Molecular Plant Breeding 2016, Vol.7, No.13, 1-11
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color, watery appearance and loose in texture were considered as non-embryogenic callus.
Callus which has embryogenic capacity helps in regeneration of plantlets and can exhibit the capacity of single or
many cells to regenerate the whole plant (Gandonu et al., 2005). External morphology of callus differentiated the
embryogenic and non-embryogenic behaviors. By increasing the percentage of auxins, embryogenic productions
can be decreased. In Inqlab-91 genotype, callus weight and size was increased by this process but the callus was
non-embryogenic. Similarly kinetin has negative effect on embryogenic callus formation (Rashid et al., 2009).
12 Somatic Embryogenesis
Embryogenic callus is produced in somatic embryogenesis of somatic cells from which different physiological
and morphological changes pass and production of somatic embryos occurs (Quiroz-Figueroa et al., 2006). During
in-vitro plant regeneration, somatic embryogenesis showed better response than direct organogenesis (Wang and
Bhalla et al., 2004). Conventional breeding program of somatic embryogenesis, cell biological techniques and
molecular techniques are proved as valuable tolls to enhance the genetics of different crop plants (Stasolla and
Yeung, 2003).
Somatic embryos have different resemblances with zygotic in diverse aspects (Fehar et al., 2003). Morphogenetic
procedure of somatic embryogenesis can easily examine the differentiation in cellular and molecular processes
(Beneli et al., 2001). This process is taken as the best for germplasms preservation, genetic engineering and
artificial seed production (Litz and Gray, 1995; Merkle et al., 1995). By encapsulating somatic embryos, artificial
seeds can be easily produced by using a gelling agent (Gosh and Sen, 1994). Different processes of embryogenesis
can be studied through this technique. Due to primordial presence of root and shoot, somatic embryos can be
easily produced without a need of separate step of rooting (Laux and Jugens, 1997).
13 Correlation of Agronomic Trait on Callus Induction and Regeneration in Wheat
At agronomic trait level, response of different genotypes can be checked towards tissue culture technique.
Correlation and regression analysis can be helpful to assess the association between tissue culture and agronomic
traits. Culturing of immature embryos and callus regeneration portrayed great differences which expresses the
strong effects of genotypes. Callus formation percentage has significant effect with early maturity, peduncle length
and its extrusion, spike index and yield/plant, while regeneration capability of callus (CR) and plants production
per regenerative embryo (PPE) showed significant correlation with the presence of chlorophyll in flag leaf (Dodig
et al., 2008). Five genotypes of wheat plant were mated and resulted crosses were examined for their embryogenic
callus potential (EC%) and regeneration percentage of plantlets. Associations between these traits were observed
by heading dates and grain yield per plant. Results showed that EC% and PRP% had significant relationship with
grain yield per plant (Khaled et al., 2013).
14 Somaclonal Variations in Wheat
Regeneration of plants from embryogenic tissues of somatic cells, showed that variations in morphology and
chromosomal changes also occurred during culturing (De Buyser et al., 1988). Immature embryo culturing
showed variations in Mt DNA plantlets and these differences quickly stabilized during Callogenesis (Hartmann et
al., 1987). Similarly, variations in Mt DNA were also noticed in regeneration of green plants resulting from
somatic tissue culture (Aubry et al., 1989). Phenotypic changes showed by plants resulting from in-vitro culturing
are the true representatives of genetic variations (Liu and Chen, 1978 a and b; Orton, 1980). Some plants
expressed their original morphology and showed that the changes occur during field conditions are due to
physiological aspects and not by genetics (Callebaut et al., 1978).
15 Acclimatization of Wheat Plants
Acclimatization of In-vitro developed plantlets is necessary before their transportation to green house. Plantlets at
21
℃
, low humidity and sixteen hours of continuous photoperiod for two weeks in an environmental chamber, are
ready for shifting into green house (Weeks et al., 1993).
