Search

Background: Sterility mosaic is the most destructive disease of pigeon pea causing yield losses up to 95 per cent. Pigeon pea genotypes are found to vary in different biochemical characteristics, thereby playing a crucial role in resistance to sterility mosaic disease. The best approach to manage the disease is by adopting resistant genotypes for cultivation, which is highly necessary in the areas with high sterility mosaic incidence. Methods: Field screening of 41 pigeon pea genotypes was conducted during Kharif 2021 and 2022 at the Indian Institute of Pulse Research, Regional Research Center, Dharwad, to identify the resistance sources to Pigeon pea sterility mosaic virus. All the test genotypes were artificially inoculated by leaf stapling technique at 15-20 days after sowing and the infector hedge row technique was also employed to develop high disease pressure. Observation on per cent disease incidence was recorded at the peak period of the disease. The study also focused on biochemical components that confer resistance in pigeon pea. Further, the leaf samples were collected from the selected pigeon pea genotypes showing resistance and susceptible reactions and statistically analysed for total phenol content, peroxidase and polyphenol oxidase activity. The genotypes showing resistance and susceptible reactions were analysed for leaf chlorophyll content using SPAD Meter. Result: Seven genotypes were found resistant to sterility mosaic disease with a mean disease incidence of 1.9-8.86 per cent. SPAD chlorophyll meter reading revealed that chlorophyll content remained high in all resistant/moderately resistant genotypes as compared to susceptible genotypes. The resistant genotypes were shown to have higher phenol content, peroxidase and polyphenol oxidase activity in comparison to susceptible genotypes suggesting their crucial role in imparting resistance. [ABSTRACT FROM AUTHOR]

Scald caused by the fungal pathogen Rhynchosporium commune is a significant foliar disease affecting barley production on a global scale, and it leads to substantial reductions in both yield and quality of barley. In the current study, the reactions of 40 Turkish barley (Hordeum vulgare L.) varieties to scald were evaluated under natural conditions in Çanakkale and Kırşehir in 2021–2022, and Antalya and Siirt locations in 2022–2023 growing seasons. Field trials were conducted according to randomized block design with three replications in each year; the spore concentration was 1 × 106 spores per mL, and it was applied to the varieties three times at different growth stages. The reactions of barley varieties were assessed using a newly designed two-digit scale ranging from 11 to 99. Based on their scale values, the varieties were categorized as immune (0), resistant (11–35), moderately resistant (36–55), moderately susceptible (56–75), and susceptible (76–99). In addition, genotype plus genotype-by-environment (GGE) interactions of scale values were analyzed through GGE Biplot and explained 97.65% of the total variation. The ranking of genotypes based on scale groups generally showed consistency with GGE Biplot results, but GGE Biplot offered a more detailed classification, especially for moderately susceptible varieties. The relationship between the two methods indicated the relative stability of variety reactions, as GGE Biplot analysis also considered genotype stability. In conclusion, the use of the newly developed scale for evaluating scald reactions in barley gives reliable results. In addition, identified resistant varieties can serve as valuable genetic resources for further breeding studies. [ABSTRACT FROM AUTHOR]

Context: Among biotic factors, bean anthracnose caused by Colletotrichum lindemuthianum (Sacc. & Magnus) Briosi & Cavara is one of the most destructive diseases of common bean (Phaseolus vulgaris L.). Resistance in common bean genotypes is controlled by anthracnose resistance loci (designated Co). Aims: The objective of this study was to evaluate the presence of Co resistance genes in common bean genotypes from Turkey and to examine promising genotypes as candidates for parent plants in breeding studies. Methods: The presence of Co resistance genes in 693 common bean genotypes from 35 provinces of Turkey was determined by 12 SCAR (sequence characterised amplified region), RAPD (random amplified polymorphic DNA), STS (sequence-tagged site) and CAPS (cleaved amplified polymorphic sequence) markers. The disease reaction of 40 agronomically promising genotypes to different pathogen isolates was evaluated in a pot study. Key results: The results indicated the presence of Co-1 , Co-1 4 , Co-1 5 , Co-2 , Co-3 3 , Co-4 , Co-4 2 , Co-6 , Co - 10 , Co - 11 and Co - 13 resistance genes, alone or in combination; Co - 5 was not detected in any of the genotypes. Among the genotypes, Co-1 5 was the most frequent resistance source, followed by Co-4 , Co-6 and Co-11 , respectively. Common bean genotypes carrying Co-1 4 , Co-2 , Co-3 3 , Co-11 and Co-13 have been identified for the first time in Turkish germplasm. Five genotypes carrying the various combinations of Co-1 , Co-1 5 , Co-4 , Co-6 , Co-10 , Co-11 and Co-13 were resistant to all isolates in pathogenicity tests. Conclusions: This study is the most comprehensive to date on Co genes linked to the resistance of common bean genotypes throughout Turkey and provides an important gene pool for breeding studies into bean anthracnose. Resistant genotypes identified will be useful as parent plants in resistance breeding studies. Implications: Resistance genotypes carrying different Co genes to bean anthracnose will contribute significantly to the disease management strategy. Host plant resistance is the most economical and environmentally friendly method of protection against plant disease. This study examined Co genes in Turkish common bean genotypes linked to resistance to bean anthracnose. The study provides an important gene pool for breeding studies and identifies genotypes resistant to the pathogen. [ABSTRACT FROM AUTHOR]

