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Sweet potato NAC transcription factor, Ib NAC 1, upregulates sporamin gene expression by binding the SWRE motif against mechanical wounding and herbivore attack
Author(s) -
Chen ShiPeng,
Lin I Winnie,
Chen Xuanyang,
Huang YinHao,
Chang ShiaoChi,
Lo HuiShan,
Lu HseuhHan,
Yeh KaiWun
Publication year - 2016
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.13171
Subject(s) - transcription factor , jasmonic acid , biology , microbiology and biotechnology , biochemistry , gene
Summary Sporamin is a tuberous storage protein with trypsin inhibitory activity in sweet potato ( Ipomoea batatas Lam.), which accounts for 85% of the soluble protein in tubers. It is constitutively expressed in tuberous roots but is expressed in leaves only after wounding. Thus far, its wound‐inducible signal transduction mechanisms remain unclear. In the present work, a 53‐bp DNA region, s poramin w ound‐ r esponse cis ‐ e lement ( SWRE ), was identified in the sporamin promoter and was determined to be responsible for the wounding response. Using yeast one‐hybrid screening, a NAC domain protein, Ib NAC 1, that specifically bound to the 5′‐ TACAATATC ‐3′ sequence in SWRE was isolated from a cDNA library from wounded leaves. Ib NAC 1 was constitutively expressed in root tissues and was induced earlier than sporamin following the wounding of leaves. Transgenic sweet potato plants overexpressing Ib NAC 1 had greatly increased sporamin expression, increased trypsin inhibitory activity, and elevated resistance against Spodoptera litura . We further demonstrated that Ib NAC 1 has multiple biological functions in the jasmonic acid ( JA ) response, including the inhibition of root formation, accumulation of anthocyanin, regulation of aging processes, reduction of abiotic tolerance, and overproduction of reactive oxygen species ( ROS ). Thus, Ib NAC 1 is a core transcription factor that reprograms the transcriptional response to wounding via the JA ‐mediated pathway in sweet potato.