hazard in animal system and also plants especially in agriculture. Microplastics are
the small plastic particles with 1 mm to 5 mm size. These are created by the natural
degeneration of several plastics such as tires, domestic goods, packing materials,
materials coated with plastics, and other plastic household things used on daily basis.
Hence it is observed more in urban environment especially in urban run-off water
finally ending up in treatment plants, river, and the final sink ocean. Marine plastics
refer to pollution of marine ecosystem with microplastics (Carpenter and Smith
1972).
Microplastics which travel this way through water will definitely reach agricultural fields and less information is available on soil as a microplastic sink (Blasing
and Amelung 2018). This in turn pollutes the terrestrial ecosystem. Even today the
Table 7.2 Microorganisms involved in plant drought stress tolerance
Microorganisms
Source and
crop plant
Mechanism/Effect
References
Pantoea
agglomerans
Wheat
Aggregation of rhizosphere soil by EPS
production
Amellal
et al. 1998
Paenibacillus
polymyxa
Arabidopsis Activation of gene ERD15 responsible
for stress resistance
Timmusk
and Wagner
(1999)
Rhizobium sp.
Sunflower
Aggregation of rhizosphere soil by EPS
production
Alami et al.
(2000)
Azospirillum sp.
Wheat
Regulating water relation
Creus et al.
(2004)
Achromobacter
piechaudii
Tomato
ACC deaminase activity
Mayak et al.
(2004)
Variovorax
paradoxus
Pea
ACC deaminase activity
Dodd et al.
(2005)
VAM fungi
Sorghum
Regulating water relation
Cho et al.
(2006)
Paraphaeosphaeria
quadriseptata
Arabidopsis HSP induction
McLellan
et al. (2007)
Rhizobium tropici
and Ps. polymyxa
Common
bean
Regulation of stomatal conductance and
hormones
Figueiredo
et al. (2008)
Pseudomonas sp.
Pea
Reduced ethylene production
Arshad et al.
(2008)
Glomus intraradices
and Ps. mendocina
Lettuce
Increase in antioxidants
Kohler et al.
(2008)
Ps. putida P45
Sunflower
Aggregation of rhizosphere soil by EPS
production
Sandhya
et al. (2009)
Azotobacter
chroococcum,
Azotobacter
salinestris
Zea mays
Increase in phosphate and potassium
solubilization associated with increased
shoot dry weight, plant height,
chlorophyll content
Shirinbayan
et al. (2019)
Azospirillum
brasilense
Maize
Increase in biomass and water content
Casanovas
et al. (2002)
Ps. koreensis
Helianthus
annuus
Increased leaf area, water content, and
IAA production by bacteria
Macleod
et al. (2015)
236
M. P. Raghavendra
the small plastic particles with 1 mm to 5 mm size. These are created by the natural
degeneration of several plastics such as tires, domestic goods, packing materials,
materials coated with plastics, and other plastic household things used on daily basis.
Hence it is observed more in urban environment especially in urban run-off water
finally ending up in treatment plants, river, and the final sink ocean. Marine plastics
refer to pollution of marine ecosystem with microplastics (Carpenter and Smith
1972).
Microplastics which travel this way through water will definitely reach agricultural fields and less information is available on soil as a microplastic sink (Blasing
and Amelung 2018). This in turn pollutes the terrestrial ecosystem. Even today the
Table 7.2 Microorganisms involved in plant drought stress tolerance
Microorganisms
Source and
crop plant
Mechanism/Effect
References
Pantoea
agglomerans
Wheat
Aggregation of rhizosphere soil by EPS
production
Amellal
et al. 1998
Paenibacillus
polymyxa
Arabidopsis Activation of gene ERD15 responsible
for stress resistance
Timmusk
and Wagner
(1999)
Rhizobium sp.
Sunflower
Aggregation of rhizosphere soil by EPS
production
Alami et al.
(2000)
Azospirillum sp.
Wheat
Regulating water relation
Creus et al.
(2004)
Achromobacter
piechaudii
Tomato
ACC deaminase activity
Mayak et al.
(2004)
Variovorax
paradoxus
Pea
ACC deaminase activity
Dodd et al.
(2005)
VAM fungi
Sorghum
Regulating water relation
Cho et al.
(2006)
Paraphaeosphaeria
quadriseptata
Arabidopsis HSP induction
McLellan
et al. (2007)
Rhizobium tropici
and Ps. polymyxa
Common
bean
Regulation of stomatal conductance and
hormones
Figueiredo
et al. (2008)
Pseudomonas sp.
Pea
Reduced ethylene production
Arshad et al.
(2008)
Glomus intraradices
and Ps. mendocina
Lettuce
Increase in antioxidants
Kohler et al.
(2008)
Ps. putida P45
Sunflower
Aggregation of rhizosphere soil by EPS
production
Sandhya
et al. (2009)
Azotobacter
chroococcum,
Azotobacter
salinestris
Zea mays
Increase in phosphate and potassium
solubilization associated with increased
shoot dry weight, plant height,
chlorophyll content
Shirinbayan
et al. (2019)
Azospirillum
brasilense
Maize
Increase in biomass and water content
Casanovas
et al. (2002)
Ps. koreensis
Helianthus
annuus
Increased leaf area, water content, and
IAA production by bacteria
Macleod
et al. (2015)
236
M. P. Raghavendra