Abstract
Future rice (Oryza sativa) crops will likely experience a range of growth conditions, and root architectural plasticity will be an important characteristic to confer adaptability across variable environments. In this study, the relationship between root architectural plasticity and adaptability (i.e. yield stability) was evaluated in two traditional × improved rice populations (Aus 276 × MTU1010 and Kali Aus × MTU1010). Forty contrasting genotypes were grown in direct-seeded upland and transplanted lowland conditions with drought and drought + rewatered stress treatments in lysimeter and field studies and a low-phosphorus stress treatment in a Rhizoscope study. Relationships among root architectural plasticity for root dry weight, root length density, and percentage lateral roots with yield stability were identified. Selected genotypes that showed high yield stability also showed a high degree of root plasticity in response to both drought and low phosphorus. The two populations varied in the soil depth effect on root architectural plasticity traits, none of which resulted in reduced grain yield. Root architectural plasticity traits were related to 13 (Aus 276 population) and 21 (Kali Aus population) genetic loci, which were contributed by both the traditional donor parents and MTU1010. Three genomic loci were identified as hot spots with multiple root architectural plasticity traits in both populations, and one locus for both root architectural plasticity and grain yield was detected. These results suggest an important role of root architectural plasticity across future rice crop conditions and provide a starting point for marker-assisted selection for plasticity.
Highlights
Future rice (Oryza sativa) crops will likely experience a range of growth conditions, and root architectural plasticity will be an important characteristic to confer adaptability across variable environments
A series of experiments was conducted in order to identify and select appropriate genotypes with plasticity traits, to investigate the role of root phenotypic plasticity in adaptation to a range of seedling establishment, nutrient, and drought stress conditions, and to identify the genetic regions related to the observed responses
The experiments were conducted (1) in a greenhouse lysimeter facility, in which plants were grown in approximately 1-m-tall cylinders and weighed and imaged weekly to monitor growth and water uptake; (2) in the field under well-watered and drought stress treatments in upland and lowland conditions to evaluate agronomic or physiological parameters; and (3) in controlled-environment Rhizoscope studies, in which root growth was imaged through transparent boxes filled with glass beads to measure the response to a lowphosphorus treatment (Table I; refer to Table I legend for abbreviations not defined in the text or figure legends)
Summary
Future rice (Oryza sativa) crops will likely experience a range of growth conditions, and root architectural plasticity will be an important characteristic to confer adaptability across variable environments. Root Architectural Plasticity for Adaptable Rice relative growth rate in 10 perennial herbaceous species (Useche and Shipley, 2010), and plasticity in maize (Zea mays) root growth angle improved yield (Trachsel et al, 2013) These examples provide strong evidence that root phenotypic plasticity can result in improved plant performance across variable conditions that include edaphic stress and would be an effective target for crop improvement efforts. A plastic response of increased root biomass to drought was located to chromosome 1BS (Ehdaie et al, 2011) These identified genetic regions can be used in selection for the development of stress-tolerant crops
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