bims-plasge 2023-10-22 papers

Issue of 2023–10–22
two papers selected by
Vera S. Bogdanova, ИЦиГ СО РАН

Front Plant Sci. 2023 ;14 1189289

Advanced backcross QTL analysis and comparative mapping with RIL QTL studies and GWAS provide an overview of QTL and marker haplotype diversity for resistance to Aphanomyces root rot in pea (Pisum sativum).

Théo Leprévost, Gilles Boutet, Angélique Lesné, Jean-Philippe Rivière, Pierrick Vetel, Isabelle Glory, Henri Miteul, Anaïs Le Rat, Philippe Dufour, Catherine Regnault-Kraut, Akiko Sugio, Clément Lavaud, Marie-Laure Pilet-Nayel.

Aphanomyces euteiches is the most damaging soilborne pea pathogen in France. Breeding of pea resistant varieties combining a diversity of quantitative trait loci (QTL) is a promising strategy considering previous research achievements in dissecting polygenic resistance to A. euteiches. The objective of this study was to provide an overview of the diversity of QTL and marker haplotypes for resistance to A. euteiches, by integrating a novel QTL mapping study in advanced backcross (AB) populations with previous QTL analyses and genome-wide association study (GWAS) using common markers. QTL analysis was performed in two AB populations derived from the cross between the susceptible spring pea variety "Eden" and the two new sources of partial resistance "E11" and "LISA". The two AB populations were genotyped using 993 and 478 single nucleotide polymorphism (SNP) markers, respectively, and phenotyped for resistance to A. euteiches in controlled conditions and in infested fields at two locations. GWAS and QTL mapping previously reported in the pea-Aphanomyces collection and from four recombinant inbred line (RIL) populations, respectively, were updated using a total of 1,850 additional markers, including the markers used in the Eden x E11 and Eden x LISA populations analysis. A total of 29 resistance-associated SNPs and 171 resistance QTL were identified by GWAS and RIL or AB QTL analyses, respectively, which highlighted 10 consistent genetic regions confirming the previously reported QTL. No new consistent resistance QTL was detected from both Eden x E11 and Eden x LISA AB populations. However, a high diversity of resistance haplotypes was identified at 11 linkage disequilibrium (LD) blocks underlying consistent genetic regions, especially in 14 new sources of resistance from the pea-Aphanomyces collection. An accumulation of favorable haplotypes at these 11 blocks was confirmed in the most resistant pea lines of the collection. This study provides new SNP markers and rare haplotypes associated with the diversity of Aphanomyces root rot resistance QTL investigated, which will be useful for QTL pyramiding strategies to increase resistance levels in future pea varieties.

Keywords: AB populations; Aphanomyces euteiches; SNPs; integrative study; sources of resistance

DOI: https://doi.org/10.3389/fpls.2023.1189289

J Integr Plant Biol. 2023 Oct 17.

Paternally Imprinted LATE-FLOWERING2 Transcription Factor Contributes to Paternal-Excess Interploidy Hybridization Barriers in Wheat.

Guanghui Yang, Man Feng, Kuohai Yu, Guangxian Cui, Yan Zhou, Lv Sun, Lulu Gao, Yumei Zhang, Huiru Peng, Yingyin Yao, Zhaorong Hu, Vincenzo Rossi, Ive De Smet, Zhongfu Ni, Qixin Sun, Mingming Xin.

Interploidy hybridization between hexaploid and tetraploid genotypes occurred repeatedly during genomic introgression events throughout wheat evolution, and is commonly employed in wheat breeding programs. Hexaploid wheat usually serves as maternal parent because the reciprocal cross generates progeny with severe defects and poor seed germination, but the underlying mechanism is poorly understood. Here, we performed detailed analysis of phenotypic variation in endosperm between two interploidy reciprocal crosses arising from tetraploid (Triticum durum, AABB) and hexaploid wheat (Triticum aestivum, AABBDD). In the paternal- vs. the maternal-excess cross, the timing of endosperm cellularization was delayed and starch granule accumulation in the endosperm was repressed, causing reduced germination percentage. The expression profiles of genes involved in nutrient metabolism differed strongly between these endosperm types. Furthermore, expression patterns of parental alleles were dramatically disturbed in interploidy vs. intraploidy crosses, leading to increased number of imprinted genes. The endosperm-specific TaLFL2 showed a paternally imprinted expression pattern in interploidy crosses partially due to allele-specific DNA methylation. Paternal TaLFL2 binds to and represses a nutrient accumulation regulator TaNAC019, leading to reduced storage protein and starch accumulation during endosperm development in paternal excess cross, as confirmed by interploidy crosses between tetraploid wild-type and CRISPR-Cas9 generated hexaploid mutants. These findings reveal a contribution of genomic imprinting to paternal excess interploidy hybridization barriers during wheat evolution history and explains why experienced breeders preferentially exploit maternal excess interploidy crosses in wheat breeding programs. This article is protected by copyright. All rights reserved.

Keywords: imprinting; interploidy cross; wheat

DOI: https://doi.org/10.1111/jipb.13574