AUTHOR=Ma Qiaomei , Liu Yaru , Fang Hanmo , Wang Ping , Ahammed Golam Jalal , Zai Wenshan , Shi Kai 

TITLE=An Essential Role of Mitochondrial α-Ketoglutarate Dehydrogenase E2 in the Basal Immune Response Against Bacterial Pathogens in Tomato

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.579772

DOI=10.3389/fpls.2020.579772

ISSN=1664-462X

ABSTRACT=<p>Plants intensely modulate respiration when pathogens attack, but the function of mitochondrial respiration-related genes in plant–bacteria interaction is largely unclear. Here, the functions of α-ketoglutarate dehydrogenase (α<italic>-kGDH</italic>) E2 subunit and alternative oxidase (<italic>AOX</italic>) were investigated in the interaction between tomato and the virulent bacterial pathogen <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> DC3000 (<italic>Pst</italic>). <italic>Pst</italic> inoculation suppressed the transcript abundance of α<italic>-kGDH E2</italic>, but enhanced <italic>AOX</italic> expression and salicylic acid (SA) accumulation. Gene silencing and transient overexpression approaches revealed that plant susceptibility to <italic>Pst</italic> was significantly reduced by silencing α<italic>-kGDH E2</italic> in tomato, but increased by overexpressing α<italic>-kGDH E2</italic> in <italic>Nicotiana benthamiana</italic>, whereas silencing or overexpressing of <italic>AOX1a</italic> did not affect plant defense. Moreover, silencing octanoyltransferase (<italic>LIP2</italic>), engaged in the lipoylation of α-kGDH E2, significantly reduced disease susceptibility and hydrogen peroxide accumulation. Use of transgenic NahG tomato plants that cannot accumulate SA as well as the exogenous SA application experiment evidenced that α-kGDH E2 acts downstream of SA defense pathway. These results demonstrate tomato α<italic>-kGDH E2</italic> plays a negative role in plant basal defense against <italic>Pst</italic> in an AOX-independent pathway but was associated with lipoylation and SA defense pathways. The findings help to elucidate the mechanisms of mitochondria-involved plant basal immunity.</p>