Phakopsora Pachyrhizi Syd Research Articles

Phenotypic Evaluation of Soybean Genotypes for Their Reaction to a Mississippi Isolate of Phakopsora pachyrhizi Causing Soybean Rust.

Soybean rust (SBR) caused by Phakopsora pachyrhizi Syd. and P. Syd. is one of the most important foliar diseases of soybean. SBR has the potential to cause major economic damage to global and U.S. soybean production. Analysis of reactions of soybean genotypes to P. pachyrhizi is an important step towards breeding for resistance to SBR. Fifty-four diverse soybean genotypes with both known and unknown Rpp resistance genes were tested for their reactions to a Mississippi P. pachyrhizi isolate. PI 567102B (Rpp6) had a near-immune reaction with the lowest disease severity score and no sporulation. Among seventeen genotypes with resistant or incomplete resistant reddish-brown (RB) reactions, eight are improved breeding lines that are available to researchers through material transfer agreements (MTAs). Thirty-six genotypes had the susceptible TAN reaction. Four soybean lines (RN06-32-1(7-b, GC 00138-29, G01-PR16, and GC 84051-9-1) had RB reactions and significantly lower SBR severity and sporulation than three of the six resistant checks, PI 230970 (Rpp2), PI 462312 (Rpp3), and PI 459025B (Rpp4). G01-PR16 is a publicly released germplasm. This research provides new information about reactions of different soybean genotypes to a midsouthern USA isolate of P. pachyrhizi and thereby aids in breeding for resistance to SBR.

Mycodiplosis sp.1: Potential Bioagent to Control Asian Soybean Rust, Phakopsora pachyrhizi Syd. & P. Syd2, in Northeast Mexico

En el presente trabajo se reporta por primera vez el consumo de las uredosporas de Phakopsora pachyrhizi Sydow & P. Sydow por las larvas del género Mycodiplosis (Rübsaamen, 1885) en el cultivo de soya (Glicine max L. Merrill). El trabo de investigación se desarrolló en la variedad de soya Huasteca-700, con fecha de siembra del 30 de diciembre del 2020, en el Sitio Experimental Ébano (SEE), ubicado en Ébano, San Luis Potosí, México. En este cultivo, las larvas del género Mycodiplosis fueron registradas en los folíolos con lesiones irregulares color caféamarillento, café-rojizo o café oscuro a los 71, 78, 85, y 92 días después de la siembra (DDS). En las fechas de muestreo, las larvas del género Mycodiplosis se observaron alimentando de uredosporas de la roya asiática. El número mayor de larvas se registró a los 78 DDS (n = 180) respecto a los 71, 85, y 92 DDS. A los 71 y 78 DDS, las larvas se observaron en los folíolos con una severidad promedio de 1.44 y 2.8%. Mientras que, a las 85 y 92 DDS, larvas se observaron en los folíolos con una severidad promedio de 26.81 y 38.5%. El registro del consumo de uredosporas de roya asiática de la soya por las larvas del género Mycodiplosis es el primer reporte para México. Con base en este resultado, las larvas del género Mycodiplosis podrían ser parte de los agentes control biológico de roya asiática en el cultivo de soya.

Effect of Zinc Oxide, Sulphur and Silver Nanoparticles against Soybean Rust Phakopsora pachyrhizi Syd.

Background: Soybean rust caused by Phakopsora pachyrhizi Syd. is one of the major constraints in the production of soybean. Nanotechnology is a new scientific approach that includes use of materials and equipment capable of using physical and chemical properties of a substance at molecular level to explore the biological and material worlds in nanometer-scale and use it in various carriers from medicine to agriculture. Nanotechnology has emerged as one of the most innovative scientific field in agriculture. Among various synthesis methods, green synthesis of nanoparticles is widely used by researchers because it is simple, convenient, eco-friendly and requires less reaction time. Methods: The chitosan based zinc oxide nanoparticles (Ch-ZnONPs), pomegranate aril based sulphur nanoparticles (PA-SNPs) and pomegranate aril based silver nanoparticles (PA-AgNPs) were synthesised, characterised and evaluated under in vitro conditions against soybean rust pustules. Result: The maximum per cent spore inhibition of 70.25, 74.70 and 86.68 per cent over control was recorded in Ch-ZnONPs (1250 ppm), PA-SNPs (2000 ppm) and PA-AgNPs (500 ppm) respectively.

