Populations of doubled haploids for genetic mapping in hexaploid winter triticale.

To create a framework for genetic dissection of hexaploid triticale, six populations of doubled haploid (DH) lines were developed from pairwise hybrids of high-yielding winter triticale cultivars. The six populations comprise between 97 and 231 genotyped DH lines each, totaling 957 DH lines. A consensus genetic map spans 4593.9 cM is composed of 1576 unique DArT markers. The maps reveal several structural rearrangements in triticale genomes. In preliminary tests of the populations and maps, markers specific to wheat segments of the engineered rye chromosome 1R (RM1B) were identified. Example QTL mapping of days to heading in cv. Krakowiak revealed loci on chromosomes 2BL and 2R responsible for extended vernalization requirement, and candidate genes were identified. The material is available to all parties interested in triticale genetics

An optimized clearing protocol for the quantitative assessment of sub-epidermal ovule tissues within whole cereal pistils

Background: Seed development in the angiosperms requires the production of a female gametophyte (embryo sac) within the ovule. Many aspects of female reproductive development in cereal crops are yet to be described, largely due to the technical difficulty in obtaining phenotypic information at the cellular or sub-cellular level. Hoyer’s solution is currently well established as a solution for clearing thin tissues samples, such as sections or whole tissues of bryophytes, mycorrhizal fungi, and small model organisms (e.g. Arabidopsis thaliana). Results: Here we report a Hoyer’s solution-based clearing method to facilitate clearing of the whole barley pistil, with high reproducibility. The clearing process takes 10 days from fixation to visualisation, whereupon tissue is sufficiently clear to obtain multiple phenotypic measurements from sub-epidermal tissues and cells within the ovule. Conclusion: Visualisation of cereal ovules that have not been dissected from the pistil allows an unprecedented capability to collect quantitative morphological information from the developing ovule, integument, nucellus and embryo sac. This will enable comparisons with genetic data to reveal the contribution of pre-fertilisation ovule tissues towards downstream seed development.Laura G. Wilkinson and Matthew R. Tucke

Anther culture response in F1 hybrids of winter wheat [Triticum aestivum L.]

The effect of cold pretreatment of spikes on somatic embryo induction and anther culture response of 25 F₁ winter wheat hybrids was investigated. The efficiency of androgenic embryos was the highest when spikes were incubated at 4°C for 6-9 days. A total of 2242 (73.0%) green and 885 (27.0%) albino plants were obtained from 9900 cultured anthers. Anther culture response in wheat was found to be markedly affected by the genotype of donor plants. The percentage of green plants varied from 0 to 115.7%. A great majority of anther-derived regenerants were haploids (82.35%), while the remaining plants were spontanoeus diploids (13.73%) and aneuploids (3.92%)

Regeneration of oat androgenic plants in relation to induction media and culture conditions of embryo-like structures

The effect of C17 and W14 induction media on the formation of embryo-like structures (ELS) from F3 generation of nine hexaploid oat hybrids was investigated in the study. In all genotypes, the highest number of ELS (0.6 - 12.1/100 anthers) was obtained on C17 medium. The efficiency of plant regeneration on medium 190-2 was tested, in relation to different ELS culture conditions. The highest rate of green plants per 100 ELS (3.3 - 42.4) was produced by incubation at 22oC in the dark for the first two weeks. Among 36 green regenerants, 28 (77.8%) were haploid and 8 (22.2%) were spontaneous doubled haploids, fully fertile. After colchicine treatment of haploid plants, 19 were partially fertile and set from 1 to 15 seed per panicle

Effect of genotype and media composition on embryoid induction and plant regeneration from anther culture in triticale

Anthers of twenty triticale genotypes were cultured on three different media: 1 - PII (Chuang et al. 1978) with increased 2,4-D to 2 mg L⁻¹ and agarose 6 g L⁻¹ , 2 - Macro-, micronutrients and vitamines like in MN6 (Chu, Hill 1988) + 2 mg L⁻¹ 2.4-D + 0.5 mg L⁻¹ KIN + 5 mg L⁻¹ FeEDTA + 90 g L⁻¹ sucrose; 3 - Macro-, micronutrients and vitamines like in MN6 (Chu, Hill, 1988) + 2 mg L⁻¹ 2.4-D + 0.5 mg L⁻¹ KIN + 5 mg L⁻¹ FeEDTA + 120 g L⁻¹ sucrose. Embryoid induction and plant regeneration were influenced by donor plant genotype and induction medium. Medium 1 was the best for embryoid induction, while for green plant regeneration the best were media 1 and 2. Out of 300 anthers from each genotype plated on each of the three media, 64-1250, 12-486 and 6-212 somatic embryos and 8-86, 3-136 and 1-26 green plants were recorded, on media 1, 2 and 3, respectively

The effect of liquid and solid medium on production of winter triticale (× Triticosecale Wittm.) anther-derived embryos and plants

The efficiency of anther culture induction in solid and liquid medium C17 was compared for nine triticale genotypes. For all genotypes androgenic embryos and green plants efficiency was higher on liquid medium. On liquid medium 22.2–135.9 and on solid medium 27.5–121.3 androgenic embryos/100 anthers were produced. The embryos were transferred to a regeneration medium 190-2 and also a higher number of green plants (ranging from 3.0 to 31.4/100 anthers) were obtained in liquid culture compared with the yield of plants (1.6–21.0) on solid medium