Comparative transient expression analyses on two conserved effectors of Colletotrichum orbiculare reveal their distinct cell death‐inducing activities between Nicotiana benthamiana and melon

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We recently reported that C. orbiculare transformants constitutively expressing NLP1 failed to develop lesions in multiple cucurbits, including melon (Azmi et al., 2018). However, in contrast to

cucurbits, C. orbiculare constitutively expressing NLP1 caused lesions in N. benthamiana (Azmi et al., 2018), although the transient

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(Figure 1b,c). These findings suggest the possibility that cytoplasmic

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In our study, the expression of C. orbiculare NIS1 in melon via the

new transient expression system showed that NIS1 did not exhibit the

ability to induce cell death in melon, in contrast to N. benthamiana, even

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suppress PTI signalling is conserved in both plants. We previously reported that NIS1-­induced cell death depends on both SGT1 and HSP90

(Yoshino et al., 2012), which suggests that NIS1-­induced cell death may

be triggered via the recognition by an unidentified resistance (R) protein. Therefore, melon may not have the R protein for NIS1 recognition.

Overall, our results show that the cell death-­inducing activities

and underlying mechanisms of the two C. orbiculare effectors differ

between N. benthamiana and melon, both of which can be infected

by this pathogen. For a greater understanding of the effector function of plant pathogens, it will be important to establish new transient expression systems in corresponding host plants in addition to

the commonly used N. benthamiana.

AC K N OW L E D G E M E N T S

The authors thank Drs Satoko Nonaka and Hiroshi Ezura for providing Agrobacterium GV2260 (gabT). The authors also thank Dr George

Lomonossoff for providing both pEAQ-­

HT and pEAQ-­

HT-­

GFP.

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S U P P O R T I N G I N FO R M AT I O N

Additional Supporting Information may be found online in the

Supporting Information section.

How to cite this article: Chen J, Inoue Y, Kumakura N, Mise

K, Shirasu K, Takano Y. Comparative transient expression

analyses on two conserved effectors of Colletotrichum

orbiculare reveal their distinct cell death-­inducing activities

between Nicotiana benthamiana and melon. Mol Plant Pathol.

2021;22:1006–­1013. https://doi.org/10.1111/mpp.13078

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