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ARS Home » Pacific West Area » Albany, California » Plant Gene Expression Center » Research » Publications at this Location » Publication #358424
Research Project: Characterization of Plant Architectural Genes in Maize for Increased Productivity

Location: Plant Gene Expression Center

Title: Tasselseed5 overexpresses a wound-inducible enzyme, ZmCYOP94B1, that affects jasmonate catabolism, sex determination, and plant architecture in maize

Author
item LUNDE, CHINA - University Of California
item KIMBERLIN, ATHEN - University Of Missouri
item LEIBOFF, SAMUEL - University Of California
item KOO, ABRAHAM - University Of Missouri
item Hake, Sarah

Submitted to: Communications Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2019
Publication Date: 3/25/2019
Citation: Lunde, C., Kimberlin, A., Leiboff, S., Koo, A., Hake, S.C. 2019. Tasselseed5 overexpresses a wound-inducible enzyme, ZmCYOP94B1, that affects jasmonate catabolism, sex determination, and plant architecture in maize. Communications Biology. 2:114. https://doi.org/10.1038/s42003-019-0354-1.
DOI: https://doi.org/10.1038/s42003-019-0354-1

Interpretive Summary: Although many plants have perfect flowers containing both staminate (male) and pistillate (female) sex organs, variations in floral sex have evolved throughout the plant lineage. Maize flowers are bisexual at initiation but achieve separate male and female identity at maturity through pistil abortion in the male inflorescence and stamen arrest in the female inflorescence. Tasselseed5 (Ts5) is a classic dominant mutant with a feminized tassel similar to the recessive ts1 and opr7opr8 in the jasmonic acid pathway. We identified the Ts5 gene as an enzyme in the jasmonic acid pathway. We propose that the Ts5 phenotype results from an interruption of JA signaling during sexual differentiation via constitutive upregulation of a JA oxidizing enzyme, ZmCYP94B1. Within a species, proper sex-determination is vital to fecundity. Our results stress the importance of rapid de-escalation of JA response after wounding to preserve monoecy, the sex determination mode of maize.

Technical Abstract: Maize flowers are initially bisexual but later achieve separate sexual identities through pistil abortion in tassels and stamen arrest in ears. Classic dominant Tasselseed5 (Ts5) mutants have a feminized tassel similar to ts1 and opr7opr8 in the jasmonic acid (JA) pathway. Positional cloning and transcriptomics identified an overexpressed gene in the CYP94B subfamily as Ts5 (ZmCYPB1). ZmCYPB1 was ectopically expressed in Ts5 tassels. Members of CYP94B are wound-inducible and oxidize bioactive jasmonoyl-L-isoleucine (JA-Ile) to biologically inactive jasmonates. Consistent with this activity, Ts5 tassels and wounded leaves displayed lower JA and JA-lle precursors and higher 12OH-JA-lle product than wild type. In addition, many genes in the wounding/jasmonate pathway were differentially expressed in tassels, fitting expectations of enhanced expression of a CYP94B. We propose that the Ts5 phenotype results from interruption of JA signaling during sexual differentiation via upregulation of ZmCYP94B1 and that proper expression of this gene maintains monoecy in maize.