Sunday April 15
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08:30-08:35 |
Announcements |
Keynote
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08:35-09:20 |
Francisco Barro Losada, Institute for Sustainable Agriculture
CRISPR/Cas in wheat: Engineering low gluten and other complex traits |
Host Resistance
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09:20-09:40 |
Dhouha Kthiri, University of Saskatchewan
Genetic and molecular characterization of leaf rust resistance from uncharacterized sources of durum wheat [View abstract]
Widening the genetic basis of leaf rust resistance is a primary objective of durum wheat breeding programs in North America, especially after the occurrence of new Puccinia triticina races in Mexico and southwestern United States. This study was conducted to characterize and map uncharacterized genes for leaf rust resistance in durum wheat sources and to develop reliable molecular markers for marker-assisted breeding. Seven RIL populations involving crosses of resistant cultivars Geromtel_3 (ICARDA), Tunsyr_2 (ICARDA), Amria (Morocco), Byblos (France), Gaza (Middle East), Saragolla (Italy) and Arnacoris (France) with the susceptible line ATRED #2, were evaluated for reaction to Mexican Pt race BBG/BP. Selective genotyping and bulked segregant analysis using the wheat 90K SNP array identified two genomic regions for leaf rust resistance; 6BS in Geromtel_3 and Tunsyr_2, and 7BL in Amria and Byblos. Composite interval mapping revealed a total of six quantitative trait loci (QTL) for leaf rust resistance; two on chromosomes 6BS and 6BL in Gaza, and major QTL on chromosomes 7BL in Arnacoris and 2BS in Saragolla. Both latter lines had an additional minor QTL on chromosome 1BL. DNA sequences associated with the SNP markers linked to the Lr genes and QTL were anchored to the wild emmer wheat reference sequence of accession Zavitan. KASP markers tightly linked to the Lr genes reported here were developed.
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09:40-10 |
Clemence Marchal, John Innes Centre
Elucidating the relationship between Yr7 and Yr5 [View abstract]
Despite over 70 designated yellow rust resistance genes (Yr) in wheat, few have been cloned. This lack of knowledge hinders efficient marker assisted breeding and exploitation of novel allelic variation. We recently exome sequenced a mutant population of UK cultivar Cadenza which carries Yr7. Screening 1,000 mutagenized individuals with a Yr7-avirulent Pst isolate identified seven susceptible lines presumed to carry mutations in Yr7. To test this, mutational resistance gene enrichment sequencing (MutRenSeq) was carried out on the susceptible lines and a candidate for Yr7 was identified. SNP markers were developed to assess their association with susceptible phenotypes in F2 populations derived from crosses of the susceptible mutant lines to wild type Cadenza. A similar approach was carried out on Yr5 susceptible mutants in the Lemhi-Yr5 near isogenic line background. A candidate gene was also identified for Yr5, which was different from the Yr7 candidate. The parallel Australian work identified susceptible mutants in AvS-Yr7 and AvS-Yr5 and respective candidates using MutRenSeq with similar outcomes. This suggests that Yr5 and Yr7 are very closely linked genes rather than true alleles. We will discuss how distinguishing linkage versus allelic relationships between genes might affect breeding.
