scholarly journals Unprecedented Heterogeneity in the Synonymous Substitution Rate within a Plant Genome

2014 ◽  
Vol 31 (5) ◽  
pp. 1228-1236 ◽  
Author(s):  
Andan Zhu ◽  
Wenhu Guo ◽  
Kanika Jain ◽  
Jeffrey P. Mower
Keyword(s):  
Substitution Rate ◽  
Synonymous Substitution ◽  
Plant Genome ◽  
Synonymous Substitution Rate

scholarly journals Genome wide identification and characterization of light-harvesting Chloro a/b binding (LHC) genes reveals their potential role in enhancing drought tolerance in Gossypium hirsutum

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Teame Gereziher MEHARI ◽  
Yanchao XU ◽  
Richard Odongo MAGWANGA ◽  
Muhammad Jawad UMER ◽  
Joy Nyangasi KIRUNGU ◽  
...  
Keyword(s):  
Drought Stress ◽  
Gossypium Hirsutum ◽  
Abiotic Stresses ◽  
Substitution Rate ◽  
Synonymous Substitution ◽  
Synonymous Substitution Rate ◽  
Drought Tolerant ◽  
Genome Wide ◽  
Identification And Characterization

Abstract Background Cotton is an important commercial crop for being a valuable source of natural fiber. Its production has undergone a sharp decline because of abiotic stresses, etc. Drought is one of the major abiotic stress causing significant yield losses in cotton. However, plants have evolved self-defense mechanisms to cope abiotic factors like drought, salt, cold, etc. The evolution of stress responsive transcription factors such as the trihelix, a nodule-inception-like protein (NLP), and the late embryogenesis abundant proteins have shown positive response in the resistance improvement to several abiotic stresses. Results Genome wide identification and characterization of the effects of Light-Harvesting Chloro a/b binding (LHC) genes were carried out in cotton under drought stress conditions. A hundred and nine proteins encoded by the LHC genes were found in the cotton genome, with 55, 27, and 27 genes found to be distributed in Gossypium hirsutum, G. arboreum, and G. raimondii, respectively. The proteins encoded by the genes were unevenly distributed on various chromosomes. The Ka/Ks (Non-synonymous substitution rate/Synonymous substitution rate) values were less than one, an indication of negative selection of the gene family. Differential expressions of genes showed that majority of the genes are being highly upregulated in the roots as compared with leaves and stem tissues. Most genes were found to be highly expressed in MR-85, a relative drought tolerant germplasm. Conclusion The results provide proofs of the possible role of the LHC genes in improving drought stress tolerance, and can be explored by cotton breeders in releasing a more drought tolerant cotton varieties.

scholarly journals Long-Term Persistence of Infection in Chimpanzees Inoculated with an Infectious Hepatitis C Virus Clone Is Associated with a Decrease in the Viral Amino Acid Substitution Rate and Low Levels of Heterogeneity

2004 ◽  
Vol 78 (18) ◽  
pp. 9782-9789 ◽  
Author(s):  
Javier Fernandez ◽  
Deborah Taylor ◽  
Duncan R. Morhardt ◽  
Kathleen Mihalik ◽  
Montserrat Puig ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Amino Acid ◽  
Substitution Rate ◽  
Selective Pressure ◽  
Nonsynonymous Substitution ◽  
Synonymous Substitution ◽  
Synonymous Substitution Rate ◽  
Nonsynonymous Substitution Rate ◽  
Over Time

ABSTRACT Two chimpanzees, 1535 and 1536, became persistently infected following inoculation with RNA transcripts from cDNA clones of hepatitis C virus (HCV). Analysis of the HCV genomes from both animals showed an accumulation of amino acid substitutions over time. The appearance of substitutions in the envelope genes was associated with increased antienvelope antibody titers. However, extensive mutations were not incorporated into hypervariable region 1 (HVR1). A comparison of the nonsynonymous substitution rate/synonymous substitution rate was made at various time points to analyze selective pressure. The highest level of selective pressure occurred during the acute phase and decreased as the infection continued. The nonsynonymous substitution rate was initially higher than the synonymous substitution rate but decreased over time from 3.3 × 10−3 (chimpanzee 1535) and 3.2 × 10−3 (chimpanzee 1536) substitutions/site/year at week 26 to 1.4 × 10−3 (chimpanzee 1535) and 1.7 × 10−3 (chimpanzee 1536) at week 216, while the synonymous substitution rate remained steady at ∼1 × 10−3 substitutions/site/year. Analysis of PCR products using single-stranded conformational polymorphism indicated a low level of heterogeneity in the viral genome. The results of these studies confirm that the persistence of infection is not solely due to changes in HVR1 or heterogeneity and that the majority of variants observed in natural infections could not arise simply through mutation during the time period most humans and chimpanzees are observed. These data also indicate that immune pressure and selection continue throughout the chronic phase.

scholarly journals Genome-Wide Identification, Characterization, and Expression Analysis of the NAC Transcription Factor in Chenopodium quinoa

Genes ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 500 ◽  
Author(s):  
Feng Li ◽  
Xuhu Guo ◽  
Jianxia Liu ◽  
Feng Zhou ◽  
Wenying Liu ◽  
...  
Keyword(s):  
Stress Responses ◽  
Substitution Rate ◽  
Functional Divergence ◽  
Expression Patterns ◽  
Chenopodium Quinoa ◽  
Synonymous Substitution ◽  
Duplication Event ◽  
Organ Specificity ◽  
Synonymous Substitution Rate ◽  
Specific Expression

The NAC (NAM, ATAF, and CUC) family is one of the largest families of plant-specific transcription factors. It is involved in many plant growth and development processes, as well as abiotic/biotic stress responses. So far, little is known about the NAC family in Chenopodium quinoa. In the present study, a total of 90 NACs were identified in quinoa (named as CqNAC1-CqNAC90) and phylogenetically divided into 14 distinct subfamilies. Different subfamilies showed diversities in gene proportions, exon–intron structures, and motif compositions. In addition, 28 CqNAC duplication events were investigated, and a strong subfamily preference was found during the NAC expansion in quinoa, indicating that the duplication event was not random across NAC subfamilies during quinoa evolution. Moreover, the analysis of Ka/Ks (non-synonymous substitution rate/synonymous substitution rate) ratios suggested that the duplicated CqNACs might have mainly experienced purifying selection pressure with limited functional divergence. Additionally, 11 selected CqNACs showed significant tissue-specific expression patterns, and all the CqNACs were positively regulated in response to salt stress. The result provided evidence for selecting candidate genes for further characterization in tissue/organ specificity and their functional involvement in quinoa’s strong salinity tolerance.

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