Genetic analysis and detection of the gene MlLX99 on chromosome 2BL conferring resistance to powdery mildew in the wheat cultivar Liangxing 99

Abstract

The effectiveness of wheat cultivar Liangxing 99 against powdery mildew was shown to be controlled by a single dominant gene located on a new locus of chromosome 2BL in the bin 2BL2-0.35-0.50. Liangxing 99, one of the most widely grown commercial cultivars in the winter wheat (Triticum aestivum) producing regions in northern China, was shown to provide a broad spectrum of resistance to Blumeria graminis f. sp. tritici (Bgt) isolates originating from that region. Using an F2 population and F2:3 lines derived from a cross of Liangxing 99 × Zhongzuo 9504, genetic analysis demonstrated that a single dominant gene, designated MlLX99, was responsible for the resistance of Liangxing 99 to Bgt isolate E09. The results of molecular analysis indicated that this gene is located on chromosome 2BL and flanked by the SSR marker Xgwm120 and EST-STS marker BE604758 at genetic distances of 2.9 and 5.5 cM, respectively. Since the flanking markers of MlLX99 were previously mapped to the bin 2BL2-0.36-0.50, MlLX99 must be located in this chromosomal region. MlLX99 showed a different resistance reaction pattern to 60 Bgt isolates from Pm6, Pm33, and PmJM22, which were all previously mapped on chromosome 2BL, but differed in their positions from MlLX99. Due to its unique position on chromosome 2BL, MlLX99 appears to be a new locus for resistance to powdery mildew. Liangxing 99 has shown superior yield performance and wide adaptation to different agricultural conditions, which has resulted in its extensive use as a wheat cultivar in China. The identification of resistance gene MlLX99 facilitates the use of this cultivar in the protection of wheat from damage caused by powdery mildew.

The gene PmYB confers broad-spectrum powdery mildew resistance in the multi-allelic Pm2 chromosome region of the Chinese wheat cultivar YingBo 700

“…Because of the similar locus, PmYB cannot be detected in these genomic backgrounds and also pyramided with these documented Pm genes. Liangxing 99 and Jimai 22 have single dominant Pm genes Pm52 and PmJM22 both on chromosome arm 2BL (Yin et al 2009;Zhao et al 2013). Although PmYB is located on a significantly different genetic locus from those of Pm52 and PmJM22, the amplification pattern by the four closely linked markers of PmYB were same as Liangxing 99 and Jimai 22.…”

“…Of these genes, some have been not effective to the new virulent Bgt isolates, some are identified in host lines with linkage drags that lead to poor agricultural performance, so are seldom used in resistance breeding, and some need further time before their use (e.g., Zeller and Hsam 1996;Friebe et al 1994;Ma et al 2014). However, one class of Pm genes has been identified in commercial cultivars that provide broad-spectrum powdery mildew resistance (e.g., Huang et al 2012;Zhao et al 2013). A combination of excellent agronomic performance and broad-spectrum resistance offers an attractive prospect in resistance breeding.…”

“…In Tangmai 4, the Pm gene PmTm4 was flanked by Gwm611 and EST92 on chromosome arm 7BL (Hu et al 2008b). Jimai 22 and Liangxing 99 both carry a single Pm gene on chromosome arm 2BL, which are linked to Wmc149 and flanked by BE604758 and Gwm120, respectively (Yin et al 2009;Zhao et al 2013). Three Pm genes PmLX66, PmW14 and PmZ155 on chromosome 5DS in Liangxing 66, Wennong 14 and Zhongmai 155, respectively, were responsible for their resistance to powdery mildew Song et al 2014;Sun et al 2015).…”

Molecular detection of disease resistance genes to powdery mildew (Blumeria graminis f. sp. tritici) in wheat (Triticum aestivum) cultivars

“…The shift in pathogenic virulence structures range from the southwest and the southeast coastal regions of China to almost all the wheat growing areas throughout the country and the damage exceeds any other known wheat disease (Liu and Shao, 1994;Luo et al, 2009;Cao et al, 2013;Zhao et al, 2013;Shen et al, 2015).…”

Identification of three new resources of resistance to Fusarium head blight in wheat

“…tritici (Bgt) single-spore isolates (Shen et al 2015) were collected from Beijing, Shandong, Hebei, Henan, and Jiangsu provinces to assess the reactions of all genotypes to the pathogen causing powdery mildew. Evaluation of seedling reactions to 27 isolates was conducted in a greenhouse using the previously reported method (Zhao et al 2013). In addition, the natural powdery mildew occurrence in a greenhouse was observed and recorded.…”