Misexpression of a transcriptional repressor candidate provides a molecular mechanism for the suppression of awns by Tipped 1 in wheat.

Awns are bristle-like structures formed at the tip of the lemma on the florets of some cereal grasses. Wild-type wheat is awned, but awnletted and awnless variants have been selected and nowadays all forms are cultivated. In this study, we dissected the genetic control underlying variation of this characteristic feature by association mapping in a large panel of 1110 winter wheat cultivars of worldwide origin. We identified the B1 (Tipped 1) locus on chromosome 5A as the major determinant of awnlessness globally. Using a combination of fine-mapping and expression analysis, we identified a putative C2H2 zinc finger protein with an EAR domain, characteristic of transcriptional repressors, as a likely candidate for Tipped 1. This gene was found to be up-regulated in awnless B1 compared with awned b1 plants, indicating that misexpression of this transcriptional regulator may contribute to the reduction of awn length in B1 plants. Taken together, our study provides an entry point towards a better molecular understanding of the evolution of morphological features in cereals through selection and breeding

Phosphorus uptake and use efficiency of diverse West and Central African sorghum genotypes under field conditions in Mali

Aims Sorghum [Sorghum bicolor (L.) Moench], a staple crop in West and Central Africa (WCA), is mostly cultivated on soils with low phosphorus (P) availability and thus adaptation to those conditions is vital for food security. Assessment of genotypic variation of WCA sorghum for P uptake and P use efficiency is undertaken to understand the diversity available and opportunities for its use. Method We assessed mature plant yield, P uptake and P use efficiency traits of 70 diverse WCA sorghum genotypes under –P (no P fertilization) and + P field conditions in Mali in 2010, to discover differences among all genotypes tested and between and within specific genotype groups. Results Large significant genotypic variation for P uptake and P use efficiency traits were observed for all genotypes among and within landrace and researcher bred pools under –P conditions. P uptake traits had a larger genotypic variation than P use efficiency traits. Landrace genotypes showed generally higher P uptake and grain P concentration while formally bred genotypes exhibited a higher P use efficiency. Photoperiod sensitivity was related to higher P uptake. Conclusion Genotypic selection for P uptake and P use efficiency traits to improve adaptation to low P soils is possible in sorghum. Use and further study of WCA sorghums for adaptation to low P availability is appropriate as this germplasm shows large variation for P uptake and use efficiency and higher levels of P use efficiency than other important cereals

Getting the Most Out of Sorghum Low-Input Field Trials in West Africa Using Spatial Adjustment

Breeding sorghum for low-input conditions is hindered by soil heterogeneity. Spatial adjustment using mixed models can help account for this variation and increase precision of low-input field trials. Large small-scale spatial variation (CV 39.4 %) for plant available phosphorus was mapped in an intensely sampled low-input field. Spatial adjustments were shown to account for residual yield differences because of this and other growth factors. To investigate the potential of such models to increase the efficiency of low- and high-input field trials, 17 experiments with 70 sorghum genotypes conducted in Mali, West Africa, were analysed for grain yield using different mixed models including models with autoregressive spatial correlation terms. Spatial models (AR1, AR2) improved broad sense heritability estimates for grain yield, averaging gains of 10 and 6 % points relative to randomized complete block (RCB) and lattice models, respectively. The heritability estimate gains were even higher under low phosphorus conditions and in two-replicate analyses. No specific model was best for all environments. A single spatial model, AR1 × AR1, captured most of the gains for heritability and relative efficiency provided by the best model identified for each environment using Akaike's Information Criterion. Spatial modelling resulted in important changes in genotype ranking for grain yield. Thus, the use of spatial models was shown to have potentially important consequences for aiding effective sorghum selection in West Africa, particularly under low-input conditions and for trials with fewer replications. Thus, using spatial models can improve the resource allocation of a breeding program. Furthermore, our results show that good experimental design with optimal placement and orientation of blocks is essential for efficient statistical analysis with or without spatial adjustment

QTL mapping and validation of fertility restoration in West African sorghum A1 cytoplasm and identification of a potential causative mutation for Rf2

