Molecular Cytogenetic Identification of a New Wheat-Rye 6R Addition Line and Physical Localization of Its Powdery Mildew Resistance Gene

Abstract

Rye (Secale cereale L.), a naturally cross-pollinating relative of wheat, is a tertiary gene donor and of substantial value in wheat improvement. Wheat powdery mildew is caused by Blumeria graminis f. sp. tritici (Bgt), which seriously affects yield and quality worldwide. Identifying and transferring new, effective resistance genes against powdery mildew from rye is important for wheat breeding. The current study developed a wheat-rye line YT2 resistant to powdery mildew by crossing, backcrossing, and self-pollination for multiple generations between octoploid triticale 09R2-100 and common wheat cultivar Shixin 616. YT2 was confirmed to be a 6R disomic addition and T1RS⋅1BL translocation line by genomic in situ hybridization (GISH), multicolor fluorescence in situ hybridization (mc-FISH), multicolor-GISH (mc-GISH), and molecular marker analyses. Disease responses to different Bgt isolates and genetic analysis showed that the powdery mildew resistance gene of YT2 was derived from the rye chromosome 6R of 09R2-100, which differed from the previously reported Pm genes from rye including Pm20 on 6RL. Resistance phenotype of different translocation lines and deletion lines derived from YT2 combined with newly developed 6RL-specific markers analysis suggested that the powdery mildew resistance gene of YT2 was localized to the region in chromosome 6RL: 890.09–967.51 Mb and flanked by markers XM189 and X4M19, corresponding to the reference genome of Weining rye. Therefore, YT2 could be used as a promising bridging parent for wheat disease resistance improvement.

Identification of the powdery mildew resistance gene in wheat breeding line Yannong 99102-06188 via bulked segregant exome capture sequencing

“…When a resistance gene was identified, less linkage drag is the critical factor associated with its easy use in wheat breeding programs, but often, disease resistance is at the expense of some agronomic traits and reduced plant adaptation (Deng et al, 2017 ; Ma et al, 2018 ; Han et al, 2022b ). Fortunately, YN99102 is an elite derivative line from the same breeding process as a famous wheat cultivar Yannong 999 in China, which is the first wheat cultivar to exceed 800 kilograms per mu yield in China.…”

“…PCR amplification was performed as described by Han et al ( 2022a , b ) with minor modification. The PCR products were then separated in 8% non-denaturing polyacrylamide gels with a 29:1 ratio of acrylamide and bisacrylamide, finally visualized by silver staining.…”

Molecular cytogenetic identification of new wheat-rye 6R, 6RS, and 6RL addition lines with resistance to stripe rust and powdery mildew

“…Several other 6R chromosomes have been introduced into the wheat genome. For example, Han et al (2022) reported a 6R addition line originating from a cross between octoploid triticale and common wheat that exhibited resistance to powdery mildew. Duan et al (2022) reported a T6RL.6BS translocation line with 2018) reported a 6RL/6D small segment translocation line with powdery mildew resistance that originated from rye Kustro.…”

“…In the past 10 years, several new 1RS chromosomes have been introduced into the wheat genome and have exhibited resistance to the new Pst and Bgt pathogens (Ren et al, 2017a(Ren et al, , 2018(Ren et al, , 2022Han et al, 2020). Additionally, 2R, 4R, 5R, 6R, and 7R chromosomes are also introduced into the wheat genome in the form of chromosome translocation, addition, and substitution, and several of these newly developed lines exhibit resistance to stripe rust or powdery mildew (An et al, 2015(An et al, , 2019Li et al, 2016;Schneider et al, 2016;Ren et al, 2017bRen et al, , 2020Johansson et al, 2020;Han et al, 2022).…”

Cytogenetic and Molecular Marker Analyses of a Novel Wheat–Psathyrostachys huashanica 7Ns Disomic Addition Line with Powdery Mildew Resistance

“…Because of the coevolution of pathogen virulence with host resistance and the rapid emergence of new virulent isolates, however, most powdery mildew resistance genes deployed in large-scale commercial production have successively lost their effectiveness against the pathogen [ 4 , 13 ]. A typical example is the “boom–bust” of Pm8 derived from chromosome arm 1RS of Petkus rye, which has triggered continual severe epidemics of powdery mildew in the main wheat production regions of China [ 14 , 15 ]. The discovery, identification, and deployment of additional sources of powdery mildew resistance in wheat-related germplasm to address this vulnerability is therefore urgently needed for breeding new resistant wheat cultivars [ 16 ].…”