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10-10:20 |
Marco Maccaferri, University of Bologna
Development and characterization of a whole-genome radiation hybrid panel from reference tetraploid wheat cultivar Svevo [View abstract]
The recent release of high-quality sequence information from hexaploid wheat (IWGSC 2014) coupled with the availability of high-density consensus maps for tetraploid wheat (Maccaferri et al. 2014) has accelerated marker and gene discovery in durum wheat, thus facilitating the genetic dissection of agronomic traits. Radiation hybrid (RH) mapping is a promising recombination-independent mapping approach, which involves the use of radiation-induced chromosomal breakage and marker segregation to reconstruct marker order (Tiwari et al. 2016). In this study, for the first time, a RH panel for tetraploid wheat was developed for the reference durum genotype Svevo: the Svevo-Whole-Genome Radiation Hybrid (Sv-WGRH) panel. The Sv-WGRH panel was developed at Kansas State University (USA) according to the protocol reported by Tiwari et al. (2016). Freshly dehiscing pollen of Svevo was irradiated with y-rays (10-Gy) and this was used to pollinate ~150 emasculated spikes of Senatore Cappelli (used as the female parent), producing ~1,300 RH1 seeds, each representing an independent RH event. Greenhouse planting of 1,000 RH1 seeds resulted in ~730 RH1 plants, each representing a RH line of the Sv-WGRH panel. Initial assessment of the panel was performed on the DNA of 613 RH1 plants by means of 23 SSR markers. Results indicated that average marker retention frequency of the panel is ~87%, with 35% of RH1 lines having a retention frequency between 20 and 90%. Approximately175 RH1 plants were obtained from planting 269 RH1 seeds in the greenhouse. DNA of these RH1 lines will be genotyped by GBS in order to construct a physical map. This RH panel is an important resource that will contribute to the assembly of the genome sequence of durum and other tetraploid wheats and will support positional cloning of important genes and QTLs in durum wheat.
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10:20-10:40 |
Tzion Fahima, University of Haifa
Positional cloning of Yr15 revealed a novel gene structure for wheat with two tandem kinase-like protein domains [View abstract]
New Pst races documented within last two decades have caused severe yield losses worldwide. Genetic bottlenecks associated with wheat polyploidization, domestication and initial selection in agroecosystems decreased wheat genetic diversity and increased its vulnerability to biotic and abiotic stresses. Wild emmer (Triticum turgidum ssp. dicoccoides, DIC), the tetraploid progenitor of common wheat distributed along the Fertile Crescent has valuable residual adaptive diversity in response to diseases, including stripe rust. Yr15, a dominant DIC gene located on chromosome 1BS confers broad-spectrum resistance to stripe rust. Yr15 was incorporated into durum and common wheat cultivars and lines in research and breeding programs in Israel, Europe, Australia, USA, China and India. Comparative genomics, chromosome walking, BAC libraries (DIC and bread wheat), whole genome assemblies, EMS mutagenesis and transgenic approaches enabled us to clone Yr15 and validate its function. The Yr15 protein has a novel structure for R-genes in wheat with two tandem kinase-like domains that are both essential for resistance. Macro- and microscopic observations of fungal development and accumulation of biomass suggest that the hypersensitive response plays a central role in the resistance mechanism. Non-functional alleles of Yr15 in T. dicoccoides, T. durum and T. aestivum differ from the functional allele of DIC G25 by indels, creating truncated proteins. We designed diagnostic markers that differentiate between functional and non-functional Yr15 alleles. Among 85 durum and common wheat accessions only Yr15 introgression lines contained the functional allele, whereas all others contained non-functional alleles. These results suggest that Yr15 has the potential to improve stripe rust resistance in a wide range of tetraploid and hexaploid wheat germplasm. The absence of the functional Yr15 in tested durum and common wheat varieties highlights the value of DIC germplasm as a reservoir of resistance genes for wheat.
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10:40-11:00 |
Coffee/Tea Break: Andalou Patio |
11:00-11:20 |
Sanu Arona, John Innes Centre
Natural variation in the immune system of a wild wheat [View abstract]
The genetic diversity of wheat has been eroded by human selection during domestication rendering the crop more susceptible to disease. In contrast, the wild progenitors and relatives of wheat represent an important source of genetically diverse disease resistance (R) genes that can be used to improve resistance in cultivated wheat. Most often, R genes encode nucleotide binding and leucine-rich repeat (NLR) immune receptors. We have devised a high-throughput NLR annotation tool and used NLR resistance gene enrichment sequencing (RenSeq), to explore the genetic diversity of NLRs in Aegilops tauschii, the diploid D genome progenitor of hexaploid bread wheat. The sequenced reference accession contains 732 full length NLRs, and we find significant NLR variation between accessions. We will report on our progress to characterize this genetic variation in a panel of 150 geographically and genetically diverse Ae. tauschii accessions, and in associating this to phenotypic variation for rust resistance with the aim of speeding up the discovery and cloning of new functional R genes.
