SSR Variation in Important U.S. Maize Inbred Lines

Historically important public inbred lines continue to play an important role in maize (Zea maysL.) improvement in many different breeding programs. Their continued use means they have undergone numerous seed increases in diverse programs since their original release. Our objective was to estimate the level of genetic diversity among and within inbred lines from different sources using SSR markers. We sampled six inbred lines (B73, CM105, Mo17, Oh43, W153R, and Wf9) obtained from 14 sources (breeding programs). The data were analyzed by analysis of molecular variance (AMOVA), genetic diversity statistics, and genetic distance (Dice\u27s coefficient). Of the total variation observed in gene frequency, 87.8% was found among inbred lines, 7.6% among sources within inbred lines, and 4.6% within sources. Genotypes of identically named inbred lines from eight different sources differed slightly on the basis of 44 SSR loci. The mean genetic similarity between sources of the same inbred was greater than 85%. It can be concluded that although more diversity exists among these six inbred lines than within them, a small but significant amount of variation exists among seed sources within inbreds. This variation may have arisen through differences in seed maintenance, since we found no evidence to suggest high mutation rates or extensive outcrossing. The small but statistically significant level of variation raises concerns in germplasm conservation, mapping studies, marker development, and long-term recombinant inbred line development, especially when high resolution is desired

Participatory Farmer Evaluation of Stem borer Resistant Maize varieties in three maize growing ecologies of Kenya

Insect Resistant Maize for Africa Project (IRMA) aims at developing and deploying insect resistant maize varieties to reduce grain losses due to insect pests. As part of incorporating farmer’s perceptions and improving the adoption of the developed varieties, participatory approaches are adopted. The paper analysis farmer’s preferences of maize germplasm developed through conventional breeding. The paper uses data collected from evaluations conducted at the end of 2006 April and October rains. Nine stem borer resistant maize varieties were evaluated alongside six commercial checks in the moist transitional zones (East and West) at vegetative and harvest stage, while in the dry transitional zone and dry mid altitude zones, 6 new varieties were evaluated together with four commercial checks at harvest stage. Each variety was assessed on a scale of 1(very poor) to 5 (very good) based on key criteria generated in earlier group discussions with farmers and overall score. Data was analyzed using ordinal regression model of Social Package for Social Sciences (SPSS). In DT zone, Katumani, CKIR06007 and CKIR06008 were more preferred to the checks based on overall score. CKIR06008 was also more preferred on yield and tolerance to insect pest criteria, while CKIR04002, CKIR06009, and CKIR04003 were perceived more superior to local check based on tolerance to insect pests. In moist transitional zone Embu only CKIR06005 was more preferred (p<0.01) to the check at harvest stage in April 2006 season based on early maturity. While there was no preference for the new varieties at vegetative stage in Embu in October rains 2006 season, a number of new varieties CKIR06001, CKIR06002, CKIR06003, CKIR06004, and CKIR06005 were more preferred based on early maturity at harvest in October rains 2006 season. In the moist transitional zone (west), CKIR06005 and CKIR06005 were more preferred on maturity criteria but CKIR06004 also had good attributes in terms of cob size vegetative stage in April rains 2007. We conclude that farmers perceive some varieties to have good tolerance to insect pests in addition to good yield and maturity characteristics attributes, which are critical to the farmers in the adoption of new varieties.Crop Production/Industries,

The Building Nutritious Food Baskets Project ‘Insights from the Field’

This booklet is a compilation of insights and success stories from the field during the implementation of the Building Nutritious Food Baskets (BNFB) project; a three-year project (November 2015 to October 2018) implemented in Nigeria and Tanzania and funded by the Bill & Melinda Gates Foundation. The objective of compiling these insights and success stories is to showcase and highlight BNFB’s experiences and interactions with various stakeholders during implementation, highlight successful partnerships and to provide a ‘human touch’ in narrating the process and how the project was able to deliver results, outcomes and the emerging impact of these efforts

Novel Sources of Witchweed (Striga) Resistance from Wild Sorghum Accessions

Sorghum is a major food staple in sub-Saharan Africa (SSA), but its production is constrained by the parasitic plant Striga that attaches to the roots of many cereals crops and causes severe stunting and loss of yield. Away from cultivated farmland, wild sorghum accessions grow as weedy plants and have shown remarkable immunity to Striga. We sought to determine the extent of the resistance to Striga in wild sorghum plants. Our screening strategy involved controlled laboratory assays of rhizotrons, where we artificially infected sorghum with Striga, as well as field experiments at three sites, where we grew sorghum with a natural Striga infestation. We tested the resistance response of seven accessions of wild sorghum of the aethiopicum, drummondii, and arundinaceum races against N13, which is a cultivated Striga resistant landrace. The susceptible control was farmer-preferred variety, Ochuti. From the laboratory experiments, we found three wild sorghum accessions (WSA-1, WSE-1, and WSA-2) that had significantly higher resistance than N13. These accessions had the lowest Striga biomass and the fewest and smallest Striga attached to them. Further microscopic and histological analysis of attached Striga haustorium showed that wild sorghum accessions hindered the ingression of Striga haustorium into the host endodermis. In one of the resistant accessions (WSE-1), host and parasite interaction led to the accumulation of large amounts of secondary metabolites that formed a dark coloration at the interphase. Field experiments confirmed the laboratory screening experiments in that these same accessions were found to have resistance against Striga. In the field, wild sorghum had low Area under the Striga Number Progressive curve (AUSNPC), which measures emergence of Striga from a host over time. We concluded that wild sorghum accessions are an important reservoir for Striga resistance that could be used to expand the genetic basis of cultivated sorghum for resistance to the parasite

