期刊
FRONTIERS IN PLANT SCIENCE
卷 12, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fpls.2021.641835
关键词
OpenSimRoot; Oryza sativa (L; ); phosphate uptake; L-type lateral roots; root branching; root hairs; modeling
资金
- Helmholtz Association (POF III Program-Research Field Key Technologies-Key Technologies for the Bioeconomy)
- CONACYT [I2T2]
Rice root system primarily absorbs phosphate through nodal roots, while thinner S-type roots and root hairs play significant roles in phosphate uptake; however, producing nodal roots requires a large investment of phosphate and has a long pay-off time, which could be a burden for P-starved plants, suggesting the need to find more efficient strategies for optimizing root system architecture in overcoming phosphate deficiency.
The rice root system develops a large number of nodal roots from which two types of lateral roots branch out, large L-types and fine S-types, the latter being unique to the species. All roots including S-types are covered by root hairs. To what extent these fine structures contribute to phosphate (P) uptake under P deficiency was investigated using a novel 3-D root growth model that treats root hairs as individual structures with their own Michaelis-Menten uptake kinetics. Model simulations indicated that nodal roots contribute most to P uptake followed by L-type lateral roots and S-type laterals and root hairs. This is due to the much larger root surface area of thicker nodal roots. This thickness, however, also meant that the investment in terms of P needed for producing nodal roots was very large. Simulations relating P costs and time needed to recover that cost through P uptake suggest that producing nodal roots represents a considerable burden to a P-starved plant, with more than 20 times longer pay-off time compared to S-type laterals and root hairs. We estimated that the P cost of these fine root structures is low enough to be recovered within a day of their formation. These results expose a dilemma in terms of optimizing root system architecture to overcome P deficiency: P uptake could be maximized by developing more nodal root tissue, but when P is growth-limiting, adding more nodal root tissue represents an inefficient use of the limiting factor P. In order to improve adaption to P deficiency in rice breeding two complementary strategies seem to exist: (1) decreasing the cost or pay-off time of nodal roots and (2) increase the biomass allocation to S-type roots and root hairs. To what extent genotypic variation exists within the rice gene pool for either strategy should be investigated.
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