Abstract
Reciprocal differences persist in nature because of the unequal contribution of cytoplasmic determinants from male and female gametes to the zygote. The inheritance of genetic differences is an important factor that influences various traits, including somatic embryogenesis and regeneration in vitro. In this report, we estimate the cytoplasmic and maternal effects in pearl millet and their adequacy in describing the observed reciprocal differences based on an in depth study of the parents, F2s and reciprocal backcross progenies needed for fitting genetical models. Our study revealed that of the two characters examined, embryogenic callus quantity and regeneration frequency, the former showed a greater proportion of cytoplasmic nuclear interaction whereas the latter showed a greater role of nuclear factors. Additive-maternal effects influenced total callus quantity and dominance-maternal effects influenced total callus quantity, embryogenic callus quantity and regeneration frequency. Dwarfing was associated with the production of large quantities of embryogenic callus that had visually recognizable characteristics. The phenotypic nature of dwarf parents (green dwarf with long narrow leaves) with a genetic basis for a given character controlled by nuclear and cytoplasmic determinants can be exploited for other breeding programs.
Highlights
In vitro characters are often used in combination with other agronomic traits for crop improvement programs
In vitro regeneration of pearl millet was obtained by culturing immature inflorescences as described earlier (Mythili et al, 1997; Satyavathi et al, 2006)
The ANOVA of genetic components from a 5x5 diallel cross revealed that general combining ability (GCA) and specific combining ability (SCA) were significant (p < 0.05) for the four in vitro characters studied, namely total callus quantity, embryogenic callus quantity, callus growth rate and frequency of regeneration (Satyavathi VV, 1998, PhD thesis, Andhra University, Visakhapatnam, India)
Summary
In vitro characters are often used in combination with other agronomic traits for crop improvement programs. An obvious challenge for tissue culture researchers is to develop in vitro technologies for faster, more predictable production of embryogenesis and plant regeneration. Despite all numerous technological advances, the successful application of plant tissue culture techniques to crop improvement is still dependent on understanding the genetic basis for ‘in vitro aptitude’ that will help to predict the in vitro responses of genotypes for further selection. The influence of genotype on in vitro characters and the genetic basis of the in vitro response have been analyzed in several plant systems, including pearl millet (Pueschel et al, 2003; Satyavathi et al, 2006; Dodig et al, 2008; Chakravarthi et al, 2010; Etedal et al, 2012; Wang et al, 2013)
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