final notes on EUCARPIA Cereals meeting (III)

Wednesday 21^st march 2018 (Spring)

Tatsuya IKEDA (NARO, Japan)

Starts by showing allelic variation in glutenin subunits, which form large complexes connected by SS-bonds. Different alleles (A1,B1,D1 & A3,B3,D3) produce different gluten networks, which are reflected on bread body and loaf volume. Combinations of glutenin alleles control dough quality. He refers to results published at http://dx.doi.org/10.1094/CCHEM-01-14-0009-R. He explains the http://www.wheatinitiative.org, which aims at improving wheat quality and safety and to integrate a research platform with shared materials and gene nomenclature (he shows examples of gene name searches in Ensembl Plants with no results due to lack of naming consensus). They already released glutenin master sets at CIMMYT Germplasm Bank. Starch/amylose content is also important for quality. Then he talks about safety and describes Fusarium toxin analysis.

Sebastian MICHEL (U Vienna, Austria)

His talk is about genomic selection for wheat breeding, aiming at simultaneous selection for grain yield and baking quality. He shows data showing a strong anti-correlation between yield and protein content (typical range 12-16%), which is clearly important for quality and trading. Therefore, they focus on outliers with high protein content. The develop yield and protein indexes, which allow selection of lines with excellent yield and good protein content, and lines with high-protein and acceptable yield, respectively.

Suong CU (Flinders U, Australia)

She talks about GWAS of Zn, Fe, Cu, Mn and P in wheat grain and rachis at two developmental stages with a bio-fortification perspective. She mentions partners CIMMYT and http://www.harvestplus.org. The calculate heritability of the uptake of those micronutrients and their correlation in mature grain and in the rachis, end they were low despite the experiments were done with fertilizer contributing enough of these. They perform GWAS correcting by Kinship and covariates and shows associated markers with most additive value. She shows some candidate genes and for Zn, for instance, there is one transporter and another annotated as a Zinc-finger.

Simon GRIFFITHS (JIC, UK)

His talk is about analysis of arabinoxylan (AX) soluble fibre in wheat grain. He mentions that in the UK there have been spectacular yield gains since 1885, but that nutritional quality has never been a breeding target until now. He focuses on fibre intake and fibre content in bread in the UK and explains that AX is the main fibre component of wheat grain endosperm, and is also part of the bran. He mentions that project https://healthgrain.org was concerned about genetic resources for improving wheat nutritional value. Shows that AX content is highly heritable. They have prepared populations with Yumai34 parent to discover QTLs for AX and found one. He explains that AX enrichment does not affect breadmaking functionality.

Peter ROGOWSKY (INRA Lyon, France)

Delivers a general lecture about CRISPR-Cas9 systems in breeding plants. Starts by explaining cellular DNA repair mechanism. The current success of Cas9 is that predicting RNA/DNA is much easier and reliable than protein-DNA binding. Stable transformation of Cas9 can be done with Agrobacterium, direct transfer (explants, protoplasts) or virus. Transient expression can be obtained by direct transfer of ribonucleoproteins. All these have been used successfully in wheat, with the bottleneck being generally plant regeneration after transformation. PAM-altered Cas9 have not yet been ported to plants, so targets must have a neighbor NGG site. Another option is to use CPF1, which recognizes TTTN sites.

Mutation and base edition have been mastered in plants, with frequencies less than 10%; gene editing still has frequencies below 1% in plants. However, currently genes can be edited by stacking base editions to modify coding sequences or promoters, when expression is important for the trait of interest. 

He also presents recent examples of gene inactivation in different crops, both monocot and dicot, still to be tested in the field, with the SDN1 (site directed nuclease) approach. He explains that Cas9 approaches are expect to have even more applications in terms of agronomic and quality traits. However, regulation is still not clearly defined for Cas9 editions at the EU (decision expected in 2018 by the European Court of Justice). He explains that this technique faces different ethical questions and their answers should be delivered case by case. He finishes with a table of promises/claims of Cas9 and the reality in 2018; this tech is still a long way from having an impact in the field and the EU market.

Fred VAN EEUWIJK (Wageningen U, Netherlands)

Presents methods for modelling genotype by environment (GxE) interactions in QTL mapping and genomic prediction, with applications to barley and wheat. How can we reduce the computing time of computing a linear mixed model per SNP when you have 10E5-E7 SNPs? With packages such as TASSEL P3D, GRAMMAR, FaST-LMM. He seems to prefer linear mixed models to Bayesian choices, as they are easier to customize. For multi-trait / environment modelling, he refers to https://dl.sciencesocieties.org/publications/cs/abstracts/56/5/2119 and this book: http://www.springer.com/gp/book/9783319205618. Fitting these multi models requires reducing the original complexity of the data. He mentions Haploview to merge SNPs in the same gene to build haplotypes/alleles and test them instead of individual SNPs. Finally, he mentiones that a software tool with their latest developments as part of the WHEALBI consortium will be available at the end of the year, and there will be training courses, but the modules will be available in CRAN as R packages (https://cran.r-project.org).

Andreas HUND (ETH Zürich, Switzerland)

Talks about GxE and modern field phenotyping techniques. He mentions that in the Swiss central plateau wheat yield (target 6-7T/ha) is limited by excess water, frost and then heat stress. They have set up all year round platform for phenotyping wheat. He shows canopy cover, height and senescence/reflectance data for winter wheat. They calculate heritabilities for their traits and obtain high values (H2>0.9) except for the duration of developmental stages. He shows data from a couple of papers (http://www.publish.csiro.au/fp/fp14226 and https://link.springer.com/article/10.1007/s10681-017-1940-2) showing, for instance, that earliest genotypes are not necessarily the tallest in terms of final height.

Friedrich LONGIN (U Hohenheim, Germany)

Just after lunch, he talks about genomic selection (GS) schemes for line breeding in wheat, are they really worth it? His simulation data suggest that direct phenotypic selection can yield higher genetic gain, but GS yield higher gains per year while having less plant material in the field. These trends depend on the GS accuracy, but with realistic values of 0.6 there seems to be a 16% annual gain advantage for GS if breeding cycle is sped up.

Daniela BUSTOS-KORTS (Wageningen U, Netherlands)

She talks about combining crop growth and statistical genetic modelling to evaluate phenotyping strategies, and shows wheat data. Genotyping is much cheaper than phenotyping, and she evaluates alternative phenotyping strategies with simulations, inspired by http://www.publish.csiro.au/cp/cp14007. She shows drought patterns observed in the Australia wheat belt, published in https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.12192.

Renaud RINCENT (INRA GDEC, France)

His talk is about genomic prediction of GxE interactions by coupling genetic and physiological modelling. He summarizes the challenges and opportunities of GxE in breeding and uses data grain yield from https://breedwheat.fr. His results indicate that considering GxE when doing phenotyping predictions provides more accurate models than simple models with no interaction. His AMMI model, which computed PCA on the residuals of the principal model, seemed promising but the gains were lost in the cross-validations, likely due to small dataset or to weak GxE in the data.

Philipp BOEVEN (Limagrain, France)

His talk discusses ways of breeding for favorable male floral traits, such as anther extrusion, in hybrid wheat. After GWAS he made BLUP genomic predictions (I had to read what Best Linear Unbiased Prediction is, a widely used genomic prediction method, at: https://www.ncbi.nlm.nih.gov/pubmed/23640517).

Funmi LADEJOBI (NIAB, UK)

The last talk of the meeting is about differentially penalized regressions, a modification of BLUP, which improve genomic prediction of wheat flowering time. She uses rrBLUP R package, documented at https://cran.r-project.org/web/packages/rrBLUP/index.html.