Abstract Key message Major A 1 cytoplasm fertility restoration loci, Rf 2 and Rf 5 , were found in the West African sorghum. A potential causative mutation for Rf 2 was identified. KASP markers were validated on independent material. Abstract To accelerate the identification and development of hybrid parental lines in West African (WA) sorghum, this study aimed to understand the genetics underlying the fertility restoration (Rf) in WA A1 cytoplasmic male sterility system and to develop markers for a routine use in WA breeding programs. We genotyped by sequencing three F2 populations to map the Rf quantitative trait loci (QTL), validated the molecular KASP markers developed from those QTL in two F2:3 populations, and assessed the most promising markers on a set of 95 R- and B-lines from WA breeding programs. Seven QTL were found across the three F2 populations. On chromosome SBI-05, we found a major fertility restorer locus (Rf5) for two populations with the same male parent, explaining 19 and 14% of the phenotypic variation in either population. Minor QTL were detected in these two populations on chromosomes SBI-02, SBI-03, SBI-04 and SBI-10. In the third population, we identified one major fertility restorer locus on chromosome SBI-02, Rf2, explaining 31% of the phenotypic variation. Pentatricopeptide repeat genes in the Rf2 QTL region were sequenced, and we detected in Sobic.002G057050 a missense mutation in the first exon, explaining 81% of the phenotypic variation in a F2:3 population and clearly separating B- from R-lines. The KASP marker developed from this mutation stands as a promising tool for routine use in WA breeding programs

No need to breed for enhanced colonization by arbuscular mycorrhizal fungi to improve low-P adaptation of West African sorghums

Aims Western Africa (WA) sorghums are predominantly cultivated under low plant available phosphorus (P) soil conditions with a diverse population of arbuscular mycorrhizal fungi (AMF) present. This study aims to determine whether sorghum breeding programs should target higher colonization by AMF through understanding the genotypic variation of sorghum for AMF-root colonization (AMF-RC) under different P-fertility conditions at different growth stages and assessing the genetics underlying AMF-RC using genome-wide association study (GWAS). Method A sorghum diversity panel of 187 WA genotypes was grown in low-P soil in a pot trial for 38 days and a subset of 13 genotypes was grown in a low- and high-P field until maturity at ICRISAT-Samanko in Mali, WA. Root samples were taken at 38 days from the pot trial plants and at flowering time in the field trials. Shoot biomass was analyzed for P concentration and dry matter yield. GWAS was conducted for shoot-P-content and AMF-RC. Results Significant genotypic variation was observed for AMF-RC, but the repeatability estimates were only low (w2 = 0.15 at 38 days) to moderate (w2 = 0.54–0.56 at flowering time). AMF-RC was significantly higher in low-P versus high-P field conditions. Large residual variation was observed for AMF-RC in both pot and field trials. None of the genotypic groups, contrasting for selection history, race and grain yield performance across multiple field trials, differed significantly for AMF-RC. AMF-RC showed no or negative relationships to shoot-P-content and grain yield, irrespective of soil-P level or plant developmental stage. AMF-RC at 38 days was significantly correlated (r = 67**) to AMF-RC at flowering. However, GWAS did not detect significant genomic regions for AMF-RC but did for shoot-P content

Selection Strategy for Sorghum Targeting Phosphorus-limited Environments in West Africa: Analysis of Multi-environment Experiments

Although sorghum [Sorghum bicolor (L.) Moench] in West Africa (WA) is generally cultivated with limited or no fertilization on soils of low phosphorus availability, no assessments of the genetic variation among WA sorghum varieties for adaptation to low soil P are known. We assessed grain yields of 70 diverse sorghum genotypes under −P (no P fertilization) and +P conditions at two locations in Mali over 5 yr. Genetic variation for grain yield under −P conditions and the feasibility and necessity of sorghum varietal testing for grain yield under −P conditions were evaluated. Delayed heading dates (0–9.8 d) and reductions of grain yield (2–59%) and plant height (13–107 cm) were observed in −P relative to the +P trials. High estimates of genetic variance and broad-sense heritabilities were found for grain yield across both −P (h2 = 0.93) and +P (h2 = 0.92) environments. The genetic correlation for grain yield performance between −P and +P conditions was high (rG = 0.89), suggesting that WA sorghum varieties generally possess good adaptation to low-P conditions. However, genotype × phosphorus crossover interaction was observed between some of the highest yielding genotypes from the −P and +P selected sets, with the variety IS 15401 showing specific adaptation to −P. Direct selection for grain yield in −P conditions was predicted to be 12% more efficient than indirect selection in +P conditions. Thus, selection under −P conditions should be useful for sorghum improvement in WA

Phosphorous Efficiency and Tolerance Traits for Selection of Sorghum for Performance in Phosphorous-Limited Environments

