Exogenous application of phytoprotectants in legumes against environmental stress - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 161

Chapter 11

Exogenous application of phytoprotectants
in legumes against environmental stress

Mirza Hasanuzzaman 1,2 , Kamrun Nahar 1,3 , Md. Mahabub Alam 1 , Shakeel Ahmad 4 and Masayuki Fujita 1
1 Laboratory of Plant Stress Responses, Department of Applied Biological Science, Kagawa University, Kagawa, Japan
2 Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
3 Department of Agricultural Botany, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
4 Department of Agronomy, Bahauddin Zakariya University, Multan, Pakistan

11.1 Introduction

or more environmental stresses (Dita et al., 2006).
Legumes are a large group of plants distributed world-
wide and having diverse uses in different continents;
hence they experience a wide range of environments
some of which might not be favourable for growth and
development. Abiotic stresses may affect root growth,
interrupt symbiotic interactions, or impede vegetative
or reproductive development, and thus limit produc-
tivity (Van Hoorn et al., 2001; Sharma & Lavanya,
2002). These stresses also lead to oxidative stress due
to excessive generation of reactive oxygen species
(ROS) derived from the reduction of molecular oxygen
(O 2 ). ROS include some free radicals such as superoxide
(O 2 • − ), hydroxyl radical (•OH), alkoxyl (RO•) and per-
oxyl (ROO•), as well as non-radical products like
hydrogen peroxide (H 2 O 2 ) and singlet oxygen ( 1 O 2 )
(Gill & Tuteja, 2010). Stress signals induce the syn-
thesis of several metabolites, including phytohormones
and osmolytes, and changes in endogenous macromol-
ecules are often involved in plant stress adaptation.
Phytohormones also activate cellular responses,
including cell death, to diverse stress situations in
plants (Eyidogan et al., 2012).
The antioxidant defense system of plants is consti-
tuted chiefly of antioxidant enzymes and non-enzymatic
antioxidant components and distributed in different cell
organelles, such as chloroplasts, mitochondria and per-
oxisomes, or in the apoplast, which are coordinated
to act together (Hasanuzzaman et al., 2012a,b). Non-
enzymatic antioxidants may include ascorbic acid (AsA),

The groups of plants included in the family Fabaceae
(or Leguminosae; McNeill et al., 2011) are commonly
known as the legumes. Legumes are the third largest
land plant family in terms of number of species, and
include 730 genera and over 19,400 species (for updates
see Stevens, 2014) of trees, shrubs and perennial or
annual herbaceous plants. Legumes are essentially dis-
tributed worldwide except for Antarctica and the high
Arctic (Stevens, 2014). Legumes rank third after cereals
and oilseeds in world production (Popelka et al., 2004)
and account for 27% of the world's primary crop pro-
duction (Graham & Vance, 2003). Legumes are utilized
as important sources of protein for human beings, and
constitute 33% of the dietary protein nitrogen (N) needs
of humans (Vance et al., 2000). Apart from their use as
human foods, legumes have multiple uses like forage,
grain, flowers, pharmaceuticals, industrial, fallow or
green manure, timber and aesthetic purposes, which
make the legumes one of the most commercially impor-
tant plant groups.
Abiotic stresses such as salinity, drought, water-
logging, high temperature (HT), low temperature,
toxic metals, ozone (O 3 ), ultraviolet (UV) radiation,
nutrient deficiency, and so on are common natural
or anthropogenic stresses responsible for reducing
the productivity of crop plants by over 50%
(Hasanuzzaman et al., 2012a). More than 90% of
arable lands or crop-growing areas experience one