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Preharvest sprouting is a serious problem in grain crop production because it causes quality deterioration and economic losses. It is well known that grain colour is closely associated with grain dormancy in wheat; white-grained lines without accumulating proanthocyanidins in testa tend to be more susceptible to preharvest sprouting than red ones. All available white-grained wheat lines are restricted to triple recessive mutations at the R loci (R-A1, R-B1, and R-D1), but barley is known to have 11 independent loci conferring the proanthocyanidin-free grain phenotype. In this study, we evaluated the dormancy levels of anthocyanin/proanthocyanidin-free ant17 mutants. Three ant17 mutants showed the same levels of dormancy as their respective wild types. Sequencing of three independent ant17 alleles detected a point mutation within the coding regions offlavanone-3-hydroxylase (F3H), which are predicted to cause a premature stop codon at different sites. The F3H locus completely cosegregated with the Ant17 position on the chromosome arm 2HL. Expression of the barley F3H gene was observed in pigmented tissues, but not in nonpigmented roots and stems. This result indicates that wheat F3H may be a promising new target locus for breeding white-grained lines with a practical level of preharvest sprouting resistance. Key words: Ant mutant, anthocyanin, grain dormancy, preharvest sprouting, proanthocyanidins. La germination sur epi est un serieux probleme en production de grains car elle entraine une deterioration de la qualite et des pertes economiques. Il est bien connu que la couleur du grain est etroitement associee a la dormance des grains chez le ble; les lignees a grains blancs qui n'accumulent pas de proanthocyanidines dans les teguments etant plus sensibles a la germination sur epi que les bles rouges. Toutes les lignees a grains blancs connues sont porteuses de trois mutations recessives aux locus R (R-A1, R-B1 et R-D1), tandis que chez l'orge 11 locus independants conferent l'absence de proanthocyanidines chez le grain. Dans ce travail, les auteurs ont evalue les niveaux de dormance chez des mutants ant17 depourvus d'anthocyanidines et de proanthocyanidines. Les trois mutants ant17 presentaient le meme niveau de dormance que les temoins sauvages. Le sequencage de trois alleles independants d'ant17 a permis de detecter des mutations ponctuelles au sein des regions codantes de laflavone-3-hyroxylase (F3H), lesquelles introduisent des codons stop prematures a differents endroits. Le locus F3H montrait une co-segregation parfaite avec le locus Ant17 sur le bras chromosomique 2HL. L'expression du gene F3H de l'orge a ete observee au sein des tissus pigmentes, mais non chez les tissus non-pigmentes (racines et tiges). Ce resultat suggere que le gene F3H constitue une nouvelle cible prometteuse pour le developpement de lignees a grains blancs avec un niveau utile de resistance a la germination sur l'epi. [Traduit par la Redaction] Mots-cles: mutant Ant, anthocyanines, dormance des grains, germination sur l'epi, proanthocyanidines., Introduction Anthocyanins and proanthocyanidins are pigments that are prevalent in plants and have important biological roles, such as the recruitment of insects and birds and protection from harmful UV light [...]

Barley (Hordeum vulgare) is the fourth most highly produced cereal in the world after wheat, rice and maize and is mainly utilized as malts and for animal feed. Barley, a model crop of the tribe Triticeae, is important in comparative analyses of Poaceae. However, molecular understanding about the developmental processes is limited in barley. Our previous work characterized one of two WUSCHEL-RELATED HOMEOBOX 3 (WOX3) genes present in the barley genome: NARROW LEAFED DWARF1 (NLD1). We demonstrated that NLD1 plays a pivotal role in the development of lateral organs. In the present study, we describe a bifurcated palea (bip) mutant of barley focusing on flower and leaf phenotypes. The palea in the bip mutant was split into two and develop towards inside the lemma surrounding the carpels and anthers. The bip mutant is devoid of lodicules, which develop in a pair at the base of the stamen within the lemma in normal barley. bip also exhibited malformations in leaves, such as narrow leaf due to underdeveloped leaf-blade width, and reduced trichome density. Map-based cloning and expression analysis indicated that BIP is identical to another barley WOX3 gene, named HvWOX3. The bip nld1 double mutant presented a more severe reduction in leaf-blade width and number of trichomes. By comparing the phenotypes and gene expression patterns of various WOX3 mutants, we concluded that leaf bilateral outgrowth and trichome development are promoted by both NLD1 and HvWOX3 , but that HvWOX3 serves unique and pivotal functions in barley development that differ from those of NLD1. [ABSTRACT FROM AUTHOR]

The physical locations of S5 and 18S-25S rDNA were found in 15 diploid Hordeum species with the I genome have been determined. Molecular cytogenetic study gives new information on the karyotype evolution of I-genome diploid species of the genus Hordeum.