Du Yu's research group at the College of Horticulture, Northwest A&F University made new progress in the mechanism of potato resistance to late blight

Recently, Professor Du Yu's research group at the School of Horticulture, Northwest A&F University published a research paper
entitled "StMPK7 phosphorylates and stabilizes a potato RNA-binding protein StUBA2a/b to enhance plant defence responses" in Horticulture Research 。 The study revealed that StMPK7 is phosphorylated and stabilizes its downstream signaling component, the RNA-binding protein StUBA2a/b, thereby enhancing plant resistance
to Phytophthora fungus.

 

Potato late blight, caused by the disease-causing Phytophthora infestans, is one of the main diseases of the potato and poses a serious threat to the sustainable production
of the potato.
The loss of pathogen resistance and variety resistance makes the prevention and control of potato late blight difficult, so accelerating the cultivation of resistant varieties is of great significance
for the green and efficient prevention and control of potato late blight.
The study of plant disease resistance mechanism is the theoretical basis of disease resistance breeding, which is expected to provide genetic resources and new ideas
for the breeding of resistant varieties.
Mitogen-activated protein kinase (MAPK) cascade plays a very important role in responding to plant biological and abiotic stresses, and the previous study of the research group found that an RXLR effector protein of Phytophthora pathogenic H.
floristoces targeted and stabilized the plant immune negative regulator StMKK1 (potato mitogen-activated protein kinase kinase) (Du et).
al.
, 2021); Further studies revealed that StMKK1 regulates plant immunity through the negative regulation of the PTI (PAMP-triggered immunity) response and the Salicylic acid (SA) signaling pathway (Chen et al.
, 2021); In addition, the research group also identified StMPK7, the direct downstream signaling component of StMKK1, and found that StMPK7 is regulating plant resistance to Phytophthora through the SA signaling pathway (Zhang et al.
, 2021).

However, the downstream signaling molecules of StMPK7 are not known
.

 

Based on StMPK7's transgenic potato as the material, the candidate intercropping protein StUBA2a/b of StMPK7 was identified by immunoprecipitation-binding mass spectrometry, and the immunocoprecipitation and luciferase complementary imaging experiments consistently showed that there was an interaction between
StMPK7 and StUBA2a/b 。 The Western blot results showed that StMPK7 phosphorylated StUBA2a/b at the T248 and T408 sites and significantly promoted the protein accumulation of StUBA2a/b, indicating that StUBA2a/b is the direct downstream signaling
component of StMPK7.

 

The researchers verified that potato StUBA2a/b, Ben's tobacco NbUBA2a/b, and tomato SlUBA2a/b can positively regulate plant resistance to Phytosis and the expression of SA-associated PR genes by techniques such as transient expression of Tobacco Ben's and virus-induced gene silencing
.

 

StUBA2a/b can trigger cell necrosis in the leaves of Honn's tobacco, and the researchers found that silencing NbMPK7 can inhibit StUBA2a/b-induced cell necrosis, while overexpression of StMPK7 can promote the necrosis of this cell, after the mutated StUBA2a/b phosphorylation site (StUBA2a/bT248/408A), the cell necrosis is also significantly weakened, indicating that StMPK7 enhances its function in disease resistance by phosphorylation of StUBA2a/b
。 In addition, silencing NbUBA2a/b significantly inhibited plant cell necrosis triggered by CA-StMPK7 (StMPK7 with constitutive kinase activity), and overexpression of StUBA2a/b promoted the cell necrosis, further confirming that StUBA2a/b is a downstream signaling molecule
of StMPK7.
In summary, the researchers revealed that StMPK7 enhances plant resistance
to Phytophthora by phosphorylation and stabilization of its downstream signaling component, StUBA2a/b.

 

Professor Du Yu of the School of Horticulture is the corresponding author of the paper, Dr.
Li Tingting, a young teacher, and Zhang Haizhu, a master's student, are the co-first authors, and many graduate students in the research group also participated in the study
.
The research was supported
by the National Natural Science Foundation of China (32072401, 32102176), the Young Talents Cultivation Program of Northwest A&F University (2452018028), and the Natural Science Foundation of Shaanxi Province (2021JQ-164).

 

Original link: https://doi.
org/10.
1093/hr/uhac177