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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

Assays for toxicity of U. virens culture filtrates with rice seeds.Seeds of rice cultivar YA-5A were incubated on filter papers soaked with blank control or filtrates of 5-day-old YT cultures of UV-8b, 7-day-old Uvhog1 mutant, and 5-day-old complementary strain. Shoot and root growth were examined after incubation at 25 °C for 5 days.
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f5: Assays for toxicity of U. virens culture filtrates with rice seeds.Seeds of rice cultivar YA-5A were incubated on filter papers soaked with blank control or filtrates of 5-day-old YT cultures of UV-8b, 7-day-old Uvhog1 mutant, and 5-day-old complementary strain. Shoot and root growth were examined after incubation at 25 °C for 5 days.

Mentions: To determine whether deletion of UvHOG1 affects the production of phytotoxic compounds, we isolated the culture filtrates from YT cultures of 5-day-old wild-type strain UV-8b, 7-day-old Uvhog1 mutant M1, and 5-day-old complementary transformant C1 as described35 with minor modifications. The dry weights of vegetative hyphae were quantified to show that the wild type and Uvhog1 mutant strains had similar biomasses in these YT cultures (see Supplementary Table S3 online). When assayed with rice seeds of cultivar YA-5A, culture filtrates of the wild type, Uvhog1 mutant, and complemented strains blocked root growth after incubation for 5 days at room temperature (Fig. 5). No visible root growth was observed in the rice seeds treated with culture filtrates of U. virens. Rice shoot growth also was significantly stunted in samples treated with culture filtrates of the wild type and complemented transformant. Whereas rice shoots were green and began to form the first leaf by 5 days in the water treatment control, only whitish, short shoots were observed in samples treated with culture filtrates of strains UV-8b or C1 (Fig. 5). However, rice shoot growth was less sensitive to culture filtrates of the Uvhog1 mutant (Fig. 5). In repeated experiments, shoot growth was significantly longer in samples treated withfiltrates of 7-day-old mutant cultures than those of 5-day-old wild type or complemented transformant cultures (Table 3), suggesting that UvHOG1 may be involved in regulating the production of phytotoxic compounds that are inhibitory to rice shoot growth during seed germination.


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)

Assays for toxicity of U. virens culture filtrates with rice seeds.Seeds of rice cultivar YA-5A were incubated on filter papers soaked with blank control or filtrates of 5-day-old YT cultures of UV-8b, 7-day-old Uvhog1 mutant, and 5-day-old complementary strain. Shoot and root growth were examined after incubation at 25 °C for 5 days.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Assays for toxicity of U. virens culture filtrates with rice seeds.Seeds of rice cultivar YA-5A were incubated on filter papers soaked with blank control or filtrates of 5-day-old YT cultures of UV-8b, 7-day-old Uvhog1 mutant, and 5-day-old complementary strain. Shoot and root growth were examined after incubation at 25 °C for 5 days.
Mentions: To determine whether deletion of UvHOG1 affects the production of phytotoxic compounds, we isolated the culture filtrates from YT cultures of 5-day-old wild-type strain UV-8b, 7-day-old Uvhog1 mutant M1, and 5-day-old complementary transformant C1 as described35 with minor modifications. The dry weights of vegetative hyphae were quantified to show that the wild type and Uvhog1 mutant strains had similar biomasses in these YT cultures (see Supplementary Table S3 online). When assayed with rice seeds of cultivar YA-5A, culture filtrates of the wild type, Uvhog1 mutant, and complemented strains blocked root growth after incubation for 5 days at room temperature (Fig. 5). No visible root growth was observed in the rice seeds treated with culture filtrates of U. virens. Rice shoot growth also was significantly stunted in samples treated with culture filtrates of the wild type and complemented transformant. Whereas rice shoots were green and began to form the first leaf by 5 days in the water treatment control, only whitish, short shoots were observed in samples treated with culture filtrates of strains UV-8b or C1 (Fig. 5). However, rice shoot growth was less sensitive to culture filtrates of the Uvhog1 mutant (Fig. 5). In repeated experiments, shoot growth was significantly longer in samples treated withfiltrates of 7-day-old mutant cultures than those of 5-day-old wild type or complemented transformant cultures (Table 3), suggesting that UvHOG1 may be involved in regulating the production of phytotoxic compounds that are inhibitory to rice shoot growth during seed germination.

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