Xanthomonas oryzae pv. oryzae TALE proteins recruit OsTFIIAγ1 to compensate for the absence of OsTFIIAγ5 in bacterial blight in rice

Abstract

Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight (BB) of rice, uses transcription activator-like effectors (TALEs) to interact with the basal transcription factor gamma subunit OsTFIIAγ5 (Xa5) and activates the transcription of host genes. However, how OsTFIIAγ1, the other OsTFIIAγ protein, functions in the presence of TALEs remains unclear. In this study, we show that OsTFIIAγ1 plays a compensatory role in the absence of Xa5. The expression of OsTFIIAγ1, which is activated by TALE PthXo7, increases the expression of host genes targeted by avirulent and virulent TALEs. Defective OsTFIIAγ1 rice lines show reduced expression of the TALE-targeted susceptibility (S) genes, OsSWEET11 and OsSWEET14, which results in increased BB resistance. Selected TALEs (PthXo1, AvrXa7 and AvrXa27) were evaluated for interactions with OsTFIIAγ1, Xa5 and xa5 (naturally occurring mutant form of Xa5) using biomolecular fluorescence complementation (BiFC) and microscale thermophoresis (MST). BiFC and MST demonstrated that the three TALEs bind Xa5 and OsTFIIAγ1 with a stronger affinity than xa5. These results provide insights into the complex roles of OsTFIIAγ1 and OsTFIIAγ5 in TALE-mediated host gene transcription.

Resistance Genes and their Interactions with Bacterial Blight/Leaf Streak Pathogens (Xanthomonas oryzae) in Rice (Oryza sativa L.)—an Updated Review

“…In the absence TFIIAγ5, the other OsTFIIAγ gene in rice, OsT-FIIAγ1 plays a compensatory role. Its expression is activated by TALE PthXo7, which increases expression of the host genes (Ma et al 2018). Interestingly, TFIIAγ5 is also employed by Xoc TALEs to cause disease (Yuan et al 2016).…”

Identification of a virulence tal gene in the cotton pathogen, Xanthomonas citri pv. malvacearum strain Xss-V2–18

“…[14][15][16][17][18][19][20]. One of the most studied groups of T3SEs are the transcriptional-activator like (tal) effector (TALE) proteins [21][22][23][24][25][26][27][28].…”

“…The number and diversity of tal effector genes varies among different species, pathovars and strains of Xanthomonas. For example, Xoo strains harbor [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] TALEs [49][50][51][52][53], Xoc strains contain 19-28 [49,54,55], Xtt strains contains 5-12 [56], Xtu strains contains 7-8 [56][57][58] and Xcm strains harbor 8-12 genes encoding tal effectors [27,46,59]. Some Xanthomonas spp.…”

Identification of a virulence tal gene in the cotton pathogen, Xanthomonas citri pv. malvacearum strain Xss-V2-18

“…[14][15][16][17][18][19][20]. One of the most studied groups of T3SEs are the transcriptional-activator like (tal) effector (TALE) proteins [21][22][23][24][25][26][27][28]. TALE proteins, functionally resemble eukaryotic transcription factors, are localized to the host plant nucleus where they bind to specific promoter sequences known as effector-binding elements (EBEs), thus regulating host gene expression [29][30][31].…”