Monsanto, through the MBBIScholars Program, has invested $13 million over an 8 year period for training rice and wheat breeders from around the World. The Judging Panel for MBBISP selected 89 Scholars from 432 applicants. The selected scholars were from 30 different countries. Scholars selected included 35 young ladies and 54 young men, 37 are in rice breeding and 52 in wheat breeding. Currently 28 Scholars are still completing their PhD programs (As of 8/8/2017). This past year Monsanto established the "Ted Crosbie Monsanto Beachell-Borlaug International Scholars Impact Award" to begin recognizing Scholar contributions. To be eligible for the "Ted Crosbie MBBIScholars Impact Award," scholars must have received their PhD and must apply for the award. Bhoja Basnet, selected as an MBBIScholar in 2009 who is now in charge of CIMMYT's Hybrid Wheat Breeding program, was selected to receive the "Ted Crosbie Monsanto Beachell-Borlaug Scholars Program Impact Award" this year. Scholar contributions are in wheat and rice breeding as well as in other crops. Hopefully the Ted Crosbie MBBIScholars Impact Award will continue to recognize accomplishments of Scholars into the future. MBBIScholars are making an impact and we look forward to recognize their career contributions. Employment of Scholars post PhD will be reviewed.
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A diverse set of winter wheat germplasm was screened for resistance to stem rust in large-scale trials in Kenya and Turkey during 2009-16. The study aimed to select resistant material and characterize types of resistance and possible genes, as well as evaluate agronomic traits and resistance to other diseases to select superior variety candidates and parental lines. The study material was comprised of various Facultative and Winter Wheat Observation Nurseries (FAWWON), which are developed and distributed by the International Winter Wheat Improvement Program (www.iwwip.org) in Turkey. More than 1600 global accessions were screened, with most evaluated for two years. Based on stem rust data from Kenya, more than 400 genotypes were identified exhibiting adequate levels of resistance to the Ug99 race group. The highest number of resistant lines originated from IWWIP (~170), USA (~100), Russia (~40), Iran (~30), Romania (~20), and South Africa (~20). Material was also tested at two sites in Turkey: Haymana (artificial inoculation) and Kastamonu (natural infection). There was no significant correlation between stem rust severities in Kenya and in Turkey, due to differences in stem rust pathotypes. However, a set of germplasm (more than 100 entries) has been identified as resistant in both countries. This set represents promising material as variety candidates and parental lines; another study is currently identifying the genes controlling the stem rust resistance in this population. IWWIP distributed stem rust resistant germplasm to its global collaborators during 2010-2015, in response to the threat from the Ug99 race group. New resistant germplasm combining broad adaptation, high yields, and resistance to other diseases is available on request.
Improvement of stripe rust resistance is one of the main aims of wheat breeding programs worldwide. Progress is dependent on the availability of genetically diverse and widely effective sources of resistance. This study focuses on genetic analysis of stripe rust resistance in landrace accession AWCC275 from the Watkins Collection. AWCC275 was scored resistant to moderately resistant under field conditions during three crop seasons and showed an intermediate seedling response (infection type 2C). AWCC275 was crossed with the susceptible genotype Avocet S and a population of 76 F3 families was generated. Twenty seedlings of each family were tested at the seedling stage with Puccinia striiformis f. sp. tritici pathotype 134 E16A+,Yr17+,Yr27+ under greenhouse conditions. Sixteen lines were homozygous resistant (HR), 43 segregated and 17 were homozygous susceptible (HS). Chi-squared analysis (?21:2:1 =1.34, non-significant at P=0.05 and 2 df) indicated segregation at a single locus. HR and HS lines were submitted for selective genotyping using the 90K SNP platform. The population is currently being advanced to F6 for detailed molecular mapping and the resistance gene is being backcrossed to three Australian wheat cultivars.
