Genetic diversity of potato for nitrogen use efficiency under low input conditions in Ethiopia

Potato is a prime food security crop for smallholder farmers in the highland part of North western Ethiopia. In this region, nutrient availability, especially nitrogen (N) is a major constraint for crop productivity. To obtain insight in the possibility of improving potato for growth under low N input conditions in Ethiopia, we evaluated CxE diploid back cross population, modern European and Ethiopian potato cultivars and local Ethiopian cultivars for their ability to grow and produce tubers under low and high N input conditions. The experiments were conducted under rainfed and irrigation conditions. Eighty-eight Dutch cultivars and 9 Ethiopian cultivars were evaluated in three locations in North-western Ethiopia, in 2013 and in 2015. The two years represent two different growth seasons: rain-fed (June-October 2013) and irrigated cultivation (February-June 2015). Similarly 100 CxE diploid back cross potato genotypes were evaluated in both rainfed and irrigation production seasons in 2014. The Growth of the plants was monitored throughout the growth cycle using canopy cover measurements, with modelled canopy characteristics, and other agronomic traits were measured as per the description. The effect of season and location was further investigated by a GGE Biplot genotype-by-environment interaction analysis, and genetic factors determining phenotypic traits and yield were identified through QTL mapping and association mapping. Ethiopian cultivars showed a remarkable, environment-dependent difference in utilisation of the canopy for tuber production. While total photosynthetic capacity was higher in Ethiopian cultivars than in Dutch cultivars in rainfed production season at Injibara, tuber production was higher in Dutch cultivars. This low radiation use efficiency was not observed in the other rain-fed location (Debre-Tabor). A Genotype by Environment analysis using GGE biplots demonstrates that, Irrespective of the N levels and locations, rainfed production season test environments were grouped as one mega environment and irrigation production season test environments as the other mega environment, indicating most of the variation for yield and nitrogen use efficiency (NUE) in the dataset may be caused by the effect of rain-fed vs irrigation season. Further trials are needed to confirm this result. The QTL mapping with the CxE diploid population and GWAS analysis with the Dutch cultivars discovered both season-environment and N-specific QTL as well as constitutive QTLs. Overall, N availability affects Dutch and Ethiopian cultivars differentially, with strong environmental interaction on canopy and yield traits. Rainfed and irrigated seasons in Ethiopia may require different breeding programs for improved yield under varying fertilizer levels. Both constitutive and environment-specific QTLs were identified that may be targets for breeding prorgams towards improved yield under Ethiopian cultivation conditions.</p

Genetic Diversity of Potato Cultivars for Nitrogen Use Efficiency Under Contrasting Nitrogen Regimes

Developing cultivars that use nitrogen more efficiently is a sustainable strategy for reducing nitrogen use in crop production. To assess the genetic diversity for nitrogen use efficiency (NUE) and related traits in potato, a total of 97 (88 for the Western-European market and 9 Ethiopian) cultivars were evaluated at two nitrogen levels (40 kg/ha and 120 kg/ha) for 24 quantitative traits in Debre-Tabor and Injibara (Ethiopia) in the 2013 main rainy season (June to September). Highly significant variation was found among genotypes for almost all measured traits. Plant height, NUE, tuber yield, and yield-related traits and model parameters for canopy development (maximum canopy covers area under the canopy curve) were significantly affected by N levels across locations. Dutch cultivars had more rapid initial canopy development and matured earlier than the Ethiopian cultivars at both N levels and locations. A hierarchical cluster analysis grouped the cultivars in 9 and 11 genetically distinct classes at low and high N, respectively. The genetic component accounted for a large portion of the phenotypic variation for plant height, tuber number per plant, average tuber weight, and NUE under both N regimes, as indicated by a high heritability. Strong phenotypic correlations were observed between NUE and tuber number per plant, days to maturity, tuber dry matter %, maximum canopy cover, and area under the canopy curve under both low and high N conditions. The result is indicative to set the best parental line selection criteria for crossing purpose and utilize the cultivars for further potato NUE breeding programmes