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11:20-11:40 |
Lesley Boyd, NIAB
Unravelling "nonhost" resistance: Is this a viable option for host resistance breeding? Natural variation in the immune system of a wild wheat [View abstract] | [Watch video]
The term "nonhost" resistance (NHR) suggests a resistance apart from host resistance. Evidence now suggests that this is not the case, the same genetic components that confer host resistance have a primary role in NHR, although the regulation of those genetic components is both pathosystem and host-species specific. In this presentation we will explore the potential of NHR for host resistance breeding, looking at the potential of individual "NHR genes", as well as the story told by global transcriptomics responses. Large-scale transcriptomics studies comparing wheat to barley, and three different pathosystems (leaf rust, powdery mildew and cereal blast) indicated that the NHR-related responses were to a great extent pathosystem-specific, the genes differentially expressed between host and nonhost interactions showed only small overlaps between the three cereal pathosystems. This pathosystem-specific reprogramming may reflect different resistance mechanisms operating against non-adapted pathogens with different lifestyles, or equally, different co-option of the hosts by the adapted isolates to create an environment optimal for infection. Comparison of wheat and barley orthologues differentially expressed between host and nonhost interactions also revealed few commonalities, rather suggesting different nonhost responses in the two cereal species. Taken together, our results suggest independent co-evolutionary forces acting on different pathosystems, mirrored by barley- or wheat-specific nonhost responses. At the individual gene level three barley receptor-like kinases (RLKs) have been identified that confer quantitative resistance to wheat powdery mildew when transiently over-expressed in wheat, as reflected by reduced establishment of haustoria in epidermal cells. We will give an update on the phenotypes observed when these HvRLK genes are expressed in wheat transgenics.
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11:40-12:00 |
Sisay Kidane Alemu, Ethiopian Institute of Agricultural Research
Genome wide association analysis identifies potentially useful QTLs for yellow rust resistance in Ethiopian durum wheat germplasm [View abstract] | [Watch video]
Yellow (stripe) rust caused by Puccinia striiformis fsp tritici is one of the most devastating diseases threatening wheat in Ethiopia. The identification of genetic resistance sources help combat the threat. Genome wide association study of yellow rust resistance was conducted on 300 durum wheat accessions comprising 261 landraces and 39 registered varieties. The accessions were evaluated for their field resistance in alpha lattice design (10 X 30) in two replications at Meraro, Kulumsa and Chefe-Donsa in 2015 and 2016 main growing seasons. Scoring was carried out using a modified Cobb scale (0 -100% severity combined with Field responses: Immune, Resistant, Moderately Resistant, Moderately Susceptible and Susceptible) and then converted to Coefficient of Infection (CI). Genotyping was done using 35k SNP chip at Genomic Facility of Bristol University. Analysis of the genotyping data with Axiom Analysis Suit v.2 resulted in a total of 8,682 polymorphic SNPs of which 6,969 satisfied the marker allele frequency (MAF) >= 5% threshold and were used in subsequent analyses. Population structure analysis suggested five sub populations in which the released varieties clearly stood out separately from the landraces. An earlier decay of Linkage disequilibrium (LD) was depicted from LD analysis in TASSEL. Nine SNPs significantly associated with candidate resistant QTLs were identified on chromosome 1A, 1B and 5B via association analysis of Combined CI data of Meraro 2015, 2016 and Kulumsa 2016 using GAPIT in R. Further investigation on approximately 10 million (bp) genomic regions encompassing the identified loci indicated the presence of some disease resistance protein (NBS-LRR class) family and RPM1 far from the loci. This study provides SNPs for tracking the QTL associated with resistance in durum wheat improvement programs. However, the diagnostic value of the identified linked SNPs needs further investigation in independent germplasm.
