Macroautophagy/autophagy is critical for normal appressorium formation and pathogenicity of the rice blast fungus Magnaporthe oryzae, but the molecular base of autophagy linked to pathogenicity ...remains elusive in this or other pathogenic fungi. We found that MoHat1, a histone acetyltransferase (HAT) homolog, had a role in the regulation of autophagy through the acetylation of autophagy related proteins MoAtg3 and MoAtg9. We also found that MoHat1 was subject to regulation by the protein kinase MoGsk1 that modulated the translocation of MoHat1 from the nucleus to the cytoplasm with the assistance of MoSsb1, a protein chaperone. The alternation of intracellular location affected MoHat1 in the modification of cytosolic autophagy proteins that maintained normal autophagy. Furthermore, we provided evidence linking acetylation of MoAtg3 and MoAtg9 by MoHat1 to functional appressorium development and pathogenicity. Together with the first report of MoAtg9 being subject to acetylation regulation by MoHat1, our studies depicted how MoHat1 regulated autophagy in conjunction with MoGsk1 and how normal autophagy was linked to appressorium formation and function and pathogenicity of M. oryzae.
Abbreviations: A/Ala: alanine; AP: autophagosome; Atg genes/proteins: autophagy-related genes/proteins; BiFC: bimolecular fluorescence complementation; co-IP: co-immunoprecipitation; DAPI: 4ʹ, 6-diamidino-2-phenylindole; D/Asp: aspartic acid; GFP: green fluorescent protein; GSK3: glycogen synthase kinase 3; HAT: histone acetyltransferase; Hsp70: heat-shock protein 70; IH: invasive hyphae; K/Lys: lysine; MMS: methyl methanesulfonate; Mo: Magnaporthe oryzae; PAS: phagophore assembly site; PE: phosphatidylethanolamine; PtdIns3K: phosphatidylinositol 3-kinase; R/Arg: arginine; S/Ser: serine; T/Thr: threonine; TOR: target of rapamycin; WT: wild type; YFP: yellow fluorescent protein
Summary
Gti1/Pac2 are conserved family proteins that regulate morphogenic transition in yeasts such as Schizosaccharomyces pombe and Candida albicans, and they also control toxin production and ...pathogenicity in filamentous fungus Fusarium graminearum. To test the functions of Gti1/Pac2 paralogues MoGti1 and MoPac2 in the rice blast fungus Magnaporthe oryzae, we generated respective ΔMogti1 and ΔMopac2 mutant strains. We found that MoGti1 and MoPac2 exhibit shared and distinct roles in hyphal growth, conidiation, sexual reproduction, stress responses, surface hydrophobility, invasive hyphal growth and pathogenicity. Consistent with the putative conserved function of MoGti1, we showed that MoGti1‐GFP is localized to the nucleus, whereas MoPac2‐GFP is mainly found in the cytoplasm. In addition, we provided evidence that the nuclear localization of MoGti1 could be subject to regulation by MoPmk1 mitogen‐activated protein kinase. Moreover, we found that the reduced pathogenicity in the ΔMopac2 mutant corresponds with an increased expression of plant defence genes, including PR1a, AOS2, LOX1, PAD4, and CHT1. Taken together, our studies provide a comprehensive analysis of two similar but distinct Gti1/Pac2 family proteins in M. oryzae, which underlines the important yet conserved functions of these family proteins in plant pathogenic fungi.
•We define a pivotal protein MoLys2 of lysine biosynthesis.•The first time elucidate its function of MoLys2 in phytopathogenic fungi.•The potential for targeting lysine biosynthesis for anti-rice ...blast management.
