Identification of quantitative trait loci associated with leaf rust resistance in rye by precision mapping

BACKGROUND

Leaf rust (LR) is among the most destructive fungal diseases of rye (Secale cereale L.). Despite intensive research using various analytical and methodological approaches, such as quantitative trait locus (QTL) mapping, candidate gene expression analysis, and transcriptome sequencing, the genetic basis of the rye immune response to LR remains unclear.

RESULTS

A genome-wide association study was employed to detect QTLs controlling the immune response to LR of rye. A mapping population, G38A, was constructed by crossing two inbred lines: 723 (susceptible to LR) and JKI-NIL-Pr3 (a donor of the LR resistance gene Pr3). For genotyping, SNP-DArT and silico-DArT markers were used. Resistance phenotyping was conducted by visual assessment of the infection severity in detached leaf segments inoculated with two isolates of Puccinia recondita f. sp. secalis, namely, 60/17/2.1 (isolate S) in the main experiment and 86/n/2.1_5x (isolate N) in the validation experiment, at 10 and 17 days post-infection (dpi), respectively. In total, 42,773 SNP-DArT and 105,866 silico-DArT markers were included in the main analysis including isolate S, of which 129 and 140 SNP-DArTs and 767 and 776 silico-DArTs were significantly associated (p ≤ 0.001; - log10(p) ≥ 3.0) with the immune response to LR at 10 and 17 dpi, respectively. Most significant markers were mapped to chromosome 1R. The number of common markers from both systems and at both time points occupying common chromosomal positions was 37, of which 21 were positioned in genes, comprising 18 markers located in exons and three in introns. This gene pool included genes encoding proteins with a known function in response to LR (e.g., a NBS-LRR disease resistance protein-like protein and carboxyl-terminal peptidase).

CONCLUSION

This study has expanded and supplemented existing knowledge of the genetic basis of rye resistance to LR by (1) detecting two QTLs associated with the LR immune response of rye, of which one located on the long arm of chromosome 1R is newly detected, (2) assigning hundreds of markers significantly associated with the immune response to LR to genes in the 'Lo7' genome, and (3) predicting the potential translational effects of polymorphisms of SNP-DArT markers located within protein-coding genes.

A STUDY ON THE USE OF METACOGNITIVE READING STRATEGIES BY LEARNERS WITH PSYCHOSOMATIC CONDITION

The study examines the influence of metacognitive reading strategies in developing the reading comprehension skills among ESL (English as Second Language) learners with the psychosomatic condition. Qualitative and quantitative research was used in the present study and it was an experimental study. Reading comprehension skill is crucial to language learners for effective decoding of the information. Metacognitive reading strategies aid the learners to develop reading strategies for effective comprehension of the text. The metacognitive strategies like pragmatic and analytical strategies were used in this research to improve the intensive and evaluative reading comprehension skills. The participants of the study are a hundred and twelve (Male and Female) tertiary level ESL learners from the undergraduate engineering program. The experiment intends to improve the reading comprehension skills among the samples with psychosomatic conditions. The sampling method used in the study was purposive sampling. Data collection tools like questionnaires, pre-test, post-test, and post-feedback questionnaires were used in the study. An android-based application will be created with the activities and instructional materials and it was circulated to the learners. Metacognitive reading activities were given to the learners through the application and data was collected. Results were quantitatively analyzed using statistical tools from the data collected through the application. The results of the present study were indicative that there is a significant improvement in the learners’ reading comprehension skills due to the intervention of metacognitive reading strategies.

Pseudopolar smectic-C phases of azo-substituted achiral bent-core hockey-stick-shaped molecules

We report experimental studies on an azo-substituted compound consisting of bent-core hockey-stick-shaped molecules. The experimental results establish two pseudopolar tilted smectic phases, which are characterized by an in-plane axial-vector order parameter in addition to tilt order in the smectic layers. Electro-optical measurements in the mesophases indicate that the birefringence of the sample strongly depends on the applied electric field. We develop a theoretical model to account for this observation. The change in the birefringence of the sample arises from the field-induced reorientation of the tilt plane of the molecules in the layer above a threshold field. The effect is analogous to the field-induced Freedericksz transition which is quadratic in the applied electric field.