BGS 48, Reaction to Pyrenophora teres 4, Rpt4

QTL for resistance to Pyrenophora teres chromosome 7 = QRpt7 (2).

Monofactorial dominant (5, 6).
Located in chromosome 7HL (6); Rpt4.e is about 7.9 cM distal from RFLP marker Xprs117 (D) in 7H bin 09 (3, 5, 6); Rpt4.e is between DArT markers bPb-0027 and bPb-3484 (2).

The seedling reactions of Galleon with the Rpt4.e gene for resistance to Pyrenophora teres f. maculata (Ptm) isolates was typically measured as 2 to 4 on a scale where 1 = very resistant and 10 = very susceptible (5, 6). The Rpt4.e gene confers a consistent, but variable level of seedling and adult resistance to isolates of Pyrenophora teres f. maculata (Ptm), spot form of net blotch (SFNB) (5, 6). The adult plant resistance (APR) conferred by Rpt4.e was considered ineffective in controlling losses caused by Ptm (6). The Rpt4.e gene does not provide resistance to the long term standard Canadian Ptm isolate WRS857 and is considered ineffective in western Canada (3). The Rpt4 region of 7HL may have four different loci involves with susceptibility to Ptm.

Natural occurrence in Galleon (Clipper/Hiproly//3*Proctor/CIho 3576) (5, 6), but may have originated from CIho 3576 (a reselection from PI 57631 that originated from Egypt) (5, 6); resistant reactions to Ptm are conferred by CIho 5791 (PI 95095) from Ethiopia (1, 4), CIho 9214 (PI 186125), and CIho 9440 (PI 190786) from Korea (4).

Rpt4.e in Galleon (5, 6); QTL for seedling and adult plant resistance to Ptm were located at the same chromosomal region in CIho 9214 (PI 186125) from Korea, Dairokkaku (CIho 10954) from Japan, and Chebec (Orge_Martin/2*Clipper//Schooner), Keel (CP118197/Clipper//WI2645), and Tilga (Forrest/Cantala) from Australia (6); the breeding line TR251 (TR229//AC Oxbow/ND7556) contains a resistance gene of unknown origin (2).

Rpt4.e in Galleon; Rpt4.e in TR251.

1. Buchannon, K.W., and W.C. McDonald. 1965. Sources of resistance in barley to Pyrenophora teres. Can. J. Plant Sci. 45:189-193.
2. Grewal, T.S., B.G. Rossnagel, C.J. Ponzniak, and G.J. Scoles. 2008. Mapping quantitative trait loci associated with barley net blotch resistance. Theor. Appl. Genet. 116: 529-539.
3. Grewal, T.S., B.G. Rossnagel, and G.J. Scoles. 2008. The utility of molecular markers for barley net blotch resistance across geographic regions, Crop Sci. 48:2321-2333.
4. Tekauz, A., and K.W. Buchannon. 1977. Distribution of and sources of resistance to biotypes of Pyrenophora teres in Western Canada. Can. J. Plant Sci. 57:389-395.
5. Williams, K.J., A. Lichon, P. Gianquitto, J.M. Kretschmer, A. Karakousis, S. Manning, P. Langridge, and H. Wallwork. 1999. Identification and mapping of a gene conferring resistance to the spot form of net blotch (Pyrenophora teres f. maculata) in barley. Theor. Appl. Genet. 99:323-327.
6. Williams, K.J., G.J. Platz, A.R. Barr, J. Cheong, K. Willsmore, M. Cakir, and H. Wallwork. 2003. A comparison of the genetics of seedling and adult plant resistance to the spot form of net blotch (Pyrenophora teres f. maculata). Aust. J. Agric. Res. 54:1387-1394.

J.D. Franckowiak and G.J. Platz. 2013. Barley Genet. Newsl. 43:61-62.