Disease resistance. Leaf Rust Resistance.
Lr34 - Yr18
Contributed by Marcelo A. Soria, Wenjun Zhang and Jorge Dubcovsky
References
1. Catalogue of gene symbols for wheat. McIntosh RA, Yamazaki Y, .Devos KM, Dubcovsky J, Rogers R, Appels R. In: KOMUGI, Integrated wheat Science Database [web link]
2. Effect of leaf rust resistance gene Lr34 on components of slow rusting at seven growth stages in wheat. Singh RP, huerta-Espino J. In: Euphytica, 2003, 129:371-376.
Leaf rust resistance gene Lr34 is known to confer slow rusting resistance in wheat (Triticum aestivum).We conducted greenhouse experiments to evaluate the effect this gene had on three components (latent period, uredinium size and receptivity) of slow rusting resistance at seven plant growth stages of the Lr34 near-isogenic lines Jupateco 73R and Jupateco 73S at three temperatures (13, 18 and 23 °C). The presence of Lr34 increased the latent period and reduced uredinium size and receptivity. Although effects of Lr34 could be seen at each growth stage, differences in latent period and receptivity between the isolines increased dramatically from the 4-leaf stage onwards and stabilized by the 5-leaf stage. The relative effect of the Lr34 gene on latent period decreases and the receptivity increases with increasing temperature. Uredinium size was least affected by temperature and growth stage.
3. Characterization of Lr46, a gene conferring partial resistance towheat leaf rust. Martínez F, Niks RE, Singh RP, Rubiales D. In: Hereditas, 2001, 135:111-114.
Components of resistance conferred by the Lr46 gene, reported as causing "slow rusting" resistance to leaf rust in wheat, were studied and compared with the effects of Lr34 and genes for quantitative resistance in cv. Akabozu. Lr34 is a gene that confers non-hypersensitive type of resistance. The effect of Lr46 resembles that of Lr34 and other wheats reported with partial resistance. At macroscopic level, Lr46 produced a longer latency period than observed on the susceptible recurrent parent Lalbahadur, and a reduction of the infection frequency not associated with hypersensitivity. Microscopically, Lr46 increased the percentage of early aborted infection units not associated with host cell necrosis and decreased the colony size. The effect of Lr46 is comparable to that of Lr34 in adult plant stage, but in seedling stage its effect is weaker than that of Lr34.
4. Inheritance of adult-plant leaf rust resistance derived from the common wheat varieties Exchange and Frontana. Dyck PL, Samborski DJ, Anderson RG. In: Canadian Journal of Genetics and Cytology, 1966, 8:665-671.
5. Dissection of quantitative and durable leaf rust resistance in Swiss winter wheat reveals a major resistance QTL in the Lr34 chromosomal region. Schnurbusch T, Paillard S, Schori A, Messmer M, Schachermayr G, Winzeler M, Keller B. In: Theoretical and Applied Genetics, 2004, 108:477-484.
The Swiss winter bread wheat cv. 'Forno' has a highly effective, durable and quantitative leaf rust (Puccinia triticina Eriks.) resistance which is associated with leaf tip necrosis (LTN). We studied 240 single seed descent lines of an 'Arina x Forno' F5:7 population to identify and map quantitative trait loci (QTLs) for leaf rust resistance and LTN. Percentage of infected leaf area (%) and the response to infection (RI) were evaluated in seven field trials and were transformed to the area under the disease progress curves (AUDPC). Using composite interval mapping and LOD>4.4, we identified eight chromosomal regions specifically associated with resistance. The largest and most consistent leaf rust resistance locus was identified on the short arm of chromosome 7D (32.6% of variance explained for AUDPC_% and 42.6% for AUDPC_RI) together with the major QTL for LTN (R2=55.6%) in the same chromosomal region as Lr34 (Xgwm295). A second major leaf rust resistance QTL (R2=28% and 31.5%, respectively) was located on chromosome arm 1BS close to Xgwm604 and was not associated with LTN. Additional minor QTLs for LTN (2DL, 3DL, 4BS and 5AL) and leaf rust resistance were identified. These latter QTLs might correspond to the leaf rust resistance genes Lr2 or Lr22 (2DS) and Lr14a (7BL).
6. Association between gene Lr34 for leaf rust resistance and leaf tip necrosis in wheat. Singh RP. In: Crop Science, 1992, 32: 874-878.
