I, roots of plants flooded for 21 d and roots of control, nonflooded plants were used to assess the extent of aerenchyma
development in adventitious and primary roots of flooded plants and primary roots of nonflooded plants.
This resistance may be related to the formation of aerenchyma
, an anatomical structure frequent in these species, according to Lewitt (1980) who concluded that lack of oxygen is the main factor inducing the formation of air canals in the roots.
In response to low oxygen concentration in the root zone, many species form aerenchyma
tissues in roots and stems, through which oxygen moves readily.
Intercellular air spaces in root cortical tissues (aerenchyma
) were quantified by measuring root porosity.
, oxygen leakage patterns and alcoholic fermentation ability of the roots of some nymphaeid and isoetid macrophytes in relation to the sediment type of their habitat.
formation is another trait that has been implicated in waterlogging tolerance in wheat (Varade et al., 1970; Huang et al., 1994a,b; Ding and Musgrave, 1995; Thomson et al., 1990; Box, 1986; Erdmann and Wiedenroth, 1988).
Until recently, studies of flooding tolerance have focused more on aerenchyma
development (Justin and Armstrong, 1987; Laan et al., 1989) and the terminal products of anaerobic respiration (McManmon and Crawford, 1971; Konings and Lambers, 1991) than on the role of hormones.
Considerable evidence exists that [CO.sub.2] generated in flooded soils can be transported up the plant through aerenchyma
, enhancing photosynthesis and shoot growth of some wetland species (Constable and Longstreth, 1994; Dacey, 1980; Grosse et al., 1991), including lowland rice (Oryza sativa L.) (Higuchi, 1982; Higuchi et al., 1984).
Outside the sclerenchymatic cells, specialized types of parenchyma, as an aerenchyma
, for instance, may differentiate in the gall outer tissue compartment, and favor gas exchanges among the cells in galls deprived of stomata (Amorim et al., 2017).
Enhanced formation of aerenchyma
and induction of a barrier to radial oxygen loss in adventitious roots of Zea nicaraguensis contribute to its waterlogging tolerance as compared with maize (Zea mays ssp.
Waterlogging usually leads to hypoxia and in severe cases to anoxia of the root system in plants, and on warmer seasons the depletion on O2 is faster; after switching the root zone environment to a hypoxic condition, reactive oxygen species are formed, and elevation of [H.sub.2][O.sub.2] levels, leading to adaptation signals and anaerobic respiration processes; Other plant response to waterlogging is to produce ethylene, which signals various adaptive functions to plant survival, such as increased number of adventitious roots, and formation of aerenchyma
in such environment (IRFAN et al., 2010).
domingensis are comprised of one-layered epidermis on both adaxial and abaxial sides, palisade parenchyma (three to four layers) also on both abaxial and adaxial leaf surfaces and the central part shows aerenchyma
chambers and collateral vascular bundles (Santos et al., 2015; Correa et al., 2016).