ABSTRACT
Hop ( L.) breeding programs seek to exploit genetic resources for bitter flavor, aroma, and disease resistance. However, these efforts have been thwarted by segregation distortion including female-biased sex ratios. To better understand the transmission genetics of hop, we genotyped 4512 worldwide accessions of hop, including cultivars, landraces, and over 100 wild accessions using a genotyping-by-sequencing (GBS) approach. From the resulting â¼1.2 million single-nucleotide polymorphisms (SNPs), prequalified GBS markers were validated by inferences in population structures and phylogeny. Analysis of pseudo-testcross (Pt) mapping data from F families revealed mixed patterns of Mendelian and non-Mendelian segregation. Three-dimensional (3D) cytogenetic analysis of late meiotic prophase nuclei from two wild and two cultivated hop revealed conspicuous and prevalent occurrences of multiple, atypical, nondisomic chromosome complexes including autosomes. We used genome-wide association studies (GWAS) and fixation index (F) analysis to demonstrate selection mapping of genetic loci for key traits including sex, bitter acids, and drought tolerance. Among the possible mechanisms underlying the observed segregation distortion from the genomic data analysis, the cytogenetic analysis points to meiotic chromosome behavior as one of the contributing factors. The findings shed light on long-standing questions on the unusual transmission genetics and phenotypic variation in hop, with major implications for breeding, cultivation, and the natural history of .
Subject(s)
Humulus/genetics , Meiosis/genetics , Polymorphism, Single Nucleotide , Chromosomes, Plant , Genetic Markers , Genome-Wide Association Study , Genotype , Humulus/cytology , PhylogenyABSTRACT
Bitter acids, known for their use as beer flavoring and for their diverse biological activities, are predominantly formed in hop (Humulus lupulus) glandular trichomes. Branched short-chain acyl-CoAs (e.g. isobutyryl-CoA, isovaleryl-CoA and 2-methylbutyryl-CoA), derived from the degradation of branched-chain amino acids (BCAAs), are essential building blocks for the biosynthesis of bitter acids in hops. However, little is known regarding what components are needed to produce and maintain the pool of branched short-chain acyl-CoAs in hop trichomes. Here, we present several lines of evidence that both CoA ligases and thioesterases are likely involved in bitter acid biosynthesis. Recombinant HlCCL2 (carboxyl CoA ligase) protein had high specific activity for isovaleric acid as a substrate (K cat /K m = 4100 s(-1) M(-1)), whereas recombinant HlCCL4 specifically utilized isobutyric acid (Kcat/K m = 1800 s(-1) M(-1)) and 2-methylbutyric acid (Kcat/K m = 6900 s(-1) M(-1)) as substrates. Both HlCCLs, like hop valerophenone synthase (HlVPS), were expressed strongly in glandular trichomes and localized to the cytoplasm. Co-expression of HlCCL2 and HlCCL4 with HlVPS in yeast led to significant production of acylphloroglucinols (the direct precursors for bitter acid biosynthesis), which further confirmed the biochemical function of these two HlCCLs in vivo. Functional identification of a thioesterase that catalyzed the reverse reaction of CCLs in mitochondria, together with the comprehensive analysis of genes involved BCAA catabolism, supported the idea that cytosolic CoA ligases are required for linking BCAA degradation and bitter acid biosynthesis in glandular trichomes. The evolution and other possible physiological roles of branched short-chain fatty acid:CoA ligases in planta are also discussed.
Subject(s)
Coenzyme A/metabolism , Fatty Acids/biosynthesis , Fatty Acids/chemistry , Humulus/metabolism , Trichomes/metabolism , Cloning, Molecular , Fatty Acids/metabolism , Gene Expression Regulation, Plant , Humulus/cytology , Humulus/genetics , Humulus/growth & development , Intracellular Space/metabolism , Ligases/genetics , Ligases/metabolism , Organ Specificity , Phylogeny , Sequence Analysis , Sequence Homology, Nucleic AcidABSTRACT
The paper reported the differences of the Radix Rubiae and the root of Humulus scardens (Lour.) Merr. on morphological and histological characteristics and UV-identification.
Subject(s)
Drugs, Chinese Herbal/chemistry , Humulus/anatomy & histology , Plant Roots/anatomy & histology , Humulus/chemistry , Humulus/cytology , Plant Roots/chemistry , Plant Roots/cytology , Spectrophotometry, UltravioletABSTRACT
In this paper, pharmacognostiacal identification of Humulus scandens was studied. The character of medicinal materials, histological and powder characteristics for the setem and leaf of H. scandens were mainly reported. The microscopical features for leaf is typical identified basis.