SSR Variation in Important U.S. Maize Inbred Lines

Historically important public inbred lines continue to play an important role in maize (Zea maysL.) improvement in many different breeding programs. Their continued use means they have undergone numerous seed increases in diverse programs since their original release. Our objective was to estimate the level of genetic diversity among and within inbred lines from different sources using SSR markers. We sampled six inbred lines (B73, CM105, Mo17, Oh43, W153R, and Wf9) obtained from 14 sources (breeding programs). The data were analyzed by analysis of molecular variance (AMOVA), genetic diversity statistics, and genetic distance (Dice's coefficient). Of the total variation observed in gene frequency, 87.8% was found among inbred lines, 7.6% among sources within inbred lines, and 4.6% within sources. Genotypes of identically named inbred lines from eight different sources differed slightly on the basis of 44 SSR loci. The mean genetic similarity between sources of the same inbred was greater than 85%. It can be concluded that although more diversity exists among these six inbred lines than within them, a small but significant amount of variation exists among seed sources within inbreds. This variation may have arisen through differences in seed maintenance, since we found no evidence to suggest high mutation rates or extensive outcrossing. The small but statistically significant level of variation raises concerns in germplasm conservation, mapping studies, marker development, and long-term recombinant inbred line development, especially when high resolution is desired.This article is published as Gethi, James G., Joanne A. Labate, Kendall R. Lamkey, Margaret E. Smith, and Stephen Kresovich. "SSR variation in important US maize inbred lines." Crop science 42, no. 3 (2002): 951-957. doi: 10.2135/cropsci2002.9510. Posted with permission.</p

Seed Abortion and Numerical Components of Seed Yield of Soyabean (Glycine max L. Merr.) in Three Contrasting Agroecologies

ABSTRACT Two trials were conducted to study the components of yield. In one trial three genotypes were planted in three blocks with the objective of studying the dynamics of seeds/pod during seed maturation. Pods were dissected to reveal the developing seed 20 days after flowering (DAF) and at harvesting. In another trial, 14 genotypes were planted in RCBD in three contrasting environments: Bureti, Njoro and Lare with the objective of studying the components of yield. Seeds/pod was significantly different, both at 20 DAF and at harvesting. Although there were more pods at harvesting compared to 20 DAF, 3-seeded pods was the mode 20 DAF while the mode was 1-seeded pod at harvesting which may be explained by seed abortion. Seeds/pod was significantly different at the three sites. Yield and its components were highest at Bureti compared with Lare. It is apparent that seeds per pod are influenced by seed abortion

Impact of anthropometry training and feasibility of 3D imaging on anthropometry data quality among children under five years in a postmortem setting.

BackgroundThe Child Health and Mortality Prevention Surveillance Network (CHAMPS) identifies causes of under-5 mortality in high mortality countries.ObjectiveTo address challenges in postmortem nutritional assessment, we evaluated the impact of anthropometry training and the feasibility of 3D imaging on data quality within the CHAMPS Kenya site.DesignStaff were trained using World Health Organization (WHO)-recommended manual anthropometry equipment and novel 3D imaging methods to collect postmortem measurements. Following training, 76 deceased children were measured in duplicate and were compared to measurements of 75 pre-training deceased children. Outcomes included measures of data quality (standard deviations of anthropometric indices and digit preference scores (DPS)), precision (absolute and relative technical errors of measurement, TEMs or rTEMs), and accuracy (Bland-Altman plots). WHO growth standards were used to produce anthropometric indices. Post-training surveys and in-depth interviews collected qualitative feedback on measurer experience with performing manual anthropometry and ease of using 3D imaging software.ResultsManual anthropometry data quality improved after training, as indicated by DPS. Standard deviations of anthropometric indices exceeded limits for high data quality when using the WHO growth standards. Reliability of measurements post-training was high as indicated by rTEMs below 1.5%. 3D imaging was highly correlated with manual measurements; however, on average 3D scans overestimated length and head circumference by 1.61 cm and 2.27 cm, respectively. Site staff preferred manual anthropometry to 3D imaging, as the imaging technology required adequate lighting and additional considerations when performing the measurements.ConclusionsManual anthropometry was feasible and reliable postmortem in the presence of rigor mortis. 3D imaging may be an accurate alternative to manual anthropometry, but technology adjustments are needed to ensure accuracy and usability