Genetic variability and association study of yield attributing traits in F2 populations of American cotton

Cotton is one of the most important fiber crops, grown all over the world. Genetic variability is a crucial factor from evolutionary point of view for crop species. It defines the adaptation of populations by allowing them to alter their genetic constitution in changing environment. Genetic variability in Gossypium hirsutum is declining due to selection pressure, hence causing low yield. Present study was conducted to evaluate ten parental genotypes with their F2 generations to uncover their genetic potential for yield by accessing genetic variability, heritability, genetic advance and association between fiber, yield and yield linked traits. High values of phenotypic and genotypic coefficient of variance were observed for node of first fruiting branch, monopodia per plant, boll weight, fiber strength and yield per plant. All morphological and fiber quality traits represented broad sense heritability ranging from 51% to 90%. High value of genetic advance was shown by plant height and yield per plant. Positive association of yield per plant was recorded for traits such as plant height, node of first fruiting branch, monopodia per plant, number of bolls per plant, seeds per boll, and ginning out turn. Additionally, F2 progeny of CIM-534×MNH-814 had high yield per plant along with maximum number of bolls per plant and seed per boll. So, such F2 progeny can further be explored to improve yield and yield contributing traits.

Genetic architecture of transmission stage production and virulence in schistosome parasites

ABSTRACTBoth theory and experimental data from pathogens suggest that the production of transmission stages should be strongly associated with virulence, but the genetic bases of parasite transmission/virulence traits are poorly understood. The blood fluke Schistosoma mansoni shows extensive variation in numbers of cercariae larvae shed and in their virulence to infected snail hosts, consistent with expected trade-offs between parasite transmission and virulence. We crossed schistosomes from two populations that differ 8-fold in cercarial shedding and in their virulence to Biomphalaria glabrata snail hosts, and determined four-week cercarial shedding profiles in F0, F1 and 376 F2 progeny from two independent crosses in inbred snails. Sequencing and linkage analysis revealed that cercarial production is polygenic and controlled by five QTLs. These QTLs act additively, explaining 28.56% of the phenotypic variation. These results demonstrate that the genetic architecture of key traits relevant to schistosome ecology can be dissected using classical linkage mapping approaches.

Transgenerational inheritance of BPA-induced obesity correlates with transmission of new CTCF sites in the Fto gene

The mechanisms by which epiphenotypes are transmitted transgenerationally through the parental germlines are poorly understood. Here we show that exposure of pregnant mouse F0 females during E7.5-E13.5 to bisphenol A results in obesity in the F2 progeny in the absence of additional exposure. This epiphenotype can be transmitted through the male and female germlines up to the F5 generation, decreases in F6, and disappears in F7. Analyses of chromatin changes in the sperm of the F1 generation reveal a widespread increase in chromatin accessibility at binding sites for CTCF and other transcription factors accompanied by alterations in 3D organization. Comparison of the transmission of obesity between F2 and F5 and its disappearance in F7 with alterations in the binding of these transcription factors points to the activation of two enhancers located in intronic and intergenic regions of the Fto gene as the cause of transgenerational inheritance. These enhancers form an autoregulatory feedback loop that, in combination with a decrease of m6A in sperm RNAs, may cause alterations of gene expression in the embryo after fertilization. Given the established involvement of SNPs in FTO in human obesity, the results suggest that both genetic and epigenetic alterations of the same gene can lead to the same phenotypic outcomes on human health.

Transgenerational inheritance of BPA-induced obesity correlates with transmission of new CTCF sites in the Fto gene

The mechanisms by which epiphenotypes are transmitted transgenerationally through the parental germlines are poorly understood. Here we show that exposure of pregnant mouse F0 females during E7.5-E13.5 to bisphenol A results in obesity in the F2 progeny in the absence of additional exposure. This epiphenotype can be transmitted through the male and female germlines up to the F5 generation, decreases in F6, and disappears in F7. Analysis of chromatin changes in the sperm of the F1 generation reveals a widespread increase in chromatin accessibility at binding sites for CTCF and other transcription factors accompanied by alterations in 3D organization. Comparison of the transmission of obesity between F2 and F5 and its disappearance in F7 with alterations in the binding of these transcription factors points to the activation of an enhancer in an intron of the Fto gene as the cause of transgenerational inheritance. Activation of the Fto enhancer results in a decrease of m6A in sperm RNAs, which may result in alterations of gene expression in the embryo after fertilization. Given the established involvement of SNPs in FTO in human obesity, the results suggest that both genetic and epigenetic alterations of the same gene can lead to the same phenotypic outcomes on human health.

