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In-Depth Information
upon onset of the cold stress. This chapter also
summarizes the accumulated knowledge of the
past 20 years in the area of genetics and genomics
of the mechanism of freezing tolerance and the
genomic tools available for enhancing freezing
tolerance in the Triticeae crops.
polymorphism among the parental lines for this
trait. The physiological, genetic, and molecular
breeding aspects for the stay-green trait are dis-
cussed at length in this chapter.
Improving Quality and Yield Through
Molecular Breeding in Rice, Maize,
Peanut, and Sugarcane
Enhancing Tolerance to Abiotic
Stresses in Sorghum
Besides increasing production and productiv-
ity, agricultural produce also should fulfill the
requirement of consumer acceptance in terms of
quality, in order to fetch a good market price.
Hence, grain quality improvement also forms
the major concern for cereal breeders. In Chap-
ter 9, Hori and Yano describe rice grain quality
traits in terms of physical and cooking quali-
ties that are of interest to the consumer. In fact,
grain quality is influenced by climate changes,
such as high temperatures at the grain ripening
stage, and grain components such as amylose,
amylopectin, and proteins are greatly affected
by such changes. This chapter summarizes the
efforts to understand the genetics of grain qual-
ity traits and the multiple genes/QTL contribut-
ing to grain quality. The chapter also emphasizes
the need for developing novel quality evaluation
instruments/approaches, such as TILLING (Tar-
get Induced Local Lesion IN Genome) that can
enhance the qualities related to the cooking and
eating of japonica rice.
About 190 million children under the age
of five years are suffering from malnutrition,
especially in the underdeveloped and develop-
ing countries in Asia and sub-Saharan Africa
(WHO, 2009). Malnutrition can be overcome
by supplementing dietary requirements with
micronutrients or through promotion of dietary
diversification. However, these strategies have
been only partially adopted and appear not to
have improved the nutrient deficiencies in South
African children since 1994 (Labadarios et al.
2005). Nevertheless “biofortification” - breeding
staple crops with increased nutritional value -
has emerged as a potential long-term strat-
egy to improve nutritional security. Babu and
Aluminum (Al) is the third most abundant ele-
ment on earth after oxygen and silicon (Ma
et al. 2001). It is a light metal that makes up
7% of the earth's crust. Half the arable soils
across the globe and especially those in Africa,
Asia, and South America are affected by alu-
minum toxicity ( http://www.news.cornell.edu/
stories/Aug07/SoilsKochian.kr.html) . Chapter 7
by Magalhaes and colleagues deals with the
existing diversity with respect to aluminum tol-
erance in sorghum and maize germplasm acces-
sions as well as the molecular, physiological,
and genetic basis of Al tolerance in both crops.
The authors provide insights into the struc-
ture and functional analysis of membrane trans-
porters such as Al-activated malate transporter
(ALMT1) and multidrug and toxic compound
efflux (MATE) involved in Al tolerance.
Furthermore, 20 to 30% of production losses
in sorghum are due to lodging. Stay-green trait,
however, has been an indirect selection criterion
used by breeders for enhancing lodging resis-
tance. Stay green is associated with increased
grain yield and grain size in the sorghum crop
under terminal drought, a common occurrence
in arid and semiarid regions across the globe
(Jordan et al. 2012). Among several genotypes
identified with the stay-green trait, BTX645 has
been a useful resource in developing commercial
hybrids (Harris et al. 2007). Four major quanti-
tative trait loci (QTLs) and several minor QTLs
can enhance stay-green traits and several efforts
are underway to introgress these QTLs into var-
ious genetic backgrounds. However, Vadez and
colleagues in Chapter 8 report that this undertak-
ing has been quite challenging owing to limited
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