ENHANCED GRAVITROPISM 2 encodes a STERILE ALPHA MOTIVE containing protein that controls root growth angle in barley and wheat

AbstractThe root growth angle defines how roots grow towards the gravity vector and is among the most important determinants of root system architecture. It controls water uptake capacity, nutrient use efficiency, stress resilience and as a consequence yield of crop plants. We demonstrated that the egt2 (enhanced gravitropism 2) mutant of barley exhibits steeper root growth of seminal and lateral roots and an auxin independent higher responsiveness to gravity compared to wild type plants. We cloned the EGT2 gene by a combination of bulked segregant analysis and whole genome sequencing. Subsequent validation experiments by an independent CRISPR/Cas9 mutant allele demonstrated that egt2 encodes a STERILE ALPHA MOTIF domain containing protein. In situ hybridization experiments illustrated that EGT2 is expressed from the root cap to the elongation zone. Subcellular localization experiments revealed that EGT2 localizes to the nucleus and cytoplasm. We demonstrated the evolutionary conserved role of EGT2 in root growth angle control between barley and wheat by knocking out the EGT2 orthologs in the A and B genomes of tetraploid durum wheat. By combining laser capture microdissection with RNA-seq, we observed that seven expansin genes were transcriptionally downregulated in the elongation zone. This is consistent with a role of EGT2 in this region of the root where the effect of gravity sensing is executed by differential cell elongation. Our findings suggest that EGT2 is an evolutionary conserved regulator of root growth angle in barley and wheat that could be a valuable target for root-based crop improvement strategies in cereals.Significance StatementTo date the potential of utilizing root traits in plant breeding remains largely untapped. In this study we cloned and characterized the ENHANCED GRAVITROPISM2 (EGT2) gene of barley that encodes a STERILE ALPHA MOTIF domain containing protein. We demonstrated that EGT2 is a key gene of root growth angle regulation in response to gravity which is conserved in barley and wheat and could be a promising target for crop improvement in cereals.

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ENHANCED GRAVITROPISM 2 encodes a STERILE ALPHA MOTIF–containing protein that controls root growth angle in barley and wheat

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2101526118 ◽

2021 ◽

Vol 118 (35) ◽

pp. e2101526118

Author(s):

Gwendolyn K. Kirschner ◽

Serena Rosignoli ◽

Li Guo ◽

Isaia Vardanega ◽

Jafargholi Imani ◽

...

Keyword(s):

Root Growth ◽

Bulked Segregant Analysis ◽

Lateral Roots ◽

Nutrient Use Efficiency ◽

Crop Improvement ◽

Elongation Zone ◽

Sterile Alpha Motif ◽

Growth Angle ◽

Root Growth Angle

The root growth angle defines how roots grow toward the gravity vector and is among the most important determinants of root system architecture. It controls water uptake capacity, nutrient use efficiency, stress resilience, and, as a consequence, yield of crop plants. We demonstrated that the egt2 (enhanced gravitropism 2) mutant of barley exhibits steeper root growth of seminal and lateral roots and an auxin-independent higher responsiveness to gravity compared to wild-type plants. We cloned the EGT2 gene by a combination of bulked-segregant analysis and whole genome sequencing. Subsequent validation experiments by an independent CRISPR/Cas9 mutant allele demonstrated that egt2 encodes a STERILE ALPHA MOTIF domain–containing protein. In situ hybridization experiments illustrated that EGT2 is expressed from the root cap to the elongation zone. We demonstrated the evolutionary conserved role of EGT2 in root growth angle control between barley and wheat by knocking out the EGT2 orthologs in the A and B genomes of tetraploid durum wheat. By combining laser capture microdissection with RNA sequencing, we observed that seven expansin genes were transcriptionally down-regulated in the elongation zone. This is consistent with a role of EGT2 in this region of the root where the effect of gravity sensing is executed by differential cell elongation. Our findings suggest that EGT2 is an evolutionary conserved regulator of root growth angle in barley and wheat that could be a valuable target for root-based crop improvement strategies in cereals.

