2008. Genetic mapping and analysis of traits related to improvement of popcorn
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SÐT: 0981800855 (A. LONG)
PRICE: 100.000 VND
EMAIL: FOODCROPS@GMAIL.COM
SÐT: 0981800855 (A. LONG)
PRICE: 100.000 VND
EMAIL: FOODCROPS@GMAIL.COM
ABSTRACT
Popcorn and dent maize are distinct gene pools and are maintained and utilized as such in maize breeding programs. Popcorn is inferior to dent maize in traits related to crop productivity. Dent maize is a potential source of favorable alleles to improve the productivity of popcorn, but its utility is hindered by dent alleles with negative effects on popping expansion volume (PEV), an important quality trait of popcorn. If the genetic architecture of popping expansion and other important traits is known in dent x popcorn populations, the negative effects of dent germplasm on PEV may be minimized by marker-assisted selection (MAS). Use of DNA markers in breeding programs requires that quantitative trait loci (QTL) associated with target traits be identified. QTL for PEV, kernel weight (KW), growing degree units to anthesis (GDU), and plant height were mapped in F2 plants and their F2:3 families in a dent (B104) x popcorn (BP3) population. Seven QTL associated with 82% of the phenotypic variance were detected for PEV on chromosomes 1 (bins 1.05 and 1.07), 2, 3, 5, 8, and 9. The BP3 allele increased PEV at six of the QTL on chromosomes 1, 2, 3, 5, and 9. The dent parent, B104 contributed the allele that increased PEV at the QTL on chromosome 8. Epistasis was detected for PEV between QTL on chromosomes 2 and 5 such that the magnitude of the additive effect on chromosome 5 was larger when the genotype on chromosome 2 was a BP3 homozygote than when it was B104 homozygote. For kernel weight, six QTL explaining 66% of the phenotypic variance were on chromosomes 1 (bins 1.03 and 1.05), 6, 7, 8, and 9. The B104 allele increased KW at all QTL. QTL for PEV and KW were less than 10 cM apart on chromosomes 1 and 9. Association of PEV and KW QTL may be the cause of the significant phenotypic (rp) and genotypic (rg) correlation detected between the two traits (rp = -0.55 ± 0.04; rg = -0.68 ± 0.05). The test of linkage vs. pleiotropy for PEV and KW QTL on chromosomes 1 and 9 suggested pleiotropy. For GDU, QTL were detected on chromosomes 1, 2, 3,4, 6, and 8. QTL for plant height were detected on chromosomes 1,2, 8, and 9. GDU and plant height QTL accounted for 68 and 48% of the phenotypic variance, respectively. QTL for both traits were in regions (bins) where QTL affecting flowering time and plant height were detected in dent maize populations, suggesting that some of the same genetic factors may be affecting these traits in both dent and popcorn gene pools. In addition, GDU and plant height QTL were in regions where genes and other genetic factors affecting both traits have been mapped in maize. Because QTL in this study were mapped a reference population relevant to popcorn breeding objectives, they can be used to augment phenotypic selection and ensure retention of favorable alleles in a breeding program to improve productivity of BP3 with B104 alleles .
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