40 / SEEDWORLD.COM DECEMBER 2017 “We’ve got the haploids; now we need to put it into production — make the doubled haploids and all the rest of the production process,” Franks says. “We are hoping that within three to four years we can have a pilot small-scale system up and running. It could happen before that but that’s our timeframe. “We are hoping to work on Phases 2 and 3, but first we have to get the technology to the next level of commercial viability,” Franks says. “That means sharing the technology through licensing.” Licensing the technology was a condition of the collaboration in which the checkoff invested $800,000. “It was a high-risk investment, because there was no guarantee that we would find anything,” Weinheimer says. “We are certainly excited to see the potential of this technology and what it would mean for crop improvement in sorghum. “For farmers, this means the entities they are purchasing seed from can now do a better, more efficient job of meeting their needs.” Weinheimer says the overarching goal of the sorghum checkoff project is to increase sorghum producer profitability through research, informa- tion and education. Continued Collaboration The search for inducer lines is just one component of DuPont Pioneer and the sorghum checkoff’s collaborative efforts. “One characteristic we are looking at includes stalk lodging,” Franks adds. “We are in the process of developing a high throughput screen for stalk lodging, which will allow us to screen our germ- plasm for this trait on a large scale.” Additionally, he says his team uses genetic screening options to examine what makes or doesn’t make for good tillering. “We are looking at tillering to see if there are ways we can develop low- or no-tillering sor- ghums,” Franks says, noting that some producers are very interested in that. Given all this work and the discovery of the two inducer lines, the sorghum community expects breeders to really explore the untapped potential of what is possible. It could be improved herbicide tol- erance, drought tolerance and insect resistance. Or it could be something entirely different. Regardless, these efforts will help meet growers’ needs and help sorghum to remain a competitive crop. SW THE ABCS OF DOUBLED HAPLOID BREEDING Homozygous inbred lines are the basis of hybrid breeding. Crossing two unrelated inbred lines leads to high-yielding hybrid varieties. Hybrid varieties exploit the phenomenon of heterosis and have been highly successful in boosting agricultural production worldwide. Traditionally, inbred lines have been formed by continuous self-pollination for six to eight generations. With each generation, a line’s vigor is reduced due to inbreeding depression. The duration of this process determines the progress achieved in a breeding program. The doubled haploid technique speeds inbred line development and is revolutionizing breeding and research. This technique centers on an inducer genotype, which when used as a pollinator in corn triggers pollinated female flowers to produce kernels with haploid embryo. The two major advantages of the doubled haploid technique is that the first doubled haploid lines are completely uniform after only two cropping cycles. Second, because of this complete uniformity, the visual differences between the individual doubled haploid lines are much clearer than between traditionally developed F3 or F4 families. It is therefore easier for breeders to make their selection decisions. Doubled haploid production requires four steps: 1. Inducing haploid. Inducers are specific lines that can induce haploidy. 2. Identifying hybrids with a haploid embryo. This step requires a reliable phenotypic identification system. 3. Doubling haploids chromosomes. Here one copy of each chromosome is made so that resulting plants have two chromosomes (diploids) and are homozygous. 4. Self pollinating doubled plants and harvest of seeds. Breeders then take these diploid plants, called D0 and containing a unique genotype, and plant them. If the doubling succeeds, selfing D0 plants should produce D1 seeds. This D1 seed constitutes the newly developed, completely homozygous doubled haploid inbred line. Many D0 plants produce a limited number of seeds, sometimes as low as one. Another method for creating doubled haploid lines is in vitro haploid induction. This method may involve anther culture combined with chromosome doubling. The success of this method depends on having: • An effective haploid inducer genotype with the high ability to induce haploids when crossed to diverse donor material, independent of environmental conditions. • An effective standardized haploid identification system for distinguishing haploid and diploid progeny. • A spontaneous or artificial doubling chromosome process to facilitate self-pollination and consequently maintenance of doubled haploid line seed. Source — CIMMYT “From a breeding perspective, this could be a game-changing discovery — quite revolutionary in terms of the way we go about product development in sorghum.” — Cleve Franks