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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Chemistry Research » Research » Publications at this Location » Publication #340000

Research Project: Disease Defense Responses Signaling in Maize

Location: Chemistry Research

Title: Dissecting a new connection between cytokinin and jasmonic acid in control of leaf growth

Author
item DEL VALLE-ECHEVARRIA, ANGEL - UNIVERSITY OF HAWAII
item UYEHARA, AIMEE - UNIVERSITY OF HAWAII
item CAHILL, JAMES - IOWA STATE UNIVERSITY
item NELISSEN, HILDE - IOWA STATE UNIVERSITY
item Hunter, Charles
item JANDER, GEORG - BOYCE THOMPSON INSTITUTE
item MUSZYNSKI, MICHAEL - UNIVERSITY OF HAWAII

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Plant growth is mediated by two cellular processes: division and elongation. The maize leaf is an excellent model to study plant growth since these processes are spatially separated into discreet zones - a division zone (DZ), transition zone (TZ), and elongation zone (EZ) - at the base of the leaf. We are studying a semi-dominant maize mutant named Hairy Sheath Frayed1 (Hsf1) that displays reduced leaf growth caused by cytokinin hypersignaling. Cytokinin (CK) is a well-studied hormone which typically functions to promote cell proliferation but, depending on cellular context, it can also repress growth; although how repression is mediated is not welldefined. During our analysis of Hsf1, we discovered that the mutant over accumulates jasmonic acid (JA), a hormone previously shown to repress cell division and growth. This result suggested CK may crosstalk with JA in the control of leaf growth, which is a previously unrecognized connection and may explain one route by which CK can repress growth in certain tissues. We evaluated JA pathway gene expression levels in the division zone and elongation zones of the emerging leaf #4 of Hsf1/+ and wild type (WT) sibs by qRT-PCR. Several JA biosynthesis genes were significantly upregulated in the growth zone of mutants compared to WT sibs. In parallel, we used a bioinformatics approach to identify candidate transcription factors associated in gene regulatory networks (GRNs) with JA pathway genes. Based on this survey, we identified a transcription factor that was also CK responsive, as its expression level in the Hsf1 leaf growth zone was also significantly upregulated. Additional molecular and genetic studies will be presented suggesting that this proposed interaction contributes to leaf growth control.