scholarly journals Cytological Studies in Cultivated Species of Camellia : I. Diploid Species and their Hybrids

1977 ◽  
Vol 27 (1) ◽  
pp. 28-38 ◽  
Author(s):  
Katsuhiko KONDO
Keyword(s):  
Diploid Species ◽  
Cultivated Species

scholarly journals Evaluation of Arachis Species for Resistance to Tomato Spotted Wilt Virus

2002 ◽  
Vol 29 (2) ◽  
pp. 79-84 ◽  
Author(s):  
J. H. Lyerly ◽  
H. T. Stalker ◽  
J. W. Moyer ◽  
K. Hoffman
Keyword(s):  
Tomato Spotted Wilt Virus ◽  
Insect Pests ◽  
Disease Incidence ◽  
Diploid Species ◽  
Breeding Programs ◽  
Arachis Species ◽  
Tomato Spotted Wilt ◽  
Arachis Hypogaea L ◽  
Cultivated Species ◽  
Wilt Virus

Abstract Tomato spotted wilt virus (TSWV) is an important plant pathogen with a wide host range, including the domesticated peanut (Arachis hypogaea L.). After initial outbreaks on peanut during the 1980s, the virus has spread to all peanut-producing states in the U.S. TSWV is transmitted by several species of thrips which are difficult to control with insecticides; therefore, control of TSWV most likely will come from selecting resistant genotypes in breeding programs. Although moderate levels of resistance have been discovered in A. hypogaea, complete virus resistance has not been found. Several Arachis species have desirable genes for plant resistances and tolerate many disease and insect pests better than the cultivated species. The objectives of this study were to (a) evaluate TSWV disease incidence and severity in accessions of Arachis species, and (b) compare levels of TSWV resistance in diploid species to selected A. hypogaea genotypes. In this study, 46 diploid Arachis spp. accessions were evaluated in the greenhouse by artificial inoculation tests for resistance to TSWV. Nine Arachis accessions were observed with no disease symptoms when TSWV isolate 10 was used as opposed to A. hypogaea lines that ranged from moderately to highly susceptible. Additional testing with more virulent isolates identified A. diogoi accession GKP 10602 and A. correntina accession GKP 9530 as highly resistant to the virus. These two accessions are being used as parents in crossing programs to incorporate TSWV resistance genes into A. hypogaea.

MEIOTIC CHROMOSOME BEHAVIOR IN TETRAPLOID HYBRIDS BETWEEN SYNTHETIC LOTUS AMPHIDIPLOIDS AND L. CORNICULATUS

1972 ◽  
Vol 14 (1) ◽  
pp. 57-64 ◽  
Author(s):  
B. H. Somaroo ◽  
W. F. Grant
Keyword(s):  
Pollen Fertility ◽  
Meiotic Chromosome ◽  
Diploid Species ◽  
Strong Tendency ◽  
Preferential Pairing ◽  
Chromosome Behavior ◽  
Important Species ◽  
Fertility Data ◽  
Cultivated Species ◽  
And Inversion

Meiotic and fertility studies were carried out on 15 different tetraploid hybrids obtained by crossing 11 synthetic amphidiploids with L. corniculatus. The predominance of bivalents m meiocytes of these hybrids indicated that there was a strong tendency for homogametic pairing and that some preferential pairing was taking place between the chromosomes of L. corniculatus. Evidence for affinity between the chromosomes of the diploid species involved in the amphidiploids and L. corniculatus was provided by the presence of multivalent configurations at MI and inversion bridges at AI and AII. The meiotic chromosome behavior in these tetraploid crosses suggests that the most important species in the evolution of L. corniculatus are L. japonicus and L. alpinus. From pollen fertility data, it is considered possible to introduce desirable germplasm from the diploid taxa to the cultivated species by means of amphidiploids.

Infrageneric chemosystematics of some cultivated species ofIxora L.

1989 ◽  
Vol 100 (11-12) ◽  
pp. 603-605
Author(s):  
K. Kiran Mai ◽  
M. Radhakrishnaiah ◽  
L. L. Narayana
Keyword(s):  
Cultivated Species

Two New Species of Aira (Poaceae) from the Iberian Peninsula and the Balearic Islands

2020 ◽  
Vol 45 (1) ◽  
pp. 75-84
Author(s):  
Llorenç Sáez ◽  
Javier López-Alvarado ◽  
Pere Fraga ◽  
Regina Berjano ◽  
M. Ángeles Ortiz ◽  
...  
Keyword(s):  
Risk Assessment ◽  
New Species ◽  
Iberian Peninsula ◽  
Diploid Species ◽  
Balearic Islands ◽  
Similar Species ◽  
Chromosome Counts ◽  
Two New Species

Abstract—Two new diploid species, Aira minoricensis and Aira hercynica, are described and illustrated, along with chromosome counts, risk assessment, distribution and habitat, phenology, and comparisons with morphologically similar species. A comparative table and a key for the species of Aira for the Iberian Peninsula and the Balearic Islands are provided to assist in the identification of these overlooked species, and their relationships to other taxa are discussed.

