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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

studies have shown that root colonization of AMF improved plant growth

under drought condition by enhancing nutrients and water uptake ability. For

instance, root colonization of AM fungi in Allium cepa, Trifolium repens,

Lactuca sativa and Triticum aestivum improved growth under drought condi­

tion by expanding root surface area for water uptake (Diagne et al., 2020).

Under drought condition, AM fungi induced leaf water potential, stomatal

conductance, improved gaseous exchange, transpiration, and photosynthesis

in plants. AMF minimizes the harmful effects of drought stress on photo-

system II reaction center (Zhu et al., 2012). AMF also improved water uptake

by producing phytohormones and organic solutes. During stress, ABA plays

an important role in plant. ABA modulates several hormonal signaling like

root water conductivity, stomatal opening, and expression of water channel

across the membrane. Colonization of AMF lowers the ABA level in the root

which helps in water retention (Yooyongwech et al., 2013). Beside ABA,

AMF also induced auxin and strigolactones that improved water stress

response in plants. Another aspect of AMF is an accumulation of organic

solutes like proline, glycine betaine and sugars which helps to adjust the

osmotic potential of plant under drought condition. Antioxidant enzymes

produced by the AMF reduced ROS accumulation protects plants from

oxidative damages under drought stress (Laxa et al., 2019). Beside drought

tolerance, AMF also induced flooding tolerance in plants. It was observed

that in wet soil high diversity of AMF are formed. Flooding tolerance in

plant is directly associated with high nutrient uptake and good photosyn­

thetic efficiency (Bao et al., 2019).

3.6.1.2 AMF AND SALINITY TOLERANCE

AMF can adopt saline condition efficiently. AMF colonization improved

several plants growth under extreme saline conditions (Table 3.3). It has

been well established that AM fungi can modulate several biochemical,

physical, and physiological processes in plants. We already know that AMF

can improve water uptake and increase nutrients availability in soil. This

attribute of AM fungi induced salt tolerance in many plants including Zea

mays, Triticum aestivum and tomato (Estrada et al., 2013). In addition to

this, AM inoculation in plant root under saline condition accumulates

osmoregulators like proline and sugars, improved water conductance of the

root tissue, enhanced photosynthesis activity and reduced Na⁺ ion toxicity

by maintaining the balance of K⁺/Na⁺ ratio (Li et al., 2020). Tomato plant

inoculated with Funneliformis mosseae under saline condition improved