A toolkit to rapidly modify root systems through single plant selection

Abstract Background The incorporation of root traits into elite germplasm is typically a slow process. Thus, innovative approaches are required to accelerate research and pre-breeding programs targeting root traits to improve yield stability in different environments and soil types. Marker-assisted selection (MAS) can help to speed up the process by selecting key genes or quantitative trait loci (QTL) associated with root traits. However, this approach is limited due to the complex genetic control of root traits and the limited number of well-characterised large effect QTL. Coupling MAS with phenotyping could increase the reliability of selection. Here we present a useful framework to rapidly modify root traits in elite germplasm. In this wheat exemplar, a single plant selection (SPS) approach combined three main elements: phenotypic selection (in this case for seminal root angle); MAS using KASP markers (targeting a root biomass QTL); and speed breeding to accelerate each cycle. Results To develop a SPS approach that integrates non-destructive screening for seminal root angle and root biomass, two initial experiments were conducted. Firstly, we demonstrated that transplanting wheat seedlings from clear pots (for seminal root angle assessment) into sand pots (for root biomass assessment) did not impact the ability to differentiate genotypes with high and low root biomass. Secondly, we demonstrated that visual scores for root biomass were correlated with root dry weight (r = 0.72), indicating that single plants could be evaluated for root biomass in a non-destructive manner. To highlight the potential of the approach, we applied SPS in a backcrossing program which integrated MAS and speed breeding for the purpose of rapidly modifying the root system of elite bread wheat line Borlaug100. Bi-directional selection for root angle in segregating generations successfully shifted the mean root angle by 30° in the subsequent generation (P ≤ 0.05). Within 18 months, BC2F4:F5 introgression lines were developed that displayed a full range of root configurations, while retaining similar above-ground traits to the recurrent parent. Notably, the seminal root angle displayed by introgression lines varied more than 30° compared to the recurrent parent, resulting in lines with both narrow and wide root angles, and high and low root biomass phenotypes. Conclusion The SPS approach enables researchers and plant breeders to rapidly manipulate root traits of future crop varieties, which could help improve productivity in the face of increasing environmental fluctuations. The newly developed elite wheat lines with modified root traits provide valuable materials to study the value of different root systems to support yield in different environments and soil types.

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A Toolkit to Rapidly Modify Root Systems Through Single Plant Selection

10.21203/rs.3.rs-882628/v1 ◽

2021 ◽

Author(s):

Charlotte Rambla ◽

Sarah Van Der Meer ◽

Kai P. Voss-Fels ◽

Manar Makhoul ◽

Christian Obermeier ◽

...

Keyword(s):

Root Biomass ◽

Root Traits ◽

Seminal Root ◽

Recurrent Parent ◽

Plant Selection ◽

Root Angle ◽

Single Plant Selection ◽

Non Destructive ◽

Elite Germplasm ◽

Seminal Root Angle

Abstract Background: The incorporation of root traits into elite germplasm is typically a slow process. Thus, innovative approaches are required to accelerate research and pre-breeding programs targeting root traits to improve yield stability in different environments and soil types. Marker-assisted selection (MAS) can help to speed up the process by selecting key genes or quantitative trait loci (QTL) associated with root traits. However, this approach is limited due to the complex genetic control of root traits and the limited number of well-characterised large effect QTL. Coupling MAS with phenotyping could increase the reliability of selection. Here we present a useful framework to rapidly modify root traits in elite germplasm. In this wheat exemplar, a single plant selection (SPS) approach combined three main elements: phenotypic selection (in this case for seminal root angle); MAS using KASP markers (targeting a root biomass QTL); and speed breeding to accelerate each cycle.Results: To develop a SPS approach that integrates non-destructive screening for seminal root angle and root biomass, two initial experiments were conducted. Firstly, we demonstrated that transplanting wheat seedlings from clear pots (for seminal root angle assessment) into sand pots (for root biomass assessment) did not impact the ability to differentiate genotypes with high and low root biomass. Secondly, we demonstrated that visual scores for root biomass were correlated with root dry weight (r = 0.73), indicating that single plants could be evaluated for root biomass in a non-destructive manner. To highlight the potential of the approach, we applied SPS in a backcrossing program which integrated MAS and speed breeding for the purpose of rapidly modifying the root system of elite bread wheat line Borlaug100. Bi-directional selection for root angle in segregating generations successfully shifted the mean root angle by 30o in the subsequent generation (P ≤ 0.05). Within 18 months, BC2F4:F5 introgression lines were developed that displayed a full range of root configurations, while retaining similar above-ground traits to the recurrent parent. Notably, the seminal root angle displayed by introgression lines varied more than 30° compared to the recurrent parent, resulting in lines with both narrow and wide root angles, and high and low root biomass phenotypes.Conclusion: The SPS approach enables researchers and plant breeders to rapidly manipulate root traits of future crop varieties, which could help improve productivity in the face of increasing environmental fluctuations. The newly developed elite wheat lines with modified root traits provide valuable materials to study the value of different root systems to support yield in different environments and soil types.

