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UvHOG1 is important for hyphal growth and stress responses in the rice false smut fungus Ustilaginoidea virens.

Zheng D, Wang Y, Han Y, Xu JR, Wang C - Sci Rep (2016)

Bottom Line: Deletion of UvHOG1 resulted in reduced expression of the stress response-related genes UvATF1 and UvSKN7.In the Uvhog1 mutant, NaCl treatment failed to stimulate the accumulation of sorbitol and glycerol.In addition, the Uvhog1 mutant had reduced toxicity on shoot growth in rice seed germination assays.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.

ABSTRACT
Rice false smut caused by Ustilaginoidea virens is one of the most important diseases of rice worldwide. Although its genome has been sequenced, to date there is no report on targeted gene deletion in U. virens and no molecular studies on genetic mechanisms regulating the infection processes of this destructive pathogen. In this study, we attempted to generate knockout mutants of the ortholog of yeast HOG1 MAP kinase gene in U. virens. One Uvhog1 deletion mutant was identified after screening over 600 hygromycin-resistant transformants generated by Agrobacterium tumefaciens mediated transformation. The Uvhog1 mutant was reduced in growth rate and conidiation but had increased sensitivities to SDS, Congo red, and hyperosmotic stress. Deletion of UvHOG1 resulted in reduced expression of the stress response-related genes UvATF1 and UvSKN7. In the Uvhog1 mutant, NaCl treatment failed to stimulate the accumulation of sorbitol and glycerol. In addition, the Uvhog1 mutant had reduced toxicity on shoot growth in rice seed germination assays. Overall, as the first report of targeted gene deletion mutant in U. virens, our results showed that UvHOG1 likely has conserved roles in regulating stress responses, hyphal growth, and possibly secondary metabolism.

No MeSH data available.


Related in: MedlinePlus

Metabolic profiles of the wild type and Uvhog1 mutant.Vegetative hyphae were harvested from two-day-old YT cultures of the wild type strain UV-8b and Uvhog1 mutant treated with or without 1.0 M NaCl for 1 h. Metabolites were extracted and analyzed by GC-MS. The X-axis represents the retention time (RT) in minutes. The Y-axis is the abundance of total ion current (TIC). The peaks with RT of 6.031 and 25.308 are glycerol and sorbitol, respectively. The peak with RT of 7.223 minutes is isocetane.
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f4: Metabolic profiles of the wild type and Uvhog1 mutant.Vegetative hyphae were harvested from two-day-old YT cultures of the wild type strain UV-8b and Uvhog1 mutant treated with or without 1.0 M NaCl for 1 h. Metabolites were extracted and analyzed by GC-MS. The X-axis represents the retention time (RT) in minutes. The Y-axis is the abundance of total ion current (TIC). The peaks with RT of 6.031 and 25.308 are glycerol and sorbitol, respectively. The peak with RT of 7.223 minutes is isocetane.

Mentions: Glycerol, sorbitol, and other neutral compatible solutes are known to be accumulated in different fungi in response to hyperosmotic stress33. To determine the compatible solutes accumulated in U. virens in response to hyperosmotic stress, we assayed metabolites in cultures treated with or without 1.0 M NaCl. In the wild type, sorbitol that has the retention time (RT) of 25.308 min was significantly induced by NaCl treatment (Fig. 4). Glycerol (RT = 6.031 min) was also slightly induced by NaCl treatment in UV-8b. However, the production of these two compatible solutes was not or barely detectable in hyphae of the Uvhog1 mutant treated with or without 1.0 M NaCl (Fig. 4). These results indicate that sorbitol is the main compatible solute in U. virens under hyperosmotic conditions, and its accumulation is under the control of the UvHOG1 MAP kinase pathway. Glycerol accumulation is also controlled by UvHOG1 but its contribution to adaptation to hyperosmotic stress may be not as significant as sorbitol.


UvHOG1 is important for hyphal growth and stress responses in the rice false smut fungus Ustilaginoidea virens.

Zheng D, Wang Y, Han Y, Xu JR, Wang C - Sci Rep (2016)

Metabolic profiles of the wild type and Uvhog1 mutant.Vegetative hyphae were harvested from two-day-old YT cultures of the wild type strain UV-8b and Uvhog1 mutant treated with or without 1.0 M NaCl for 1 h. Metabolites were extracted and analyzed by GC-MS. The X-axis represents the retention time (RT) in minutes. The Y-axis is the abundance of total ion current (TIC). The peaks with RT of 6.031 and 25.308 are glycerol and sorbitol, respectively. The peak with RT of 7.223 minutes is isocetane.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837404&req=5

f4: Metabolic profiles of the wild type and Uvhog1 mutant.Vegetative hyphae were harvested from two-day-old YT cultures of the wild type strain UV-8b and Uvhog1 mutant treated with or without 1.0 M NaCl for 1 h. Metabolites were extracted and analyzed by GC-MS. The X-axis represents the retention time (RT) in minutes. The Y-axis is the abundance of total ion current (TIC). The peaks with RT of 6.031 and 25.308 are glycerol and sorbitol, respectively. The peak with RT of 7.223 minutes is isocetane.
Mentions: Glycerol, sorbitol, and other neutral compatible solutes are known to be accumulated in different fungi in response to hyperosmotic stress33. To determine the compatible solutes accumulated in U. virens in response to hyperosmotic stress, we assayed metabolites in cultures treated with or without 1.0 M NaCl. In the wild type, sorbitol that has the retention time (RT) of 25.308 min was significantly induced by NaCl treatment (Fig. 4). Glycerol (RT = 6.031 min) was also slightly induced by NaCl treatment in UV-8b. However, the production of these two compatible solutes was not or barely detectable in hyphae of the Uvhog1 mutant treated with or without 1.0 M NaCl (Fig. 4). These results indicate that sorbitol is the main compatible solute in U. virens under hyperosmotic conditions, and its accumulation is under the control of the UvHOG1 MAP kinase pathway. Glycerol accumulation is also controlled by UvHOG1 but its contribution to adaptation to hyperosmotic stress may be not as significant as sorbitol.

Bottom Line: Deletion of UvHOG1 resulted in reduced expression of the stress response-related genes UvATF1 and UvSKN7.In the Uvhog1 mutant, NaCl treatment failed to stimulate the accumulation of sorbitol and glycerol.In addition, the Uvhog1 mutant had reduced toxicity on shoot growth in rice seed germination assays.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.

ABSTRACT
Rice false smut caused by Ustilaginoidea virens is one of the most important diseases of rice worldwide. Although its genome has been sequenced, to date there is no report on targeted gene deletion in U. virens and no molecular studies on genetic mechanisms regulating the infection processes of this destructive pathogen. In this study, we attempted to generate knockout mutants of the ortholog of yeast HOG1 MAP kinase gene in U. virens. One Uvhog1 deletion mutant was identified after screening over 600 hygromycin-resistant transformants generated by Agrobacterium tumefaciens mediated transformation. The Uvhog1 mutant was reduced in growth rate and conidiation but had increased sensitivities to SDS, Congo red, and hyperosmotic stress. Deletion of UvHOG1 resulted in reduced expression of the stress response-related genes UvATF1 and UvSKN7. In the Uvhog1 mutant, NaCl treatment failed to stimulate the accumulation of sorbitol and glycerol. In addition, the Uvhog1 mutant had reduced toxicity on shoot growth in rice seed germination assays. Overall, as the first report of targeted gene deletion mutant in U. virens, our results showed that UvHOG1 likely has conserved roles in regulating stress responses, hyphal growth, and possibly secondary metabolism.

No MeSH data available.


Related in: MedlinePlus