Economic impact assessment of soybean rust (Phakopsora pachyrhizi) resistance breeding in India: An ex-ante analysis

Soybean rust (Phakopsora pachyrhizi Syd.) is one of the most prevalent soybean diseases particularly in Krishna basin area of Karnataka and Maharashtra, which can cause losses from 10-100%. The research conducted to estimate benefits from adoption of rust resistant soybean varieties in rust prone districts of Karnataka and Maharashtra using primary data collected from adopter and non-adopter farmers for the crop year 2017-18. Rust resistant varieties require less chemical pesticides and reduce yield loss. The study estimated potential economic benefits in terms of economic surplus for rust resistant varieties. In normal conditions, total benefits from the adoption of rust resistant soybean varieties using the economic surplus model was estimated at ` 198.8 crores per annum at a discount rate of 5% and ` 99.3 crores at 8% discount rate, respectively. Adoption of rust resistant varieties performed well over other varieties in reducing yield loss and cost of cultivation. The popularization of these varieties in rust prone areas to cope up with this biotic stress is needed.

Performance of soybean genotypes (Glycine Max L.) against Asian rust (Phakopsora Pachyrhizi Syd.) in Cameroon

Asian rust caused by Phakopsora pachirhizi, which is a major constraint to production of soybean, causing 90% yield losses in field. Synthetic fungicides used to control this disease are environmentally degrading and have negative impact on the health of producers and consumers. The use of resistant soybean genotypes can be an effective control alternative. The aim of this work is to evaluate the tolerance of soybean varieties to Asian rust disease under natural conditions. Forty-three soybean varieties were screened using a completely randomized block design with three replicate. Incidence and severity of disease at 6, 8 and 10 weeks after sowing (WAS) and yields were evaluated. Results show that disease incidence of Asian rust was significantly higher in the local variety R3 (16.67%; 29.63%; 75.93%) at 6, 8 and 10 WAS respectively. At 6 and 8 WAS severity of disease was higher in local variety R3 (21.17% and 24.14% respectively). The variety TGX-2010-12F has the highest yield (1.17 t ha-1) than the local variety R3 (0.17 t ha-1). Principal component analysis realized with incidence, severity of disease at 6, 8, 10 WAS and yield shows that 12 varieties are highly susceptible to Asian rust, 12 varieties are moderately resistant, and 19 varieties are susceptible. This study shows that Asian rust attacks all soybean varieties in the field. Moderately resistant varieties, can be advised to growers with appropriate protection methods or be subject to varietal improvement through genetic techniques.

Performance of soybean genotypes (Glycine Max L.) against Asian rust (Phakopsora Pachyrhizi Syd.) in Cameroon

Performance of soybean genotypes (Glycine Max L.) against Asian rust (Phakopsora Pachyrhizi Syd.) in Cameroon

Multiple resistance to DMI, QoI and SDHI fungicides in field isolates of Phakopsora pachyrhizi

Asian soybean rust (ASR), caused by the fungus Phakopsora pachyrhizi Syd & P. Syd, is the main disease that affects soybean crop in South America. Disease control is based on the use of site-specific fungicides (QoIs, DMIs and SDHIs), multisite fungicides and host-free period. Continuous and intensive use of fungicides has selected isolates of P. pachyrhizi, with reduced sensitivity to DMIs, QoIs and SDHIs. This work includes sensitivity studies for prothioconazole and SDHIs and genetic analysis of target site mutations in P. pachyrhizi related to sensitivity reduction to DMIs, QoIs and SDHIs collected from different regions of soybean production areas. Different CYP51 genotypes with distinct point mutations known to influence DMI sensitivity are present in Brazilian isolates. Combined mutation F120L + Y131H on CYP51 gene was the most frequent among Brazilian isolates. Mutant isolates showed higher EC50 values to the DMI prothioconazole compared to wild type isolates. Regarding QoI, almost all Brazilian isolates carried the mutation F129L in the CYTB gene. Wild type of the SdhC gene was the most frequent genotype to SDHI fungicides, but the mutation leading to the I86F amino acid exchange has also been detected. Such isolates showed higher EC50 values to the SDHIs bixafen, benzovindiflupyr and fluxapyroxad compared to wild type isolates. The most frequent genotype in our collection presented target site mutations in the CYP51 and CYTB genes. A monouredinial isolate with mutations in all three target genes was detected and is here described for the first time. Its current and further spread, and the impact on field performance of fungicides with these modes of action needs further evaluation.

