Characterization of resistance to the wheat stem sawfly in spring wheat landrace accessions from targeted geographic regions of the world

Abstract

Plant landraces have long been recognized as potential gene pools for biotic and abiotic stressrelated genes. This research used spring wheat landrace accessions to identify new sources of resistance to the wheat stem sawfly (WSS) (Cephus cinctus Norton), an important insect pest of wheat in the northern Great Plains of North America. Screening efforts targeted 1,409 accessions from six geographical areas of the world where other species of grain sawflies are endemic or where a high frequency of accessions possesses the resistance characteristic of solid stems. Resistance was observed in approximately 14% of accessions. Half of the lines displayed both antixenosis and antibiosis types of resistance. Among the resistant accessions, 41% had solid or semi-solid stems. Molecular genetic screening for haplotypes at the solid stem QTL, Qss.msub.3BL, showed that 15% of lines shared the haplotype derived from 'S-615', the original donor of the solid stem trait to North American germplasm. Other haplotypes associated with solid stems were also observed. Haplotype diversity was greater in the center of origin of wheat. Evaluation of a representative set of resistant landrace accessions in replicated field trials at four locations over a three year period identified accessions with potential genes for reduced WSS infestation, increased WSS mortality, and increased indirect defense via parasitoids. Exploitation of distinct types of plant defense will expand the genetic diversity for WSS resistance currently present in elite breeding lines.

Characterization of Resistance to Cephus cinctus (Hymenoptera: Cephidae) in Barley Germplasm

“…Three barley lines had increased parasitism rates despite their intermediate level of WSS infestation. Similar results were recently observed in several wheat landrace accessions from different geographical regions of the world ( Varella et al 2017b ). In wheat, WSS infestation is known to cause changes in the pattern of emitted volatiles.…”

Antioxidant and Secondary Metabolite Responses in Wheat under Cereal Leaf Beetle (Oulema melanopus L.) Infestation

“…Over generations, these plant populations have undergone natural selection, developing defense mechanisms to withstand insect attacks. These mechanisms include physical barriers, secondary metabolite production, and the induction of defense‐related genes (Tadesse et al, 2022; Yumurtaci, 2015; Bouhssini et al, 2009; Varella et al, 2017). Modern cultivars can be fortified against insect pests by harnessing these traits through breeding.…”

Genetic diversity and agronomic performance of wheat landraces currently grown in Tajikistan

“…Worldwide, Tajik wheat landraces have proven to be of high value as sources of resistance to diseases and pests. The landrace PI639349 (collected in 2003 by ICARDA in the Pamir Region above 2,800 m asl) had solid stem and antibiosis to wheat stem sawfly ( Cephus cinctus Norton) in Montana, United States (Varella et al., 2017). Tajikistan wheat line CI2401 (PI9781 acquired in 1963 from Sugdt region) was one of the sources of resistance to biotypes 1 and 2 of Russian wheat aphid ( Diuraphis noxia Mordvilko) and used for cultivar development in the United States (Qureshi et al., 2006).…”

“…According to the Genesys database (https://www.genesys-pgr.org/a/overview/v2p5gg6By79) there are 1,598 Tajik wheat landraces conserved in the Gene Banks, including Russia (656), ICARDA (582), United States (269), and CIMMYT (87). Several wheat landraces originating from Tajikistan were found to have resistance to important pests and pathogens: leaf rust (Rahmatov et al., 2019), stem sawfly (Varella et al., 2017), Russian wheat aphid (Qureshi et al., 2006; El Bouhssini et al., 2011), and sunn pest (El Bouhssini et al., 2009). These resistant landraces have been evaluated and used to develop resistant wheat germplasm.…”