جداسازی و شناسایی باکتری‌های محرک‌ رشد گیاه متحمل به شوری از ریزوسفر گیاهان شورزی

نوع مقاله : مقاله کامل علمی پژوهشی

نویسندگان

1 دانشجوی دکتری ، گروه علوم خاک، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران.

2 دانشیار ، گروه علوم خاک، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران.

3 استادیار، گروه علوم خاک، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران

4 استادیار پژوهشکده ژنتیک و زیست‌فناوری کشاورزی طبرستان، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران.

چکیده

سابقه و هدف: شوری یک مشکل جدی و یکی از عوامل اصلی کاهش تولید محصولات کشاورزی در سراسر جهان است. استفاده از ریزجانداران برای بهبود رشد گیاه در خاک بی‌کیفیت، یک راهکار بالقوه برای مقابله با این مشکل می‌باشد. جامعه میکروبی مقاوم به شوری، سلامت خاک تحت تاثیر شوری را بهبود بخشیده، عملکردهای اکولوژیکی را حفظ و رشد گیاهان را تقویت می‌کند. باکتری-های محرک رشد گیاه متحمل به شوری (ST-PGPR)، از طریق مکانیسم‌های متعددی قادر به تعدیل شرایط نامساعد تنش شوری برای گیاهان همزیست خود می‌باشند. هدف از پژوهش حاضر، جداسازی، شناسایی و بررسی ویژگی‌های باکتری‌های محرک رشد گیاه متحمل به شوری از ریزوسفر گیاهان شورزی می‌باشد.
مواد و روش‌ها: باکتری‌های محرک رشد گیاه متحمل به شوری از ریزوسفر گیاهان شورزی بومی شمال ایران جداسازی و مورد بررسی قرار گرفتند. جدایه‌های باکتری با توانایی رشد در محیط حداقل 2 مولار کلرید سدیم انتخاب و صفات تحرک، توانایی انحلال فسفات معدنی در محیط کشت PKV-آگار با استفاده از محاسبه شاخص انحلال فسفات، تولید سیدروفور در محیط کشت CAS-آگار و توان تولید آن با محاسبه شاخص توان تولید در آن‌ها ارزیابی شد. بر اساس نتایج بدست آمده، 10 جدایه برتر انتخاب شدند و توانایی تثبیت نیتروژن در محیط کشت Burk، انحلال پتاسیم در محیط Aleksandrov و توان انحلال آن توسط جدایه‌ها با استفاده از محاسبه شاخص انحلال پتاسیم و نیز تولید IAA-ذاتی و تولید IAA در حضور پیش ماده ال-تریپتوفان در آن‌ها مورد بررسی قرار گرفت و در نهایت شناسایی مولکولی جدایه‌های باکتری منتخب بر اساس توالی یابی ژن 16S rDNA انجام شد.
یافته‌ها: با بررسی توالی ژن 16S rDNA ، چهار جنس Bacillus، Klebsiella، Proteus و Halomonas شناسایی شدند. بیشترین جدایه‌ها به جنس Bacillus تعلق داشتند. گونه‌های متعلق به جنس‌های Klebsiella و Halomonas بیش ترین تحمل به نمک را داشتند. جنس Klebsiella توان انحلال فسفر و پتاسیم بیش تری نسبت به سایر جدایه‌ها نشان داد. بیش ترین میزان تولید سیدروفور در جدایه متعلق به جنس Proteus مشاهده شد. همه جدایه‌ها قادر به تثبیت نیتروژن بودند. در بین جدایه‌های مورد بررسی جدایه‌های Bacillus بیش ترین میزان تولید IAA-ذاتی را داشتند و در حضور پیش ماده ال-تریپتوفان میزان تولید IAA در جدایه B. licheniformis بیش از سایر جدایه‌ها بود.
نتیجه‌گیری: جداسازی طیف وسیعی از باکتری‎های متحمل به شوری با خصوصیات مطلوب از محیط ریزوسفر گیاهان شورزی نشان دهنده غنای میکروبی بالقوه این ناحیه می‌باشد که امکان یافتن ریزجانداران مفید محرک رشد گیاه به منظور کاستن اثرات نامطلوب تنش در گیاهان را فراهم می‌کند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Isolation and identification of salt tolerant-plant growth promoting bacteria from the rhizosphere of halophyte plants

نویسندگان [English]

  • Tahereh Safarzadeh 1
  • Mohsen Olamaee 2
  • Elham Malekzadeh 3
  • Seyed Alireza Movahedi naini 2
  • Ali Pakdin-Parizi 4
1 PhD student, Soil Science Department, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
2 Associate Professor, Soil Science Department, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran.
3 Assistant Professor, Soil Science Department, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
4 Assistant Professor, Tabaristan Agricultural Genetics and Biotechnology Research Institute, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran.
چکیده [English]

Isolation and identification of salt tolerant-plant growth promoting bacteria from the rhizosphere of halophyte plants
Background and purpose: Salinity is a serious problem and one of the main factors in reducing agricultural productivity worldwide. The use of microorganisms to improve plant growth in low quality soil is a potential solution to address this problem. The salinity resistant microbiome improves the health of the salinity affected soils, maintains ecological functions and enhances plant growth. Salt tolerant plant growth promoting rhizobacteria (ST-PGPR) are able to adjust the salinity stress adverse conditions for their symbiotic plants through several mechanisms. This study aimed to isolation, identification and investigation the characteristics of salt tolerant-plant growth promoting rhizobacteria from the rhizosphere of halophyte plants.
Materials and methods: Salinity tolerant plant growth promoting bacteria were isolated from the rhizosphere of native halophyte plants collected from the north of Iran. Bacterial isolates were selected according to their ability to growth in 2 M sodium chloride and traits of the motility, inorganic phosphate solubilization ability in PKV-Agar medium using phosphate solubilization index calculation, and siderophore production capacity in CAS-agar medium by calculating of its production index. Then, the top 10 isolates were selected and the ability of nitrogen fixation in Burk's medium, potassium dissolution in Aleksandrov's medium by using potassium solubilization index, as well as, the production of intrinsic IAA and the tryptophan-dependent IAA were investigated. Finally, molecular identification of selected bacterial isolates was performed based on 16S rDNA gene sequencing.
Findings: Four genera of Bacillus, Klebsiella, Proteus and Halomonas were identified after 16S rDNA gene sequencing. All isolates were motile. The most of isolates belonged to the genus Bacillus. Species belonging to Klebsiella and Halomonas genera had the highest salt tolerance. Klebsiella genus showed phosphorus and potassium solubilizing ability more than other isolates. The highest amount of siderophore production was observed in the isolate belonging to Proteus genus. All isolates were able to fix nitrogen. Among the studied isolates, Bacillus isolates had the highest rate of intrinsic IAA, and the tryptophan-dependent IAA production in B. licheniformis was higher than other isolates.
Conclusion: Isolation of wide range of salt-tolerant bacteria with favorable characteristics from the rhizosphere of halophyte plants indicates the microbial richness potential of this area, which provides the possibility of finding useful microorganisms that promote plant growth and reduce the adverse effects of stress in plants.
Keywords: Plant growth promoting bacteria, Salinity stress, Halophyte plants, Indole acetic acid

کلیدواژه‌ها [English]

  • Plant growth promoting bacteria
  • Salinity stress
  • Halophyte plants
  • Indole acetic acid
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