Leaf Rust and Stem Rust Resistance in Triticum dicoccoides Populations in Israel Y. Anikster and J. Manisterski, Institute for Cereal Crops Improvement, Tel Aviv University, Ramat Aviv 69978, Israel; D. L. Long, U.S. Department of Agriculture - Agricultural Research Service, Cereal Disease Laboratory, Uni- versity of Minnesota, St. Paul 55108; and K. J. Leonard, Plant Pathology Department, University of Minnesota, St. Paul 55108 tritici to identify useful sources of leaf rust ABSTRACT and stem rust resistance for transfer to Anikster, Y., Manisterski, J., Long, D. L., and Leonard, K. J. 2005. Leaf rust and stem rust resis- cultivated wheat. Tests for leaf rust resis- tance in Triticum dicoccoides populations in Israel. Plant Dis. 89:55-62. tance included exposure of the accessions to epidemics in inoculated field plots in A total of 742 single plant accessions of Triticum dicoccoides were collected from 26 locations Israel to screen for adult plant resistance as in Israel. All accessions were evaluated for leaf rust (Puccinia triticina) resistance in field plots well as greenhouse tests for seedling resis- at Tel Aviv, and subsets of 284 and 468 accessions were tested in the greenhouse in Tel Aviv and tance. Tests for stem rust resistance were St. Paul, MN, respectively, for seedling resistance to leaf rust; 460 accessions were also tested done only with seedlings in the green- for seedling resistance to stem rust (Puccinia graminis f. sp. tritici) in St. Paul. One accession was highly resistant to leaf rust in seedling tests in Tel Aviv, and 21 others had moderately sus- house. ceptible to moderately resistant seedling resistance. Four accessions were highly resistant to leaf rust in seedling tests in St. Paul, and 11 were resistant to at least one stem rust race. Adult resis- MATERIALS AND METHODS tance to leaf rust was more common than seedling resistance among the accessions; 21 acces- Seeds were collected from 742 single sions had less than 25% leaf rust severity in field plots compared with 80 to 90% severity for plants of T. dicoccoides from natural popu- highly susceptible accessions. Most of the accessions with effective adult plant resistance came lations at 22 locations in nine regions of from two nearby locations in Upper Galilee, a region where populations of T. dicoccoides are northern Israel and at three locations in most extensive and genetically diverse. These accessions may provide valuable new partial resis- Jerusalem in the Judean Mountains (Table tance genes for durable protection against leaf rust in cultivated wheat. 1, Fig. 1). Seed of single plant accessions were increased through two to five genera- Additional keywords: slow rusting resistance, wild emmer tions in screen houses and nurseries at Tel Aviv. All accessions are deposited in the Lieberman Germplasm Bank, Institute for Cereal Crops Improvement, Tel Aviv Uni- Leaf rust, caused by Puccinia triticina, land races of T. aestivum, wheat breeders versity. Accessions were grown in a field and stem rust, caused by P. graminis f. sp. have turned their attention to wild relatives nursery at Tel Aviv, where they were in- tritici, are two of the most important dis- of wheat. Wild emmer, T. dicoccoides, is oculated with a bulk collection of P. eases of wheat worldwide. Although stem the closest wild relative to cultivated du- triticina from both wild and cultivated rust has been largely controlled by resis- rum and bread wheat. Durum (AABB) and wheats in Israel. Depending on seed avail- tance, it remains a potential threat, particu- bread wheat (AABBDD) derived their A ability, most of the accessions were also larly in areas such as Australia, Argentina, and B genomes from the tetraploid T. di- tested for seedling resistance in green- and the Great Plains of the United States, coccoides and are fully fertile in crosses houses at Tel Aviv and St. Paul, MN. At where the climate is favorable for devastat- with it. Thus, genes from T. dicoccoides Tel Aviv, 284 accessions were tested as ing epidemics. Leaf rust epidemics gener- can be transferred readily to cultivated seedlings for resistance against a compos- ally have been less destructive than the wheats in crosses by recombination of ite inoculum of P. triticina derived from most severe stem rust epidemics, but leaf homologous chromosomes (4,18,24,25). aeciospores from Thalictrum speciosis- rust is a more widespread and persistent Native stands of T. dicoccoides can be simum, the alternate host for wheat leaf problem throughout the world. Much of the found in small scattered populations across rust. These accessions came from locations breeding effort against leaf rust in wheat has southern Turkey, northeastern Iraq, west- in the following regions: Eastern Upper concentrated on genes for race-specific ern Iran, and in the Caucasus, but the cen- Galilee, the Hula Valley, Korazim, and resistance. Race-specific resistance to leaf ter of diversity for T. dicoccoides is in the Upper Galilee. At St. Paul, 