Genotypic Effects on the Response of Soybean (Glycine max (L.) Merrill) to Sulfonylurea Herbicides

In soybean cropping, sulfonylurea (SU) herbicides are a potentially useful alternative to glyphosate-based herbicides. Normally, soybeans are susceptible to SU herbicides, but two unlinked non-GMO genes (ALS1 and ALS2), have been identified that confer SU tolerance. In this project, we explored the effectiveness of these genes in Australian soybean genetic backgrounds. Four lines, carrying both ALS1 and ALS2, were derived by backcrossing different Australian genotypes to a SU-tolerance donor line ‘W4-4’ and then using molecular markers, plants homozygous for both ALS genes were selected. The W4-4 donor and the four derived lines were evaluated in a hydroponic system at increments up to 4× the recommended field rate of metsulfuron-methyl. The ALS genes provided high levels of tolerance, with evidence of some minor interaction with the genetic background. To further test whether there was an effect of background, the five lines were crossed together in a half-diallel mating design and the resulting ten F2 populations were screened hydroponically for tolerance to metsulfuron-methyl herbicide at 4× the recommended field rate. Analyses of seedling dry weight of the five parental lines and their F2 progeny in response to the herbicide, identified differences among the crosses. These results indicated that the development of commercial varieties with maximum herbicide tolerance requires incorporation of both ALS genes, and if combined with selection in segregating populations in the presence of SU herbicide may capture additional tolerance from background genes of minor effect.

Studi Pola Segregasi Karakter Morfologi – Agronomi Tanaman Padi Hasil Persilangan Kultivar Pandan Ungu x Roti Pada F2

The efforts to increase rice production at East Borneo apart from the improvement of cultivation systems also could be done by using superior variety. Hybridization of rice plants has been done between the female local variety Pandan Ungu and the male local variety Roti. The research toward F2 progeny to find out the segregation patterns of inheritance of the characters number of tillers, plant height, stem leaves color, and palea-lemma color has been done at the paddy field at Desa Sidomulyo, Kecamatan Anggana, Kabupaten Kutai Kartanegara since October 2016 until March 2017. The F2 identification method that was used is single plant selection methods, based on Standard Evaluation Systems (SES) for Rice. Suitability test between observed value and expected value used Chi-square test, and to see the characters segregation pattern ratio used Mendelian genetics analysis. The inheritance character of stem leaves color was managed by two pairs of genes followed segregation ratio 9:6:1 with the action epistatic genes with cumulative effect, the inheritance of palea-lemma character was managed by two pairs of genes followed Mendelian ratio 13:3 with the action epistatic dominant-recessive, while the characters plant height and number of tillers was managed by polygenes so the inheritance patterns was not following Mendelian ratio.

Morpho-genetic variability in F2 progeny cowpea genotypes tolerant to Bruchid (Callosobruchus maculatus)

Callosobruchus maculatus Fab. is a major threat to cowpea production reducing the quality, quantity and market value of cowpea grains. A cheap and easy identification method would be a valuable tool in identifying and breeding resistant genotypes in the vast cowpea germplasm. Hence, the purpose of the study was to identify and evaluate the genetics of cowpea traits between resistant and susceptible plant genotypes to C. maculatus. Contrasting qualitative and quantitative traits in C. maculatus resistant and susceptible parents were evaluated in 72 F2 progeny cowpea plants. Heritability, segregation and association of investigated traits with the C. maculatus resistant performance of the F2 cowpea genotypes were evaluated to determine closely related traits with C. maculatus resistance. Results from the study showed high heritability for all cowpea quantitative traits except leaf petiole length. Both Mendelian inheritance and non-Mendelian inheritance were observed among qualitative traits. However, association evaluation between cowpea traits and mean bruchid development period, percentage adult emergence and oviposition preference were weak (r < 0.5) and not significant (p < 0.05). This indicates that C. maculatus resistance in cowpea may be attributed to factors other than morphological variations.