Reactions of 52 soybean germplasm accessions with Rpp3 alleles to a panel of 13 Phakopsora pachyrhizi (soybean rust) isolates from the southern United States

Soybean rust (SBR) caused by Phakopsora pachyrhizi Syd. is one of the most economically important foliar diseases of soybean [Glycine max (L.) Merr.]. At least 52 soybean plant introductions (PIs) with resistance to SBR have a resistance gene at the Rpp3 locus on chromosome 6, but little is known about the degree of similarity between those alleles and the Rpp3 alleles from PI 462312 and ‘Hyuuga’, which has resistance genes at the Rpp3 and Rpp5 loci. Reactions of 52 PIs to a panel of 13 P. pachyrhizi isolates from the United States were assessed to identify accessions with reaction patterns that differed from those of PI 462312 and Hyuuga. Thirty-two PIs were similar to PI 462312 and eight more similar to Hyuuga. Twelve PIs had reactions to 2011 and 2012 isolates from Florida that differed from both PI 462312 and Hyuuga. Although the majority of the 52 accessions appear to have the same Rpp3 allele as PI 462312, at least some of the 12 PIs with different reaction patterns are likely to have unique alleles. This information will be useful in breeding rust-resistant soybean cultivars, and potentially for identifying regions of the Rpp3 locus that are involved in P. pachyrhizi pathotype recognition. None of the P. pachyrhizi isolates collected after 2012 were as virulent as 2011 and 2012 isolates from north-central Florida, demonstrating that virulence shifts in P. pachyrhizi populations are not necessarily permanent.

Foliar fortification of Copper (Cu) in Glycine max L. for the protection against Asian Soybean Rust (Phakopsora pachyrhizi Syd. & P.Syd.)

The Asian Soybean Rust caused by the fungus Phakopsora pachyrhizi is one of the serious phytosanitary problems faced by soybean [Glycine max (L.) Merrill], which cause up to 80% yield loss. An alternative for the integrated management of the disease is the use of mineral nutrition together with phytosanitary treatments. Thus, the objective of this study is to understand the effect of foliar fortification with copper (Cu) along with phytosanitary treatments in the soybean reaction to Rust by lignin content variation in leaf tissues, and how it reflects the yield. The experimental design was a randomized block with four replicates. Four concentrations Cu (30, 60, 90, 120 g Cu ha-1) were tested in two distinct sources (cuprous oxide and copper carbonate) together with phytosanitary treatments. Evaluations were made to determine the progression of Asian Rust severity, micronutrient content in leaves and grains, as well as lignin content in leaves. The grain yield components and productivity were also evaluated. The Cu contents in the soybean leaves and grains were influenced by foliar spraying. Foliar spray with Cu retarded the disease progression, reducing the severity of Asian Rust and positively impacting grain yield. The amount of lignin present in the leaves was altered considerably with the application of the Cu associated with phytosanitary treatments. The results suggest that the leaf nutrition with copper together with phytosanitary treatments, may reduce the rust severity and improvement the plant performance. Future research with Cu application and analysis of specific enzymes, secondary metabolites and cell wall thickness may further contribute to the understanding of the role of Cu in defence against Asian Soybean Rust.

Estimation of Avoidable Loss in Elite Genotypes of Soybean due to Soybean Rust caused by Phakopsora pachyrhizi Syd

Seven different types of elite varieties were studied for loss estimation during Kharif 2010 and eight varieties during 2011. The pooled analysis over two years indicated maximum per cent loss (61.43) in VLS 63 genotype followed by TK 5 (59.83) and PK 1029 (58.07) during Kharif 2010. During Kharif 2011, maximum yield loss of 56.89 was recorded in TK 13 followed by JS 335 (49.63) and PK 1029 (48.50). The genotypes which are slow rusters such as Dsb 21 and DS 2309 recorded yield loss of 11.81 and 39.95. The most susceptible genotypes recorded yield loss of 55.63 and 53.29 percent respectively. The crop loss estimation due to rust revealed that lower disease index with increased seed yield was recorded in protected plots receiving two sprays of hexaconazole in both susceptible and resistant varieties than unprotected treatment.

