Ancestral QTL Alleles from Wild Emmer Wheat Enhance Root Development under Drought in Modern Wheat

A near-isogenic line (NIL-7A-B-2), introgressed with a quantitative trait locus (QTL) on chromosome 7AS from wild emmer wheat (Triticum turgidum ssp. dicoccoides) into the background of bread wheat (T. aestivum L.) cv. BarNir, was recently developed and studied in our lab. NIL-7A-B-2 exhibited better productivity and photosynthetic capacity than its recurrent parent across a range of environments. Here we tested the hypothesis that root-system modifications play a major role in NIL-7A-B-2’s agronomical superiority. Root-system architecture (dry matter and projected surface area) and shoot parameters of NIL-7A-B-2 and ‘BarNir’ were evaluated at 40, 62, and 82 days after planting (DAP) in a sand-tube experiment, and root tip number was assessed in a ‘cigar-roll’ seedling experiment, both under well-watered and water-limited (WL) treatments. At 82 DAP, under WL treatment, NIL-7A-B-2 presented greater investment in deep roots (depth 40–100 cm) than ‘BarNir,’ with the most pronounced effect recorded in the 60–80 cm soil depth (60 and 40% increase for root dry matter and surface area, respectively). NIL-7A-B-2 had significantly higher root-tip numbers (∼48%) per plant than ‘BarNir’ under both treatments. These results suggest that the introgression of 7AS QTL from wild emmer wheat induced a deeper root system under progressive water stress, which may enhance abiotic stress resistance and productivity of domesticated wheat

In-Depth Field Characterization of Teff [Eragrostis tef (Zucc.) Trotter] Variation: From Agronomic to Sensory Traits

Teff is an important food crop that serves to prepare Injera-flat-bread. It is cultivated worldwide and is particularly susceptible to lodging. A diverse collection of teff [Eragrostis tef (Zucc.) Trotter] populations was characterized for a wide range of traits, ranging from agronomic to final Injera sensory parameters, under well-irrigated Mediterranean spring conditions. The populations tested were collected from single plants presenting lodging resistance at the site of collection and their traits were characterized herein. An early type of lodging was observed, which was most likely triggered by a fast and sharp inflorescence weight increase. Other populations were ‘strong’ enough to carry the inflorescence during most of the grain-filling period, up to a point where strong lodging occurred and plants where totally bent to the ground. Three mixed color seed populations were established from a single plant. These were separated into ‘white’ and ‘brown’ seeds and were characterized separately under field conditions. The newly ‘brown’ populations appear to be the result of a rather recent non-self (external) airborne fertilization from a dark pollen donor. Some of these hybrids were found to be promising in terms of Injera sensory traits. The population of these studies might serve as breeding material. Integration between a wide range of parameters and the correlations obtained between agronomic and sensory traits might improve our ability to breed towards a “real world” better end-product

Data from: Genome scan identifies flowering-independent effects of barley HsDry2.2 locus on yield traits under water deficit

Increasing crop productivity under climate change requires the identification, selection and utilization of novel alleles for breeding. We analyzed the genotype and field phenotype of the barley HEB-25 multi-parent mapping population under well-watered and water-limited (WW and WL) environments for two years. A genome-wide association study (GWAS) for genotype by-environment interactions was performed for ten traits including flowering time (HEA) and plant grain yield (PGY). Comparison of the GWAS for traits per-se to that for QTL-by-environment interactions (QxE), indicates the prevalence of QxE mostly for reproductive traits. One QxE locus on chromosome 2, Hordeum spontaneum Dry2.2 (HsDry2.2), showed a positive and conditional effect on PGY and grain number (GN). The wild allele significantly reduced HEA, however this earliness was not conditioned by water deficit. Furthermore, BC2F1 lines segregating for the HsDry2.2 showed the wild allele confers an advantage over the cultivated in PGY, GN and harvest index as well as modified shoot morphology , longer grain filling period and reduced senescence (only under drought), therefore suggesting adaptation mechanism against water deficit other than escape. This study highlights the value of evaluating wild relatives in search of novel alleles and clues to resilience mechanism underlying crop adaptation to abiotic stress

LOM et al JXB_PHENO_GENO-2

Genotypic and phenotypic data for the HEB-25 barley mapping population grown under well-watered (WW) and water-limited (WL) environments for two years (2015 and 2016). The genotypic data: 11, homozygous for the cultivated Hordeum vulgare allele; 12, heterozygous; 22, homozygous for the wild donor (H. spontaneum). Phenotype: Heading time (HEA), defined as the time between sowing to time at which the first spike of 50% of the plants in a plot reaches BBCH49 (first awns visible), was recorded based on daily inspection. Days from sowing to stage BBCH87 (hard dough: grain content solid: fingernail impression held) was recorded as maturity (MAT). At maturity, plant height (HEI) was measured from the soil surface to the base of the three first spikes per plot. At full grain maturity and after plants were fully dried, all aboveground biomass was harvested and weighed to determine total dry matter (TDM). Notably, all the free-thrashing material (app. ¼ of the material) was caged between BBCH49 and BBCH87 to avoid loss of spikes. Spikes were then threshed and weighed to determine plant grain yield (PGY). Finally, grains were counted to estimate grain number per mini-plot (GN) and average grain weight (GW). Harvest index (HI) was calculated as the ratio between PGY and TDM. Vegetative dry matter (VDW) was calculated by subtracting PGY from TDM. The grain-filling period (GFP) was calculated by subtracting HEA from MAT. Trait values were adjusted based on the ratio between population mean values in the two years. The adjusted HEB means across years were used in the GWAS

Genomic Architecture of Phenotypic Plasticity in Response to Water Stress in Tetraploid Wheat

Phenotypic plasticity is one of the main mechanisms of adaptation to abiotic stresses via changes in critical developmental stages. Altering flowering phenology is a key evolutionary strategy of plant adaptation to abiotic stresses, to achieve the maximum possible reproduction. The current study is the first to apply the linear regression residuals as drought plasticity scores while considering the variation in flowering phenology and traits under non-stress conditions. We characterized the genomic architecture of 17 complex traits and their drought plasticity scores for quantitative trait loci (QTL) mapping, using a mapping population derived from a cross between durum wheat (Triticum turgidum ssp. durum) and wild emmer wheat (T. turgidum ssp. dicoccoides). We identified 79 QTLs affected observed traits and their plasticity scores, of which 33 reflected plasticity in response to water stress and exhibited epistatic interactions and/or pleiotropy between the observed and plasticity traits. Vrn-B3 (TaTF1) residing within an interval of a major drought-escape QTL was proposed as a candidate gene. The favorable alleles for most of the plasticity QTLs were contributed by wild emmer wheat, demonstrating its high potential for wheat improvement. Our study presents a new approach for the quantification of plant adaptation to various stresses and provides new insights into the genetic basis of wheat complex traits under water-deficit stress