Santra Meenakshi, Wang Hong, Seifert Scott, Haley Scott
Department of Soil and Crop Science, Colorado State University, 307 University Ave., Fort Collins, CO, 80523, USA.
Methods Mol Biol. 2017;1679:235-249. doi: 10.1007/978-1-4939-7337-8_14.
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.
在传统小麦育种中，育种群体衍生品系的一致性是通过从F1代开始反复自交获得的，这需要几代时间才能使控制目标性状的位点达到纯合状态。然而，利用双单倍体技术，有可能在一代中使所有位点达到100%纯合，并且在1至2年内就能获得完全一致的育种品系。因此，双单倍体技术可能会显著缩短品种培育时间。产生小麦双单倍体的两种主要方法是雄核发育（花药培养和小孢子培养）以及利用小麦-玉米远缘杂交进行胚培养，后者是最有效且应用最广泛的方法。小麦与玉米的远缘杂交方法虽然费力，但在快速获得纯合品系方面广泛取得成功。该技术包括六个主要步骤：对小麦花去雄；用玉米花粉对去雄后的花授粉；激素处理；胚拯救；在组织培养基中使单倍体植株再生；以及染色体加倍。据观察，双单倍体的产生效率取决于玉米和小麦的基因型、植株健康状况良好以及适宜的温室条件（无病害、虫害或干旱胁迫），以及所有程序的正确操作。因此，可能需要对这些程序进行细微调整，以产生更多的胚、单倍体绿色植株和双单倍体植株。
