Effects of powdery mildew infection on chloroplast and mitochondrial functions in rubber tree

Powdery mildew causes substantial losses in crop and economic plant yields worldwide. Although powdery mildew infection of rubber trees (Hevea brasiliensis), caused by the biotrophic fungus Erysiphe quercicola, severely threatens natural rubber production, little is known regarding the mechanism by which E. quercicola adapts to H. brasiliensis to invade the host plant. In barley and Arabidopsis thaliana, lifeguard (LFG) proteins, which have topological similarity to BAX INHIBITOR-1, are involved in host plant susceptibility to powdery mildew infection. In this study, we characterized an H. brasiliensis LFG protein, HbLFG1, with a focus on its function in regulating defence against powdery mildew. HbLFG1 gene expression was found to be upregulated during E. quercicola infection. HbLFG1 showed conserved functions in cell death inhibition and membrane localization. Expression of HbLFG1 in Nicotiana benthamiana leaves and A. thaliana Col-0 was demonstrated to significantly suppress callose deposition induced by conserved pathogen-associated molecular patterns chitin and flg22. Furthermore, we found that overexpression of HbLFG1 in H. brasiliensis mesophyll protoplasts significantly suppressed the chitin-induced burst of reactive oxygen species. Although A. thaliana Col-0 and E. quercicola displayed an incompatible interaction, Col-0 transformants overexpressing HbLFG1 were shown to be susceptible to E. quercicola. Collectively, the findings of this study provide evidence that HbLFG1 acts as a negative regulator of plant immunity that facilitates E. quercicola infection in H. brasiliensis.

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AtSTP8, an endoplasmic reticulum‐localized monosaccharide transporter from Arabidopsis , is recruited to the extrahaustorial membrane during powdery mildew infection

New Phytologist ◽

10.1111/nph.17347 ◽

2021 ◽

Author(s):

Jie Liu ◽

Mengxue Liu ◽

Liqiang Tan ◽

Baoyu Huai ◽

Xianfeng Ma ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Powdery Mildew ◽

Monosaccharide Transporter ◽

Powdery Mildew Infection

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The ultrastructure of M1-a-mediated resistance to powdery mildew infection in barley

Canadian Journal of Botany ◽

10.1139/b75-286 ◽

1975 ◽

Vol 53 (22) ◽

pp. 2589-2597 ◽

Cited By ~ 10

Author(s):

H. H. Edwards

Keyword(s):

Powdery Mildew ◽

Host Cell ◽

Electron Density ◽

Epidermal Cells ◽

Dense Material ◽

Ultrastructural Changes ◽

Electron Dense Material ◽

Host Cytoplasm ◽

Powdery Mildew Infection ◽

Cell Protoplast

M1-a-mediated resistance in barley to invasion by the CR3 race of Erysiphe graminis f. sp. hordei does not occur in every host cell with the same speed and severity. In some cells ultrastructural changes within the host cell as a result of resistance will occur within 24 h after inoculation, whereas in other cells these changes may take up to 72 h. In some cells the ultrastructural changes are so drastic that they give the appearance of a hypersensitive death of the host cell, whereas in other cells the changes are very slight. In any case, at the end of these changes the fungus ceases growth. The ultrastructural changes occur in penetrated host epidermal cells as well as non-infected adjacent epidermal and mesophyll cells.The following ultrastructural changes have been observed: (1) an electron-dense material which occurs either free in the vacuole or adhering to the tonoplast (the material is granular or in large clumps); (2) an increased electron density of the host cytoplasm and nucleus; (3) a breakdown of the tonoplast so that the cytoplasmic constituents become dispersed throughout the cell lumen; and (4) the deposition of papillar-like material in areas other than the penetration site. The first three changes take place within the host cell protoplasts and are directly attributable to the gene M1-a. These changes are typical of stress or incompatibility responses and thus M1-a appears to trigger a generalized incompatibility response in the presence of race CR3. The papillar-like material occurs outside the host cell protoplast in the same manner as the papilla and probably is not directly attributable to M1-a.

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