Comparative Analysis of Genetic and Morphological Variation within the Platanthera hyperborea Complex (Orchidaceae)

2020 ◽  
Vol 45 (4) ◽  
pp. 767-778
Author(s):  
Eranga Wettewa ◽  
Nick Bailey ◽  
Lisa E. Wallace
Keyword(s):  
North America ◽  
Diploid Species ◽  
Morphological Characters ◽  
Evolutionary Patterns ◽  
Founding Population ◽  
Multiple Origins ◽  
Geographic Structure ◽  
Species Complexes ◽  
Nuclear Its ◽  
Cryptic Taxa

Abstract—Species complexes present considerable problems for a working taxonomy due to the presence of intraspecific variation, hybridization, polyploidy, and phenotypic plasticity. Understanding evolutionary patterns using molecular markers can allow for a more thorough assessment of evolutionary lineages than traditional morphological markers. In this study, we evaluated genetic diversity and phylogenetic patterns among taxa of the Platanthera hyperborea (Orchidaceae) complex, which includes diploid (Platanthera aquilonis) and polyploid (Platanthera hyperborea, P. huronensis, and P. convallariifolia) taxa spanning North America, Greenland, Iceland, and Asia. We found that three floral morphological characters overlap among the polyploid taxa, but the diploid species has smaller flowers. DNA sequence variation in a plastid (rpL16 intron) and a nuclear (ITS) marker indicated that at least three diploid species have contributed to the genomes of the polyploid taxa, suggesting all are of allopolyploid origin. Platanthera convallariifolia is most like P. dilatata and P. stricta, whereas P. huronensis and P. hyperborea appear to have originated from crosses of P. dilatata and P. aquilonis. Platanthera huronensis, which is found across North America, has multiple origins and reciprocal maternal parentage from the diploid species. By contrast, P. hyperborea, restricted to Greenland and Iceland, appears to have originated from a small founding population of hybrids in which P. dilatata was the maternal parent. Geographic structure was found among polyploid forms in North America. The area of Manitoba, Canada appears to be a contact zone among geographically diverse forms from eastern and western North America. Given the geographic and genetic variation found, we recommend continued recognition of four green-flowered species within this complex, but caution that there may be additional cryptic taxa within North America.

Chromosomal organization of a sequence related to LTR-like elements of Ty1-copia retrotransposons in Avena species

Genome ◽  
1999 ◽  
Vol 42 (4) ◽  
pp. 706-713 ◽  
Author(s):  
Concha Linares ◽  
Antonio Serna ◽  
Araceli Fominaya
Keyword(s):  
In Situ Hybridization ◽  
Diploid Species ◽  
D Genome ◽  
Specific Sequence ◽  
Chromosomal Organization ◽  
Intergenomic Translocations ◽  
A Genome ◽  
Slot Blot Analysis ◽  
Copia Retrotransposons

A repetitive sequence, pAs17, was isolated from Avena strigosa (As genome) and characterized. The insert was 646 bp in length and showed 54% AT content. Databank searches revealed its high homology to the long terminal repeat (LTR) sequences of the specific family of Ty1-copia retrotransposons represented by WIS2-1A and Bare. It was also found to be 70% identical to the LTR domain of the WIS2-1A retroelement of wheat and 67% identical to the Bare-1 retroelement of barley. Southern hybridizations of pAs17 to diploid (A or C genomes), tetraploid (AC genomes), and hexaploid (ACD genomes) oat species revealed that it was absent in the C diploid species. Slot-blot analysis suggested that both diploid and tetraploid oat species contained 1.3 × 104 copies, indicating that they are a component of the A-genome chromosomes. The hexaploid species contained 2.4 × 104 copies, indicating that they are a component of both A- and D-genome chromosomes. This was confirmed by fluorescent in situ hybridization analyses using pAs17, two ribosomal sequences, and a C-genome specific sequence as probes. Further, the chromosomes involved in three C-A and three C-D intergenomic translocations in Avena murphyi (AC genomes) and Avena sativa cv. Extra Klock (ACD genomes), respectively, were identified. Based on its physical distribution and Southern hybridization patterns, a parental retrotransposon represented by pAs17 appears to have been active at least once during the evolution of the A genome in species of the Avena genus.Key words: chromosomal organization, in situ hybridization, intergenomic translocations, LTR sequence, oats.

