AUTHOR=Zhao Jiaojie , Bi Weishuai , Zhao Shuqing , Su Jun , Li Mengyu , Ma Lisong , Yu Xiumei , Wang Xiaodong 

TITLE=Wheat Apoplast-Localized Lipid Transfer Protein TaLTP3 Enhances Defense Responses Against Puccinia triticina

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.771806

DOI=10.3389/fpls.2021.771806

ISSN=1664-462X

ABSTRACT=<p>Plant apoplast serves as the frontier battlefield of plant defense in response to different types of pathogens. Many pathogenesis-related (PR) proteins are accumulated in apoplastic space during the onset of plant–pathogen interaction, where they act to suppress pathogen infection. In this study, we found the expression of <italic>Triticum aestivum</italic> lipid transfer protein 3 (<italic>TaLTP3</italic>) gene was unregulated during incompatible interaction mediated by leaf rust resistance genes <italic>Lr39/41</italic> at the early infection stage. Stable transgenic wheat lines overexpressing <italic>TaLTP3</italic> exhibited enhanced resistance to leaf rust pathogen <italic>Puccinia triticina</italic>. Transcriptome analysis revealed that overexpression of <italic>TaLTP3</italic> specifically activated the transcription of pathogenesis-related protein 1a (TaPR1a) and multiple plant hormone pathways, including salicylic acid (SA), jasmonic acid (JA), and auxin, in response to the infection of the model bacterial pathogen <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> DC3000. Further investigation indicated that <italic>TaLTP3</italic> physically associated with wheat <italic>TaPR1a</italic> protein in the apoplast. Transgenic wheat lines overexpressing <italic>TaLTP3</italic> and <italic>TaPR1a</italic> showed higher accumulations of reactive oxygen species (ROS) during plant defense responses. All these findings suggested that <italic>TaLTP3</italic> is involved in wheat resistance against leaf rust pathogen infection and forming a <italic>TaLTP3-TaPR1a</italic> complex in apoplast against this pathogen, which provides new insights into the functional roles of PR proteins.</p>