Wheat Genotypes With Combined Resistance to Wheat Curl Mite,Wheat Streak Mosaic Virus,Wheat Mosaic Virus, andTriticum Mosaic Virus

Abstract

The wheat curl mite, Aceria tosichella Keifer, (WCM) is a global pest of bread wheat that reduces yields significantly. In addition, WCM carries Wheat streak mosaic virus (WSMV, family Potyviridae, genus Tritimovirus), the most significant wheat virus in North America; High Plains wheat mosaic virus (HPWMoV, genus Emaravirus, formerly High plains virus); and Triticum mosaic virus (TriMV, family Potyviridae, genus Poacevirus). Viruses carried by WCM have reduced wheat yields throughout the U.S. Great Plains for >50 yr, with average yield losses of 2-3% and occasional yield losses of 7-10%. Acaricides are ineffective against WCM, and delayed planting of winter wheat is not feasible. Five wheat breeding lines containing Cmc4, a WCM resistance gene from Aegilops tauschii, and Wsm2, a WSMV resistance gene from wheat germplasm CO960293-2 were selected from the breeding process and assessed for phenotypic reaction to WCM feeding, population increase, and the degree of WSMV, HPWMoV, and TriMV infection. Experiments determined that all five lines are resistant to WCM biotype 1 feeding and population increase, and that two breeding lines contain resistance to WSMV, HPWMoV, and TriMV infection as well. These WCM-, WSMV-, HPWMoV-, and TriMV-resistant genotypes can be used improve management of wheat yield losses from WCM-virus complexes.

Differences in Aceria tosichella population responses to wheat resistance genes and wheat virus transmission

“…Similarly, plants of the KSU2R-2 breeding line containing Cmc4 and Wsm2 also showed significantly less leaf folding than susceptible Jagger plants in response to all mite populations except those in three counties in Kansas and three counties in Missouri (Table 1). These responses are similar to those determined by Chuang et al (2017) with KSU2R-2. Mite population reductions resulting from feeding on breeding line KSU2R-2 paralleled leaf folding scores on KSU2R-2 plants, where mite populations were significantly lower than those on susceptible plants in 20 of 25 populations sampled (Table 2).…”

“…Each caged plant was assessed for mite-induced leaf folding using protocols of Chuang et al (2017) at 14 days post infestation, and all plants were then cut just above the soil level and their leaves were folded and spread on adhesive 5 × 9 cm gridded blue paper sheets. Each sheet was then stored in a 50 mL Falcon tube (Fisher Scientific, Waltham, MA, USA) for 4-5 days or until the leaves dried at room temperature) and placed in a tube holder at a 45° angle to prevent mites from falling into the bottom of the tube (Murugan et al 2011).…”

“…Right: plant processing for mite population counts seedlings of the mite-susceptible cultivar Jagger were each infested in the second leaf stage with a piece of wheat leaf containing 10 mites from each of the 25 populations. Plants were caged for 21 days to allow virus infection symptoms to occur using protocols of Chuang et al (2017). Each cage represented an individual experiment with each mite population.…”

Barley Varieties Stoneham and Sydney Exhibit Mild Antibiosis and Antixenosis Resistance to the Wheat Curl Mite, Aceria tosichella (Keifer)

“…Only one seedling was used in the experiment if multiple plants germinated per pot. For each variety, eight pairs of equal-sized two-leaf stage plants were selected 10 days after planting [16,18,21,[35][36][37], and, in each pair, one plant served as a non-infested control and the other infested with a piece of leaf containing 30 A. tosichella adults (Figure 1), counted with a stereoscope (Nikon SMZ645, Tokyo, Japan). tosichella adults.…”

“…Host plant resistance to A. tosichella and summer control of volunteer wheat are key components in the integrated pest management of this pest and associated viruses [2,15]. Reduced mite populations and virus transmission are valuable benefits resulting from A. tosichella-resistant wheat genotypes [16,17]. Although wheat cultivars resistant to A. tosichella have been successfully developed for more than 30 years [18][19][20], A. tosichella-resistant barley remains unknown and unavailable to barley producers.…”