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

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Title:ENHANCED GRAVITROPISM 2 encodes a STERILE ALPHA MOTIF–containing protein that controls root growth angle in barley and wheat
Creators Name:Kirschner, G.K. and Rosignoli, S. and Guo, L. and Vardanega, I. and Imani, J. and Altmüller, J. and Milner, S.G. and Balzano, R: and Nagel, K.A. and Pflugfelder, D. and Forestan, C. and Bovina, R. and Koller, R. and Stöcker, T.G. and Mascher, M. and Simmonds, J. and Uauy, C. and Schoof, H. and Tuberosa, R. and Salvi, S. and Hochholdinger, F.
Abstract: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.
Keywords:CRISPR/Cas9, EGT2, Barley, Gravitropism, Root Angle
Source:Proceedings of the National Academy of Sciences of the United States of America
Publisher:National Academy of Sciences
Page Range:e2101526118
Date:31 August 2021
Official Publication:https://doi.org/10.1073/pnas.2101526118
PubMed:View item in PubMed

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