Elite barley breeding lines from the Australian Northern Region Barley Breeding Program were evaluated at the seedling and adult growth stages for resistance to leaf rust (LR) caused by Puccinia hordei. F3:5 lines derived from parental germplasm of different geographic origins were screened in the glasshouse and field spanning four years of trials. The 2009 and 2011 breeding populations (BP1 and BP2) comprised 360 lines and were genotyped with 3,244 polymorphic diversity arrays technology (DArT) markers. The 2012 and 2013 breeding populations (BP3 and BP4) comprised 320 lines genotyped with the DArT GBS array (DArTseq), providing 15,400 high quality polymorphic markers. Association mapping (AM) using the DArT/DArT-seq datasets and phenotypic data from 15 independent LR response assays identified a number of genomic regions associated with resistance. The BP1 and BP2 study detected a total of 15 QTL; 5 QTL co-located with catalogued LR resistance genes (Rph1, Rph3/19, Rph8/14/15, Rph20, and Rph21), 6 QTL aligned with previously reported genomic regions and 4 QTL (3 on chromosome 1H and 1 on 7H) were novel. Markers in common between the DArT and DArTseq datasets enabled integration of mapping results for LR response across the four breeding populations and all QTL detected were visualised on a single map for validation. The adult plant resistance (APR) locus Rph20 was the only region detected in all field environments. Markers and their associated sequences identified in this study will be useful for building QTL combinations involving Rph20, thereby providing stable LR resistance in improved barley cultivars. We will also highlight the advantages of AM using breeding germplasm over traditional bi-parental mapping approaches that underutilise genetic diversity and divert valuable resources into populations of low breeding value.
The CIMMYT durum Bairds is susceptible to leaf rust (LR) at the seedling stage but shows an adequate level of slow rusting adult plant resistance (APR) in Mexican field environments. A recombinant inbred line (RIL) population developed from a cross of Bairds and the susceptible parent Atred#2 was phenotyped for LR response at Ciudad Obregon, Mexico, during 2013, 2014 and 2015 under artificial epidemics created with Pt race BBG/BP. Genetic analysis indicated that 3-4 additive genes conferred LR resistance. The RILs and parents were also genotyped with the 50K diversity arrays technology (DArT) sequence system and 93 SSR markers. A genetic map comprising 1,150 markers was used to map the resistance loci. Inclusive composite interval mapping analysis detected four quantitative trait loci (QTL) on chromosomes 1BL, 2BC (centromere region), 5BL and 6BL. These QTL, designated as QLr.cim-1BL, QLr.cim-2BC, QLr.cim-5BL and QLr.cim-6BL, explained 20.1-60.7%, 6.4-13.1%, 4.3-11.2%, and 7.1-28.0%, respectively, of the variation in leaf rust severity. QLr.cim-1BL was close to the previously reported APR gene Lr46, whereas QLr.cim-6BL, detected in all three seasons, is a new resistance locus in durum wheat. The four QTL combined showed a significant additive effect on resistance with a disease severity of 18-20%, whereas RILs carrying the individual QTL showed mean leaf rust severities ranging from 56 to 98%. Three QTL, except for QLr.cim-2BC, were derived from Bairds. The final LR severity of Bairds ranged from 15-25% across three years. This cultivar can be used as a source for complex APR in durum wheat breeding.
Our research objective is to identify new resistance genes in cultivated and wild tetraploid wheats that are effective against race TTKSK and other Pgt races, and could be utilized in durum breeding. We characterized 7,000 durum and 360 emmer accessions for field resistance at Debre Zeit, Ethiopia, and Saint Paul, Minnesota. Accessions with resistant to moderately resistant responses in multiple field evaluations were characterized at the seedling stage for resistance to races TTKSK, TRTTF, TTTTF, JRCQC, TKTTF, and an additional six representative U.S. races. We identified 208 durum and 28 emmer accessions resistant to moderately resistant in all field and seedling evaluations. A search for resistance through seedling evaluations was also conducted on wild emmer (840 accessions) and four cultivated tetraploids (Persian, Polish, Oriental, and Pollard wheats, 560 accessions). About 20% of the accessions were resistant to race TTKSK. Thirty-six resistant accessions of cultivated and wild tetraploids were selected to investigate the genetics of TTKSK and TRTTF resistance. Results from evaluating F2 and F2:3 generations from biparental crosses revealed that resistance to race TTKSK in various subspecies of T. turgidum was conferred mostly by one or two genes with dominant and recessive actions. Additional resistance genes were identified when populations were evaluated against race TRTTF. A bulk segregant analysis approach is being used to map the resistance genes in selected resistant parents using the 90K SNP platform.
