Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 30, 2005
Publication Date: February 24, 2006
Citation: Wang, R. 2006. Registration of tbte001 and tbte002 thinopyrum amphidiploid genetic stocks differing for leaf glaucousness. Crop Science 46:1013-1014 Interpretive Summary: Amphidiploids derived from the Thinopyrum bessarabicum X Th. elongatum hybrids are released as two genetic stocks, TBTE001 and TBTE002. The former is heterozygous for the leaf glaucousness and the latter is homozygous for the trait thus having blue-colored leaves. Since glaucousness of leaves results from the deposition of epicuticular wax on leaf surfaces, this trait has implications on photosynthesis and biotic/abiotic stress resistance or tolerance. Interestingly, the thousand seed weight is 8.6 g and 6.7 g in TBTE001 and TBTE002, respectively, suggesting lower photosynthetic products in the latter. TBTE001 and TBTE002 are intended for scientists interested in studying leaf glaucousness or in isolating the gene controlling the trait. Furthermore, the amphidiploids can be crossed with tetraploid species of Thinopyrum to produce fertile hybrids, in which genetic recombinations can occur between closely related Eb and Ee genomes. Thus, they will be useful in the improvement of forage species in the genus Thinopyrum. Attempts to transfer useful traits in Thinopyrum species to wheat by hybridizing these amphidiploids with durum wheat have also been reported. TBTE001 and TBTE002 can be useful to scientists studying inheritance patterns, either disomic or tetrasomic, of other traits (such as mode of pollination) or molecular markers in known linkage groups. Those traits found to have tetrasomic segregation would indicate that the chromosomes carrying genes for the traits were homologous and capable of forming quadrivalents. Chromosomes carrying genes for traits that segregate in a disomic pattern are those that had undergone substantial structural changes to become homoeologous.
Technical Abstract: Two wheatgrass Thinopyrum bessarabicum X Th. elongatum amphidiploid (tetraploid, 2n=28, EbEbEeEe) genetic stocks, TBTE001 and TBTE002 were developed at USDA-ARS Forage and Range Research Laboratory, Utah State University, Logan, Utah. They were jointly released by USDA-ARS and Utah Agricultural Experiment Station on June 2, 2005. These genetic stocks were derived from amphidiploids of diploid hybrids between Th. bessarabicum (2n=14, Eb genome; cross-pollinating) and Th. elongatum (2n=14, Ee; self-pollinating). Original diploid hybrids were made in 1984 between each of two accessions of Th. bessarabicum, PI 531710 and PI 531711, with one accession of Th. elongatum PI 531719. The sterile F1 hybrids were produced only when Th. bessarabicum was used as maternal parent. Colchicine treatments of 19 diploid hybrids resulted in seed-set from some spikes arising from chimeric chromosome-doubled sectors in 10 F1 hybrids. Germination of these C0 seeds established many fertile amphidiploids, 13 of which were cytologically analyzed. The amphidiploids have larger seeds (thousand seed weight, 8.4-8.5 g. vs. 3.4 g for Th. elongatum and 4.8-5.8 g for Th. bessarabicum) and are more vigorous (coleoptile length 10 days after seed imbibition, 79-92 mm vs. 44 and 33-52 mm, respectively) than both parents; although their salt tolerance was variable depending on the accession of Th. bessarabicum used in the production of diploid hybrids. These C0 amphidiploids had green leaves as did the F1 diploid hybrids. However, plants with glaucous-blue leaves appeared in the advanced generations, C1 and C2, following tetrasomic segregation of the alleles governing the trait. The glaucous-leaf trait is controlled by a recessive gene located on a chromosome of Th. bessarabicum. Therefore, plants with glaucous-blue leaves were isolated in a greenhouse crossing block to facilitate cross-pollination among them. Seeds produced from four green-leaved C2 plants were bulked to constitute the TBTE001 genetic stock, which contains plants of all three genotypes for leaf glaucousness. Seeds from intercrossed seven blue-leaved C2 amphidiploids that consitute the TBTE002 genetic stock will give rise to only homozygous glaucous-leaved plants.