Angular leaf spot (ALS) caused by Pseudocercospora griseola is a major disease of french bean (Phaseolus vulgaris L.) worldwide. A good diversity of French bean is present in the Garhwal Himalayas of Uttarakhand, India, which is unexplored. The purpose of this study was to identify ALS-resistant accessions among local landraces of French bean in this region. One hundred seventy-six local accessions were collected from different villages of Garhwal, Uttarakhand. All the accessions were screened by four SCAR primers SN02 (Phg- 2), SAA19, SM02, SBA16 (Phg- 3), one STS primer TGA1.1 (Phg-1) and one SSR primer Pv-at006 (Phg- 5). All the accessions were also screened for ALS resistance under field condition in the years 2019 and 2020. The disease-resistant score was recorded on 1–9 scale. After field screening, 48 accessions (19 resistant, 24 moderately resistant and five susceptible) were selected for in-vitro screening under screen house condition. These 46 accessions were artificially inoculated by two different isolates of P. griseola P5 and P9, which are the most virulent pathotype characterized by microbiology lab, College of Forestry, Tehri, Uttarakhand. After in-vitro screening, seven accessions (GFB-25, GFB-26, GFB-30, GFB-32, GFB-93, GFB-97 and GFB-136) were found resistant to both the isolates P5 and P9. The P. griseola -resistant accessions may further be used in future breeding programmes to develop new and more resistant varieties of French bean against ALS. [ABSTRACT FROM AUTHOR]

Common bean (Phaseolus vulgaris L.) is the most important grain legume. Crop production of common bean is affected by a number of diseases, such as Rhizoctonia root rot, being detected worldwide. Herein, we aimed to genetically and pathologically characterize Rhizoctonia solani isolates obtained from different provinces in Turkey. Anastomosis groups (AG) and subgroups of isolates were identified based on the sequence analysis of the rDNA-ITS region. The most prevalent subgroup was AG-4 HGIII, according to BLAST analysis and the phylogeny of resultant sequences, followed by AG-4 HGI and AG-4 HGII, respectively. iPBS retrotransposons highly supported the phylogenetic tree and provided a high level of genetic variability among isolates to discriminate AG subgroups. The results indicated that the iPBS DNA marker system based on retrotransposons could be used to discriminate Rhizoctonia isolates relying on AG grouping. The virulence of the pathogen isolates changed from 3.67 to 5 based on the agar-plate assay on the susceptible cv. Gina. The reactions of thirty common bean cultivars were also evaluated against the most aggressive isolate in each subgroup. The reaction assay showed significant differences among both isolates and cultivars; the highest disease severity among cultivars was observed to AG-4 HGI, followed by AG-4 HGIII and AG-4 HGII, respectively. None of the cultivars showed resistance to all AG subgroups. Screening of AGs among the isolates and selecting cultivars are critical to managing Rhizoctonia disease due to the range of host suitability according to AG subgroups. • IPBS is as effective as DNA sequence analysis in distinguishing R. solani subgroups. • Among cultivars, AG-4 HGI showed the highest disease severity, followed by AG-4 HGIII, AG-4 HGII. • Seher Yıldızı, Sarıkız, Perolar were resistant to AG-4 HGII-HGIII, sensitive to HGI. [ABSTRACT FROM AUTHOR]

Experiment was conducted during 2012- 2014 to screen 41 green gram genotypes against anthracnose (Colletotrichum truncatum) under the effect of challenge inoculation both in vivo and in field at university research farm AB block, Gayespur and Jaguli, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India. Attempt was also made to evaluate the stability in yield and disease reactions under this specific biotic stress. Under in-vivo condition all the 38genotypes were found to be moderately resistant except three Sonali, PM-4 and Pusa- 1174 showed moderately susceptible reaction. Whereas, in field stability analysis showed that four genotypes TARM- 18, CZMK-1, PM-D5 and Sukumar were resistant, three genotypes were moderately susceptible (Sonali, PM-4 Pusa-1174) and 34 genotypes showed moderately resistant reaction. Whereas, among the 34 moderately resistant genotypes, 18 genotypes RMG-62, RVSM-14, NVL- 638, HUM-16, Utkarsha, CZMS-1, AKMN-09-02, ML-1464, KM12-29, AKM-10-13, PM-2, PUSA 0932, RMG- 975, IPM- 306-6, MB-37, IPM-3/2-2, ML-1741 appeared to be stable for disease reaction and yield with high regression co- efficient (bi>_1 ) and low deviation from regression. (s²di<1). [ABSTRACT FROM AUTHOR]

