© Benaki Phytopathological Institute
Molecular Biotechnology on agricultural crop improvement
41
evoke the full potential of this valuable crop
(Fig. 1).
Resistance to pathogens
MAS technology has been used in sun-
flower breeding for various disease resis-
tance traits (Brahm and Friedt 2000). With
the development of an array of molecular
markers and a dense genetic map of the
sunflower genome, MAS for both single
genes and QTLs is now possible (Babu
et
al.,
2004; Bowers
et al.,
2012). For example,
biotechnology offers a variety of meth-
ods for managing white rot caused by
Stro-
matinia cepivora
(also known as
Sclerotium
cepivorum
) (Schnabl
et al.,
2002), includ-
ing defense activation, pathogen inhibi-
tion and detoxification (Lu, 2003). Accord-
ing to Hu
et al.
(2003), the enzyme oxalate
oxidase can confer resistance against
Scle-
rotinia sclerotiorum,
(Lib.) de Bary which
causes sclerotinia wilt (midstalk rot), in
transgenic sunflower plants while accord-
ing to Sawahel and Hagran (2006), overex-
pression of a human lysozyme gene in sun-
flower confers resistance to the pathogen.
Recently, the quantitative nature of Scle-
rotinia resistance has been exploited and
QTL analysis showed that different genom-
ic regions may contribute to resistance in
different tissues of the plant (Würschum
et
al.,
2014).
Alternative transgenic methods have
been developed to reinforce sunflower resis-
tance to diseases. A number of homologues
resistance (R) gene have been isolated from
sunflower, providing a valuable resource for
engineering disease resistance in sunflow-
er (Dimitrijevic and Horn 2018; Hewezi
et al.,
2006; Qi
et al.,
2016; Talukder
et al.,
2016).
Quality traits.
Sunflower with high oleic
acid content is optimal for the biodiesel in-
dustry since the produced oil has up to 90%
mono-unsaturated fatty acid concentra-
tion, which has high oxidative stability and
uniformity. Therefore, producing high con-
centrations of industrially valuable fatty ac-
ids in plant seeds through biotechnological
improvements along with modifications of
the fatty acid composition can make vege-
table oil more versatile for its use (Burton
et
al.,
2004).
One of the challenges for oil composi-
tion modification in sunflower is increas-
ing the extent of the new fatty acids. Much
work has been performed for the identifica-
tion of genes involved in primary metabol-
ic pathways and signal transduction at var-
ious growth and stress conditions (Liang
et
al.,
2017; Pan
et al.,
2016; Velasco
et al.,
2014)
to gain insight into the mechanism of an-
tioxidant defense. New genes have been
identified and the metabolism of ROS and
RNS have been analyzed under various biot-
Fig. 1.
Schematic depiction of the available resources in sunflower for marker-assisted selection and future genomic selec-
tion. Sunflower diverse genetic information is available for breeding and represents a large portion of genetic diversity that
can be exploited for improving sunflower traits. Accessing sunflower genome sequences, large resources of SNP or high res-
olution maps and/or SNP arrays, along with huge amount of expression data can accelerate sunflower breeding by making
the selection steps more efficient and precise. Marker-assisted breeding toward genomic selection can produce high qual-
ity breeding values.
