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An auxin signaling gene BnaA3 . IAA 7 contributes to improved plant architecture and yield heterosis in rapeseed
Author(s) -
Li Haitao,
Li Juanjuan,
Song Jurong,
Zhao Bo,
Guo Chaocheng,
Wang Bo,
Zhang Qinghua,
Wang Jing,
King Graham J.,
Liu Kede
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15632
Subject(s) - biology , rapeseed , auxin , mutant , silique , heterosis , plant stem , brassica , botany , canola , arabidopsis , genetics , gene , hybrid
Summary Plant architecture is the key factor affecting overall yield in many crops. The genetic basis underlying plant architecture in rapeseed ( Brassica napus ), a key global oil crop, is elusive. We characterized an ethyl methanesulfonate ( EMS) ‐mutagenized rapeseed mutant, sca , which had multiple phenotypic alterations, including crinkled leaves, semi‐dwarf stature, narrow branch angles and upward‐standing siliques. We identified the underlying gene, which encodes an Aux/ IAA protein (BnaA3. IAA 7). A G‐to‐A mutation changed the glycine at the 84 th position to glutamic acid (G84E), disrupting the conserved degron motif GWPPV and reducing the affinity between BnaA3. IAA 7 and TIR 1 ( TRANSPORT INHIBITOR RESPONSE 1) in an auxin dosage‐dependent manner. This change repressed the degradation of BnaA3. IAA 7 and therefore repressed auxin signaling at low levels of auxin that reduced the length of internodes. The G84E mutation reduced branch angles by enhancing the gravitropic response. The heterozygote +/ sca closely resembled a proposed ideal plant architecture, displaying strong yield heterosis through single‐locus overdominance by improving multiple component traits. Our findings demonstrate that a weak gain‐of‐function mutation in BnaA3 . IAA 7 contributes to yield heterosis by improving plant architecture and would be valuable for breeding superior rapeseed hybrid cultivars and such a mutation may increase the yield in other Brassica crops.