Introgression Breeding for Improvement of Winter Hardiness in \u3cem\u3eLolium /Festuca\u3c/em\u3e Complex Using Androgenenesis

Intergeneric hybrids between closely related Lolium and Festuca species are used to broaden the gene pool and provide plant breeders with options to combine complementary traits to develop robust but high quality grass varieties. Androgenesis was found to be an effective procedure for selecting Lolium-Festuca genotypes comprising gene combinations rarely or never recovered by conventional backcross breeding programs. Here we describe the optimisation of androgenesis in Lolium perenne x Festuca pratensis. The male fertility and freezing tolerance of the Festulolium microspore-derived progenies were analysed and these progenies were also analysed by using genomic in situ hybridisation (GISH). The object of this study is to initiate introgression breeding for the improvement of winter hardiness in Lolium /Festuca complex

Introgression Breeding for Improvement of Winter Hardiness in \u3cem\u3eLolium /Festuca\u3c/em\u3e Complex Using Androgenenesis

Intergeneric hybrids between closely related Lolium and Festuca species are used to broaden the gene pool and provide plant breeders with options to combine complementary traits to develop robust but high quality grass varieties. Androgenesis was found to be an effective procedure for selecting Lolium-Festuca genotypes comprising gene combinations rarely or never recovered by conventional backcross breeding programs. Here we describe the optimisation of androgenesis in Lolium perenne x Festuca pratensis. The male fertility and freezing tolerance of the Festulolium microspore-derived progenies were analysed and these progenies were also analysed by using genomic in situ hybridisation (GISH). The object of this study is to initiate introgression breeding for the improvement of winter hardiness in Lolium /Festuca complex

Disorder-induced topological change of the superconducting gap structure in iron pnictides

In superconductors with unconventional pairing mechanisms, the energy gap in the excitation spectrum often has nodes, which allow quasiparticle excitations at low energies. In many cases, e.g. $d$-wave cuprate superconductors, the position and topology of nodes are imposed by the symmetry, and thus the presence of gapless excitations is protected against disorder. Here we report on the observation of distinct changes in the gap structure of iron-pnictide superconductors with increasing impurity scattering. By the successive introduction of nonmagnetic point defects into BaFe$_2$(As$_{1-x}$P$_x$)$_2$ crystals via electron irradiation, we find from the low-temperature penetration depth measurements that the nodal state changes to a nodeless state with fully gapped excitations. Moreover, under further irradiation the gapped state evolves into another gapless state, providing bulk evidence of unconventional sign-changing $s$-wave superconductivity. This demonstrates that the topology of the superconducting gap can be controlled by disorder, which is a strikingly unique feature of iron pnictides.Comment: 5 pages, 4 figure