leaves (Wang et al. 2016). Besides, it was also speculated that MSP1-induced
signaling in rice leaves is mediated by the activity of protein kinase(s). Furthermore,
it was shown that the phytohormones jasmonic acid and abscisic acid positively
regulate the MSP1 induced signaling while salicylic acid was involved in the
suppression of MSP1 induced signaling in rice (Wang et al. 2016). In contrast, a
recent report showed the accumulation of both JA and SA in MSP1 overexpression
lines of rice together with the upregulation of SA and JA signaling genes. Further,
MSP1 overexpression lines conferred broad-spectrum resistance to rice blast and
bacterial blight diseases, however, no effects on the resistance against sheath blight
and drought and salt stress tolerance were observed in the MSP1 overexpressing
lines as compared to the wild type (Hong et al. 2017). Moreover, MSP1
overexpression did not affect the grain yield, suggesting that MSP1 overexpression
lines of rice can be used in the future to combat the two deadliest rice pathogens
including M. oryzae and X. oryzae without compromising the overall yield.
In order to understand the molecular mechanism of MSP1 induced signaling in
rice, transcriptomic, high-throughput proteomic, and phosphoproteomic analyses of
rice leaves have been carried out upon exogenous treatment of recombinant MSP1
(Gupta et al. 2019; Meng et al. 2018a, b, 2019a). It was shown that exogenous
treatment of recombinant MSP1 protein resulted in the oxidative burst, MAPK3/6
phosphorylation, and upregulation of pathogenesis-related genes such as DUF26,
PBZ, and PR-10 in rice leaves. Transcriptomic analysis showed that the proteins
related to photosynthesis, secondary metabolism, lipid synthesis, and protein synthesis were specifically downregulated in response to MSP1 treatment. In contrast,
the upregulated proteins were found to be related to the protein and lipid degradation, posttranslational modifications, and signaling (Meng et al. 2018a). These
results were further supplemented by the proteome analysis using a label-free
quantitative proteomics approach (Meng et al. 2019a). In addition, proteomics
results also showed an increased abundance of various peroxidases and receptor
kinases and proteins related to jasmonic acid biosynthesis, redox signaling, and
MAP kinase signaling upon MSP1 perception, suggesting key functions of these in
MSP1 induced signaling in rice (Gupta et al. 2019; Meng et al. 2018b, 2019a).
Phosphoproteome analysis showed MSP1 induced phosphorylation of some of the
key proteins associated with the PTI response, suggesting the function of MSP1 as a
PAMP (Gupta et al. 2019).
12.2.4 MoHRIP1-Induced Signaling in Rice
MoHrip1 is a 14.32 kDa Alt A 1 (AA1) family protein, which was found to be
secreted out from the M. oryzae as well as associated with the fungal cell wall.
Downstream responses of MoHrip1 are similar to that of MSP1 as exogenous
treatment of recombinant MoHrip1 resulted in H 2 O 2 production, callose deposition,
and induction of hypersensitive response in tobacco (Chen et al. 2012). Further, it
was shown that rice seedlings treated with MoHrip1 showed upregulation of
PR-proteins, and enhanced systemic resistance against M. oryzae (Chen et al.
368
N. Khatri et al.
signaling in rice leaves is mediated by the activity of protein kinase(s). Furthermore,
it was shown that the phytohormones jasmonic acid and abscisic acid positively
regulate the MSP1 induced signaling while salicylic acid was involved in the
suppression of MSP1 induced signaling in rice (Wang et al. 2016). In contrast, a
recent report showed the accumulation of both JA and SA in MSP1 overexpression
lines of rice together with the upregulation of SA and JA signaling genes. Further,
MSP1 overexpression lines conferred broad-spectrum resistance to rice blast and
bacterial blight diseases, however, no effects on the resistance against sheath blight
and drought and salt stress tolerance were observed in the MSP1 overexpressing
lines as compared to the wild type (Hong et al. 2017). Moreover, MSP1
overexpression did not affect the grain yield, suggesting that MSP1 overexpression
lines of rice can be used in the future to combat the two deadliest rice pathogens
including M. oryzae and X. oryzae without compromising the overall yield.
In order to understand the molecular mechanism of MSP1 induced signaling in
rice, transcriptomic, high-throughput proteomic, and phosphoproteomic analyses of
rice leaves have been carried out upon exogenous treatment of recombinant MSP1
(Gupta et al. 2019; Meng et al. 2018a, b, 2019a). It was shown that exogenous
treatment of recombinant MSP1 protein resulted in the oxidative burst, MAPK3/6
phosphorylation, and upregulation of pathogenesis-related genes such as DUF26,
PBZ, and PR-10 in rice leaves. Transcriptomic analysis showed that the proteins
related to photosynthesis, secondary metabolism, lipid synthesis, and protein synthesis were specifically downregulated in response to MSP1 treatment. In contrast,
the upregulated proteins were found to be related to the protein and lipid degradation, posttranslational modifications, and signaling (Meng et al. 2018a). These
results were further supplemented by the proteome analysis using a label-free
quantitative proteomics approach (Meng et al. 2019a). In addition, proteomics
results also showed an increased abundance of various peroxidases and receptor
kinases and proteins related to jasmonic acid biosynthesis, redox signaling, and
MAP kinase signaling upon MSP1 perception, suggesting key functions of these in
MSP1 induced signaling in rice (Gupta et al. 2019; Meng et al. 2018b, 2019a).
Phosphoproteome analysis showed MSP1 induced phosphorylation of some of the
key proteins associated with the PTI response, suggesting the function of MSP1 as a
PAMP (Gupta et al. 2019).
12.2.4 MoHRIP1-Induced Signaling in Rice
MoHrip1 is a 14.32 kDa Alt A 1 (AA1) family protein, which was found to be
secreted out from the M. oryzae as well as associated with the fungal cell wall.
Downstream responses of MoHrip1 are similar to that of MSP1 as exogenous
treatment of recombinant MoHrip1 resulted in H 2 O 2 production, callose deposition,
and induction of hypersensitive response in tobacco (Chen et al. 2012). Further, it
was shown that rice seedlings treated with MoHrip1 showed upregulation of
PR-proteins, and enhanced systemic resistance against M. oryzae (Chen et al.
368
N. Khatri et al.