Alfalfa(Medicago sativa L.)is a nutritious forage crop with wide ecological adaptability.The molecular breeding of alfalfa is restricted by its heterozygous tetraploid genome and the difficult genetic manipu-lation process.Under time and resource constraints,we applied a more convenient approach.We inves-tigated two MtGA3ox genes,MtGA3ox1 and MtGA3ox2,of Medicago truncatula,a diploid legume model species,finding that MtGA3ox1 plays a major role in GA-regulated plant architecture.Mutation of neither gene affected nitrogenase activity.These results suggest that MtGA3ox1 can be used in semidwarf and prostrate alfalfa breeding.Based on the M.truncatula MtGA3ox1 sequence,MsGA3ox1 was cloned from alfalfa,and two knockout targets were designed.An efficient CRISPR/Cas9-based genome editing protocol was used to generate msga3ox1 mutants in alfalfa.We obtained three lines that carried mutations in all four alleles in the T0 generation.Fifteen clonal plants were vegetatively propagated from each transgenic line using shoot cuttings.The plant height and internode length of msga3ox1 null mutants were signifi-cantly decreased.The number of total lateral branches,leaf/stem ratio and crude protein content of aerial plant parts of msga3ox1 mutants were significantly increased.Thus,we obtained semi-dwarf and pros-trate alfalfa by gene editing.

Lihua Zheng;Jiangqi Wen;Jinling Liu;Xiangzhao Meng;Peng Liu;Na Cao;Jiangli Dong;Tao Wang

State Key Laboratory of Agrobiotechnology,College of Biological Sciences,China Agricultural University,Beijing 100193,China;Institute for Agricultural Biosciences,Oklahoma State University,Ardmore,OK 73401,USA;Department of Plant and Soil Sciences,Oklahoma State University,Stillwater,OK 74078,USA

作物学报（英文版）

[1]Lihua Zheng;Jiangqi Wen;Jinling Liu;Xiangzhao Meng;Peng Liu;Na Cao;Jiangli Dong;Tao Wang-.From model to alfalfa:Gene editing to obtain semidwarf and prostrate growth habits)[J].作物学报（英文版）,2022(04):932-941

semidwarf,MtGA3ox,MtGA3ox1,MtGA3ox2,MsGA3ox1,msga3ox1,vegetatively

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