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标题：INTERMEDIUM-M encodes an HvAP2L-H5 ortholog and is required for inflorescence indeterminacy and spikelet determinacy in barley
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作者：Jinshun Zhong ; G. Wilma van Esse ; Xiaojing Bi 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：8
页码：1
DOI：10.1073/pnas.2011779118
出版社：The National Academy of Sciences of the United States of America
摘要：Inflorescence architecture dictates the number of flowers and, ultimately, seeds. The architectural discrepancies between two related cereals, barley and wheat, are controlled by differences in determinacy of inflorescence and spikelet meristems. Here, we characterize two allelic series of mutations named intermedium-m ( int-m ) and double seed1 ( dub1 ) that convert barley indeterminate inflorescences into wheat-like determinate inflorescences bearing a multifloreted terminal spikelet and spikelets with additional florets. INT-M / DUB1 encodes an APETALA2-like transcription factor (HvAP2L-H5) that suppresses ectopic and precocious spikelet initiation signals and maintains meristem activity. HvAP2L-H5 inhibits the identity shift of an inflorescence meristem (IM) to a terminal spikelet meristem (TSM) in barley. Null mutations in AP2L-5 lead to fewer spikelets per inflorescence but extra florets per spikelet. In wheat, prolonged and elevated AP2L-A5 activity in rAP2L-A5 mutants delays but does not suppress the IM−TSM transition. We hypothesize that the regulation of AP2L-5 orthologs and downstream genes contributes to the different inflorescence determinacy in barley and wheat. We show that AP2L-5 proteins are evolutionarily conserved in grasses, promote IM activity, and restrict floret number per spikelet. This study provides insights into the regulation of spikelet and floret number, and hence grain yield in barley and wheat.
关键词：barley and wheat ; inflorescence determinacy ; APETALA2/Q ; MADS1 ; MADS3/58