Cotton GhMKK1 Induces the Tolerance of Salt and Drought Stress, and Mediates Defence Responses to Pathogen Infection in Transgenic Nicotiana benthamiana

Abstract

Mitogen-activated protein kinase kinases (MAPKK) mediate a variety of stress responses in plants. So far little is known on the functional role of MAPKKs in cotton. In the present study, Gossypium hirsutum MKK1 (GhMKK1) function was investigated. GhMKK1 protein may activate its specific targets in both the nucleus and cytoplasm. Treatments with salt, drought, and H2O2 induced the expression of GhMKK1 and increased the activity of GhMKK1, while overexpression of GhMKK1 in Nicotiana benthamiana enhanced its tolerance to salt and drought stresses as determined by many physiological data. Additionally, GhMKK1 activity was found to up-regulate pathogen-associated biotic stress, and overexpression of GhMKK1 increased the susceptibility of the transgenic plants to the pathogen Ralstonia solanacearum by reducing the expression of PR genes. Moreover, GhMKK1-overexpressing plants also exhibited an enhanced reactive oxygen species scavenging capability and markedly elevated activities of several antioxidant enzymes. These results indicate that GhMKK1 is involved in plants defence responses and provide new data to further analyze the function of plant MAPK pathways.

Sp-miR396a-5p acts as a stress-responsive genes regulator by conferring tolerance to abiotic stresses and susceptibility to Phytophthora nicotianae infection in transgenic tobacco

“…This suggested that Sp-miR396a-5p might play a positive role in the regulation of abiotic stress and a negative role in P. nicotianae infection. It is not unusual for a gene to have multiple functions, including those that result in opposing results in the regulation of abiotic and biotic responses Lu et al 2013). Previous studies have indicated that members of the miR396 family also play a role in the response to infection by multiple pathogens.…”

“…After 7 days inoculated with P. nicotianae, the tobacco leaves were collected for trypan blue staining assays, performed as described by Lu et al (2013).…”

LcMKK, a novel group A mitogen-activated protein kinase kinase gene in Lycium chinense, confers dehydration and drought tolerance in transgenic tobacco via scavenging ROS and modulating expression of stress-responsive genes

“…As the nodal point of the MAPK cascades, MAPKKs play paramount roles in amplifying, integrating, and channeling information between the extracellular stimuli and intracellular responses (Kong et al 2011a;Lu et al 2013). L. chinense has great capability for environmental adaption.…”

“…It has been proposed that plant MAPKKs can be classified into four distinct groups (A, B, C and D) from the homology analysis of the predicted proteins (Lu et al 2013). The phylogenetic analysis showed that LcMKK exhibited a high similarity with members of the group A MAPKKs, such as AtMKK1 and AtMKK2.…”

“…NtMEK2 can activate WIPK and SIPK to transmit osmotic stress signals (Mikołajczyk et al 2000). Overexpression of GhMKK1 in Nicotiana benthamiana enhanced its tolerance to drought stress (Lu et al 2013). Although many studies have focused on how MAPKKs function in response to abiotic stresses, the role of MAPKK signaling following drought stress is still an issue of great interest.…”