Genetic effects and genetic relationships among shrunken (sh2) sweet corn lines and F1 hybrids

Abstract

The objectives of this study were to quantify the components of genetic variance and the genetic effects, and to examine the genetic relationship of inbred lines extracted from various shrunken2 (sh2) breeding populations. Ten diverse inbred lines developed from sh2 genetic background, were crossed in half diallel. Parents and their F1 hybrids were evaluated at three environments. The parents were genotyped using 20 polymorphic simple sequence repeats (SSR). Agronomic and quality traits were analysed by a mixed linear model according to additive-dominance genetic model. Genetic effects were estimated using an adjusted unbiased prediction method. Additive variance was more important than dominance variance in the expression of traits related to ear aspects (husk ratio and percentage of ear filled) and eating quality (flavour and total soluble solids). For agronomic traits, however, dominance variance was more important than additive variance. The additive genetic correlation between flavour and tenderness was strong (r = 0.84, P \ 0.01). Flavour, tenderness and kernel colour additive genetic effects were not correlated with yield related traits. Genetic distance (GD), estimated from SSR profiles on the basis of Jaccard's similarity coefficient varied from 0.10 to 0.77 with an average of 0.56. Cluster analysis classified parents according to their pedigree relationships. In most studied traits, F1 performance was not associated with GD.

Genetic Variability and Association Analysis of SomeQuantitative Characters in Sweet Corn

“…Positive correlations were existed between plant height and starch content; 1000 seed weight and dry matter content in 2009; 1000 seed weight and dry matter content; 1000 seed weight and soluble solid concentration; plant height and starch content in 2010. Similar negative correlations reported between yield and yield components and kernel quality traits (Wong et al, 1994;Saleh et al, 2002;Solomon, 2011). This indicates that the difficulty of simultaneous improvement of sweet corn for both yield ability and kernel quality (Ha, 1999;Saleh et al, 2002).…”

Microsatellite-based genetic diversity analyses of sugary1-, shrunken2- and double mutant- sweet corn inbreds for their utilization in breeding programme

“…The mean genetic dissimilarity (0.73) was relatively high indicating that the sweet corn inbreds are developed from diverse sources. Mean genetic similarity of 0.56 among the sweet corn inbreds was reported by Solomon et al (2012) and Srdic et al (2011). 48 genotypes were grouped into three major clusters (Fig.…”

“…Only Jun et al (2012) has used 56 markers to analyse the genetic diversity in 54 genotypes. Number of alleles per SSR marker ranged from two to seven with a mean of 3.8 ( (Lopes et al 2015), and 3.40 (Solomon et al 2012). High number of alleles per marker locus observed in the present study is due to utilization of higher number (56) of genome wide SSRs and inbreds (48) compared to less number of sweet corn genotypes (6-22) and SSRs (13-32) used in majority of the earlier studies.…”

“…Among them, Amorim et al (2003) analyzed F 2 plants of 13 populations, of which three were of sh2sh2-type, and seven belonged to bt2bt2 (brittle2)-type. Ten sh2sh2-based sweet corn inbreds were used by Solomon et al (2012). 15 su1-su1-based inbreds were used by Lopes et al (2014) and Rupp et al (2009), while six su1su1-based inbreds were used by Srdic et al (2011).…”

“…Shrunken2 located on chromosome 3L codes for large sub-unit of AGPase that involves in the synthesis of ADP-glucose from glucose-1-phosphate (Bhave et al1990). The sh2sh2-based sweet corn types popularly called 'super sweet' or 'extra sweet corn' accumulate about six-fold more reducing sugars at milky ripening stage (Feng et al 2008;Khanduri et al 2011;Solomon et al 2012). Moreover, the depletion of sugar level is much slower in sh2sh2-type even without refrigeration, thus varieties have extended shelf life, and are better suited for prolonged storage as compared to su1su1-type.…”