scholarly journals Phenotyping seedlings for selection of root system architecture in alfalfa (Medicago sativa L.)

Plant Methods ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Bruna Bucciarelli ◽  
Zhanyou Xu ◽  
Samadangla Ao ◽  
Yuanyuan Cao ◽  
Maria J. Monteros ◽  
...  

Abstract Background The root system architecture (RSA) of alfalfa (Medicago sativa L.) affects biomass production by influencing water and nutrient uptake, including nitrogen fixation. Further, roots are important for storing carbohydrates that are needed for regrowth in spring and after each harvest. Previous selection for a greater number of branched and fibrous roots significantly increased alfalfa biomass yield. However, phenotyping root systems of mature alfalfa plant is labor-intensive, time-consuming, and subject to environmental variability and human error. High-throughput and detailed phenotyping methods are needed to accelerate the development of alfalfa germplasm with distinct RSAs adapted to specific environmental conditions and for enhancing productivity in elite germplasm. In this study methods were developed for phenotyping 14-day-old alfalfa seedlings to identify measurable root traits that are highly heritable and can differentiate plants with either a branched or a tap rooted phenotype. Plants were grown in a soil-free mixture under controlled conditions, then the root systems were imaged with a flatbed scanner and measured using WinRhizo software. Results The branched root plants had a significantly greater number of tertiary roots and significantly longer tertiary roots relative to the tap rooted plants. Additionally, the branch rooted population had significantly more secondary roots > 2.5 cm relative to the tap rooted population. These two parameters distinguishing phenotypes were confirmed using two machine learning algorithms, Random Forest and Gradient Boosting Machines. Plants selected as seedlings for the branch rooted or tap rooted phenotypes were used in crossing blocks that resulted in a genetic gain of 10%, consistent with the previous selection strategy that utilized manual root scoring to phenotype 22-week-old-plants. Heritability analysis of various root architecture parameters from selected seedlings showed tertiary root length and number are highly heritable with values of 0.74 and 0.79, respectively. Conclusions The results show that seedling root phenotyping is a reliable tool that can be used for alfalfa germplasm selection and breeding. Phenotypic selection of RSA in seedlings reduced time for selection by 20 weeks, significantly accelerating the breeding cycle.

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 173
Author(s):  
Vijaya Singh ◽  
Marisa Collins ◽  
Colin Andrew Douglas ◽  
Michael Bell

In recent years phosphorus application methods have become an important management strategy for optimising the uptake of the immobile nutrient phosphorus (P). Root system architecture (RSA) could play a particularly important role in the uptake of P by grain legumes, due to their relatively coarse root systems. The objective of this study was to understand the response of mungbean root systems to P application methods. Four mungbean varieties were grown in purpose-built soil filled root chambers that received five P application methods. Phosphorus treatments consisted of a control (no application of P) compared with 30 mg P/kg soil throughout the soil volume (high P treatment) or restricted to 10cm deep layers in the topsoil or in a layer from 20-30cm deep. A fifth treatment consisted of the same amount of P as applied in deeper dispersed layer applied in a concentrated band at 25cm depth. After 50 days of growth, plant were destructively harvested and shoot and root parameters were measured. Mungbean varieties responded differently to P application methods, with Jade and Berken varieties showing greater root proliferation at depth and greater shoot growth in response to banded and deeper dispersed P applications, relative to the late maturing variety Putland. Shallow dispersed P and the no-P control both resulted in poor root growth in all the genotypes except Celera II, which did not respond to P application from any placement strategy. Results suggest that P application strategies may need to vary with variety to maximize the uptake of P.


2021 ◽  
Author(s):  
Pankaj K Verma ◽  
Shikha Verma ◽  
Nalini Pandey

Abstract BackgroundIn order to feed expanding population, new crop varieties were generated which significantly contribute to world food security. However, the growth of these improved plants varieties relied primarily on synthetic fertilizers, which negatively affect the environment as well as human health. Plants adapt to adverse environmental changes by adopting root systems through architectural changes at the root-type and tissue-specific changes and nutrient uptake efficiency. ScopePlants adapt and operate distinct pathways at various stages of development in order to optimally establish their root systems, such as change in the expression profile of genes, changes in phytohormone level and microbiome induced Root System Architecture (RSA) modification. Many scientific studies have been carried out to understand plant response to microbial colonization and how microbes involved in RSA improvement through phytohormone level and transcriptomic changes.ConclusionIn this review, we spotlight the impact of genes, phytohormones and root microbiota on RSA and provide specific, critical new insights that have been resulted from recent studies on rice root as a model. First, we discuss new insights into the genetic regulation of RSA. Next, hormonal regulation of root architecture and the impact of phytohormones in crown root and root branching is discussed. Finally, we discussed the impact of root microbiota in RSA modification and summarized the current knowledge about the biochemical and central molecular mechanisms involved.


HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 440D-440
Author(s):  
R.E. Gough

In 1999, `Sweet Banana' pepper plants were grown under clean cultivation or SMR—red, silver, or black polyethylene mulches. Plants in each of three replications per treatment were field-set on 15 June. On 22 Sept., plants were excavated, and their root systems were examined. The total number of roots per plant at 5-, 10-, 15-, 20-, and 25-cm depths and 10-, 20-, 30-, 40-, 50-, and 60-cm distances from plant stems were recorded. Distribution and architecture of the root systems also were examined. Plants grown under clean cultivation developed 50 to 60 adventitious roots each, while those grown under red mulch developed about 20, and those under black and silver mulch about nine adventitious roots each. In all treatments, the adventitious roots radiated from the stem at an oblique, downward 35° angle. No plants had vertical roots. Root system architecture was similar among treatments, with 40% of the roots in the upper 5 cm of soil and 70% in the upper 10 cm. Thirty percent of roots were within 10 cm of the plant stem, and 50% were within 20 cm. Nearly 100% of the roots were located within 40 cm of the plant stem. Root count decreased with increasing depth and distance from the plant stem. Plants grown beneath the silver mulch produced the greatest number of lateral roots, followed by plants grown in clean cultivation and under black mulch. Plants grown under red mulch produced the fewest roots. Differences among treatments were significant. Colored mulches influence the total number of adventitious and lateral roots but not the root system architecture of pepper plants.


1996 ◽  
Author(s):  
Yoav Waisel ◽  
Bobbie McMichael ◽  
Amram Eshel

Architecture of a root system is the expression of the potential of various root types to branch, to grow and to coordinate with other plant organs, under the specific limitations of the environmental conditions. The present investigation has proven the following points. 1) Genotypes with different types of root systems were identified. The growth patterns of their roots and the distribution of laterals along their main axes were recorded. 2) The patterns of development of the root systems of four cotton genotypes, throughout the entire life cycle of the plants, were described, even at such a late stage of development when the total length of the roots exceeded two kilometers. To the best of our knowledge, this is the first time that an analysis of this type is accomplished. 3) The development of root systems under restrictive soil conditions were compared with those that have developed under the non-restrictive conditions of aeroponics. Results indicate that in the absence of the mechanical impedance of the soil, cotton plants develop single roots that reach the length of 6 m, and have a total root length of 2000 m. Thus, root growth is strongly inhibited by the soil, with some root types being inhibited more than others. 4) One of the important decisions, in constructing an operational root system architecture of mature plants, is the shift of the balance between various root fractions in favor of the very fine roots. 5) Root system architecture is determined, in part, by the sites of initiation of the lateral roots. This is determined genetically by the number of xylem archs and by the totuosity of the stele. Selection for such traits should be sought.


Biologia ◽  
2017 ◽  
Vol 72 (9) ◽  
Author(s):  
Margarita L. Himmelbauer ◽  
Peter Scholl ◽  
Gernot Bodner ◽  
Willibald Loiskandl

AbstractQuantifications of root system architecture and growth dynamics became essential in sustainable agriculture, bio-engineering and underground ecology in general. Assessing of root architectural parameters is still challenging also owing to different methodological challenges and high-cost facilities required. The objective of this study was to design and examine a performance of a simple experimgal set-up for monitoring and analyses of root system architecture. The proposed system was examined with two cover crops – white mustard and sweet clover – grown in sand filled pots under controlled climate conditions for several weeks. Root systems of each crop were harvested in regular intervals of 2 to 3 weeks in 3 to 4 replicates. After careful washing, the intact root systems were photo captured in water filled cylinder in their quasi-natural position over entire rotation and then scanned using a flatbed professional scanner. The gained images (photos and scans) were analysed with AutoCAD and WinRhizo software for measuring of diverse root architectural parameters for modelling. The results showed that the selected experimental and methodical approaches were appropriate for monitoring and delivering data of good quality. Both, digital camera and scanner were regarded as essential complementary imaging tools for correct assessment of the root system architecture. To maximise the accuracy of the measurements, recommendation for improving the system were provided. Extracted root data are intended for parametrisation of root architectural models, but they also support researcher and experts in their efforts to improve crop uptake efficiency in sustainable agriculture and for bio-engineering purposes.


2019 ◽  
Author(s):  
Thibaut Bontpart ◽  
Cristobal Concha ◽  
Valerio Giuffrida ◽  
Ingrid Robertson ◽  
Kassahun Admkie ◽  
...  

AbstractThe analysis of root system growth, root phenotyping, is important to inform efforts to enhance plant resource acquisition from soils. However, root phenotyping remains challenging due to soil opacity and requires systems that optimize root visibility and image acquisition. Previously reported systems require costly and bespoke materials not available in most countries, where breeders need tools to select varieties best adapted to local soils and field conditions. Here, we present an affordable soil-based growth container (rhizobox) and imaging system to phenotype root development in greenhouses or shelters. All components of the system are made from commodity components, locally available worldwide to facilitate the adoption of this affordable technology in low-income countries. The rhizobox is large enough (~6000 cm2 visible soil) to not restrict vertical root system growth for at least seven weeks after sowing, yet light enough (~21 kg) to be routinely moved manually. Support structures and an imaging station, with five cameras covering the whole soil surface, complement the rhizoboxes. Images are acquired via the Phenotiki sensor interface, collected, stitched and analysed. Root system architecture (RSA) parameters are quantified without intervention. RSA of a dicot (chickpea, Cicer arietinum L.) and a monocot (barley, Hordeum vulgare L.) species, which exhibit contrasting root systems, were analysed. The affordable system is relevant for efforts in Ethiopia and elsewhere to enhance yields and climate resilience of chickpea and other crops for improved food security.Significance StatementAn affordable system to characterize root system architecture of soil-grown plants was developed. Using commodity components, this will enable local efforts world-wide to breed for enhanced root systems.


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