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12:00-12:20 |
Bernard Nyamesorto, Montana State University
Development of new rust resistant germplasm via modifications of wheat MYC4 transcription factors [View abstract] | [Watch video]
Breeding for durable resistance to rust diseases in bread wheat (Triticum aestivum L.) relies largely on continually introgressing new resistance genes into adapted varieties, often from wild relatives due to low genetic diversity in the wheat genomes. The process of integrating genes from a different species is not only time consuming, but also not always completely successful in eliminating unfavorable traits brought in by linkage drag. Developing new resistant germplasms in wheat provides a great advantage to overcome the aforementioned challenges. The focus of resistance breeding over the decades has been on using resistance genes or genes that can enhance the host defense response, not enough attention has been given to the host genes targeted by the pathogen effectors to enhance the host susceptibility. Our study was conducted to identify the wheat genes targeted by rust pathogens. In this study, we identified MYC4 transcription factors (TFs) located on the wheat chromosomes 1A, 1B and 1D were upregulated from 1-8 days post- rust inoculation in a susceptible wheat line but not in a resistant wheat line. Down regulation of MYC4 TFs using barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) in the susceptible cultivar Chinese Spring enhanced its resistance to stem rust pathogen. Knock-out of MYC4 TFs from A and B genomes in Cadenza by Ethyl methanesulfonate mutagenesis render new resistance to stem rust pathogen. From this discovery, we have created new germplasms in wheat via modifications of wheat MYC4 transcription factors.
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12:20-13:20 |
Lunch: Atlas Restaurant |
Women in Triticum Early Career and Mentor awards and panel session
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13:20-14:05 |
Women Speak Up: Building capacity in the talent pipeline Moderators: Amor Yahyaoui, CIMMYT Mexico and Jeanie Borlaug Laube, Chair, BGRI Panelists: Wafaa El Khoury, U.N. International Fund for Agricultural Development, Italy; Silvia Germán, National Agricultural Research Institute, Uruguay; Lesley Boyd, NIAB, U.K. |
14:05-14:50 |
WIT Awards Ceremony Presented by Jeanie Borlaug Laube, Chair, BGRI |
Pathogen Biology
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14:50-15:10 |
Muhammad Rameez, The University of Agriculture, Pakistan
Multiple distinct genotypes causing yellow rust on susceptible wheat variety (Galaxy-2013) at the pathogen centre of diversity in Pakistan [View abstract]
The wheat yellow rust pathogen Puccinia striiformis has been hypothesized to have its centre of origin in the Himalayan region, where the pathogen is highly diverse. However, the detection of pathogen diversity on same host varieties at a given location and across locations still needs to be assessed. In present study we attempted to assess the genetic diversity in P. striiformis sampled on the same host variety at multiple locations across Pakistan. The recently released high yielding but highly susceptible variety Galaxy was cultivated throughout the country during 2016. The variety was scored and sampled in 46 locations from 24 districts across three provinces of Pakistan. Out of 46 locations surveyed the variety was highly infected (>60S score) at 30 locations across the country, with 16 locations at Khyber Pakhtunkhwa province, 12 at Punjab province and 2 at Sindh province. Microsatellite data of a total of 90 samples collected from these 46 locations on Galaxy-2013, resulted in the detection of 84 multilocus genotypes (MLGs) from at least five genetic groups of P. striiformis, as identified through population genetics analyses. At least two genetic lineages were detected at a given district on the same variety, when assessed across all 24 districts. Similarly, multiple MLGs were also detected on Galaxy-2013 at a given district. This could be expected from the high diversity and recombinant structure of P. striiformis in Pakistan, where isolates from distinct genetic groups carrying virulence to a given variety could infect the host. The pattern, however, needs to be confirmed on other susceptible varieties present at multiple locations and over temporal scale.
