TITLE:
Mapping Qtls for Grain Yield and Yield Components in Kenyan Maize (Zea mays L.) Under Low Phosphorus Using Single Nucleotide Polymorphism (SNPS)
AUTHORS:
Evans Ochieng Ouma, Gudu Samuel
KEYWORDS:
SNP Markers, Additive, Dominance, Heritability, Low P, Maize, QTLs
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.12 No.7,
July
28,
2021
ABSTRACT: Selection for tolerance to low phosphorus (P) using morphological traits
alone is slow and often confounded by environmental effects. This study
identified some Quantitative Trait Loci (QTLs) associated with
grain yield (GYLD), Plant (PHT) and Ear heights (EHT) under low P in maize using single
nucleotide polymorphic markers. 228 F2:3 individuals derived from a cross between two contrasting maize
inbred lines together with 239 SNPs were mapped onto ten linkage groups (LGs)
spanning 2255 centiMorgans (cM) with an average inter-marker distance of 9.44
cM. Majority of the SNP markers (63%) followed the Mendelian segregation and
were fairly distributed in all the LGs. Mean performance for all the traits in
the F3 population was higher than the parental values, which suggested
transgressive segregation for all traits. Low to moderate broad sense
heritability (0.35 - 0.50) in the F3 population for GYLD, PHT and EHT indicated that tolerance to
low P is controlled by complex multi genetic factors. A full multi-QTL model
analysis suggested six QTLs (2 QTLs each for GYLD, PHT and EHT) located
on chromosomes 1, 3, 4 and 8. The two QTLs for GYLD increased maize yield under low P soils by 173
kg/ha while the 2 QTLs for PHT increased plant growth by 18.14 cm. The %
phenotypic variance explained by these QTLs under low P environments had a wide
range (0.242% - 53.34%) and was much lower for GYLD compared to plant growth.
Both additive and dominance gene actions contributed differentially to the
observed phenotypic variance for tolerance to low P soils with dominance
contributing more genetic effects compared additive effects for majority of the
QTLs. The findings of this study will provide some basis for marker-assisted
selection for yield improvement and further guide breeding strategies under low
P soils of western Kenya.