scholarly journals Physical mapping of repetitive oligonucleotides facilitates the establishment of a genome map-based karyotype to identify chromosomal variations in peanut

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Liuyang Fu ◽  
Qian Wang ◽  
Lina Li ◽  
Tao Lang ◽  
Junjia Guo ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Physical Mapping ◽  
Tandem Repeats ◽  
Genetic Research ◽  
Diploid Species ◽  
Reference Sequence ◽  
A Genome ◽  
Genome Map ◽  
Chromosomal Variants

Abstract Background Chromosomal variants play important roles in crop breeding and genetic research. The development of single-stranded oligonucleotide (oligo) probes simplifies the process of fluorescence in situ hybridization (FISH) and facilitates chromosomal identification in many species. Genome sequencing provides rich resources for the development of oligo probes. However, little progress has been made in peanut due to the lack of efficient chromosomal markers. Until now, the identification of chromosomal variants in peanut has remained a challenge. Results A total of 114 new oligo probes were developed based on the genome-wide tandem repeats (TRs) identified from the reference sequences of the peanut variety Tifrunner (AABB, 2n = 4x = 40) and the diploid species Arachis ipaensis (BB, 2n = 2x = 20). These oligo probes were classified into 28 types based on their positions and overlapping signals in chromosomes. For each type, a representative oligo was selected and modified with green fluorescein 6-carboxyfluorescein (FAM) or red fluorescein 6-carboxytetramethylrhodamine (TAMRA). Two cocktails, Multiplex #3 and Multiplex #4, were developed by pooling the fluorophore conjugated probes. Multiplex #3 included FAM-modified oligo TIF-439, oligo TIF-185-1, oligo TIF-134-3 and oligo TIF-165. Multiplex #4 included TAMRA-modified oligo Ipa-1162, oligo Ipa-1137, oligo DP-1 and oligo DP-5. Each cocktail enabled the establishment of a genome map-based karyotype after sequential FISH/genomic in situ hybridization (GISH) and in silico mapping. Furthermore, we identified 14 chromosomal variants of the peanut induced by radiation exposure. A total of 28 representative probes were further chromosomally mapped onto the new karyotype. Among the probes, eight were mapped in the secondary constrictions, intercalary and terminal regions; four were B genome-specific; one was chromosome-specific; and the remaining 15 were extensively mapped in the pericentric regions of the chromosomes. Conclusions The development of new oligo probes provides an effective set of tools which can be used to distinguish the various chromosomes of the peanut. Physical mapping by FISH reveals the genomic organization of repetitive oligos in peanut chromosomes. A genome map-based karyotype was established and used for the identification of chromosome variations in peanut following comparisons with their reference sequence positions.

scholarly journals Molecular characteristics of S-RNase alleles as the determinant of self-incompatibility in the style of Fragaria viridis

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jianke Du ◽  
Chunfeng Ge ◽  
Tingting Li ◽  
Sanhong Wang ◽  
Zhihong Gao ◽  
...  
Keyword(s):  
Diploid Species ◽  
The Self ◽  
Molecular Characteristics ◽  
Self Incompatibility ◽  
Intraspecific Hybridization ◽  
Noncoding Sequences ◽  
Family Analysis ◽  
The Family ◽  
Genotype Identification ◽  
Rnase T2

AbstractStrawberry (Fragaria spp.) is a member of the Rosoideae subfamily in the family Rosaceae. The self-incompatibility (SI) of some diploid species is a key agronomic trait that acts as a basic pollination barrier; however, the genetic mechanism underlying SI control in strawberry remains unclear. Two candidate S-RNases (Sa- and Sb-RNase) identified in the transcriptome of the styles of the self-incompatible Fragaria viridis 42 were confirmed to be SI determinants at the S locus following genotype identification and intraspecific hybridization using selfing progenies. Whole-genome collinearity and RNase T2 family analysis revealed that only an S locus exists in Fragaria; however, none of the compatible species contained S-RNase. Although the results of interspecific hybridization experiments showed that F. viridis (SI) styles could accept pollen from F. mandshurica (self-compatible), the reciprocal cross was incompatible. Sa and Sb-RNase contain large introns, and their noncoding sequences (promotors and introns) can be transcribed into long noncoding RNAs (lncRNAs). Overall, the genus Fragaria exhibits S-RNase-based gametophytic SI, and S-RNase loss occurs at the S locus of compatible germplasms. In addition, a type of SI-independent unilateral incompatibility exists between compatible and incompatible Fragaria species. Furthermore, the large introns and neighboring lncRNAs in S-RNase in Fragaria could offer clues about S-RNase expression strategies.

Sign in / Sign up

Export Citation Format

Share Document