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Genetic improvement for root growth angle to enhance crop production

Breeding Science ◽

10.1270/jsbbs.65.111 ◽

2015 ◽

Vol 65 (2) ◽

pp. 111-119 ◽

Cited By ~ 51

Author(s):

Yusaku Uga ◽

Yuka Kitomi ◽

Satoru Ishikawa ◽

Masahiro Yano

Keyword(s):

Root Growth ◽

Genetic Improvement ◽

Crop Production ◽

Growth Angle ◽

Root Growth Angle

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A Comparative Analysis of Quantitative Metrics of Root Architecture

Plant Phenomics ◽

10.34133/2021/6953197 ◽

2021 ◽

Vol 2021 ◽

pp. 1-21

Author(s):

Harini Rangarajan ◽

Jonathan P. Lynch

Keyword(s):

Root Growth ◽

Measurement Errors ◽

Root Architecture ◽

Projection Methods ◽

Root Diameter ◽

Reliable Estimate ◽

Imaging Method ◽

Root Branching ◽

Growth Angle ◽

Root Growth Angle

High throughput phenotyping is important to bridge the gap between genotype and phenotype. The methods used to describe the phenotype therefore should be robust to measurement errors, relatively stable over time, and most importantly, provide a reliable estimate of elementary phenotypic components. In this study, we use functional-structural modeling to evaluate quantitative phenotypic metrics used to describe root architecture to determine how they fit these criteria. Our results show that phenes such as root number, root diameter, and lateral root branching density are stable, reliable measures and are not affected by imaging method or plane. Metrics aggregating multiple phenes such as total length, total volume, convex hull volume, and bushiness index estimate different subsets of the constituent phenes; they however do not provide any information regarding the underlying phene states. Estimates of phene aggregates are not unique representations of underlying constituent phenes: multiple phenotypes having phenes in different states could have similar aggregate metrics. Root growth angle is an important phene which is susceptible to measurement errors when 2D projection methods are used. Metrics that aggregate phenes which are complex functions of root growth angle and other phenes are also subject to measurement errors when 2D projection methods are used. These results support the hypothesis that estimates of phenes are more useful than metrics aggregating multiple phenes for phenotyping root architecture. We propose that these concepts are broadly applicable in phenotyping and phenomics.

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Conserved LBL1-ta-siRNA and miR165/166-RLD1/2 modules regulate root development in maize

Development ◽

10.1242/dev.190033 ◽

2020 ◽

Vol 148 (1) ◽

pp. dev190033

Author(s):

Vibhav Gautam ◽

Archita Singh ◽

Sandeep Yadav ◽

Sharmila Singh ◽

Pramod Kumar ◽

...

Keyword(s):

Root Growth ◽

Root Development ◽

Lateral Roots ◽

Root System Architecture ◽

Maize Root ◽

Altered Expression ◽

Auxin Distribution ◽

Seminal Roots ◽

Crown Roots

ABSTRACTRoot system architecture and anatomy of monocotyledonous maize is significantly different from dicotyledonous model Arabidopsis. The molecular role of non-coding RNA (ncRNA) is poorly understood in maize root development. Here, we address the role of LEAFBLADELESS1 (LBL1), a component of maize trans-acting short-interfering RNA (ta-siRNA), in maize root development. We report that root growth, anatomical patterning, and the number of lateral roots (LRs), monocot-specific crown roots (CRs) and seminal roots (SRs) are significantly affected in lbl1-rgd1 mutant, which is defective in production of ta-siRNA, including tasiR-ARF that targets AUXIN RESPONSE FACTOR3 (ARF3) in maize. Altered accumulation and distribution of auxin, due to differential expression of auxin biosynthesis and transporter genes, created an imbalance in auxin signalling. Altered expression of microRNA165/166 (miR165/166) and its targets, ROLLED1 and ROLLED2 (RLD1/2), contributed to the changes in lbl1-rgd1 root growth and vascular patterning, as was evident by the altered root phenotype of Rld1-O semi-dominant mutant. Thus, LBL1/ta-siRNA module regulates root development, possibly by affecting auxin distribution and signalling, in crosstalk with miR165/166-RLD1/2 module. We further show that ZmLBL1 and its Arabidopsis homologue AtSGS3 proteins are functionally conserved.