Amino acid biosyntheses are complex but essential processes in growth and differentiation of eukaryotic cells. In the budding yeast Saccharomyces cerevisiae, the lysine biosynthesis via the α-aminoadipate (AA) pathway involves several steps, including reduction of AA to AA 6-semialdehyde by AA reductase ScLys2. In filamentous fungus Penicillium chrysogenum, disruption of the LYS2 gene blocked the lysine biosynthesis but promoted the production of the secondary metabolite penicillin. In comparison, little is known about the function of AA reductase Lys2 in phytopathogenic fungi. We here characterized the functions of MoLys2, a homolog of ScLys2, from the rice blast fungus Magnaporthe oryzae. Our results showed that the ΔMolys2 mutants were auxotrophic for lysine. The ΔMolys2 mutants also exhibited drastic reduction in pathogenicity on rice, inducing small disease lesions. Microscopic examination of the lesions revealed that the invasive hyphae of ΔMolys2 mutants were mostly restricted to the primary infected leaf sheath cells. In addition, exogenous lysine restored the production of conidia and near wild-type appressoria differentiation, and rescued the defect of pathogenicity in conidia infection of detached barely and rice leaf sheath. Our results indicated that MoLys2 is necessary for lysine biosynthesis that affects growth, conidiogenesis, and pathogenicity of the fungus. This study does implicate the potential for targeting lysine biosynthesis for the development of novel fungicides against M. oryzae.
Summary
The basic leucine zipper (bZIP) domain‐containing transcription factors (TFs) function as key regulators of cellular growth and differentiation in eukaryotic organisms including fungi. We ...have previously identified MoAp1 and MoAtf1 as bZIP TFs in Magnaporthe oryzae and demonstrated that they regulate the oxidative stress response and are critical in conidiogenesis and pathogenicity. Studies of bZIP proteins could provide a novel strategy for controlling rice blast, but a systematic examination of the bZIP proteins has not been carried out. Here, we identified 19 additional bZIP TFs and characterized their functions. We found that the majority of these TFs exhibit active functions, most notably, in conidiogenesis. We showed that MoHac1 regulates the endoplasmic reticulum stress response through a conserved unfolded protein response pathway, MoMetR controls amino acid metabolism to govern growth and differentiation, and MoBzip10 governs appressorium function and invasive hyphal growth. Moreover, MoBzip5 participates in appressorium formation through a pathway distinct from that MoBzip10, and MoMeaB appears to exert a regulatory role through nutrient uptake and nitrogen utilization. Collectively, our results provide insights into shared and specific functions associated with each of these TFs and link the regulatory roles to the fungal growth, conidiation, appressorium formation, host penetration and pathogenicity.
Summary
The basic leucine zipper (
bZIP
) domain‐containing transcription factors (
TFs
) function as key regulators of cellular growth and differentiation in eukaryotic organisms including fungi. We ...have previously identified
MoAp
1 and
MoAtf
1 as
bZIP TFs
in
M
agnaporthe oryzae
and demonstrated that they regulate the oxidative stress response and are critical in conidiogenesis and pathogenicity. Studies of
bZIP
proteins could provide a novel strategy for controlling rice blast, but a systematic examination of the
bZIP
proteins has not been carried out. Here, we identified 19 additional
bZIP TFs
and characterized their functions. We found that the majority of these
TFs
exhibit active functions, most notably, in conidiogenesis. We showed that
MoHac
1 regulates the endoplasmic reticulum stress response through a conserved unfolded protein response pathway,
MoMetR
controls amino acid metabolism to govern growth and differentiation, and
MoBzip
10 governs appressorium function and invasive hyphal growth. Moreover,
MoBzip
5 participates in appressorium formation through a pathway distinct from that
MoBzip
10, and
MoMeaB
appears to exert a regulatory role through nutrient uptake and nitrogen utilization. Collectively, our results provide insights into shared and specific functions associated with each of these
TFs
and link the regulatory roles to the fungal growth, conidiation, appressorium formation, host penetration and pathogenicity.