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15:10-15:30 |
John Fellers, USDA-ARS
P. triticina avirulence effector gene candidates for wheat Lr2A and Lr2C [View abstract] | [Watch video]
Each year new races of P. triticina are found in the field and arise from selection pressure due to the monoculture of just a few wheat cultivars. It is assumed that changes in effectors in the rust, caused by deletions, nucleotide changes, amino acid changes, and expression differences are the causal agents of the virulence shifts. The P. triticina genome has been published and almost 1400 secreted effector candidates were identified. Crosses are difficult to make in the rust, so a mutagenesis approach was employed to identify specific effectors recognized by Lr resistance genes. Purified spores of BBBD Race 1 were exposed to fast neutrons and inoculated onto the Thatcher Lr2A and Lr2C isolines. Typically, BBBD induces a 0; response on these lines, however, pustules that formed were assumed to be mutants. Two rounds of single pustule culture, under selection on the specific isoline were used to increase the spores. Seven mutants each were isolated for virulence to Lr2A and Lr2C. DNA has been isolated and sequenced. Effector gene candidates are being identified and will be reported.
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Physiology and abiotic stresses
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15:30-15:50 |
Samir Alahmad, University of Queensland
Adapting durum wheat to drought and crown rot environments [View abstract] | [Watch video]
Durum wheat (Triticum turgidum L. ssp. durum) producers can experience significant yield and grain losses due to crown rot (CR) disease, caused primarily by the fungal pathogen, Fusarium pseudograminearum. Losses due to CR are exacerbated when disease infection coincides with terminal drought. Durum wheat is very susceptible to CR and resistant germplasm is not currently available in elite breeding pools. Deploying physiological traits for drought adaption (e.g. deeper roots), to reduce stress due to water deficit may, therefore, potentially minimise losses due to CR infection. The rapid generation advance technology, "speed breeding", was used to rapidly develop recombinant inbred lines (RIL) populations (F6) derived from crosses between Australian cultivars and ICARDA elite breeding lines pre-selected for drought adaptation in Syria and Morocco. Populations were evaluated in the field and under controlled conditions for several physiological traits, including seminal root angle and number and CR severity. This provided the genetic predisposition of lines for rooting behaviour and CR susceptibility in the absence of water stress. Field experiments were established in Queensland, Australia, which allowed an examination of the value of root development traits to improve adaptation to each of the stresses. NDVI measurements were recorded weekly, which enabled modelling of the senescence pattern and calculation of stay-green traits for each genotype. Genome-wide association studies using DArT markers identified key genomic regions underpinning the traits. Our genetic analyses highlighted the genetic relationships between yield as well as above- and below-ground physiological traits. Through this study, we have provided new insights into the genetic controls and value of these traits, which we anticipate will assist breeders to design improved durum varieties that may mitigate production losses due to water deficit and CR.
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15:50-16:10 |
Hannah Robinson, InterGrain
VERNALIZATION1 modulates root system architecture in wheat [View abstract] | [Watch video]
As the primary interface for resource acquisition, plant roots play a key role in growth regulation. Evidence from rice, maize and sorghum demonstrates that the below-ground plant architecture significantly impacts plant performance under abiotic constraints. Roots assume critical functions in water uptake, nutrient acquisition and anchorage, an essential characteristic to maintain plant stability under increased grain load. Despite their fundamental importance, knowledge about genetic control of root growth in major grain crops is limited and very little is known about interactions between below-ground and above-ground plant development. Here we demonstrate that VERNALIZATION1 (VRN1), a key regulator of flowering behavior in cereals, also modulates root architecture in wheat and barley. Associations of VRN1 haplotypes to root growth habit were discovered in wheat by genome-wide association studies, and confirmed by allelic analyses in wheat and barley populations. Functional characterization in transgenic barley confirmed that VRN1 influences root growth angle directly, via gravitropism. These discoveries provide unexpected insight into underground functions of a major player in the well-characterized flowering pathway, revealing the intersection of above-ground gene regulation with the largely unexplored genetic architecture of plant root development. Understanding the pleiotropic involvement of this key developmental gene in overall plant architecture will help to breed cereal cultivars adapted to specific environmental scenarios.
