The plant membrane surrounding powdery mildew haustoria shares properties with the endoplasmic reticulum membrane

TY - JOUR

T1 - The plant membrane surrounding powdery mildew haustoria shares properties with the endoplasmic reticulum membrane

AU - Kwaaitaal, Mark Adrianus Cornelis J

AU - Nielsen, Mads Eggert

AU - Böhlenius, Henrik

AU - Thordal-Christensen, Hans

PY - 2017

Y1 - 2017

N2 - Many filamentous plant pathogens place specialized feeding structures, called haustoria, inside living host cells. As haustoria grow, they are believed to manipulate plant cells to generate a specialized, still enigmatic extrahaustorial membrane (EHM) around them. Here, we focused on revealing properties of the EHM. With the help of membranespecific dyes and transient expression of membrane-associated proteins fused to fluorescent tags, we studied the nature of the EHM generated by barley leaf epidermal cells around powdery mildew haustoria. Observations suggesting that endoplasmic reticulum (ER) membrane-specific dyes labelled the EHM led us to find that Sar1 and RabD2a GTPases bind this membrane. These proteins are usually associated with the ER and the ER/cis-Golgi membrane, respectively. In contrast, transmembrane and luminal ER and Golgi markers failed to label the EHM, suggesting that it is not a continuum of the ER. Furthermore, GDP-locked Sar1 and a nucleotide-free RabD2a, which block ER to Golgi exit, did not hamper haustorium formation. These results indicated that the EHM shares features with the plant ER membrane, but that the EHM membrane is not dependent on conventional secretion. This raises the prospect that an unconventional secretory pathway from the ER may provide this membrane's material. Understanding these processes will assist future approaches to providing resistance by preventing EHM generation.

AB - Many filamentous plant pathogens place specialized feeding structures, called haustoria, inside living host cells. As haustoria grow, they are believed to manipulate plant cells to generate a specialized, still enigmatic extrahaustorial membrane (EHM) around them. Here, we focused on revealing properties of the EHM. With the help of membranespecific dyes and transient expression of membrane-associated proteins fused to fluorescent tags, we studied the nature of the EHM generated by barley leaf epidermal cells around powdery mildew haustoria. Observations suggesting that endoplasmic reticulum (ER) membrane-specific dyes labelled the EHM led us to find that Sar1 and RabD2a GTPases bind this membrane. These proteins are usually associated with the ER and the ER/cis-Golgi membrane, respectively. In contrast, transmembrane and luminal ER and Golgi markers failed to label the EHM, suggesting that it is not a continuum of the ER. Furthermore, GDP-locked Sar1 and a nucleotide-free RabD2a, which block ER to Golgi exit, did not hamper haustorium formation. These results indicated that the EHM shares features with the plant ER membrane, but that the EHM membrane is not dependent on conventional secretion. This raises the prospect that an unconventional secretory pathway from the ER may provide this membrane's material. Understanding these processes will assist future approaches to providing resistance by preventing EHM generation.

KW - Barley organelle markers

KW - endoplasmic reticulum (ER)

KW - extrahaustorial membrane (EHM)

KW - powdery mildew

KW - Rab GTPase

KW - Sar1 GTPase

KW - secretion

U2 - 10.1093/jxb/erx403

DO - 10.1093/jxb/erx403

M3 - Journal article

C2 - 29237056

AN - SCOPUS:85042649764

SN - 0022-0957

VL - 68

SP - 5731

EP - 5743

JO - Journal of Experimental Botany

JF - Journal of Experimental Botany

IS - 21-22

ER -