.

Keywords: Arabidopsis thaliana; auxin; lateral root density; lateral root initiation index; mutant phenotype; pericycle; root architecture; root branching; root primordium; Solanum lycopersicum

Document Type: Research article

DOI: http://dx.doi.org/10.1093/aob/mcn267

Publication date: 2009-03-06

More about this publication?

• Annals of Botany is an international plant science journal with editorial offices in Australia, China, Japan, Mainland Europe, UK and USA. It is published monthly in both electronic and printed forms with at least one extra issue each year that focuses on a particular theme in plant biology. The Journal is managed by the Annals of Botany Company, a not-for-profit educational charity established to promote plant science worldwide.

Related content

• In this: publication
• By this: publisher
• In this Subject: Botany
• By this author: Dubrovsky, J. G. ;  Soukup, A. ;  Napsucialy-Mendivil, S. ;  Jekni, Z. ;  Ivanchenko, M. G.

Website © Publishing Technology. Article copyright remains with the publisher, society or author(s) as specified within the article.

• Terms and conditions
• Privacy policy
• Information for advertisers