Cotton GhMPK6a negatively regulates osmotic tolerance and bacterial infection in transgenic Nicotiana benthamiana, and plays a pivotal role in development

Abstract

Mitogen-activated protein kinase (MAPK) cascades play important roles in the perception of external signals and the generation of suitable responses. Cotton (Gossypium hirsutum) is an important fibre-producing and oil-producing crop worldwide. However, few MAPKs and their interaction partners have been functionally characterized in cotton. In the present study, the group A MAPK G. hirsutum (Gh)MPK6a was identified and characterized. GhMPK6a expression can be induced through multiple defence-related signal molecules and abiotic and biotic stresses. The ectopic expression of GhMPK6a in Nicotiana benthamiana reduced drought and salt tolerance, with elevated malondialdehyde content, higher reactive oxygen species content and lower abscisic acid content than in wild-type plants. Moreover, plants overexpressing GhMPK6a were sensitive to the bacterial pathogen Ralstonia solanacearum. Histochemical analysis of b-glucuronidase activity revealed that GhMPK6a showed tissue-specific expression during postgermination development, mixed bud differentiation, and pollination. Most importantly, GhMPK6a interacts with the upstream MAPK kinase GhMKK4, as shown by the use of yeast two-hybrid and bimolecular fluorescence complementation systems, compensating for a deficiency of MAPK interaction partners in cotton crops. Taken together, these results suggest that GhMPK6a negatively regulates osmotic stress and bacterial infection, and plays an important role in developmental processes. These results provide useful information for elucidating the roles of MAPK cascades in cotton crops. Structured digital abstractGhMPK6a physically interacts with GhMPK4 by two hybrid (View interaction) GhMPK6a and GhMPK4 physically interact by bimolecular fluorescence complementation (View interaction)

Genome-wide identification of mitogen-activated protein kinase gene family in Gossypium raimondii and the function of their corresponding orthologs in tetraploid cultivated cotton

“…OsMPK5 is also induced by abiotic stresses, pathogen infection and ABA treatment [56]. In cotton, GhMPK6a, GhMPK7 and GhMPK16 are involved in the pathogen-resistance response [24][25][26]. Here, we found that MPK9, MPK13 and MPK25 were significantly upregulated in cotton roots after inoculation with V. dahliae, and these three genes were upregulated in leaves after exposure to JA, H 2 O 2 , ABA and SA.…”

“…In cotton, GhMPK2 and GbMPK3 are upregulated by diverse abiotic stresses and likely play a role in drought and oxidative stress tolerance [21,22]. GhMPK6 plays an important role in ABA-induced CAT1 expression and H 2 O 2 production [23], whereas GhMPK6a negatively regulates responses to osmotic stress and bacterial infection [24]. GhMPK7 and GhMPK16 are involved in plant defense responses and the regulation of certain components of multiple stress-signaling pathways [25,26].…”

GhWRKY40, a Multiple Stress-Responsive Cotton WRKY Gene, Plays an Important Role in the Wounding Response and Enhances Susceptibility to Ralstonia solanacearum Infection in Transgenic Nicotiana benthamiana

“…The last decade of research has shown that MPKs regulate WRKY TFs in response to multiple stresses. In previous studies, we functionally identified two MAPK genes from cotton, GhMPK6a [43] and GhMPK20 (unpublished). The results obtained in the present study indicate that GhWRKY40 interacts with GhMPK20 but not with GhMPK6a (Fig.…”

Genome-Wide Identification and Expression Analysis of the Mitogen-Activated Protein Kinase Gene Family in Cassava

“…As an ancestor of the wild cassava subspecies, W14 had greater drought tolerance than SC124 and Arg7 (Wang et al, 2014). Numerous evidences have confirmed that MAPK cascades play a positive role in response to drought or osmotic stress in plants (Ichimura et al, 2000; Teige et al, 2004; Kim et al, 2011; Li et al, 2013); therefore, we speculated that the high ratio of MAPK genes induced by drought in W14 might contribute to its strong drought tolerance. The response of plants to drought stress are complicated process, including perception of stress signals and their transduction that activate various stress-related genes and synthesis of proteins with diverse functions resulting in physiological and metabolic responses (Hu et al, 2013).…”

“…Several studies have demonstrated that MAPK genes play a positive role in osmotic stress, including GhMPK17, SpMPK3, GhMPK2 , and CsNMAPK (Xu et al, 2010; Zhang et al, 2011, 2014b; Li et al, 2014). On the other hand, some MAPKs , including AtMPK4 and GhMPK6a , were reported to negatively regulate osmotic stress tolerance (Droillard et al, 2004; Li et al, 2013). Based on these results, we speculated that MeMAPKs might play an important role in osmotic stress response.…”