Durable resistance to leaf rust (Puccinia recondita f.sp. tritici) in bread wheat (Triticum aestivum) cultivars is known to result from the interaction of Lr34 with other minor additive genes that are effective in the adult growth state. The Lr34 gene seems to be present in several CIMMYT germplasm-derived Mexican cultivars that display temperature- and light-sensitive seedling responses similar to those displayed by near-isogenic Thatcher lines that contain Lr34. Adult plants of these two Thatcher lines and all Mexican cultivars postulated to carryLr34 display resistance to leaf rust and exhibit leaf tip necrosis symptoms. This study was conducted to determine whether Lr34 and a gene or genes for leaf tip necrosis are linked. The simultaneous presence of Lr34 and leaf tip necrosis in the two Thatcher near-isogenic lines and Mexican cultivars was confirmed by evaluating F2 plants or F3 lines obtained from various intercrosses. Lr34 and leaf tip necrosis were inherited together in a population of 117 F3 lines obtained from the cross of leaf rust resistant Jupateco 73R (carrying Lr34 and leaf tip necrosis) with its susceptible counterpart Jupateco 73S. Linkage or pleiotropism was also evident in the crosses of six Lr34-carrying Mexican cultivars with Siete Cerros 66 (which does not have Lr34). The gene for leaf tip necrosis, designated Ltn, could be used as a marker for Lr34.
7. Microsatellite markers for genes Lr34/Yr18 and other quantitative trait loci for leaf rust and stripe rust resistance in bread wheat. Suenaga K, Singh RP, Huerta-Espino J, William HM. In: Phytopathology, 2003, 93:881-890.
Leaf rust and stripe rust, caused by Puccinia triticina [Puccinia recondita] and P. striiformis, respectively, are important diseases of wheat in many countries. In this study we sought to identify molecular markers for adult plant resistance genes that could aid in incorporating such durable resistance into wheat. We used a doubled haploid population from a Japanese cv. Fukuho-komugi x Israeli wheat Oligoculm cross that had segregated for resistance to leaf rust and stripe rust in field trials conducted in Obregon, Sonora, Mexico, during 1999-2001. Joint and/or single-year analyses by composite interval mapping identified two quantitative trait loci (QTL) that reduced leaf rust severity and up to 11 and 7 QTLs that might have influenced stripe rust severity and infection type, respectively. Four common QTLs reduced stripe rust severity and infection type. Except for a QTL on chromosome 7DS, no common QTL for leaf rust and stripe rust was detected. QTL-7DS derived from "Fukuho-komugi" had the largest effect on both leaf rust and stripe rust severities, possibly due to linked resistance genes Lr34/Yr18. The microsatellite locus Xgwm295.1, located almost at the peak of the likelihood ratio contours for both leaf and stripe rust severity, was closest to Lr34/Yr18. QTLs located on 1BL for leaf rust severity and 3BS for stripe rust infection type were derived from "Oligoculm" and considered to be due to genes Lr46 and Yr30, respectively. Most of the remaining QTLs for stripe rust severity or infection type had smaller effects. Our results indicate that there is significant diversity for genes that have minor effects on stripe rust resistance, and that successful detection of these QTLs by molecular markers should be helpful both for characterizing wheat genotypes effectively and combining such resistance genes.
8. Effect of leaf rust resistance gene Lr34 on grain yield and agronomic traits of spring wheat. Singh RP, Huerta-Espino J. In: Crop-Science, 1997, 37:390-395.
Leaf rust, caused by Puccinia recondita f.sp. tritici, is an important disease of wheat (Triticum aestivum) worldwide. The Lr34 gene is known to confer durable resistance. The effects of Lr34 on grain yield and other traits in the absence and presence of leaf rust were evaluated. Jupateco 73R and Jupateco 73S (near-isogenic reselections from the Mexican spring wheat cultivar Jupateco 73 for the presence and absence of Lr34, respectively) and 22 random inbred F6 lines, 11 with and 11 without Lr34 (derived from the cross Jupateco 73R/Jupateco 73S), were planted in replicated field trials during the 1992-93 and 1993-94 seasons in northwestern Mexico. The mean grain yield of Jupateco 73R was 5.9% lower (P<0.05) than that of Jupateco 73S in protected plots in the 1992-93 experiment. Significant reductions (P<0.05) were also observed for biomass, grains per spike and grains/m2. Significant (P<0.01) reductions of 5% in mean grain yield and 3.7% in mean grain weight were again evident in one of the two experiments sown during the 1993-94 season. Comparison of grain yield in protected and non-protected treatments indicated that though leaf rust could significantly (P<0.01) reduce grain yield by approximately 15% in the presence of Lr34, the reductions in the absence of Lr34 were substantially higher and ranged from 42.5 to 84% depending on planting date and year. Reductions in all other traits were also significantly higher in the absence of Lr34. It is concluded that although the presence of Lr34, which is linked with leaf tip necrosis of adult plants, may carry a slight yield penalty in some disease-free environments, its use in leaf rust prone areas could provide substantial protection to grain yield and other traits.
