Doubled Haploid Laboratory Protocol for Wheat Using Wheat-Maize Wide Hybridization.

In traditional wheat breeding, the uniformity of lines derived from a breeding population is obtained by repeated selfing from the F1 which takes several generations to reach homozygosity in loci controlling traits of interest. Using doubled haploid technology, however, it is possible to attain 100% homozygosity at all loci in a single generation and completely homogeneous breeding lines can be obtained in 1-2 years. Thus, doubled haploid technology may significantly reduce cultivar development time. Two major methods for producing wheat doubled haploids are androgenesis (anther culture and microspore culture) and embryo culture using wheat-maize wide hybridization, the latter being the most effective and widely used method. The method of wide hybridization between wheat and maize is laborious but is widely successful for rapidly obtaining homozygous lines. This technique includes six major steps: emasculation of the wheat flower; pollination of the emasculated flower with maize pollen; hormone treatment; embryo rescue; haploid plant regeneration in tissue culture medium; and chromosome doubling. It has been observed that the efficiency of doubled haploid production depends on both maize and wheat genotypes, good plant health and proper greenhouse conditions (without disease, insects, or drought stress), and proper conduct of all procedures. Therefore, the procedures may need minor modification in order to produce higher numbers of embryos, haploid green plants, and doubled haploid plants.

Metabolite profiling of a diverse collection of wheat lines using ultraperformance liquid chromatography coupled with time-of-flight mass spectrometry.

Genetic differences among major types of wheat are well characterized; however, little is known about how these distinctions affect the small molecule profile of the wheat seed. Ethanol/water (65% v/v) extracts of seed from 45 wheat lines representing 3 genetically distinct classes, tetraploid durum (Triticum turgidum subspecies durum) (DW) and hexaploid hard and soft bread wheat (T. aestivum subspecies aestivum) (BW) were subjected to ultraperformance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOF-MS). Discriminant analyses distinguished DW from BW with 100% accuracy due to differences in expression of nonpolar and polar ions, with differences attributed to sterol lipids/fatty acids and phospholipids/glycerolipids, respectively. Hard versus soft BW was distinguished with 100% accuracy by polar ions, with differences attributed to heterocyclic amines and polyketides versus phospholipid ions, respectively. This work provides a foundation for identification of metabolite profiles associated with desirable agronomic and human health traits and for assessing how environmental factors impact these characteristics.