Predictive ability of genomic selection models in a multi-population perennial ryegrass training set using genotyping-by-sequencing.

KEY MESSAGE: Genomic prediction models for multi-year dry matter yield, via genotyping-by-sequencing in a composite training set, demonstrate potential for genetic gain improvement through within-half sibling family selection. Perennial ryegrass (Lolium perenne L.) is a key source of nutrition for ruminant livestock in temperate environments worldwide. Higher seasonal and annual yield of herbage dry matter (DMY) is a principal breeding objective but the historical realised rate of genetic gain for DMY is modest. Genomic selection was investigated as a tool to enhance the rate of genetic gain. Genotyping-by-sequencing (GBS) was undertaken in a multi-population (MP) training set of five populations, phenotyped as half-sibling (HS) families in five environments over 2 years for mean herbage accumulation (HA), a measure of DMY potential. GBS using the ApeKI enzyme yielded 1.02 million single-nucleotide polymorphism (SNP) markers from a training set of n = 517. MP-based genomic prediction models for HA were effective in all five populations, cross-validation-predictive ability (PA) ranging from 0.07 to 0.43, by trait and target population, and 0.40-0.52 for days-to-heading. Best linear unbiased predictor (BLUP)-based prediction methods, including GBLUP with either a standard or a recently developed (KGD) relatedness estimation, were marginally superior or equal to ridge regression and random forest computational approaches. PA was principally an outcome of SNP modelling genetic relationships between training and validation sets, which may limit application for long-term genomic selection, due to PA decay. However, simulation using data from the training experiment indicated a twofold increase in genetic gain for HA, when applying a prediction model with moderate PA in a single selection cycle, by combining among-HS family selection, based on phenotype, with within-HS family selection using genomic prediction.

(1->3),(1->4)-{beta}-d-Glucans in the cell walls of the Poales (sensu lato): an immunogold labeling study using a monoclonal antibody.

(1→3),(1→4)-ß-Glucans had previously been detected in nonlignified cell wall preparations of only the Poaceae and five other families in the graminoid clade of the Poales (s.l.). Cell walls of vegetative organs of 12 species in nine families of the Poales (s.l.) were examined by immunogold labeling using a monoclonal antibody to (1→3),(1→4)-ß-glucans. Three types of wall-labeling patterns were identified depending on the density of labeling of the nonlignified walls of epidermal and parenchyma cells and the lignified walls of sclerenchyma fibers and xylem tracheary elements: type 1 in Poaceae and Flagellariaceae, type 2 in Restionaceae and Xyridaceae, and type 3 in Cyperaceae and Juncaceae. Type 1 had the heaviest labeling of nonlignified walls and type 2 the heaviest labeling of lignified walls. Type 3 had the least wall labeling, with only very light labeling of nonlignified and lignified walls. No labeling was found over walls of Typhaceae, Sparganiaceae, or Bromeliaceae. The results are discussed in relation to Poales phylogeny.

Location of (1 → 3)- and (1 → 3),(1 → 4)-ß-D-glucans in vegetative cell walls of barley (Hordeum vulgare) using immunogold labelling.

• (1 â†’ 3),(1 â†’ 4)-ß-Glucans occur only in the cell walls of the family Poaceae (grasses and cereals) and related families, but little is known about their distribution among walls of different cell types or within walls. • The locations of (1 â†’ 3)- and (1 â†’ 3),(1 â†’ 4)-ß-glucans in the walls of the coleoptile, first leaf and root tip of barley (Hordeum vulgare) seedlings were determined using immunogold labelling. • All the walls were labelled with the (1 â†’ 3),(1 â†’ 4)-ß-glucan antibody, except those of the outer root cap cells. Labelling of the primary walls was heavy in the coleoptile and leaf, but light or very light in the root tip. Two types of primary wall labelling occurred: in the coleoptiles (except the walls of the epidermis and two layers of parenchyma under this) and in the leaf, labelling was throughout the walls; in the root tips, labelling was only adjacent to the plasma membrane. Small amounts of labelling occurred with the (1 â†’ 3)-ß-glucan antibody, mostly over plasmodesmata. Both antibodies labelled cell plates. • (1 â†’ 3),(1 â†’ 4)-ß-Glucans occur widely in the cell walls of vegetative organs of the barley seedlings, including the walls of meristematic tissues.