Recognition of floral homeotic MADS domain transcription factors by a phytoplasmal effector, phyllogen, induces phyllody. (15th April 2014)

• Record Type: Journal Article
• Authors: Maejima, Kensaku; Iwai, Ryo; Himeno, Misako; Komatsu, Ken; Kitazawa, Yugo; Fujita, Naoko; Ishikawa, Kazuya; Fukuoka, Misato; Minato, Nami; Yamaji, Yasuyuki; Oshima, Kenro; Namba, Shigetou
• Is Part Of: Plant journal. Volume 78:Number 4(2014:May)
• Page Start: 541
• Page End: 554
• Publication Date: 2014-04-15
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12495
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12495-abs-0001"> <title>Summary</title> <p>Plant pathogens alter the course of plant developmental processes, resulting in abnormal morphology in infected host plants. Phytoplasmas are unique plant‐pathogenic bacteria that transform plant floral organs into leaf‐like structures and cause the emergence of secondary flowers. These distinctive symptoms have attracted considerable interest for many years. Here, we revealed the molecular mechanisms of the floral symptoms by focusing on a phytoplasma‐secreted protein, PHYL1, which induces morphological changes in flowers that are similar to those seen in phytoplasma‐infected plants. PHYL1 is a homolog of the phytoplasmal effector SAP54 that also alters floral development. Using yeast two‐hybrid and <italic>in planta</italic> transient co‐expression assays, we found that PHYL1 interacts with and degrades the floral homeotic MADS domain proteins SEPALLATA3 (SEP3), APETALA1 (AP1) and CAULIFLOWER (CAL). This degradation of MADS domain proteins was dependent on the ubiquitin–proteasome pathway. The expression of floral development genes downstream of SEP3 and AP1 was disrupted in <italic>35S::PHYL1</italic> transgenic plants. <italic>PHYL1</italic> was genetically and functionally conserved among other phytoplasma strains and species. We designate <italic>PHYL1</italic>, <italic> SAP54</italic> and their homologs as members of the phyllody‐inducing gene family of 'phyllogens'.</p> </abstract>