A functional-structural modelling approach to autoregulation of nodulation.
OBJECTIVE
Autoregulation of nodulation is a long-distance shoot-root signalling regulatory system that regulates nodule meristem proliferation in legume plants. However, due to the intricacy and subtleness of the signalling nature in plants, molecular and biochemical details underlying mechanisms of autoregulation of nodulation remain largely unknown. The purpose of this study is to use functional-structural plant modelling to investigate the complexity of this signalling system. There are two major challenges to be met: modelling the 3D architecture of legume roots with nodulation and co-ordinating signalling-developmental processes with various rates.


METHODS
Soybean (Glycine max) was chosen as the target legume. Its root system was observed to capture lateral root branching and nodule distribution patterns. L-studio, a software tool supporting context-sensitive L-system modelling, was used for the construction of the architectural model and integration with the internal signalling.


RESULTS
A branching pattern with regular radial angles was found between soybean lateral roots, from which a root mapping method was developed to characterize the laterals. Nodules were mapped based on 'nodulation section' to reveal nodule distribution. A root elongation algorithm was then developed for simulation of root development. Based on the use of standard sub-modules, a synchronization algorithm was developed to co-ordinate multi-rate signalling and developmental processes.


CONCLUSIONS
The modelling methods developed here not only allow recreation of legume root architecture with lateral branching and nodulation details, but also enable parameterization of internal signalling to produce different regulation results. This provides the basis for using virtual experiments to help in investigating the signalling mechanisms at work.
Han
Liqi
L
The University of Queensland, ARC Centre of Excellence for Integrative Legume Research, Brisbane, QLD, Australia.
Gresshoff
Peter M
PM
Hanan
Jim
J
D000465:Algorithms; D003198:Computer Simulation; D003710:Demography; D006706:Homeostasis; D008954:Models, Biological; D009586:Nitrogen Fixation / Q000502:physiology; D055170:Plant Root Nodulation / Q000502:physiology*; D018517:Plant Roots / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D053204:Root Nodules, Plant / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction; D013025:Glycine max / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D013559:Symbiosis
Ann Bot. 2006 May;97(5):883-93
16473866
New Phytol. 2010 Mar;185(4):1074-86
20100211
Plant Physiol. 2006 Apr;140(4):1494-506
16489131
New Phytol. 2005 Jun;166(3):705-8
15869632
Nat Rev Mol Cell Biol. 2004 Jul;5(7):566-76
15232574
Nature. 2002 Nov 28;420(6914):422-6
12442170
Science. 2003 Jan 3;299(5603):109-12
12411574
Appl Environ Microbiol. 1991 Aug;57(8):2205-10
16348535
Mol Plant Microbe Interact. 2007 Jul;20(7):769-80
17601165
Plant Physiol. 2003 Mar;131(3):872-7
12644639
Curr Opin Plant Biol. 2007 Feb;10(1):44-51
17157052
Plant Physiol. 1985 May;78(1):34-40
16664203
New Phytol. 2005 Jun;166(3):859-67
15869647
Annu Rev Microbiol. 1991;45:345-82
1741618
Proc Natl Acad Sci U S A. 1985 Jun;82(12):4162-6
16593577
Plant Mol Biol. 2005 Aug;58(6):809-822
16240175
Funct Plant Biol. 2006 Aug;33(8):707-721
32689281
PLoS One. 2008;3(11):e3673
18989371
Ann Bot. 2006 May;97(5):903-15
16390845
Genome Biol. 2003;4(1):201
12540294
Plant Physiol. 1986 Oct;82(2):588-90
16665072
Mol Plant Microbe Interact. 2008 Jun;21(6):843-53
18624647
Curr Opin Plant Biol. 2006 Oct;9(5):496-502
16877028
Plant Cell Physiol. 2009 Jan;50(1):67-77
19074184
J Biol Chem. 2008 Sep 12;283(37):25381-25391
18606823
Plant Physiol. 2010 May;153(1):222-37
20348212
Ann Bot. 2008 May;101(8):1109-23
17766311