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Genotypic Variation in Root Growth Angle in Rice (Oryza sativa L.) and its Association with Deep Root Development in Upland Fields with Different Water Regimes

Plant and Soil ◽

10.1007/s11104-006-9008-4 ◽

2006 ◽

Vol 287 (1-2) ◽

pp. 117-129 ◽

Cited By ~ 130

Author(s):

Yoichiro Kato ◽

Jun Abe ◽

Akihiko Kamoshita ◽

Junko Yamagishi

Keyword(s):

Oryza Sativa ◽

Root Growth ◽

Root Development ◽

Oryza Sativa L ◽

Genotypic Variation ◽

Water Regimes ◽

Growth Angle ◽

Deep Root ◽

Root Growth Angle

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Phene Synergism between Root Hair Length and Basal Root Growth Angle for Phosphorus Acquisition

PLANT PHYSIOLOGY ◽

10.1104/pp.15.00145 ◽

2015 ◽

Vol 167 (4) ◽

pp. 1430-1439 ◽

Cited By ~ 91

Author(s):

Magalhaes Amade Miguel ◽

Johannes Auke Postma ◽

Jonathan Paul Lynch

Keyword(s):

Root Growth ◽

Root Hair ◽

Hair Length ◽

Phosphorus Acquisition ◽

Root Hair Length ◽

Growth Angle ◽

Root Growth Angle

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Association between root growth angle and root length density of a near-isogenic line of IR64 rice with DEEPER ROOTING 1 under different levels of soil compaction

Plant Production Science ◽

10.1080/1343943x.2017.1288550 ◽

2017 ◽

Vol 20 (2) ◽

pp. 162-175 ◽

Cited By ~ 7

Author(s):

Poornima Ramalingam ◽

Akihiko Kamoshita ◽

Vivek Deshmukh ◽

Sousuke Yaginuma ◽

Yusaku Uga

Keyword(s):

Root Growth ◽

Root Length ◽

Soil Compaction ◽

Root Length Density ◽

Isogenic Line ◽

Near Isogenic Line ◽

Growth Angle ◽

Root Growth Angle ◽

Different Levels

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Allele mining for a drought responsive gene DRO1 determining root growth angle in donors of drought tolerance in rice (Oryza sativa L.)

Physiology and Molecular Biology of Plants ◽

10.1007/s12298-021-00950-2 ◽

2021 ◽

Vol 27 (3) ◽

pp. 523-534

Author(s):

Bablee Kumari Singh ◽

M. K. Ramkumar ◽

Monika Dalal ◽

Archana Singh ◽

Amolkumar U. Solanke ◽

...

Keyword(s):

Oryza Sativa ◽

Drought Tolerance ◽

Root Growth ◽

Oryza Sativa L ◽

Allele Mining ◽

Growth Angle ◽

Root Growth Angle ◽

Responsive Gene

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Rootstocks to improve root function and resource-use efficiency

Understanding and improving crop root function - Burleigh Dodds Series in Agricultural Science ◽

10.19103/as.2020.0075.25 ◽

2021 ◽

pp. 561-588

Author(s):

Francisco Pérez-Alfocea ◽

◽

Stephen Yeboah ◽

Ian C. Dodd ◽

◽

...

Keyword(s):

Resource Use ◽

Stomatal Closure ◽

Nutrient Use Efficiency ◽

Crop Improvement ◽

Resource Use Efficiency ◽

Form And Function ◽

Nutrient Use ◽

Use Efficiency ◽

And Function

Grafting, a surgical technique to attach genetically different shoots and roots (scions and rootstocks) allows “designer root systems” to enhance agricultural productivity and sustainability. Rootstocks improve plant nutrient relations by increasing nutrient capture and/or nutrient use efficiency, by multiple mechanisms including altered root morphology. Moreover, rootstocks can enhance water uptake and/or diminish water loss according to changes in root form and function, and root-to-shoot phytohormonal signalling. While the role of root-to-shoot ABA signalling in effecting stomatal closure is equivocal, root-sourced cytokinins and ACC regulate shoot senescence and vegetative growth respectively. Rootstock-mediated crop improvement offers opportunities to enhance crop resource use efficiency, especially in the developing world.

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