9. The influence of leaf rust resistance genes Lr29, Lr34, Lr35 and Lr37 on breadmaking quality in wheat. Labuschagne MT, Pretorius ZA, Grobbelaar B. In: Euphytica, 2002, 124: 65–70.
Leaf rust, caused by Puccinia triticina, is considered one of the most important diseases of wheat. In South Africa the genes Lr29, Lr34, Lr35 and Lr37 confer effective resistance to leaf rust, qualifying them for use in cultivar improvement. To study possible secondary effects of these genes, a collection of BC6 lines containing each of the genes singly, was evaluated for breadmaking quality. The recurrent parent Karee, and Thatcher NILs used as resistance donors in the primary crosses, as well as Thatcher, were included as checks. The presence of Lr29, Lr34, Lr35 and Lr37 caused a significant increase in flour protein and water absorption. For most of the other characteristics the NILs performed statistically similar to the recurrent parent. Some sib lines performed significantly better than others, emphasising the value of selecting for improved quality among backcross lines.
10. Tagging and validation of a major quantitative trait locus for leaf rust resistance and leaf tip necrosis in winter wheat cultivar Forno. Schnurbusch T, Bossolini E, Messmer B, Keller B.In: Phytopathology, 2004, 94:1036-1041.
A major leaf rust (Puccinia triticina Eriks.) resistance QTL (QLrP.sfr-7DS) has previously been described on chromosome 7DS in the winter wheat (Triticum aestivum L.) cultivar 'Forno'. It was detected in a population of single seed descent (SSD) lines derived from the cross 'Arina x Forno'. QLrP.sfr-7DS conferred a durable and slow-rusting resistance phenotype, co-segregated with a QTL for leaf tip necrosis (LTN), and was mapped close to Xgwm295 at a very similar location as the adult plant leaf rust resistance gene Lr34 found in some spring wheat lines. Here, we describe the validation of this QTL by mapping it to the same chromosomal region close to Xgwm295 on chromosome 7DS in a population of SSD lines from the winter wheat x spelt (T. spelta L.) cross 'Forno x Oberkulmer'. In both populations, the LOD curves for leaf rust resistance and LTN peaked at identical or very similar locations, indicating that both traits are due to the same locus. We have improved the genetic map in the target region of QLrP.sfr-7DS using microsatellite and EST markers. Two EST loci define a genetic interval of 7.6 cM containing QLrP.sfr-7DS, a considerably more precise genetic location for this QTL than previously described both in spring and winter wheat. The identified genetic interval is physically located in the distal thirty-nine percent of chromosome 7DS. In the rice genome, the two ESTs flanking the QLrP.sfr-7DS/QLtn.sfr-7DS chromosomal segment in wheat are conserved on chromosome 6S in a region colinear with wheat chromosome 7DS. There, they define a physical region of three rice BACs spanning ~ 300 kb.
11. A putative ABC transporter confers durable resistance to multiple fungal pathogens in wheat. Krattinger SG, Lagudah ES, Spielmeyer W, Singh RP, Huerta-Espino J,McFadden H, Bossolini E, Selter LL, Keller B. In: Science, 2009, 323:1360-1363. DOI: 10.1126/science.1166453.
12. Molecular genetic characterization of the Lr34/Yr18 slow rusting resistance gene region in wheat. Lagudah ES, McFadden H, Singh RP, Huerta-Espino J, Bariana HS, Spielmeyer W. In: TAG Theoretical and Applied Genetics, 2006, 114:21-30. DOI: 10.1007/s00122-006-0406-z.