Reactions of Soybean Germplasm Accessions to Six Phakopsora pachyrhizi Isolates from the United States

Soybean rust, caused by Phakopsora pachyrhizi Syd. & P. Syd., is one of the most economically important foliar diseases of soybean. Resistant cultivars could reduce yield losses and management costs but considerable pathogenic diversity exists among populations of the fungus; thus, resistance to a range of pathotypes is essential. Seedling and detached-leaf assays were conducted to characterize the resistance of 55 soybean plant introductions (PIs) to six purified isolates of P. pachyrhizi originating from the southern United States. In the greenhouse resistance assays, the differentials Hyuuga (PI 506764) and PI 471904 and accessions PI 224268, PI 567025A, PI 567039, PI 567046A, and DT 2000 (PI 635999) were resistant to all six isolates, including Florida isolates from 2011 and 2012 that were able to defeat resistance conditioned by the Rpp1 through Rpp4 genes. Twenty-six other PIs were resistant to four or five of the six isolates. In the detached-leaf assays, eight accessions developed reddish-brown reactions to all six isolates, with an average of only 0.23 to 0.55 uredinia/lesion. These included Hyuuga, DT 2000, two differentials with a resistance allele at the Rpp5 locus, and accessions PI 224268, PI 423960B, PI 567025A, and PI 567046A. Many of the resistant accessions have subsequently been reported to have a resistance allele at the Rpp3 locus, and two others have resistance genes at the Rpp4 or Rpp6 locus. This study provided new information about resistance reaction phenotypes that can be useful for understanding mechanisms of resistance, which Rpp genes and alleles could be combined to obtain broader and more durable rust resistance in soybean cultivars, and pathotype diversity among the six isolates used.

(2689–2690) Proposals to conserve the names Phakopsora pachyrhizi against Uredo erythrinae and U. sojae (Malupa sojae) and Physopella meibomiae (Phakopsora meibomiae) against Aecidium crotalariicola, U. teramni, and U. vignae (M. vignae) (Basidiomycota, Pucciniales)

(2689–2690) Proposals to conserve the names <i>Phakopsora pachyrhizi</i> against <i>Uredo erythrinae</i> and <i>U. sojae</i> (<i>Malupa sojae</i>) and <i>Physopella meibomiae</i> (<i>Phakopsora meibomiae</i>) against <i>Aecidium crotalariicola</i>, <i>U. teramni</i>, and <i>U. vignae</i> (<i>M. vignae</i>) (<i>Basidiomycota</i>, <i>Pucciniales</i>)

Droplet spectrum and fungicide efficiency in the control of Asian soybean rust (Phakopsora pachyrhizi Syd. &amp; P. Syd.)

El objetivo de este estudio fue evaluar el control químico de la roya asiática de la soya (Phakopsora pachyrhizi Syd. Y P. Syd.) Utilizando diferentes puntas y boquillas en condiciones controladas.La trifolia enraizada colocada dentro de una caja acrílica que contiene macronutrientes, micronutrientes y vitaminas se trataron con los siguientes fungicidas: epoxiconazol + piraclostrobina, ciproconazol + azoxistrobina y tebuconazol. Estos fungicidas se pulverizaron a una altura de 0.5 m con dos pulverizadores de mochila presurizados con gas CO2 (generador de caída en cuatro puntas de pulverización espaciados 0.5 m uno del otro) y otra boquilla giratoria (generador de caída a través de una boquilla giratoria). La trifolia no tratada eran controles. Se colocó papel sensible al agua junto a cada caja de acrílico para obtener el diámetro medio del volumen (MVD), el número de gotas.cm-2 y la cobertura (%). Trifolia se inocularon 24 horas después de que estos se trataron con fungicida, usando una concentración de esporas ajustada a 2 x 104 uredosporas.mL-1. Luego, se cuantificó el número de lesiones y uredia.cm-2 en las valvas centrales. Se observó un menor número de lesiones y uredia.cm-2 en folíolos tratados con dos mezclas de fungicidas usando una punta AIRMIX 11001. Se encontró una menor VMD en foliolos pulverizados con los fungicidas azoxystrobin + epoxiconazol y tebuconazol, en comparación con los folíolos tratados con otra mezcla. El control de la roya asiática, así como el número de gotas.cm-2 y la cobertura, parece depender de las interacciones entre los fungicidas y las puntas o boquillas.

Discovery of a seventh Rpp soybean rust resistance locus in soybean accession PI 605823.

