research strategies galvanized to control the wheat killer genus Puccinia. It will also highlight the outcome and research impact of cost-effective NGS technologies and cloning of rust resistance genes amid the public availability of common and tetraploid wheat reference genomes.
Drought is one of the major abiotic stresses affecting wheat yield. A recurrent selection program was conducted to improve the drought tolerance and yield of bread wheat using drought tolerant advanced breeding lines from a drought tolerant x susceptible cross (HI 1500 x HUW 510). The parental lines were evaluated for yield, biomass and harvest index (HI) in addition to the drought adaptive traits like Canopy Temperature (CT), chlorophyll content and Normalized Difference Vegetative Index (NDVI). After three rounds of recurrent selection, the half sib progenies exhibited a marked reduction in CT, chlorophyll content and biomass; whereas improvement was noted for yield, HI and NDVI. Drought tolerance of the half-sib population appeared enhanced as indicated by drought indices and grain yield. Compared to base population, half-sibs showed better HI, grain filling and a significant (17.1%) increase in grain yield under water stress conditions. Cooler canopies and increased early vigour might have contributed to drought tolerance. A favourable combination of gibberellin sensitive and insensitive Rhtalleles was observed in the recombinant progenies. However, increased yield under water stress had a negative trade off in reduction of biomass. The study also identified potential lines with high yield and drought tolerance for subsequent varietal development for water limited areas.
Identification of markers associated with major physiological and yield component traits under moisture deficit stress conditions in preferred donor lines paves the way for marker-assisted selection (MAS). In the present study, a set of 183 backcross inbred lines (BILs) derived from the cross HD2733/2*C306 were genotyped using 35K Axiom genotyping array and SSR markers. The multi-trait, multi-location field phenotyping of BILs was done at three locations covering two major wheat growing zones of India, north-western plains zone (NWPZ) and central zone (CZ) under varying moisture regimes. A linkage map was constructed using 705 SNPs and 86 SSR polymorphic markers. A total of 43 genomic regions and QTL × QTL epistatic interactions were identified for 14 physiological and yield component traits, including NDVI, chlorophyll content, CT, CL, PH, GWPS, TGW and GY. Chromosomes 2A, 5D, 5A and 4B harbors greater number of QTLs for these traits. Seven Stable QTLs were identified across environment for DH (QDh.iari_6D), GWPS (QGWPS.iari_5B), PH (QPh.iari_4B-2, QPh.iari_4B-3) and NDVI (QNdvi1.iari_5D, QNdvi3.iari_5A). Nine genomic regions identified carrying major QTLs for CL, NDVI, RWC, FLA, PH, TGW and biomass explaining 10.32–28.35% of the phenotypic variance. The co-segregation of QTLs of physiological traits with yield component traits indicate the pleiotropic effects and their usefulness in the breeding programme. Our findings will be useful in dissecting genetic nature and marker-assisted selection for moisture deficit stress tolerance in wheat.
A series of meso-tetraarylporphyrins bearing electron-donor or electron-withdrawing substituents at the meso-phenyl groups were examined for antipodal β-pyrrole tetrabromination using different brominating agents. Porphyrins bearing electron-donor substituents undergo bromination at moderate temperatures with N-bromosuccinimide as the brominating agent while the electron-deficient porphyrins require liq. Br2 at room temperature. The brominated porphyrins were isolated in moderate to very good yields. Synthesized compounds were characterized by electronic absorption, 1H NMR, and mass spectroscopic methods. Regioselectivity of an electron-deficient porphyrin, 2,3,12,13-tetrabromo-5,10,15,20-tetrakis(4-methoxycarbonylphenyl)porphyrin was examined by single-crystal X-ray structure analysis and showed antipodal β-pyrrole bromo substitution.
The present study reports the introgression of the genomic regions linked with drought tolerance traits viz., NDVI, staygreen, chlorophyll content/chlorophyll fluorescence and yield from a drought tolerant parent HI1500 in to a popular high yielding but drought susceptible wheat variety GW322 following the marker assisted backcross breeding. Background selection with 109 polymorphic SSR markers accelerated genome recovery of recurrent parent which ranged from 72.14 to 86.9% in BC1F1, 90.33 to 92.02% in BC2F1 and 91.6 to 94.95% with an average of 93.5% in BC2F2 generation. Eighteen homozygous BC2F3 progenies were found to be phenotypically superior for morpho-physiological and agronomic traits over the recurrent parent GW322.
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