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Plant Cell. 2020 Mar 23. pii: tpc.00677.2019. doi: 10.1105/tpc.19.00677. [Epub ahead of print]

The Maize Hairy Sheath Frayed1 (Hsf1) Mutation Alters Leaf Patterning Through Increased Cytokinin Signaling.

Author information

1
University of Hawaii CITY: Honolulu United States Of America [US] mgmuszyn@hawaii.edu.
2
Iowa State University CITY: Ames United States Of America [US].
3
Iowa State University CITY: Ames STATE: Iowa POSTAL_CODE: 50011 United States Of America [US].
4
University of Hawaii CITY: Honolulu United States Of America [US].
5
Universidad de la República (IESTA-UdelaR) CITY: Montevideo, Uruguay [UY].
6
Nagoya University CITY: Nagoya POSTAL_CODE: 464-8601 Japan [JP].
7
Vologda State University CITY: Vologda Russia.
8
Russian Academy of Sciences, Inst of Plant Physiology CITY: Moscow Russia.
9
Russian Academy of Sciences, Inst of Plant Physiology CITY: Moscow POSTAL_CODE: 127276 Russia.
10
SASTRA University; CITY: Thanjavur India [IN].
11
DuPont Crop Genetics CITY: Wilmington POSTAL_CODE: 19805 United States Of America [US].
12
DuPont, Pioneer CITY: Johnston STATE: Iowa United States Of America [US].
13
Corteva Agriscience CITY: Johnston STATE: Iowa POSTAL_CODE: 50131 United States Of America [US].

Abstract

Leaf morphogenesis requires growth polarized along three axes - proximal-distal, medial-lateral and abaxial-adaxial. Grass leaves display a prominent proximal-distal (P-D) polarity consisting of a proximal sheath separated from the distal blade by the auricle and ligule. Although proper specification of the four segments is essential for normal morphology, our knowledge is incomplete regarding the mechanisms which influence P-D specification in monocots like maize (Zea mays). Here we report the identification of the gene underlying the semi-dominant, leaf patterning, maize mutant Hairy Sheath Frayed1 (Hsf1). Hsf1 plants produce leaves with outgrowths consisting of proximal segments - sheath, auricle and ligule - emanating from the distal blade margin. Analysis of three independent Hsf1 alleles revealed gain-of-function missense mutations in the ligand binding domain of the maize cytokinin (CK) receptor Zea mays Histidine Kinase1 (ZmHK1) gene. Biochemical analysis and structural modeling suggest the mutated residues near the CK binding pocket affect CK binding affinity. Treatment of wild type seedlings with exogenous CK phenocopied the Hsf1 leaf phenotypes. Results from expression and epistatic analyses indicated the Hsf1 mutant receptor appears to be hypersignaling. Our results demonstrate that hypersignaling of CK in incipient leaf primordia can reprogram developmental patterns in maize.

PMID:
32205456
DOI:
10.1105/tpc.19.00677
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