© Benaki Phytopathological Institute
Molecular Biotechnology on agricultural crop improvement
45
breeding in elite germplasms when favored
and stress environments are been examined
(Crosbie
et al.,
2006; Eathington
et al.,
2007;
Edgerton 2009). Most recently, the role of
Abscisic Acid (ABA) pathway in drought re-
sistance has been investigated and natural
variants of ABA-(PYR1/PYL/RCAR) protein
(PYL) receptors have been identified that
can serve as potential molecular markers for
breeding drought-resistant maize cultivars
(He
et al.,
2018).
Resistance against pathogens.
Efforts to
scale down maize losses from pathogen at-
tacks through resistant crop varieties could
provide tremendous opportunities for in-
creasing and stabilizing maize productivity.
QTL related to resistance to several diseas-
es, such as downy mildew and rust, and in-
sect-pests are known and mapped in maize,
creating marker assisted choice as a poten-
tially viable strategy to improve resistance
to these biotic stresses (Ali and Yan 2012;
García-Lara
et al.,
2009; Krakowsky
et al.,
2004; Wisser
et al.,
2006).
Resistance against insect pests.
The indus-
try has made substantial progress with in-
sect resistant maize through transformation
with insecticidal proteins from
Bacillus thu-
ringiensis
(Bt) which have been particularly
successful in providing protection against
several corn borers (Glaser and Matten 2003;
Jiang
et al.,
2018).
Quality traits.
Quality traits, like oil con-
tent or high nutritional value molecules,
have induced a shift in maize production
far from strictly an identity-preserved culti-
vation to more a value-added product. The
capability of changing cell membrane poly-
saccharides into possible sugars for grain
ethanol production depends on cell mem-
brane structure. Molecular markers can be a
valuable tool when breeding for feed maize
but with improved quality on grain ethanol.
QTLs with comparatively efficient results
are found for feedmaize including cell mem-
brane composition and glucose release (GL-
CRel) (Lorenzana
et al.,
2010), and some im-
portant constitutive and adaptive QTLs are
identified by using meta-analysis (Hao
et al.,
2010). (Torres
et al.,
2015) presented the mo-
lecular progress that has been made in al-
tering maize’s cellulosic content in order to
exploit useful biomass characteristics and
design new breeding strategies.
Quality traits and tolerance to abiot-
ic stress.
There has been increasing inter-
est in addressing advanced traits like grain
quality and abiotic/biotic stress toleranc-
es through recombinant DNA technology.
Elite inbred South African transgenic corn
plants were modified in 3 separate metabol-
ic pathways to produce increased quantities
of vitamin β-carotene, ascorbate and folate
(Naqvi
et al.,
2009). It has been demonstrat-
ed that engineering of the alkaloid synthe-
sis pathway could have great impact on im-
Fig. 2.
Schematic representation that highlights the required key steps to facilitate enhanced adoption and impacts of im-
proved climate-resilient maize varieties in the developing world. Increasing maize yields in stress-prone environments and
reducing year-to-year variability is an important step in improving food safety, livelihoods and adaptation to the changing
climate in the developing world (Cairns and Prasana, 2018).
