Portion Of Phenotypic Variation Research Articles

Genome wide association study and genomic prediction for stover quality traits in tropical maize (Zea mays L.)

Maize is rapidly replacing traditionally cultivated dual purpose crops of South Asia, primarily due to the better economic remuneration. This has created an impetus for improving maize for both grain productivity and stover traits. Molecular techniques can largely assist breeders in determining approaches for effectively integrating stover trait improvement in their existing breeding pipeline. In the current study we identified a suite of potential genomic regions associated to the two major stover quality traits—in-vitro organic matter digestibility (IVOMD) and metabolizable energy (ME) through genome wide association study. However, considering the fact that the loci identified for these complex traits all had smaller effects and accounted only a small portion of phenotypic variation, the effectiveness of following a genomic selection approach for these traits was evaluated. The testing set consists of breeding lines recently developed within the program and the training set consists of a panel of lines from the working germplasm comprising the founder lines of the newly developed breeding lines and also an unrelated diversity set. The prediction accuracy as determined by the Pearson’s correlation coefficient between observed and predicted values of these breeding lines were high even at lower marker density (200 random SNPs), when the training and testing set were related. However, the accuracies were dismal, when there was no relationship between the training and the testing set.

The Influence of Parental Myopia on Children’s Myopia in Different Generations of Parent-Offspring Pairs in South Korea

ABSTRACTPurpose: To compare the heritabilities of myopia and high myopia across three different generations in Korea. Methods: Parent-offspring pairs of different age groups were included: two parents and their offspring aged 10–19 (“young families”), two parents and their offspring aged 20–29 (“middle-aged families”), and two parents and their offspring aged 30–45 (“older families”) were selected from the 2008–2012 Korea National Health and Nutrition Examination Survey. Variance component methods were used to obtain the heritability estimates for myopia and high myopia using parent-offspring pairs from three generations. Spherical equivalents measured in the right eyes were used. Results: From the 2008–2012 data, 2,716, 1,211, and 477 offspring from 1,807 young, 956 middle-aged, and 434 older families were eligible for the study, respectively. For myopia, the additive genetic portion of phenotypic variance was smaller in the younger families (74.7% in the older families, 48.1% in the middle-aged families, and 40.1% in the young families), and the non-shared environmental portion was greater in the younger families (12.4% in older families, 24.9% in middle-aged families, and 46.5% in young families). In contrast, for high myopia, the additive genetic portion remained roughly constant at approximately 60% in all three generations. Conclusions: With myopia, the environmental portion of the phenotypic variance increased and the additive genetic portion decreased as South Korea became more urbanized. With high myopia, the additive genetic portion remained roughly constant at approximately 60%, despite the urbanization.

Construction of a melon genetic map with fruit and seed QTLs

A genetic map of melon was constructed using 143 F2 population developed from a cross between two distant lines Ano2 of Japan and Hami melon K413. The map contains 12 linkage groups and 142 markers, including 121 AFLPs, 16 SSRs, 3 STSs, 2 trait markers and covers 1 014.2 cM. Composite interval mapping (CIM) method was used to detect QTLs involved in melon fruit and seed traits: fruit length (FL), fruit width (FW), fruit shape (length/width, FS), centre sugar (CS), edge sugar (ES), flesh texture (FT), seed length (SL), seed width (SW), seed shape (SS), and seed weight (SW). The result showed that Flesh was located between AFLP markers NDAA and NCFA on C9. A total of 25 QTLs were detected for other traits and some QTLs were co-located with each other. The QTLs Sl5.1, Sw5.1, and Swt5.1 located on linkage C5 between NCA and N73C explained a significant portion of associated phenotypic variation (R2=17%, 19%, 23%). The allele from Ano2 obviously suppressed the length, width, and weight of melon seed; the QTLs between N73A and NFDA on C8 were involved in seed width, shape, and weight; the QTL Fs8.1 on C8 was detected using both F2 and F3 fruit data and explained a significant portion of phenotypic variation 25% and 19%. Fs8.1 showed partly dominant, and the allele from Ano2 sup-pressed elongation of fruit to form round melon. The QTLs related to centre sugar, edge sugar, and fruit texture were also detected in this research.