468 accessions rust typically remains effective for only a region of northern Israel, northwestern were tested as seedlings for resistance to a few years, and recent studies suggest that Jordan, southwestern Syria, and eastern composite inoculum of P. triticina, and the available resistance genes in hexaploid Lebanon (6,19,25). Within Israel, the most 460 were tested for resistance to a compos- cultivated wheat, Triticum aestivum, have extensive populations and the greatest ite inoculum of P. graminis f. sp. tritici. been nearly exhausted (2,15). genetic diversity of T. dicoccoides are in Accessions tested in St. Paul came from With the diminishing success in finding Jordan River watershed regions of eastern the following regions: Eastern Upper Gali- new rust resistance genes in cultivars and Galilee, eastern Samaria, and areas of the lee, the Golan Heights, Mt. Hermon, the Golan Heights overlooking the Sea of Hula Valley, the Judean Mountains, Lower Galilee (20,25). In this area, uncultivated Galilee, Korazim, Samaria, Upper Galilee, Corresponding author: K. J. Leonard sites where grazing is controlled can sup- and the Valley of Esdraelon. Subsets of E-mail: [email protected] port natural stands of T. dicoccoides as these accessions were also tested as seed- Accepted for publication 25 August 2004. dense as cultivated wheat fields (6). lings against a single isolate of P. triticina The objective of this study was to sam- from the United States (216 accessions) ple collections of T. dicoccoides from a and against a single isolate of P. graminis DOI: 10.1094/PD-89-0055 diverse range of sites throughout northern f. sp. tritici (217 accessions). This article is in the public domain and not copy- Israel and to test the accessions for resis- Tel Aviv tests. Accessions of T. dicoc- rightable. It may be freely reprinted with custom- ary crediting of the source. The American Phyto- tance to Israeli and North American iso- coides were planted in November in single pathological Society, 2005. lates of P. triticina and P. graminis f. sp. 1-m rows in a field nursery at Tel Aviv. Plant Disease / January 2005 55 Spreader rows of a leaf rust susceptible considered resistant, ITs of 3 to 4 were In each test, seeds of the accessions to wheat cultivar were inoculated by spraying considered susceptible, and ITs scored as be inoculated were grown in vermiculite in with a suspension of urediniospores of P. 2,3 or 3,2 (i.e., with mixtures of IT2 and 8-cm-square plastic pots with three to five triticina in light mineral oil in February. IT3 uredinia) were considered less than seeds each of four accessions planted in Inoculum consisted of a bulk uredinial fully susceptible. the corners of each pot. Glumes were re- population of P. triticina derived from St. Paul tests. Accessions were tested moved from the seeds before planting. The aeciospores from leaves of Thalictrum for seedling resistance to leaf rust and stem pots were arranged in trays holding six speciosissimum. The basidiospores that rust in two tests each at St. Paul. In the pots each, and the plants were grown in a infected the T. speciosissimum plants were first seedling test for leaf rust resistance, rust-free greenhouse for 7 days before produced by incubating the plants with plants were inoculated with a single isolate inoculation. The seedlings were fertilized germinating teliospores from collections of of race TBBL of P. triticina, which was at 5 and 8 days after planting with a water telia obtained from cultivated wheat and common in the United States. In the sec- soluble fertilizer (23-19-17, NPK) at 2.5 g wild emmer at multiple locations through- ond leaf rust test, the seedlings were inocu- per tray. On the seventh day after planting, out Israel. The accessions of T. dicoccoides lated with a composite of 12 races: BBGL, the seedlings were inoculated by spraying in the nursery were evaluated twice for leaf CBGB, DBBG, KDBL, MFBL, MGBL, them with a suspension of urediniospores rust severity and reaction type in late April PBRG, PLMQ, PQRS, SBDJ, TBBL, and in light mineral oil. The oil was allowed to and early May. TLGG, all of which had been isolated from evaporate for 30 min, and the inoculated Accessions tested for seedling resistance wheat fields in the United States. Virulence seedlings were placed in a dew chamber to leaf rust in the greenhouse at Tel Aviv formulas for these races are derived as overnight at 18°C. For stem rust, the dew were grown in a 1:1 vermiculite:soil mix- described in Long et al. (11). Together, this chamber was programmed for fluorescent ture in 10-cm-diameter pots. Four acces- composite of races included virulence to lights to turn on for 3 to 4 h before the dew sions were planted per pot with four seeds Lr1, Lr2a, Lr2c, Lr3, Lr9, Lr16, Lr24, chamber was opened to allow the seedlings per accession and grown in a temperature- Lr26, Lr3ka, Lr11, Lr17, Lr30, LrB, Lr10, to dry slowly for 2 h while the temperature controlled greenhouse at 20 ± 2°C.