Molecular Plant Breeding 2016, Vol.7, No.13, 1-11
4
effects on regeneration of plantlets (Kohlenbach and Wemicke, 1978; Jaramillo and Summers, 1990). Due to High
cost and inhibitory effects of agarose, other gelling agents were used (Fadel and Wenzel, 1990). Starch extraction
from wheat, barley, rice, maize and potato can be used in comparison with agar (Sorvari, 1987;Riera-Lizarazu and
Pienaar and Lesch , 1994) used gelrite medium for solidifying of culture.
8 Effect of Genotype in In-Vitro Planlet-regeneration
Developing a best regeneration system is the prime step in wheat transgenic plant production. In case of wheat
plant, different genotypes showed different responses towards tissue culturing.
Embryogenic capabilities of
genotypes also express different responses to different culture mediums in in-vitro conditions. In the case of plant
breeding studies, embryogenic response of genotypes and genetic transformation of wheat are considered as the
development of new cultivars for commercial purpose (Vendruscolo et al., 2008). Genotypes had great effect on
callus induction, embryogenic formation and plant regeneration (Sears and Deckard, 1982; Mathies and Simpson,
1986; Fennel et al., 1996; Aydin et al., 2011). Ex- plants of Triticum which belong to different genotypes having
same age were cultured on medium with same combination of growth regulators. This experiment was conducted
for callus formation and regeneration of plantlets. Results showed that callus formation and plantlet regeneration
change their course with different genotypes (Arzani and Mirudjagh, 1999; Zale et al., 2004). Similar results were
obtained in rice (Hoque and Mansfield, 2004), primula species (Schween and Schwenkel, 2003) and coffee
(Molina et al., 2002). Fahmy et al. (2012) conducted an experiment in which they used seven different cultivars on
different media to check their regeneration response through somatic embryogenesis. Genotype Giza-164 showed
strong performance over all tested cultures.
9 Media and Genotype Interaction on Callus Induction and Regeneration in Wheat
Usually in tissue culturing of wheat, response depends upon genotypes, composition of media and their interaction,
Significant interaction was observed for callus induction and plantlet regeneration between phytoharmones and
genotype. Chakwal-50 performed best (91.25%) at 6 mg/l 2, 4-D while genotype AS-2002 and GA-2002 produced
92.75% and 91.25% callus induction on media consisting 4 mg/l 2, 4-D (Mahmood et al., 2012). Media
composition, genotype and their interaction all three had great effect on callus induction and plantlet regeneration.
Different types of sugar, Dicamba and genotypes increase the callus formation and regeneration of plantlets (Jiang
Ping et al., 2010). By using different growth regulators in media, regeneration capacity can be enhanced. In case
of mature embryos, genotypes had strong effects when different growth regulators were used in culture (Nasircilar
et al., 2006). Embryogenic ability of callus can be obtained by genetic makeup of genotypes and concentration of
exogenous application of harmones (Nawaz et al., 2013).
10 Effect of Culturing Conditions on Callus Induction and Regeneration
In-vitro culture can be affected by different conditions and sources (Caswell et al., 2000; Deplorte et al., 2001).
In-vitro plant regeneration in wheat rely on different culturing conditions like callus maintenance and regeneration
ability for longer period of time (Domelles et al., 1997). (Naranayaswamy and Norstog, 1964) obtained that the
best temperature for growth of most plant embryos is 25-30
℃
. Some species like Dhatura did not
show
response
to light intensity during embryo growth (Norstog, 1972). Triticale showed positive effect when red light was
expressed on immature embryo regeneration (Angus et al., 1986). For embryo recovery optimum light intensity is
1000 Lux, while temperature is 17-22
℃
and 60-65% relative humidity (Campbell et al., 1998; Khan and Ahmed,
2011). Mature culturing in Barley plant showed best response at 22
℃
, and 55% relative humidity (Hongbo et al.,
2005). Lectin levels can be affected by light intensity as it grows 14 times more in light as compared to 10 times
growth in dark conditions (Raikhel et al., 1986). To break the seed dormancy, cold treatment at 4
℃
is required
while some embryos like Lilium need low temperature up to 17
℃
(Pierik, 1987).
11 Embryogenic Callus as a Source of Plantlet Regeneration
MackinNon et al. (1987) isolated non-embryogenic callus from embryogenic callus in bread wheat. Callus which
was obtained from embryogenic was compact, multicellular and showed off-white to light green colour. This
callus was proficient in proliferating to bulbous embryoids, while callus that are dirty whitish, brown or grayish in