A novel Rpp gene from PI 605823 for resistance to Phakopsora pachyrhizi was mapped on chromosome 19. Soybean rust, caused by the obligate biotrophic fungal pathogen Phakopsora pachyrhizi Syd. & P. Syd, is a disease threat to soybean production in regions of the world with mild winters. Host plant resistance conditioned by resistance to P. pachyrhizi (Rpp) genes has been found in numerous soybean accessions, and at least 10 Rpp genes or alleles have been mapped to six genetic loci. Identifying additional disease-resistance genes will facilitate development of soybean cultivars with durable resistance. PI 605823, a plant introduction from Vietnam, was previously identified as resistant to US populations of P. pachyrhizi in greenhouse and field trials. In this study, bulked segregant analysis using an F2 population derived from 'Williams 82'×PI 605823 identified a genomic region associated with resistance to P. pachyrhizi isolate GA12, which had been collected in the US State of Georgia in 2012. To further map the resistance locus, linkage mapping was carried out using single-nucleotide polymorphism markers and phenotypic data from greenhouse assays with an F2:3 population derived from Williams 82×PI 605823 and an F4:5 population derived from '5601T'×PI 605823. A novel resistance gene, Rpp7, was mapped to a 154-kb interval (Gm19: 39,462,291-39,616,643 Glyma.Wm82.a2) on chromosome 19 that is different from the genomic locations of any previously reported Rpp genes. This new gene could be incorporated into elite breeding lines to help provide more durable resistance to soybean rust.

First Report on Physiological Races of Phakopsora pachyrhizi Syd Causing Asian Soybean Rust in India

First Report on Physiological Races of Phakopsora pachyrhizi Syd Causing Asian Soybean Rust in India The physiological variability studies were carried out for 17 isolates collected from different growing environment of India. Three pathotypes were identified based on physiological variability on 13 international set of differentials namely Cluster I-Reddish Brown (RB) lesion producing pathotypes, Cluster II- TAN lesion producing pathotypes and Cluster III- Mixed or RB + TAN producing pathotypes. Based on the reaction of Phakopsora pachyrhizi isolates on two differentials PI 230971 and PI 200492, Race 2 produced RB type lesions on PI 230971 and TAN type on the other differentials and Race 3 produced TAN type lesion PI 200492 and RB type lesion on the other differentials were identified. Based on reaction on these two differentials, Race 2 and Race 3 are prevalent in Karnataka state while, only Race 2 was prevalent in Maharashtra and north eastern states...

Molecular Characterization of Resistance to Soybean Rust (Phakopsora pachyrhizi Syd. & Syd.) in Soybean Cultivar DT 2000 (PI 635999).

Resistance to soybean rust (SBR), caused by Phakopsora pachyrhizi Syd. & Syd., has been identified in many soybean germplasm accessions and is conferred by either dominant or recessive genes that have been mapped to six independent loci (Rpp1 –Rpp6), but No U.S. cultivars are resistant to SBR. The cultivar DT 2000 (PI 635999) has resistance to P. pachyrhizi isolates and field populations from the United States as well as Vietnam. A F6:7 recombinant inbred line (RIL) population derived from Williams 82 × DT 2000 was used to identify genomic regions associated with resistance to SBR in the field in Ha Noi, Vietnam, and in Quincy, Florida, in 2008. Bulked segregant analysis (BSA) was conducted using the soybean single nucleotide polymorphism (SNP) USLP 1.0 panel along with simple sequence repeat (SSR) markers to detect regions of the genome associated with resistance. BSA identified four BARC_SNP markers near the Rpp3 locus on chromosome (Chr.) 6. Genetic analysis identified an additional genomic region around the Rpp4 locus on Chr. 18 that was significantly associated with variation in the area under disease progress curve (AUDPC) values and sporulation in Vietnam. Molecular markers tightly linked to the DT 2000 resistance alleles on Chrs. 6 and 18 will be useful for marker-assisted selection and backcrossing in order to pyramid these genes with other available SBR resistance genes to develop new varieties with enhanced and durable resistance to SBR.

Characteristics of superior soybean breeding lines tolerance to rust (Phakopsora pachyrhizi Syd.)

&lt;p&gt;Soybean rust caused by Phakopsora pachyrhizi is one of the most important diseases which limits soybean production. The aim of this study was to evaluate the resistance of 28 superior soybean lines and their tolerance to rust. The study was conducted at a screen house and arranged in a completely randomized design (CRD); three replications. All genotypes tested were artificially inoculated with P. pachyrhizi, and a set of un-inoculated genotypes was planted as a comparison. Number of pustules was recorded weekly, and resistant criteria was rated based on the International working group on soybean rust IWGSR method. Lesion color (LC), sporulation level (SL), number of uredia (NoU), frequency of pustule which had uredia, and yield were also recorded. Among 28 genotypes tested, only one was categorized as resistant and 2 genotypes were susceptible. Resistant genotypes had few pustules, lower AUDPC values, low disease severity, and Reddish Brown lesion type. Soybean rust affected yield components, i.e. number of intact pods and yield per plant. Yield loses due to rust in this study varied from 5-89%, and the average was 51%. The set of lines from Tanggamus pedigree showed more resistant to rust but less tolerant compared to Sinabung pedigree.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;How to Cite&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Inayati, A., &amp;amp; Yusnawan, E. (2016). Characteristics of superior soybean breeding lines tolerancet to rust (Phakopsora pachyrhizi Syd.).&lt;em&gt; Biosaintifika: Journal of Biology &amp;amp; Biology Education&lt;/em&gt;, 8(1), 47-55.&lt;/p&gt;