Summary
G
ti1/
P
ac2 are conserved family proteins that regulate morphogenic transition in yeasts such as
S
chizosaccharomyces pombe
and
C
andida albicans
, and they also control toxin production and ...pathogenicity in filamentous fungus
F
usarium graminearum
. To test the functions of
G
ti1/
P
ac2 paralogues
MoGti1
and
MoPac2
in the rice blast fungus
M
agnaporthe oryzae
, we generated respective
Δ
M
ogti1
and
Δ
M
opac2
mutant strains. We found that
MoGti1
and
MoPac2
exhibit shared and distinct roles in hyphal growth, conidiation, sexual reproduction, stress responses, surface hydrophobility, invasive hyphal growth and pathogenicity. Consistent with the putative conserved function of
MoGti1
, we showed that
MoGti1
‐
GFP
is localized to the nucleus, whereas
MoPac2
‐
GFP
is mainly found in the cytoplasm. In addition, we provided evidence that the nuclear localization of
MoGti1
could be subject to regulation by
MoPmk1
mitogen‐activated protein kinase. Moreover, we found that the reduced pathogenicity in the
Δ
M
opac2
mutant corresponds with an increased expression of plant defence genes, including
PR1a
,
AOS2
,
LOX1
,
PAD4
, and
CHT1
. Taken together, our studies provide a comprehensive analysis of two similar but distinct
G
ti1/
P
ac2 family proteins in
M
. oryzae
, which underlines the important yet conserved functions of these family proteins in plant pathogenic fungi.
The effects of dietary supplementation with two particle sizes of nano zinc oxide (ZnO) on growth performance, immune function, intestinal morphology, and the gut microbiome were determined in a ...42-day broiler chicken feeding experiment. A total of 75 one-day-old Arbor Acres broilers were randomized and divided into three groups with five replicates of five chicks each, including the conventional ZnO group (NC), the nano-ZnO group with an average particle size of 82 nm (ZNPL), and the nano-ZnO group with an average particle size of 21 nm (ZNPS). Each group was supplemented with 40 mg/kg of ZnO or nano-ZnO. Our results revealed that birds in the ZNPS group had a higher average daily gain and a lower feed-to-gain ratio than those in the NC group. ZNPS significantly increased the thymus index and spleen index, as well as the levels of serum metallothionein (MT), superoxide dismutase (SOD), and lysozyme (LZM). The ZNPS treatments reduced interleukin (IL)-1β and tumor necrosis factor-alpha (TNF-α) levels and increased IL-2 and interferon (IFN)-γ levels compared to that in the NC group. Additionally, compared with the birds in the NC group, those in the nano-ZnO group had a higher villus height to crypt depth ratio of the duodenum, jejunum, and ileum. Bacteroides increased in the ZNPS group at the genus level. Further, unidentified_Lachnospiraceae, Blautia, Lachnoclostridium, unidentified_Erysipelotrichaceae, and Intestinimonas were significantly increased in the ZNPL group. In conclusion, nano-ZnO improved the growth performance, promoted the development of immune organs, increased nonspecific immunity, improved the villus height to crypt depth ratio of the small intestine, and enriched the abundance of beneficial bacteria. Notably, the smaller particle size (21 nm) of nano-ZnO exhibited a more potent effect.
Iron toxicity is a nutrient disorder that severely affects crop development and yield in some soil conditions. Vacuolar detoxification of metal stress is an important strategy for plants to survive ...and adapt to this adverse environment. Vacuolar iron transporter (VIT) members are involved in this process and play essential roles in iron storage and transport. In this study, we identified a rapeseed VIT gene BnMEB2 (BnaC07g30170D) homologs to Arabidopsis MEB2 (At5g24290). Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old) leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other VIT genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops.
The applicability of a novel macrocyclic multi-carbonyl compound, pillar4quinone (P4Q), as the cathode active material for lithium-ion batteries (LIBs) was assessed theoretically. The molecular ...geometry, electronic structure, Li-binding thermodynamic properties, and the redox potential of P4Q were obtained using density functional theory (DFT) at the M06-2X/6-31G(d,p) level of theory. The results of the calculations indicated that P4Q interacts with Li atoms via three binding modes: Li–O ionic bonding, O–Li···O bridge bonding, and Li···phenyl noncovalent interactions. Calculations also indicated that, during the LIB discharging process, P4Q could yield a specific capacity of 446 mAh g
−1
through the utilization of its many carbonyl groups. Compared with pillar5quinone and pillar6quinone, the redox potential of P4Q is enhanced by its high structural stability as well as the effect of the solvent. These results should provide the theoretical foundations for the design, synthesis, and application of novel macrocyclic carbonyl compounds as electrode materials in LIBs in the future.
Graphical Abstract
Schematic representation of the proposed charge-discharge mechanism of Pillar4quinone as cathode for lithium-ion batteries
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