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Table 6 This table summarizes the TRS optimization methods employed in this study, indicating their purpose (either optimization of size or composition) and type (whether genetic-based, phenotypic-based, or mixed and targeted or untargeted)

From: Maximizing efficiency in sunflower breeding through historical data optimization

Method

Purpose

Type

Mechanism

\(\begin{array}{cc} \text {PCA\_CDmean/} \\ \text {PLS\_CDmean} \end{array}\)

Composition

\(\begin{array}{cc} \text {Genetic/Mixed} \\ \text {targeted} \end{array}\)

\(\begin{array}{cc} D_1 = diag(X_{TS;All}X'_{TS;All}) \\ X_1 = X'_{TRS;All}X_{TRS;All};\\ X_2 = (X_1+I\lambda )^{-1} \\ D_2 = diag(X_{TS;All}X_2X_1X_2X'_{TS;All}) \\ \text {\textit{CDmean}} = -sum(D_2/D_1)/n_{TS} \\ argmax(CDmean) \end{array}\)

Avg_GRM_self

Composition

\(\begin{array}{cc} \text {Genetic} \\ \text {untargeted} \end{array}\)

\(\begin{array}{cc} \text {\textit{Avg\_GRM\_self}} = -mean(G_{TRS;TRS})\\ argmax(\text {\textit{Avg\_GRM\_self}}) \end{array}\)

Avg_GRM_MinMax

Composition

\(\begin{array}{cc} \text {Genetic} \\ \text {targeted} \end{array}\)

\(\begin{array}{cc} \text {\textit{Avg\_GRM\_MinMax}} = mean(G_{TRS;TS}) -mean(G_{TRS;TRS})\\ argmax(\text {\textit{Avg\_GRM\_MinMax}}) \end{array}\)

Avg_GRM

Composition

\(\begin{array}{cc} \text {Genetic} \\ \text {targeted} \end{array}\)

\(\begin{array}{cc} \text {\textit{Avg\_GRM}}_i = mean(G_{i;TS}) \end{array}\)

\(\begin{array}{l} \text {1) Compute \textit{Avg\_GRM} for all hybrids in the candidate set} \\ \text {2) Select for the TRS the } n_{TRS} \text { hybrids with the highest} \\ \text {\textit{Avg\_GRM} values} \end{array}\)

\(\begin{array}{c} \text {Min\_GRM} \end{array}\)

Composition

\(\begin{array}{cc} \text {Genetic} \\ \text {targeted} \end{array}\)

\(\begin{array}{cc} \text {\textit{Min\_GRM}}_i = min(G_{i;TS}) \end{array}\)

\(\begin{array}{l} \text {1) Compute \textit{Min\_GRM} for all hybrids in the candidate set} \\ \text {2) Select for the TRS the } n_{TRS} \text { hybrids with the highest} \\ \text {\textit{Min\_GRM} values} \end{array}\)

 

Size

\(\begin{array}{cc} \text {Genetic} \\ \text {targeted} \end{array}\)

\(\begin{array}{l} \text {1) Optimize composition of training sets of increasing size using} \\ \text {\textit{Min\_GRM}. Sizes tested range from 1 to entire candidate set} \\ \text {2) The \textit{fitness} value for every TRS is the smallest \textit{Min\_GRM}} \\ \text {value among its hybrids} \\ \text {3) Plot \textit{TRS size} against \textit{-fitness} as in Figure S9} \\ \text {4) Fit sigmoidal function to the plot} \\ \text {5) Optimal TRS size is the one corresponding to the second} \\ \text {inflexion point of the sigmoidal} \end{array}\)

Tails

Composition

\(\begin{array}{cc} \text {Phenotypic} \\ \text {untargeted} \end{array}\)

\(\begin{array}{l} \text {1) Rank hybrids according to their genotypic values} \\ \text {2) Select } \frac{n_{TRS}}{2} \text { hybrids with highest genotypic values} \\ \text {and } \frac{n_{TRS}}{2} \text { hybrids with lowest genotypic values} \end{array}\)

Tails_GEGVs

Composition

\(\begin{array}{cc} \text {Mixed} \\ \text {untargeted} \end{array}\)

\(\begin{array}{l} \text {1) Rank hybrids according to their GEGVs} \\ \text {2) Select } \frac{n_{TRS}}{2} \text { hybrids with highest GEGVs} \\ \text {and } \frac{n_{TRS}}{2} \text { hybrids with lowest GEGVs} \end{array}\)

Tails_GEGVs_sd1

Composition and size

\(\begin{array}{cc} \text {Mixed} \\ \text {untargeted} \end{array}\)

\(\begin{array}{l} \text {1) Scale GEGVs distribution to have } \mu = 0, sd = 1 \\ \text {2) Select hybrids whose scaled GEGVs are lower than } -\alpha \cdot sd \\ \text {and hybrids with scaled GEGVs higher than } \alpha \cdot sd \end{array}\)

  1. \(n_{set}\); the number of instances present in the set indicated in the subindex. For all matrices a subindex indicates that a subset is taken. For instance, \(X_{TRS;All}\) represents the marker matrix whose rows are the individuals in the TRS and with all columns taken
  2. TRS training set, TS test set, i an individual hybrid, G additive genomic relationship matrix, \(\lambda\) shrinkage parameter, X can be the marker matrix or the markers can be replaced with principal components (for PCA_CDmean) or partial least squares variables (for PLS_CDmean), \(diag({\cdot })\) main diagonal of a matrix, \(mean({\cdot })\) average of all elements of a vector or matrix, I identity matrix, \(argmax({\cdot })\) its argument has to be maximized, which was done using TrainSel heuristic, \(\alpha\) parameter controlling TRS size in Tails_GEGVs_sd1