Rhizoctonia solani, one of the most detrimental necrotrophic pathogens, causes rice sheath blight and poses a severe threat to production. Focus on the function of effectors secreted by necrotrophic pathogens during infection has grown rapidly in recent years. However, little is known about the virulence and mechanisms of these proteins. In this study, we performed functional studies on putative effectors in R. solani and revealed that AGLIP1 out of 13 putative effectors induced cell death in Nicotiana benthamiana. AGLIP1 was also demonstrated to trigger cell death in rice protoplasts. The predicted lipase active sites and signal peptide (SP) of this protein were required for the cell death-inducing ability. AGLIP1 was greatly induced during R. solani infection in rice sheath. The AGLIP1’s virulence function was further demonstrated by transgenic technology. The pathogenesis-related genes induced by pathogen-associated molecular pattern and bacteria were remarkably inhibited in AGLIP1-expressing transgenic Arabidopsis lines. Ectopic expression of AGLIP1 strongly facilitated disease progression in Arabidopsis caused by the type III secretion system-defective mutant from Pseudomonas syringae pv. tomato DC3000. Collectively, these results indicate that AGLIP1 is a possible effector that plays a significant role in pathogen virulence through inhibiting basal defenses and promoting disease development in plants.
New derivatives of α-phenyl-N-tert-butyl nitrone (PBN) bearing a hydroxyl,
an acetate, or an acetamide
substituent on the N-tert-butyl
moiety and para-substituted phenyl or naphthlyl moieties
were synthesized. Their ability to trap hydroxymethyl radical was
evaluated by electron paramagnetic resonance spectroscopy. The presence
of two electron-withdrawing substituents on both sides of the nitronyl
function improves the spin-trapping properties, with 4-HOOC–PBN–CH2OAc and 4-HOOC–PBN–CH2NHAc being
∼4× more reactive than PBN. The electrochemical properties
of the derivatives were further investigated by cyclic voltammetry
and showed that the redox potentials of the nitrones are largely influenced
by the nature of the substituents both on the aromatic ring and on
the N-tert-butyl function. The acetamide
derivatives PBN–CH2NHAc, 4-AcNHCH2–PBN–CH2NHAc, and 4-MeO–PBN–CH2NHAc were
the easiest to oxidize. A computational approach was used to rationalize
the effect of functionalization on the free energies of nitrone reactivity
with hydroxymethyl radical as well as on the electron affinity and
ionization potential. Finally, the neuroprotection of the derivatives
was evaluated in an in vitro model of cellular injury
on cortical neurons. Five derivatives showed good protection at very
low concentrations (0.1–10 μM), with PBN–CH2NHAc and 4-HOOC–PBN being the two most promising agents.
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