Prevalence of pathotypes of &lt;em&gt;Phakopsora pachyrhizi&lt;/em&gt; Syd. causing Asian soybean rust in India

Soybean rust caused by Phakopsora pachyrhizi Syd. is a potential disease causing severe losses in yield and oil quality of soybean [Glycine max (L.) Merr.]. The physiological variability studies were carried out for 25 isolates collected from different growing environment of Karnataka, India during Kharif 2010-2012. Morphological and cultural characters of 25 isolates were studied under identical condition. Among 25 isolates, the maximum uredospore size was found in Ugarkhurd isolate (90.93×70.05 μm). The differential JS-335 reacted to the maximum of eight isolates, and isolate Rayanal produced both RB and TAN reaction on most of the differentials. In the clustering of different isolates into pathotypes, the cluster analysis indicated the expression of eight isolates on differential JS-335 and there was no expression of all the isolates on differential PI-459024B. In cluster-II, nine isolates expressed on PI-200492, while one isolate expressed on JS-335. In cluster-III, 23 isolates expressed on PI-459024B and 12 isolates expressed on PI-200492. Hence, this study described the three pathotypes that causes soybean rust in India namely, Cluster I-Reddish Brown (RB) lesion producing pathotypes, Cluster II - TAN lesion producing pathotypes and Cluster III - Mixed or RB + TAN producing pathotypes. This information could further be used for identification of race pattern in Karnataka and other major rust prone areas of India.

Identification of a soybean rust resistance gene in PI 567104B.

Using a combination of phenotypic screening and molecular, statistical, and linkage analyses, we have mapped a dominant soybean rust resistance gene in soybean PI 567104B. Asian soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi Syd. and P. Syd., is one of the most economically important diseases that affect soybean production worldwide. A long-term strategy for minimizing the effects of SBR is the development of genetically resistant cultivars. The objectives of the study were to identify the location of a rust-resistance (Rpp) gene(s) in plant introduction (PI) 567104B, and to determine if the gene(s) in PI 567104B was different from previously mapped Rpp loci. The progeny of the cross of 'IAR 2001 BSR' × PI 567104B was phenotyped from field assays of the F 2:3 and F 4:5 generations and from a growth chamber assay of 253 F 5:6 recombinant inbred lines (RILs). For the growth chamber, the phenotyping was conducted by inoculation with a purified 2006 fungal isolate from Mississippi. A resistance gene locus on PI 567104B was mapped to a region containing the Rpp6 locus on chromosome 18. The high level of resistance of F 1 plants from two other crosses with PI 567104B as one of the parents indicated that the gene from PI 567104B was dominant. The interval containing the gene is flanked by the simple sequence repeat (SSR) markers Satt131 and Satt394, and includes the SSR markers BARCSOYSSR_18_0331 and BARCSOYSSR_18_0380. The results also indicated that the resistance gene from PI 567104B is different from the Rpp1 to the Rpp4 genes previously identified. To determine if the gene from PI 567104B is different from the Rpp6 gene from PI 567102B, additional research will be required.

Quantitative detection of soybean rust using image processing techniques

Rust caused by Phakopsora pachyrhizi Syd. is a major constraint to soybean product in Asia. Early detection and possibilities of controlling plant diseases by the integration of several image processing methods has been the subject of extensive research. The main contribution of this paper is to present different methodologies for quantitatively detecting soybean rust at each stage of disease development, identify disease even before specific symptoms become visible and grade based on percentage of disease severity. Severity of rust infection levels at each stage of disease development was observed for 25 days on soybean leaf. Then color distribution and pixel relationship in rust infected leaf image was calculated based on global and local features for quantifying rust severity. Further, rust disease was categorized into grades based on infection severity levels and percentage disease index (PDI) was calculated. The maximum PDI of 95.5 was observed at 25 th day and minimum PDI of 0.2 was observed at 6 th day.