Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annus

The present study was aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from the rhizosphere of rainfed area (Karak) in Pakistan. The influence of isolated rhizobacteria, in association with salicylic acid (SA), physiological attributes, drought tolerance potential, and p...

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Main Authors: Naeem Khan, Peiman Zandi, Shahid Ali, Asif Mehmood, Muhammad Adnan Shahid, Jianjun Yang
Format: Article
Language:English
Published: Frontiers Media S.A. 2018-10-01
Series:Frontiers in Microbiology
Subjects:
Online Access:https://www.frontiersin.org/article/10.3389/fmicb.2018.02507/full
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author Naeem Khan
Peiman Zandi
Shahid Ali
Asif Mehmood
Muhammad Adnan Shahid
Jianjun Yang
author_facet Naeem Khan
Peiman Zandi
Shahid Ali
Asif Mehmood
Muhammad Adnan Shahid
Jianjun Yang
author_sort Naeem Khan
collection DOAJ
description The present study was aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from the rhizosphere of rainfed area (Karak) in Pakistan. The influence of isolated rhizobacteria, in association with salicylic acid (SA), physiological attributes, drought tolerance potential, and phytoremediation in drought-stressed sunflower exposed was investigated. The isolated bacteria were named P1 and P2 and characterized on the basis of colony morphology and biochemical traits. Both PGPR P1 and P2 were identified on the basis of 16S-rRNA gene sequencing as Planomicrobium chinense strain P1 (Accession No. MF616408) and Bacillus cereus strain P2 (Accession No. MF616406). The fresh cultures (24 h old) of isolates were used to soak the seeds pre-sowing. SA was foliar applied at three-leaf-stage. Likewise, the 30-days-old seedlings (three leaf stage) were exposed to drought stress. Drought stress was imposed to 30-days-old plants (three-leaf stage) by withholding water supply for the next 15 days until the soil water content reached 10%. The PGPR and/or SA treatment resulted in significant accumulation of Cd (84%), Pb (66%), and Ni (65%) in the rhizosphere. PGPR also induced accumulation of Cd and Ni in plant shoot. Combined treatment of PGPR and SA increased the Cu (21%), Co (11%), and Zn (8%) accumulation but decreased (12%) the Fe accumulation as compared to coinoculation of PGPR P1 and P2. Inoculation of plants with PGPR significantly increased shoot length (60%), root length (68%), root fresh (61%), and dry (63%) biomass under water stress. The inoculated plants had increased chlorophyll (67%), carotenoid (70%), leaf protein (64%), sugar (64%), and phenolic (62%) contents while lower leaf proline (62%) content, malondialdehyde (MDA) (64%), and antioxidant enzymes (67%) which suggest their role in drought tolerance. It is concluded that integrative use of PGPR in combination with SA found to be an efficacious strategy to improve the phytoremediation of heavy metals and plant growth under stressed conditions particularly under water-deficient conditions.
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spelling doaj.art-12511e6ca18d450a9386111d48eeec922022-12-21T19:20:23ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2018-10-01910.3389/fmicb.2018.02507413204Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annusNaeem Khan0Peiman Zandi1Shahid Ali2Asif Mehmood3Muhammad Adnan Shahid4Jianjun Yang5Department of Plant Sciences, Quaid-i-Azam University, Islamabad, PakistanInstitute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, ChinaPlant Epigenetics and Development Lab, Northeast Forestry University, Harbin, ChinaDepartment of Botany, Abdul Wali Khan University Mardan, Mardan, PakistanHorticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United StatesInstitute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, ChinaThe present study was aimed to isolate and characterize plant growth promoting rhizobacteria (PGPR) from the rhizosphere of rainfed area (Karak) in Pakistan. The influence of isolated rhizobacteria, in association with salicylic acid (SA), physiological attributes, drought tolerance potential, and phytoremediation in drought-stressed sunflower exposed was investigated. The isolated bacteria were named P1 and P2 and characterized on the basis of colony morphology and biochemical traits. Both PGPR P1 and P2 were identified on the basis of 16S-rRNA gene sequencing as Planomicrobium chinense strain P1 (Accession No. MF616408) and Bacillus cereus strain P2 (Accession No. MF616406). The fresh cultures (24 h old) of isolates were used to soak the seeds pre-sowing. SA was foliar applied at three-leaf-stage. Likewise, the 30-days-old seedlings (three leaf stage) were exposed to drought stress. Drought stress was imposed to 30-days-old plants (three-leaf stage) by withholding water supply for the next 15 days until the soil water content reached 10%. The PGPR and/or SA treatment resulted in significant accumulation of Cd (84%), Pb (66%), and Ni (65%) in the rhizosphere. PGPR also induced accumulation of Cd and Ni in plant shoot. Combined treatment of PGPR and SA increased the Cu (21%), Co (11%), and Zn (8%) accumulation but decreased (12%) the Fe accumulation as compared to coinoculation of PGPR P1 and P2. Inoculation of plants with PGPR significantly increased shoot length (60%), root length (68%), root fresh (61%), and dry (63%) biomass under water stress. The inoculated plants had increased chlorophyll (67%), carotenoid (70%), leaf protein (64%), sugar (64%), and phenolic (62%) contents while lower leaf proline (62%) content, malondialdehyde (MDA) (64%), and antioxidant enzymes (67%) which suggest their role in drought tolerance. It is concluded that integrative use of PGPR in combination with SA found to be an efficacious strategy to improve the phytoremediation of heavy metals and plant growth under stressed conditions particularly under water-deficient conditions.https://www.frontiersin.org/article/10.3389/fmicb.2018.02507/fullPGPR16S RNA gene sequencingsalicylic acidphytoremediationheavy metals
spellingShingle Naeem Khan
Peiman Zandi
Shahid Ali
Asif Mehmood
Muhammad Adnan Shahid
Jianjun Yang
Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annus
Frontiers in Microbiology
PGPR
16S RNA gene sequencing
salicylic acid
phytoremediation
heavy metals
title Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annus
title_full Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annus
title_fullStr Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annus
title_full_unstemmed Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annus
title_short Impact of Salicylic Acid and PGPR on the Drought Tolerance and Phytoremediation Potential of Helianthus annus
title_sort impact of salicylic acid and pgpr on the drought tolerance and phytoremediation potential of helianthus annus
topic PGPR
16S RNA gene sequencing
salicylic acid
phytoremediation
heavy metals
url https://www.frontiersin.org/article/10.3389/fmicb.2018.02507/full
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