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JRE 4 is a master transcriptional regulator of defense‐related steroidal glycoalkaloids in tomato
Author(s) -
Nakayasu Masaru,
Shioya Naoki,
Shikata Masahito,
Thagun Chonprakun,
Abdelkareem Ayman,
Okabe Yoshihiro,
Ariizumi Tohru,
Arimura Genichiro,
Mizutani Masaharu,
Ezura Hiroshi,
Hashimoto Takashi,
Shoji Tsubasa
Publication year - 2018
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13911
Subject(s) - transcription factor , jasmonate , biochemistry , plant defense against herbivory , mutant , population , solanum , chemistry , biology , arabidopsis , gene , botany , demography , sociology
Summary Steroidal glycoalkaloids ( SGA s) are specialized anti‐nutritional metabolites that accumulate in Solanum lycopersicum (tomato) and Solanum tuberosum (potato). A series of SGA biosynthetic genes is known to be upregulated in Solanaceae species by jasmonate‐responsive Ethylene Response Factor transcription factors, including JRE 4 (otherwise known as GAME 9), but the exact regulatory significance in planta of each factor has remained unaddressed. Here, via TILLING ‐based screening of an EMS ‐mutagenized tomato population, we isolated a JRE 4 loss‐of‐function line that carries an amino acid residue missense change in a region of the protein important for DNA binding. In this jre4 mutant, we observed downregulated expression of SGA biosynthetic genes and decreased SGA accumulation. Moreover, JRE 4 overexpression stimulated SGA production. Further characterization of jre4 plants revealed their increased susceptibility to the generalist herbivore Spodoptera litura larvae. This susceptibility illustrates that herbivory resistance is dependent on JRE 4 ‐mediated defense responses, which include SGA accumulation. Ethylene treatment attenuated the jasmonate‐mediated JRE 4 expression induction and downstream SGA biosynthesis in tomato leaves and hairy roots. Overall, this study indicated that JRE 4 functions as a primary master regulator of SGA biosynthesis, and thereby contributes toward plant defense against chewing insects.