Sorghum (Sorghum bicolor (L.) Moench) is widely cultivated in West Africa (WA) on soils with low phosphorus (P) availability. Large genetic variation for grain yield (GY) under low-P conditions was observed among WA sorghum genotypes, but information is lacking on the usefulness of P-tolerance ratios (relative performance in –P [no P fertilizer] vs. +P [with P fertilizer] conditions) and measures of P-acquisition and internal P-use efficiency as selection criteria for enhancing GY under low-P conditions. We evaluated 70 WA sorghum genotypes for GY performance under −P and +P conditions for 5 yr in two locations in Mali and assessed P acquisition (e.g., P content in biomass) and P-use efficiency (e.g., grain produced per unit P uptake) traits under −P and +P conditions in one site in 2010. Significant genetic variation existed for all P-tolerance ratios across multiple sites. Photoperiod-sensitive landrace genotypes showed significantly better P tolerance and less delay of heading under P-limited conditions compared with photoperiod-insensitive varieties. Genotypic correlations of P-tolerance ratios to GY under −P were moderate. Phosphorous acquisition and P-use efficiency traits independent of harvest index were of similar importance for GY under −P conditions in statistically independent trials. However grain-P and stover-P concentrations from one −P trial showed only weak correlations with GYs in statistically independent trials. Highest predicted gains for −P GY were obtained by theoretical index selection based on −P GY combined with P-use efficiency traits (e.g., low-grain P concentration). Such index selection is expected to achieve both increased sorghum productivity and P sustainability in the P-limited WA production systems

Phosphorus uptake and utilization efficiency in West African pearl millet inbred lines

Pearl millet [Pennisetum glaucum (L.) R. Br] production on the acid sandy Sahelian soils in West Africa (WA) is severely limited by low plant-available phosphorus (P) in addition to erratic rainfall. We sought to examine the genetic variability for P uptake and P utilization efficiency in 180 WA pearl millet inbred lines or subsets thereof under low (LP) and high P (HP) conditions in one field and two pot experiments, determine the relationships among the measured traits and grain yield under field conditions at three other independent WA sites, and identify potential secondary selection traits for improving grain yield under LP. We observed genetic variation for P uptake and utilization in both seedling and mature plants. P utilization efficiency increased under LP conditions. Total P uptake was more important for grain production than P utilization under LP field conditions (r = 0.57*** vs r = 0.30***). The estimated response to indirect selection was positive for most of the measured morphological and P-efficiency parameters. We conclude that both seedling and mature plant traits are potentially useful as secondary traits in selection of pearl millet for low-P adaptation. These results should be validated using heterozygous pearl millet genetic materials. Ultimately, pearl millet breeding activities for low P tolerance in WA should be integrated with other system-oriented research such as nutrient cycling, intercropping or rotations with legumes, better crop-tree-livestock integration, and modest applications of locally available rock phosphate

Solitary splenic metastasis from ovarian carcinosarcoma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Metastatic tumors to the spleen are rare but are usually found in conjunction with metastasis to other organs. The most common sources of splenic metastasis are breast, lung and colorectal cancers as well as melanoma and ovarian carcinoma. A solitary carcinosarcoma metastasis to the spleen of any origin is very rare. To the best of our knowledge, there are fewer than 30 reported cases of ovarian primary tumors with solitary metastasis to the spleen, and only three solitary primary carcinosarcomas to the spleen have been reported, of which one is female. We present what is, to the best of our knowledge, the first case of a solitary metastatic carcinosarcoma to the spleen arising from a primary ovarian carcinsarcoma.</p> <p>Case presentation</p> <p>A 72-year-old Hispanic woman status post-total abdominal hysterectomy for ovarian carcinosarcoma presented with complaints of early satiety and abdominal pain for the past two months with a 30-lb unintentional weight loss. An initial computed tomographic scan of her abdomen and pelvis revealed a 30 cm × 27 cm splenic mass with displacement of the left kidney, stomach and liver. The patient was found to have a solitary metastatic carcinosarcoma of the spleen with biphasic epithelial (carcinomatous) and mesenchymal (sarcomatous) elements consistent with carcinosarcoma.</p> <p>Conclusion</p> <p>Carcinosarcoma of the spleen is a rare tumor. Carcinosarcomas are a biphasic neoplasm comprising malignant epithelial and mesenchymal components arising from a stem cell capable of differentiation. They can arise anywhere in the female genital tract, most commonly from the endometrium. Even though it is rare, carcinosarcomas can metastasize to the spleen. This unique case of a solitary splenic metastasis from ovarian carcinosarcoma has particular interest in medicine, especially for the specialties of surgical oncology, pathology and hematology/oncology.</p