Genetic Diversity of Potato Cultivars for Nitrogen Use Efficiency Under Contrasting Nitrogen Regimes

Developing cultivars that use nitrogen more efficiently is a sustainable strategy for reducing nitrogen use in crop production. To assess the genetic diversity for nitrogen use efficiency (NUE) and related traits in potato, a total of 97 (88 for the Western-European market and 9 Ethiopian) cultivars were evaluated at two nitrogen levels (40 kg/ha and 120 kg/ha) for 24 quantitative traits in Debre-Tabor and Injibara (Ethiopia) in the 2013 main rainy season (June to September). Highly significant variation was found among genotypes for almost all measured traits. Plant height, NUE, tuber yield, and yield-related traits and model parameters for canopy development (maximum canopy covers area under the canopy curve) were significantly affected by N levels across locations. Dutch cultivars had more rapid initial canopy development and matured earlier than the Ethiopian cultivars at both N levels and locations. A hierarchical cluster analysis grouped the cultivars in 9 and 11 genetically distinct classes at low and high N, respectively. The genetic component accounted for a large portion of the phenotypic variation for plant height, tuber number per plant, average tuber weight, and NUE under both N regimes, as indicated by a high heritability. Strong phenotypic correlations were observed between NUE and tuber number per plant, days to maturity, tuber dry matter %, maximum canopy cover, and area under the canopy curve under both low and high N conditions. The result is indicative to set the best parental line selection criteria for crossing purpose and utilize the cultivars for further potato NUE breeding programmes.</p

Global, regional, and national incidence of six major immune-mediated inflammatory diseases: findings from the global burden of disease study 2019Research in context

Summary: Background: The causes for immune-mediated inflammatory diseases (IMIDs) are diverse and the incidence trends of IMIDs from specific causes are rarely studied. The study aims to investigate the pattern and trend of IMIDs from 1990 to 2019. Methods: We collected detailed information on six major causes of IMIDs, including asthma, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, psoriasis, and atopic dermatitis, between 1990 and 2019, derived from the Global Burden of Disease study in 2019. The average annual percent change (AAPC) in number of incidents and age standardized incidence rate (ASR) on IMIDs, by sex, age, region, and causes, were calculated to quantify the temporal trends. Findings: In 2019, rheumatoid arthritis, atopic dermatitis, asthma, multiple sclerosis, psoriasis, inflammatory bowel disease accounted 1.59%, 36.17%, 54.71%, 0.09%, 6.84%, 0.60% of overall new IMIDs cases, respectively. The ASR of IMIDs showed substantial regional and global variation with the highest in High SDI region, High-income North America, and United States of America. Throughout human lifespan, the age distribution of incident cases from six IMIDs was quite different. Globally, incident cases of IMIDs increased with an AAPC of 0.68 and the ASR decreased with an AAPC of −0.34 from 1990 to 2019. The incident cases increased across six IMIDs, the ASR of rheumatoid arthritis increased (0.21, 95% CI 0.18, 0.25), while the ASR of asthma (AAPC = −0.41), inflammatory bowel disease (AAPC = −0.72), multiple sclerosis (AAPC = −0.26), psoriasis (AAPC = −0.77), and atopic dermatitis (AAPC = −0.15) decreased. The ASR of overall and six individual IMID increased with SDI at regional and global level. Countries with higher ASR in 1990 experienced a more rapid decrease in ASR. Interpretation: The incidence patterns of IMIDs varied considerably across the world. Innovative prevention and integrative management strategy are urgently needed to mitigate the increasing ASR of rheumatoid arthritis and upsurging new cases of other five IMIDs, respectively. Funding: The Global Burden of Disease Study is funded by the Bill and Melinda Gates Foundation. The project funded by Scientific Research Fund of Sichuan Academy of Medical Sciences &amp; Sichuan Provincial People's Hospital (2022QN38)