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Selection in Early Generations to Shift Allele Frequency for Seminal Root Angle in Wheat

The Plant Genome ◽

10.3835/plantgenome2017.08.0071 ◽

2018 ◽

Vol 11 (2) ◽

pp. 170071 ◽

Cited By ~ 11

Author(s):

Cecile Richard ◽

Jack Christopher ◽

Karine Chenu ◽

Andrew Borrell ◽

Mandy Christopher ◽

...

Keyword(s):

Allele Frequency ◽

Seminal Root ◽

Root Angle ◽

Seminal Root Angle

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Variation in root system architecture among the founder parents of two 8-way MAGIC wheat populations for selection in breeding

10.1101/2021.07.12.451891 ◽

2021 ◽

Author(s):

Shree Pariyar ◽

Kerstin A Nagel ◽

Jonas Lentz ◽

Anna Galinski ◽

Jens Wilhelm ◽

...

Keyword(s):

Root System ◽

System Architecture ◽

Phenotypic Diversity ◽

Lateral Roots ◽

Crop Productivity ◽

Root System Architecture ◽

Seminal Root ◽

Wheat Crop ◽

Root Angle ◽

Seminal Root Angle

Root system architecture (RSA) is a target for breeding because of the interest to develop crops with roots that use nutrients and water more effectively. Breeding for RSA requires phenotypic diversity in populations amenable to QTL identification to provide markers for large breeding programs. This study examined the variation for root traits across the parents of two multi-parent advanced generation inter-cross (MAGIC) wheat populations from NIAB and CSIRO for 16 days in an upgraded version of the non-invasive, germination paper-based phenotyping platform, GrowScreen-PaGe. Across all parents, total root length varied up to 1.90 fold, root biomass 2.25 fold and seminal root angle 1.16 fold. The CSIRO parents grew faster, exhibited slightly wider seminal root angle and produced larger root systems compared to NIAB parents. Lateral root lengths, leaf lengths and biomass contrasted most between fastest (Robigus - NIAB and AC Barrie - CSIRO) and slowest growing parents (Rialto - NIAB and G204 Xiaoyan54 - CSIRO). Lengths of lateral and total root, and leaf number and length had moderate to high heritability (0.30-0.67) and repeatability. Lengths of lateral roots and leaves are good targets for enhancing wheat crop establishment, a critical stage for crop productivity.

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Chemical and physical influence of sodic soils on the coleoptile length and root growth angle of wheat genotypes

Annals of Botany ◽

10.1093/aob/mcz094 ◽

2019 ◽

Vol 124 (6) ◽

pp. 1043-1052 ◽

Cited By ~ 1

Author(s):

Monia Anzooman ◽

Jack Christopher ◽

Yash P Dang ◽

Julian Taylor ◽

Neal W Menzies ◽

...

Keyword(s):

Bulk Density ◽

Seedling Emergence ◽

Triticum Aestivum L ◽

Seminal Root ◽

Sodic Soils ◽

Coleoptile Length ◽

Wheat Genotypes ◽

Root Angle ◽

Emergence Rate ◽

Seminal Root Angle

Abstract Background and Aims High exchangeable sodium percentage (ESP) and bulk density of sodic soils can reduce seedling emergence. This study examined variation in seedling coleoptile length and seminal root angle of wheat (Triticum aestivum. L) genotypes to determine whether these traits vary between genotypes that differ in their tolerance to sodic soils. Methods Wheat genotypes were grown in three different experiments. First, four wheat genotypes were grown using soils of three ESPs (4, 10 and 17 %) and secondly in soils of three different bulk densities (1.2, 1.4 and 1.5 g cm–3) and ESP 10 %. Thirdly, seedling coleoptile length and seminal root angle were determined for 16 genotypes grown in a soil of ESP 10 % and bulk density 1.2 g cm–2. Seminal root angle and coleoptile length measurements from the current study were compared with seedling emergence rate and force measured previously. Key Results The seedling coleoptile length of all genotypes decreased with increasing soil ESP and bulk density, but with no significant differences between genotypes. In contrast, seminal root angles differed significantly between genotypes, but were not significantly affected by ESP or bulk density. There was an inverse relationship between the seminal root angle of the 16 genotypes and seedling emergence rate (R2 = 0.89) and also between seminal root angle and seedling emergence force (R2 = 0.61). Conclusions Lack of significant variation in coleoptile length between genotypes suggests that this may not be a suitable characteristic to identify wheat tolerance to sodic conditions. However, a narrower seminal root angle was correlated with rate and force of seedling emergence, traits likely to improve establishment. The mechanism underlying this correlation is not yet clear. Genotypes with a narrow root angle had greater root depth. One possible mechanism might be that genotypes with narrow root angles were able to take up more soil moisture at depth, leading to a higher proportion of seedling emergence.

