The release of the complete rice prime genome with high quality sequence allows unprecidented opportunities to discover new genes. In rice disease management, both qualitative and quantitative types ...of resistance conferred by major genes and QTLs, respectively, have been used extensively. The authors presented two cases of utilizing these type of resistance in bacterial blight of rice caused by Xanthomonas oryzae pv. oryzae and rice blast caused by Magnoporthe grisea. Bacterial blight was managed through the use of single major genes. But, as the pathogen evolved to overcome single genes, pyramid lines with two or more genes conferring qualitative resistance have been employed. For rice blast, the authors used a candidate gene approach to integrate molecular analysis of host-pathogen interactions, gene mapping, and selection of phenotype predicted to confer durable, broad-spectrum resistance. They associated candidate defence response genes with quantitative resistance to rice blast using selected advance backcross populations and evaluated them in multiple environments. To identify the functional variants in defence response genes that condition resistance, the authors examined these genes and their potential regulatory elements using in-silico analysis of their sequences and by sequencing these genes from various rice germplasm. The results will guide the breeding of rice lines using either conventional or biotechnology approaches with highly effective quantitative traits, and enhance the stability of resistance to the disease leading to a sustainable rice production.
In this work we present data from observations with the MAGIC telescopes of SN 2014J detected on January 21 2014, the closest Type Ia supernova since Imaging Air Cherenkov Telescopes started to ...operate.Aims. We aim to probe the possibility of very-high-energy (VHE; E ≥ 100 GeV) gamma rays produced in the early stages of Type Ia supernova explosions.Methods. We performed follow-up observations after this supernova (SN) explosion for five days, between January 27 and February 2 2014. We searched for gamma-ray signals in the energy range between 100 GeV and several TeV from the location of SN 2014J using data from a total of ~5.5 h of observations. Prospects for observing gamma rays of hadronic origin from SN 2014J in the near future are also being addressed.Results. No significant excess was detected from the direction of SN 2014J. Upper limits at 95% confidence level on the integral flux, assuming a power-law spectrum, dF/dE ∝ E− Γ, with a spectral index of Γ = 2.6, for energies higher than 300 GeV and 700 GeV, are established at 1.3 × 10$^{-12}$ and 4.1 × 10$^{-13}$ photons cm$^{-2}$ s$^{-2}$, respectively.Conclusions. For the first time, upper limits on the VHE emission of a Type Ia supernova are established. The energy fraction isotropically emitted into TeV gamma rays during the first ~ 10 days after the supernova explosion for energies greater than 300 GeV is limited to 10$^{-6}$ of the total available energy budget (~1051 erg). Within the assumed theoretical scenario, the MAGIC upper limits on the VHE emission suggest that SN 2014J will not be detectable in the future by any current or planned generation of Imaging Atmospheric Cherenkov Telescopes.
QSO B0218+357 is a gravitationally lensed blazar located at a redshift of 0.944. The gravitational lensing splits the emitted radiation into two components that are spatially indistinguishable by ...gamma-ray instruments, but separated by a 10–12 day delay. In July 2014, QSO B0218+357 experienced a violent flare observed by the Fermi-LAT and followed by the MAGIC telescopes.Aims. The spectral energy distribution of QSO B0218+357 can give information on the energetics of z ~ 1 very high energy gamma-ray sources. Moreover the gamma-ray emission can also be used as a probe of the extragalactic background light at z ~ 1.Methods. MAGIC performed observations of QSO B0218+357 during the expected arrival time of the delayed component of the emission. The MAGIC and Fermi-LAT observations were accompanied by quasi-simultaneous optical data from the KVA telescope and X-ray observations by Swift-XRT. We construct a multiwavelength spectral energy distribution of QSO B0218+357 and use it to model the source. The GeV and sub-TeV data obtained by Fermi-LAT and MAGIC are used to set constraints on the extragalactic background light.Results. Very high energy gamma-ray emission was detected from the direction of QSO B0218+357 by the MAGIC telescopes during the expected time of arrival of the trailing component of the flare, making it the farthest very high energy gamma-ray source detected to date. The observed emission spans the energy range from 65 to 175 GeV. The combined MAGIC and Fermi-LAT spectral energy distribution of QSO B0218+357 is consistent with current extragalactic background light models. The broadband emission can be modeled in the framework of a two-zone external Compton scenario, where the GeV emission comes from an emission region in the jet, located outside the broad line region.
Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different ...wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three " target-of-opportunity" observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e. g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at greater than or similar to 4 x 10(-4) Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies.
