agridat (version 1.23)

hadasch.lettuce: Lettuce resistance to downy mildew resistance (with marker data)

Description

Lettuce resistance to downy mildew resistance (with marker data).

Usage

data("hadasch.lettuce")

Format

A data frame with 703 observations on the following 4 variables.

loc

locations

gen

genotype

rep

replicate

dmr

downy mildew resistance

Details

A biparental cross of 95 recombinant inbred lines of "Salinas 88" (susceptible) and "La Brillante" (highly resistant to downy mildew). The 89 RILs were evaluated in field experiments performed in 2010 and 2011 near Salinas, California. Each loc had a 2 or 3 rep RCB design. There were approximately 30 plants per plot. Plots were scored 0 (no disease) to 5 (severe disease).

The authors used the following model in a first-stage analysis to compute adjusted means for each genotype:

y = loc + gen + gen:loc + block:loc + error

where gen was fixed and all other terms random. The adjusted means were used as the response in a second stage:

mn = 1 + Zu + error

where Z is the design matrix of marker effects. The error term is fixed to have covariance matrix R be the same as from the first stage.

Genotyping was performed with 95 SNPs and 205 amplified fragment length polymporphism markers so that a marker matrix M (89×300) was provided. The biallelic marker M(iw) for the ith genotype and the wth marker with alleles A1 (i.e. the reference allele) and A2 was coded as 1 for A1,A1, -1 for A2,A2 and 0 for A1,A2 and A2,A2.

The electronic version of the lettuce data are licensed CC-BY 4 and were downloaded 20 Feb 2021. https://figshare.com/articles/dataset/Lettuce_trial_phenotypic_and_marker_data_/8299493

References

Hayes, R. J., Galeano, C. H., Luo, Y., Antonise, R., & Simko, I. (2014). Inheritance of Decay of Fresh-cut Lettuce in a Recombinant Inbred Line Population from "Salinas 88" × "La Brillante". J. Amer. Soc. Hort. Sci., 139(4), 388-398. https://doi.org/10.21273/JASHS.139.4.388

Examples

if (FALSE) {
  library(agridat)
  data(hadasch.lettuce)
  data(hadasch.lettuce.markers)
  dat <- hadasch.lettuce
  datm <- hadasch.lettuce.markers
  
  libs(agridat)
  # loc 1 has 2 reps, loc 3 has higher dmr
  dotplot(dmr ~ factor(gen)|factor(loc), dat,
        group=rep, layout=c(1,3),
        main="hadasch.lettuce")

  # kinship matrix
  # head( tcrossprod(as.matrix(datm[,-1])) )

  if(require("asreml", quietly=TRUE)){
    libs(asreml)
    dat <- transform(dat, loc=factor(loc), gen=factor(gen), rep=factor(rep))
    m1 <- asreml(dmr ~ 1 + gen, data=dat,
                 random = ~ loc + gen:loc + rep:loc)
    p1 <- predict(m1, classify="gen")$pvals
  }
  
  libs(sommer)
  m2 <- mmer(dmr ~ 0 + gen, data=dat,
             random = ~ loc + gen:loc + rep:loc)
  p2 <- coef(m2)
  head(p1)
  head(p2)

}