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Varietal differences of seminal root angle among barley cultivars

Root Research ◽

10.3117/rootres.30.119 ◽

2021 ◽

Vol 30 (4) ◽

pp. 119-123

Author(s):

Junpei KONISHI ◽

Yuuki NAKANO ◽

Hirotake ITOH ◽

Takashi NAGAMINE

Keyword(s):

Seminal Root ◽

Varietal Differences ◽

Barley Cultivars ◽

Root Angle ◽

Seminal Root Angle

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Genetic Mapping of Quantitative Trait Loci (QTLs) Associated with Seminal Root Angle and Number in Three Populations of Bread Wheat (Triticum aestivum L.) with Common Parents

Plant Molecular Biology Reporter ◽

10.1007/s11105-020-01214-1 ◽

2020 ◽

Vol 38 (4) ◽

pp. 572-585

Author(s):

Christopher E. Hohn ◽

Harun Bektas

Keyword(s):

Triticum Aestivum ◽

Quantitative Trait Loci ◽

Genetic Mapping ◽

Bread Wheat ◽

Quantitative Trait ◽

Triticum Aestivum L ◽

Seminal Root ◽

Root Angle ◽

Trait Loci ◽

Seminal Root Angle

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Durum Wheat Seminal Root Traits within Modern and Landrace Germplasm in Algeria

Agronomy ◽

10.3390/agronomy10050713 ◽

2020 ◽

Vol 10 (5) ◽

pp. 713

Author(s):

Ridha Boudiar ◽

Juan M. González ◽

Abdelhamid Mekhlouf ◽

Ana M. Casas ◽

Ernesto Igartua

Keyword(s):

Durum Wheat ◽

Root Length ◽

Root Traits ◽

Seminal Root ◽

Laboratory Setting ◽

Wheat Cultivars ◽

Root Angle ◽

Seminal Roots ◽

Root Size ◽

Paper Method

Seminal roots are known to play an important role in crop performance, particularly under drought conditions. A set of 37 durum wheat cultivars and local landraces was screened for variation in architecture and size of seminal roots using a laboratory setting, with a filter paper method combined with image processing by SmartRoot software. Significant genetic variability was detected for all root and shoot traits assessed. Four rooting patterns were identified, with landraces showing overall steeper angle and higher root length, in comparison with cultivars, which presented a wider root angle and shorter root length. Some traits revealed trends dependent on the genotypes’ year of release, like increased seminal root angle and reduced root size (length, surface, and volume) over time. We confirm the presence of a remarkable diversity of root traits in durum wheat whose relationship with adult root features and agronomic performance should be explored.

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Terminal regions of chromosome arms 6AL and 6BL carry QTL affecting seminal root angle in wheat (Triticum aestivum L.)

Plant Root ◽

10.3117/plantroot.14.23 ◽

2020 ◽

Vol 14 (0) ◽

pp. 23-31

Author(s):

Masahiko Mori ◽

Atsushi Oyanagi ◽

Emdadul Haque ◽

Kentaro Kawaguchi ◽

Hideho Miura ◽

...

Keyword(s):

Triticum Aestivum ◽

Seminal Root ◽

Root Angle ◽

Seminal Root Angle

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Effects of warming and fertilization interacting with intraspecific competition on fine root traits of Picea asperata

Journal of Plant Ecology ◽

10.1093/jpe/rtaa074 ◽

2020 ◽

Author(s):

Dan-Dan Li ◽

Hong-Wei Nan ◽

Chun-Zhang Zhao ◽

Chun-Ying Yin ◽

Qing Liu

Keyword(s):

Root Growth ◽

Climate Warming ◽

Tree Growth ◽

Root Length ◽

Root Biomass ◽

Fine Root ◽

Root Traits ◽

Root Surface ◽

Root Branching ◽

Picea Asperata

Abstract Aims Competition, temperature, and nutrient are the most important determinants of tree growth in the cold climate on the eastern Tibetan Plateau. Although many studies have reported their individual effects on tree growth, little is known about how the interactions of competition with fertilization and temperature affect root growth. We aim to test whether climate warming and fertilization promote competition and to explore the functional strategies of Picea asperata in response to the interactions of these factors. Methods We conducted a paired experiment including competition and non-competition treatments under elevated temperature (ET) and fertilization. We measured root traits, including the root tip number over the root surface (RTRS), the root branching events over the root surface (RBRS), the specific root length (SRL), the specific root area (SRA), the total fine root length and area (RL and RA), the root tips (RT) and root branching events (RB). These root traits are considered to be indicators of plant resource uptake capacity and root growth. The root biomass and the nutrient concentrations in the roots were also determined. Important Findings The results indicated that ET, fertilization and competition individually enhanced the nitrogen (N) and potassium (K) concentrations in fine roots, but they did not affect fine root biomass or root traits, including RL, RT, RA and RB. However, both temperature and fertilization, as well as their interaction, interacting with competition increased RL, RA, RT, RB, and nutrient uptake. In addition, the SRL, SRA, RTRS and RBRS decreased under fertilization, the interaction between temperature and competition decreased SRL and SRA, while the other parameters were not affected by temperature or competition. These results indicate that Picea asperata maintains a conservative nutrient strategy in response to competition, climate warming, fertilization, and their interactions. Our results improve our understanding of the physiological and ecological adaptability of trees to global change.

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