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16:10-16:30 |
Coffee/Tea Break: Andalou Patio |
16:30-16:50 |
Madhav Bhatta, University of Nebraska
Genome wide association studies for yield and yield related traits in drought stressed synthetic wheat [View abstract]
Genome-wide association studies (GWAS) are useful tool for accelerating crop improvement and rate of genetic gain via enhanced knowledge of marker-trait associations. Synthetic hexaploid wheat (Triticum aestivum) are used as a means of introducing novel genetic variation into bread wheat, however, reports on genome wide association studies (marker-trait associations) remain limited in synthetic hexaploid wheat under drought stressed conditions. GWAS for grain yield and yield-related traits were conducted using a diverse panel of 126 primary synthetic wheats and two bread-wheat (checks) genotypes under drought stressed conditions across two growing seasons (2016 and 2017). The population was genotyped using genotype-by-sequencing (GBS) approach and 37,592 high quality SNPs were used in GWAS analysis. Analysis of variance showed significant genotype effects for days to heading and maturity, grain filling period, plant height, grain and biomass yield, grain protein content, thousand grain weight, grain and spike harvest index. A number of genotypes were superior compared to checks for yield (seven entries in 2016 and four entries in 2017) and yield related traits. Markers associated with multiple traits observed on chromosomes 1A, 1B, 1D, 2D, 3A, 3B, 3D, 4A, 4D, 5A, 5B, 6A, 6B,7A, 7B, and 7D from a GWAS model that accounted for kinship and population structure. These markers associated with yield and yield related traits will be validated in a different population and will be converted to KASP markers that can be used in wheat breeding programs to improve grain yield under drought stressed conditions. Additionally, these lines showed resistance several biotic stresses such as stem rust (21 entries), leaf rust (80), stripe rust (13), common bunt (46), cereal cyst nematode (11), crown root rot (3), and barley yellow dwarf virus (15). Therefore, these synthetic lines are potential source for integration of resistance genes into high yielding modern wheat germplasm.
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16:50-17:10 |
Roberto Tuberosa, University of Bologna
The genetic diversity and molecular mapping of root traits in durum wheat [View abstract]
Durum wheat is one of the most important crops in Mediterranean countries, where drought conditions often occur. Therefore, optimisation of root system architecture (RSA) is an important objective for enhancing yield and the sustainability of durum wheat grown under different water regimes. In the present study, linkage and association mapping (AM; panel of 183 elite accessions; Maccaferri et al. 2005) for RSA evaluated at the seedling stage evidenced 20 clusters of quantitative trait loci (QTLs) for root length and number as well as 30 QTLs for root growth angle (RGA). The most divergent RGA phenotypes observed by seminal root screening were validated by root phenotyping of field-grown adult plants. QTLs were mapped based on the Illumina 90K SNPs profiles, thus allowing cross-referencing of RSA QTLs between durum and bread wheat. QTL analysis of RSA and grain yield data indicates root growth angle (RGA) as a valuable target to enhance grain yield and yield stability across different soil moisture regimes (Maccaferri et al. 2016). Based on their relative additive effects, allelic distribution in the AM panel and co-location with QTLs for yield, eight RGA QTLs have been prioritised in terms of breeding interest and value. These QTLs were investigated for gene content based on the chromosomal pseudomolecules of Chinese Spring T. aestivum, Zavitan T. dicoccoides genome assembly (Distelfeld et al. 2017) and Svevo durum genome. The chromosome regions contained 25 to 242 predicted genes (123 on average). In six RGA QTLs, from one to four gene annotations were involved in auxin pathways. The comparison between the three assemblies indicates their high quality and usefulness to identify candidates to explore the polymorphism and the structural variation present in the A and B wheat genomes.
