Evaluation of Soybean Germplasm for Resistance to Soybean Rust (Phakopsora pachyrhizi) in Nigeria

Abstract

Soybean rust, caused by Phakopsora pachyrhizi, is one of the most important constraints to soybean production worldwide. The absence of high levels of host resistance to the pathogen has necessitated the continued search and identification of sources of resistance. In one set of experiments, 178 soybean breeding lines from the International Institute of Tropical Agriculture were rated for rust severity in the field in 2002 and 2003 at Ile-Ife, Yandev, and Ibadan, Nigeria. Thirty-six lines with disease severity ≤3 (based on a 0-to-5 scale) were selected for a second round of evaluation in 2004 at Ibadan. In the third round of evaluation under inoculated field conditions, 11 breeding lines with disease severity ≤2 were further evaluated for rust resistance at Ibadan in 2005 and 2006. The breeding lines TGx 1835-10E, TGx 1895-50F, and TGx 1903-3F consistently had the lowest level of disease severity across years and locations. In another set of experiments, 101 accessions from the United States Department of Agriculture–Agricultural Research Service and National Agriculture Research Organization (Uganda) were evaluated in the first round in 2005 under inoculated conditions in the screenhouse; 12 accessions with disease severity ≤20% leaf area infected were selected for evaluation in the second round in 2005 and 2006 under inoculated field conditions at Ibadan. Highly significant differences (P < 0.0001) in disease severity were observed among the 101 accessions during this first round of rust evaluation. Significant (P < 0.0001) differences in rust severity and sporulation also were observed among the 12 selected accessions. Accessions PI 594538A, PI 417089A, and UG-5 had significantly (P < 0.05) lower disease severity than all other selected accessions in both years of evaluation, with rust severities ranging from 0.1 to 2.4%. These results indicate that some of the breeding lines (TGx 1835-10E, TGx 1895-50F, and TGx 1903-3F) and accessions (PI 594538A, PI 417089A, and UG-5) would be useful sources of soybean rust resistance genes for incorporation into high-yielding and adapted cultivars.

Stability of Four New Sources of Bacterial Leaf Blight Resistance in Thailand Obtained from Indigenous Rice Varieties

“…The GGE biplot was used to identify disease resistance and associated stability in several crops, such as soybean (Twizeyimana et al, 2008), chick pea (Sharma et al, 2012), wheat (Gitonga, Ojwang, Macharia, & Njau, 2016), mung bean (Alam, Somta, Jompuk, Chatwachirawong, & Srinives, 2014) and rice (Idowu, Salami, Ajayi, Akinwale, & Sere, 2013;Tabien, Samonte, Abalos, & San Gabriel, 2008). Moreover, genotype and GE interaction, graphically represented using a GGE biplot to assess the genotypes and environment, play an important role in variety selection (Yan, 2001;Yan & Hunt, 2002).…”

Assessment of som (Persea bombycina) clones for resistance against Phyllosticta persae

“…It has been shown that smaller values for LD and LF are characteristic of partial resistance (Wang & Hartman, 1992;Twizeyimana et al, 2008). In the current study, it has been shown for the first time that the M-5 clone, which had the lowest measures of disease intensity during the entire experiment, possibly possesses partial resistance.…”

Characterization of soybean genotypes for Asian soybean rust reaction under screen house condition

“…Significant yield loss occurs on early infected soybean crops than late infection. Severe infection significantly reduces the yield up to 80% (Twizeyimana et al 2008).…”

“…Factors affecting the susceptibility of resistant cultivars are durability of the resistance to ASR which is easily broken due to pathogen variability (Oliveira et al 2005), the complexity of genes that controls resistance to ASR, and environmental factors (Garcia et al 2008). Thus, tolerant cultivars are more reasonable for ASR integrated control (Twizeyimana et al 2008). Tolerance can be defined as plant capacity to resist pathogen infection and development, without significant reduction in yield or quality of the product (Schafer 1970).…”