Dual impact of donor service area removal from kidney allocation system and Coronavirus Disease 2019 pandemic on access to transplantation.

INTRODUCTION: Donor service area was removed from kidney and pancreas allocation system in the United States on March 15, 2021 in favor of a distance based policy to provide geographic equity to access to transplantation. The policy change was introduced at a time when ongoing Coronavirus Disease 2019 (COVID-19) pandemic cases were declining following the first delta wave. METHODS: In this Scientific Registry of Transplant Recipients based study, deceased donor kidney transplant recipients between March 15 and December 2 of 2019, 2020 and 2021 were compared representing pre-policy change, pre-COVID cohort; pre-policy change, early COVID cohort; and post-policy change, late COVID cohort. RESULTS: There were 11336, 11808, and 12914 kidney transplants in the 2019, 2020, and 2021 cohorts, respectively. Proportion of kidney transplants increased from 8798 (78%) to 9496 (80%) to 11152 (86%), and decreased from 2538 (22%) to 2312 (20%) to 1762 (14%) within and beyond 250 nautical miles in subsequent years. Median distance between donor and transplant hospital increased (73 vs. 63 vs. 119 nautical miles, P < .001) and mean cold ischemia time increased (18.1 vs. 17.8 vs. 19.9 h, P < .001). Access to transplantation did not change for various racial groups (P = .07), pediatric patients (P = .29), dialysis vintage of >5 years (P = .21), veterans (P = .07) and decreased for those with calculated PRA of 99% and 100% (P < .001). Rate of kidney discard (19.6% vs. 20.4% vs. 24%) remained high. Although there were numerical increases in transplants from donors with donation after circulatory death, donor acute kidney injury, kidney donor profile index >85% and donor age >60 years in successive years, rates of kidney discard also increased proportionally. CONCLUSION: Improvement in the access to transplantation following the policy change was attenuated by the concurrent prevalence of the COVID-19 pandemic.

Genetic dissection of seed characteristics in field pennycress via genome-wide association mapping studies.

Field pennycress (Thlaspi arvense L.) is a new winter annual cash cover crop with high oil content and seed yield, excellent winter hardiness, early maturation, and resistance to most pests and diseases. It provides living cover on fallow croplands between summer seasons, and in doing so reduces nutrient leaching into water sources, mitigates soil erosion, and suppresses weed growth. The first ever genome-wide association study (GWAS) was conducted on a pennycress diversity panel to identify marker trait associations with important seed size and composition related traits. The entire population was phenotyped in three total environments over 2 yr, and seed area, length, width, thousand grain weight, total oil, and total protein were measured post-harvest with specialized high-throughput imaging and near-infrared spectroscopy. Basic unbiased linear prediction values were calculated for each trait. Seed size traits tended to have higher entry mean reliabilities (0.76-0.79) compared with oil content (0.51) and protein content (0.37). Genotyping-by-sequencing identified 33,606 high quality genome-wide single nucleotide polymorphism (SNPs) that were coupled with phenotypic data to perform GWAS for seed area, length, width, thousand grain weight, total oil, and total protein content. Fifty-nine total marker-trait associations were identified revealing genomic regions controlling each trait. The significant SNPs explained 0.06-0.18% of the total variance for that trait in our population. A list of candidate genes was identified based on their functional annotations and characterization in other species. Our results confirm that GWAS is an efficient strategy to identify significant marker-trait associations that can be incorporated into marker-assisted selection pipelines to accelerate pennycress breeding progress.

Field pennycress is an excellent winter annual oilseed that can serve as a cash cover crop. Genotyping-by-sequencing is an effective strategy to genotype pennycress affordably for high-quality genome-wide single nucleotide polymorphisms. First-ever mapping study in a field pennycress association mapping population was conducted. GWAS identified 59 significant marker-trait associations for important quantitative traits. Seed size traits had a higher reliability estimate compared with seed composition traits.

Chromosome-level Thlaspi arvense genome provides new tools for translational research and for a newly domesticated cash cover crop of the cooler climates.

Thlaspi arvense (field pennycress) is being domesticated as a winter annual oilseed crop capable of improving ecosystems and intensifying agricultural productivity without increasing land use. It is a selfing diploid with a short life cycle and is amenable to genetic manipulations, making it an accessible field-based model species for genetics and epigenetics. The availability of a high-quality reference genome is vital for understanding pennycress physiology and for clarifying its evolutionary history within the Brassicaceae. Here, we present a chromosome-level genome assembly of var. MN106-Ref with improved gene annotation and use it to investigate gene structure differences between two accessions (MN108 and Spring32-10) that are highly amenable to genetic transformation. We describe non-coding RNAs, pseudogenes and transposable elements, and highlight tissue-specific expression and methylation patterns. Resequencing of forty wild accessions provided insights into genome-wide genetic variation, and QTL regions were identified for a seedling colour phenotype. Altogether, these data will serve as a tool for pennycress improvement in general and for translational research across the Brassicaceae.