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17:10-17:30 |
Matthew Reynolds, CIMMYT
Incorporating complex physiological traits into wheat breeding pipelines [View abstract] | [Watch video]
Phenotyping is the cornerstone of plant breeding but until the advent of remote sensing (RS) technologies, selection was largely restricted to relatively heritable traits like phenology and a few essential complex traits including end-use quality and yield per se. However, RS permits integrative traits -that by definition are genetically complex- to be evaluated on a scale that overcomes some of the disadvantages of their relatively low heritability. For example, canopy temperature is a good predictor of yield and root function under abiotic stress, and a number of spectral indices –including NDVI and water index- can be used to measure other physiological and performance traits like biomass and stay-green. Our data show that aerial phenotyping platforms permit physiological traits to be measured with increased precision resulting in better prediction of yield compared with ground-based sensing approaches. Additional traits that lend themselves to aerial high throughput screening include photosynthetic pigments and photo-inhibition using indices in the visible spectrum, while water-sensitive indices in infra-red (IR) and near IR bands are associated with hydration status of tissue. Many of the RS indices mentioned, by virtue of being high throughput, lend themselves well to large-scale genetic resource screening as well as genetic analysis. However, integrative traits have less power to predict performance under high yield environments. Here, physiological breeding approaches focus more on the characterization of potential parents in order to design complementary crosses. We have developed conceptual models for different mega-environments that consider a range of traits for which there is evidence of useful unexplored genetic diversity. One novel example of such a trait is spike photosynthesis (SPS) which is difficult to measure and as a result has been largely ignored in breeding, despite the fact that spikes intercept up to half of the radiation during grain-filling. The trait is also interesting because spikes have extremely high water use efficiency and are often the only organs that remain green under post-anthesis stress. Three innovations have been applied to better characterize SPS including a 360 degree LED illumination chamber for gas exchange measurement, long duration spike shading treatments, and use of stable carbon isotopes analysis of grain, all of which help estimate the integrated contribution of SPS to yield, leading to identification of useful genetic sources for crossing as well as novel QTL for SPS. An innovative crossing strategy -involving complex traits- has recently demonstrated genetic gains compared to local checks, and in several cases CIMMYT elite checks, in international yield trials. The crosses are designed to combine complementary traits, specifically sources of high biomass (source) with good sources of spike fertility (sink). The rationale is to translate expression of high radiation use efficiency -often coming from exotics like primary synthetics and landraces- into yield by crossing with elite lines that optimize partitioning of biomass to grain. This pre-breeding exercise has already provided novel genetic sources of yield potential and heat tolerance to national programs, broadening the genetic basis of their crossing blocks, and in some cases delivering candidates for release, for example in Pakistan.
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17:30-17:50 |
Tadesse Degu, ICARDA
Genetic gains for yield, drought/heat tolerance and resistance to diseases in ICARDA's spring bread wheat germplasm [View abstract] | [Watch video]
Wheat is the main food crop in Central and West Asia and North Africa (CWANA) regions with average consumption of 200 kg/capita/year. However, its productivity is very low (2.5 t/ha) mainly due to drought, heat and stripe rust. The wheat breeding program at ICARDA applies both conventional and molecular breeding tools following inter-countries shuttle breeding and key locations yield testing approaches to combine yield potential and wide adaptation with resistance to biotic and abiotic stresses. Following this approach, climate resilient wheat varieties combining high yield potential, rust resistance with heat and drought tolerance have been identified. Using marker assisted selection, major genes have been pyramided into adapted varieties with minor gene background for rust resistance. Molecular markers linked to heat tolerance and yellow rust resistances have been identified. Yield levels of some of these genotypes range up to 6t/ha at Wadmedani station of Sudan under extreme heat stress, 7t/ha at Merchouch station of Morocco under terminal moisture stress (260 -300 mm) and 11 t/ha at Sids station in Egypt under optimum conditions. Pedigree analysis showed that resistance sources for heat and drought tolerance in such elite germplasm were introgressed from synthetic wheats and wild relatives mainly T. dicoccoides. On an annual basis, ICARDA’s spring bread wheat program composes and distributes about 400 elite set of these genotypes through international nurseries and yield trials to countries in the CWANA and SSA regions and beyond upon request for potential direct release/or parentage purposes. In the last 5 years, more than 32 spring bread wheat varieties of ICARDA origin have been released by the national programs in the CWANA and SSA regions. It is important to deploy these varieties rapidly with improved crop management technologies to increase wheat production and enhance food and nutritional security.
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Evening Reception and Poster Viewing
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19:00-21:30 |
Reception: Andalou Patio and Atlas Restaurant
Posters will remain up throughout the workshop Agdal Room |