The most economically important disease of cultivated grapevines worldwide is powdery mildew caused by the biotrophic fungal pathogen Erysiphe necator . To integrate effective genetic resistance into cultivated grapevines, numerous disease resistance screens of diverse Vitis germplasm, including wild species, have been conducted to identify powdery mildew resistance, but the results have been inconsistent. Here, a new powdery mildew isolate that is infectious on grapevines, designated Erysiphe necator NAFU1 ( En. NAFU1), was identified and characterized by phylogeny inferred from the internal transcribed spacer (ITS) of pathogen ribosomal DNA sequences. Three classical methods were compared for the maintenance of En. NAFU1, and the most convenient method was maintenance on detached leaves and propagation by contact with infected leaves. Furthermore, controlled inoculations of En. NAFU1 were performed using detached leaves from 57 wild Chinese grapevine accessions to quickly evaluate powdery mildew resistance based on trypan blue staining of leaf sections. The results were compared with previous natural epidemics in the field. Among the screened accessions inoculated with En. NAFU1, 22.8% were resistant, 33.3% were moderately resistant, and 43.9% were susceptible. None of the accessions assessed herein were immune from infection. These results support previous findings documenting the presence of race-specific resistance to E. necator in wild Chinese grapevine. The resistance of wild Chinese grapevine to En. NAFU1 could be due to programmed cell death. The present results suggest that En. NAFU1 isolate could be used for future large-scale screens of resistance to powdery mildew in diverse Vitis germplasms and investigations of the interaction between grapevines and pathogens. [ABSTRACT FROM AUTHOR]

Cultivar selection is one of the most economically important decisions made by peanut producers. The development of genotypes capable of maintaining yield and quality under a wide range of conditions is important so that profitability can be maximized. Issues such as declining irrigation capacity and diseases limit production in parts of Texas. Efforts of the Texas AgriLife Peanut Breeding Program are to develop breeding lines with improved yield potential, total sound mature kernels (TSMK), and disease resistance. Cultivar trials were conducted in 2009, 2010, and 2011 to evaluate the performance of the cultivar Tamrun OL11. Trials were established in several different production areas under various field conditions and included the commercial standards Flavor Runner 458 and Tamrun OL07. Yields were similar for Flavor Runner 458 and Tamrun OL07 at 4538 and 4534 kg/ha, respectively; whereas, Tamrun OL11 averaged 4845 kg/ha ( P = 0.02). TSMK plus sound splits (SS) for Tamrun OL11 were 1.3% higher than Flavor Runner 458 and 2.4% higher Tamrun OL07. When comparing cultivars in fields with a history of severe Sclerotinia blight (caused by Sclerotinia minor) yield increases of 1240 and 2229 kg/ha were observed for Tamrun OL11 over Tamrun OL07 and Flavor Runner 458, respectively. Results from these studies illustrate the high yield potential and superior TSMK of Tamrun OL11. [ABSTRACT FROM AUTHOR]

Spot blotch caused by Bipolaris sorokiniana is a destructive disease of wheat worldwide. This study investigated the aggressiveness of B. sorokiniana isolates from different wheat-growing areas of Bolu province in Turkey on the cultivar Seri-82. Host susceptibility of 55 wheat cultivars was evaluated against the most aggressive isolate. Our results indicated that the cultivars Anafarta and Koç-2015 were the most resistant. A specific and sensitive qPCR assay was developed for detecting the pathogen in plant tissues and evaluating wheat plants with different resistance levels. Three primer sets, BsGAPDHF/BsGAPDHR, BsITSF/BsITSR, and BsSSUF/BsSSUR, were designed based on glyceraldehyde-3-phosphate dehydrogenase, internal transcribed spacers, and 18S rRNA loci of B. sorokiniana with detection limits of 1, 0.1, and 0.1 pg of pathogen DNA, respectively. The qPCR assay was highly sensitive and did not amplify DNA from the other closely related fungal species and host plants. The protocol differentiated wheat plants with varying degrees of resistance. The assay developed a useful tool for the quantification of the pathogen in the early stages of infection and may provide a significant contribution to a more efficient selection of wheat genotypes in breeding studies. In the present study, expression levels of PR proteins, phenylalanine ammonia-lyase, catalase, ascorbate peroxidase, and superoxide dismutase enzymes were upregulated in Anafarta (resistant) and Nenehatun (susceptible) cultivars at different post-infection time points, but more induced in the susceptible cultivar. The results showed considerable variation in the expression levels and timing of defense genes in both cultivars. [ABSTRACT FROM AUTHOR]

Isolates of X. campestris pv. sesami used in the present work behaved almost similarly on the basis of their morphological, biochemical and physiological characterization. The studies failed to differentiate any strains within the isolates. Pathogenicity of the isolates to sesame plants was proved by inoculation experiments. When other plant species were inoculated infection did not occur. The levels of resistance of some naturally selected sesame cultivars were investigated following artificial infection with the pathogen. Seven cultivars proved resistant, three (cvs Tozi 3, S-76F2-22 and K 112) were highly resistant.. [ABSTRACT FROM AUTHOR]