This study was conducted to detect new races of Puccinia striiformis f. sp. tritici in Iraq. Trap nurseries were planted in different locations throughout the main wheat growing areas. Stripe rust severities and infection types on each genotype were recorded at different stages of crop development. Yellow rust samples collected from commercial wheat fields at different locations were sent to the Global Rust Center for race analysis. Local adult plant tests indicated virulence for host genes Yr2, Yr6, Yr7, Yr9, Yr18, YrA, Yr20, Yr21, Yr27, Yr28, Yr29, and Yr31 at the adult plant stage in Sulaimania, and virulence to Yr2, Yr6, Yr7, Yr9, YrSD, YrSP, YrA, Yr21, Yr27, Yr28, and Yr31 at Nineveh. Virulence on lines carrying Yr5, Yr6, Yr7, Yr9, Yr20, Yr21, Yr27, Yr28 and Yr31 were recorded in Babylon and to Yr2, Yr5, Yr6, Yr7, Yr9, Yr18, YrA, Yr20, Yr25, Yr28, Yr29, and Yr31 at Diyala. Of 21 YR samples sent to GRRC for race analysis, cultures were recovered from ten. Two Pst pathotypes (races) were identified; one was virulent to Yr2, Yr6, Yr7, Yr8, Yr9, Yr27, and AvS whereas the other had additional virulence to Yr25 (Strubes Dickkopf). None was virulent for Yr5. Both pathotypes were aggressive based on Milus et al. measures.
During the past 15 years, significant efforts have been directed to develop the grass species Brachypodium distachyon as a genetically tractable model for monocot plants, especially economically valuable cereals such as wheat, barley and oat. Such efforts have led to an increasing availability of genomic, genetic and bioinformatics tools designed to bypass the experimental challenges faced when addressing important biological questions in complex systems. Moreover, such advances may translate in the use of other valuable species of Brachypodium (e.g., B. hybridum), which are not nearly as well characterized as B. distachyon. Given the 2050 global food demands and needs to increase grain production we seek to develop innovative and sustainable approaches to decrease crop yield losses due to rust fungi. One possible strategy is the use of transgenic plants harboring non-host resistance-related genes from closely related species. B. distachyon and B. hybridum can serve as potential sources to engineer plant resistance against highly destructive rust fungi, such as Puccinia graminis and P. coronata. Advancing our understanding of non-host resistance in monocot species has been a slow process. However, the amenability of Brachypodium as a model system offers a means to accelerate scientific discovery of factors controlling non-host pathogen interactions involving stem and crown rust fungi. In a multi-pronged approach, we are leveraging genetic and genomic tools, as well as generating new resources to provide foundational knowledge in order to support plant genetic engineering programs.
Stripe rust of wheat was estimated to cause losses of A$127 m annually in Australia. Although stripe rust can be controlled through the use of chemicals, breeding for resistance is considered to be the best means of control. Identification and characterization of diverse sources of resistance is essential to achieve durable stripe rust control. A common wheat landrace AWCC618 showed resistance (IT 1CN) to Australian Puccinia striiformis f. sp. tritici (Pst) pathotypes. AWCC618 was crossed with the susceptible genotype Avocet S (AvS) to determine the genetic basis of resistance. Seedling tests on 123 AWCC618/AvS F3 families using Australian Pst pathotype 134 E16 A+ 17+ 27+ indicated monogenic inheritance of resistance (22HR:68SEG:33HS; χ21:2:1=3.34, non-significant at P=0.05 and 2 d.f.). The resistance locus was temporarily named YrAW3. Selective genotyping of eight homozygous resistant (HR) and eight homozygous susceptible (HS) F3 families using the 90K SNP Infinium assay tentatively located YrAW3 on chromosome 6A. The AWCC618/AvS population was advanced to F6 for detailed mapping of the target region. YrAW3 appears to be a new locus. AWCC618 was crossed with three current Australian cultivars to transfer YrAW3 to modern wheat backgrounds. Backcross-derivatives will also be useful for validation of linked markers.