Puccinia Substriata Research Articles

Diseases prevalent in Kharif crops grown in Barmer district of Rajasthan, India

In the Kharif season, pearl millet (Pennisetum glaucum) is the predominant crop of the Barmer district followed by cluster bean (Cyamopsis tetragonoloba) and moth bean (Vigna aconitifolia). Sesame (Sesamum indicum) and green gram (Vigna radiata) are other important Kharif oilseed and pulse crops, respectively. A survey was conducted to determine the status of major diseases of Kharif crops grown in the Barmer district of the Marwar region of Rajasthan, India. Five blocks and three villages in each block were surveyed through a random field survey method during the collection of diseased samples every Sunday for the practical classes of agricultural students of the College of Agriculture, Baytu; in August and September 2023. Per cent disease incidence was recorded on randomly selected plants in a particular field of selected location. The incidence of diseases was observed based on typical field symptoms and later the association was confirmed through microscopic examinations in the laboratory. In survey, yellow mosaic (virus), leaf crinkle/ curl (virus), bacterial leaf spot/ blight (Xanthomonas phaseoli) of green gram;green ear/ downy mildew (Sclerospora graminicola), rust (Puccinia substriata) and blast (Pyricularia grisea) of pearl millet; Phytophthora stem blight (Phytophthora parasitica var. sesame) and phyllody (Phytoplasma) of sesame; yellow mosaic (virus)and bacterial leaf spot/ blight (Xanthomonas axonopodis pv. cyamopsidis) of cluster beanwere recorded with >50% incidence. However; charcoal rot (Macrophomina phaseolina), web blight (Rhizoctonia solani), Cercospora leaf spot (Cercospora canescens) and anthracnose (Colletotrichum lindemuthianum) of green gram; Alternaria blight/ leaf spot (Alternaria sesame) of sesame,sorghum rust (Puccinia purpurea) and Alternaria blight/ leaf spot (Alternaria cyamopsidis) of cluster beanwere noticed with 10 to 50% incidence.

Screening of Pearl Millet Lines against Downy Mildew Incited by Sclerospora graminicola (Sacc.) J. Schrot in Madhya Pradesh, India

Pearl millet (Pennisetum glaucum L.) is the oldest cultivated crop prone to attack by many pathogens viz., Sclerospora graminicola, Moesziomyces penicillariae and Puccinia substriata. The present investigation is on the management of the downy mildew pathogen by exploiting the resistance mechanism of the host. Out of 163 lines and two checks were tested against downy mildew disease. The germplasms were screened in the downy mildew sick plot. The finding exposes that 40 lines were never present of downy mildew and another 68 lines showed < 5% and > 10% downy mildew incidence was recorded in 23 lines and remaining 33 lines were recorded in the category of 5-10% incidence, while a maximum of 83.27 and 97.05% downy mildew incidence was noted in 7042-S at 30 and 60 days after sowing. When compared to all the test lines, the susceptible check 7042-S showed considerably greater incidence of downy mildew at 30 and 60 days. The present investigation suggests that the resistance in the Pearl millet germplasms can be exploited for the management of the pathogens and is an effective management practice with less use of inputs.

Evaluation of pearl millet R-line under field condition to identify resistance sources of foliar blast pathogen

Pearl millet (Pennisetum glaucum), an important staple food crop in the semi­arid tropics of the world, is infected by a number of diseases. Important among these are downy mildew (Sclerospora graminicola), blast (Pyricularia grisea), rust (Puccinia substriata var. indica). Ergot (Claviceps fusiformis) and smut (Moesiziomyces penicillariae) that individually or in combination cause substan­tial yield and quality losses. Effective and economic control of these diseases can be achieved by growing disease resistant varieties and hybrids. One hundred thirty potential R-lines were evaluated for blast resistance in the field. One hundreds eighteen lines identified as blast resistant (score ≤3.0 on 1–9 scale). These resistant lines would be useful in breeding blast resistant pearl millet hybrids.

Tapping Pennisetum violaceum, a Wild Relative of Pearl Millet (Pennisetum glaucum), for Resistance to Blast (caused by Magnaporthe grisea) and Rust (caused by Puccinia substriata var. indica).

Blast (Magnaporthe grisea) and rust (Puccinia substriata var. indica) are the two important foliar diseases of pearl millet (Pennisetum glaucum (L.) R. Br.) that can be best managed through host plant resistance. For identification of diverse sources of blast and rust resistance, 305 accessions of Pennisetum violaceum, a wild relative of pearl millet, were screened under greenhouse conditions against five pathotype-isolates of M. grisea and a local isolate of P. substriata var. indica collected from ICRISAT farm, Patancheru, India. Based on the mean blast score (1 to 9 scale), 17 accessions (IP 21525, 21531, 21536, 21540, 21594, 21610, 21640, 21706, 21711, 21716, 21719, 21720, 21721, 21724, 21987, 21988, and 22160) were found resistant (score ≤3.0) to all five pathotypes, and 24 accessions were resistant to four pathotypes of M. grisea. As there was variability for rust resistance within some accessions, individual rust-resistant (<5% severity) plants from 17 accessions were selected, grown in pots and advanced to next generation by selfing, and rescreened for three to four generations following pedigree selection to develop rust-resistant genetic stocks. Single plant selections from nine accessions (IP 21629, 21645, 21658, 21660, 21662, 21711, 21974, 21975, and 22038) were found highly resistant to rust (0% rust severity) after four generations of pedigree selection and subsequent screening. Some of the blast-resistant accessions and rust-resistant genetic stocks are being utilized in a prebreeding program at ICRISAT for introgressing resistance genes from the wild into the parental lines of cultivated and potential pearl millet hybrids and varieties.

Research trends in growth and productivity of pearl millet as influenced by biotic factors–A review†

The present review discusses that several diseases affect the growth and productivity of pearl millet such as downy mildew (Sclerospora graminicola) and rust (Puccinia substriata). Among these, downy mildew causes devastating problem in some pearl millet growing areas leading to a severe yield reduction. Some studies have been undertaken to investigate the gravity of the problems, epidemiology of the disease and control measures as well as genetic improvement of these diseases with reasonable successes, specially in the case of downy mildew. Besides several minor diseases affecting pearl millet are reported. Insects and weeds are of minor importance in pearl millet.

Response of locally adapted pearl millet populations to s1 progeny recurrent selection for grain yield and resistance to rust

In the semi-arid zones of Uganda, pearl millet ( Pennisetum glaucum (L.) R. Br.) is mainly grown for food and income; but rust ( Puccinia substriata var indica (L.) R. Br.) is the main foliar constraint lowering yield. The objective of the study was to genetically improve grain yield and rust resistance of two locally adapted populations (Lam and Omoda), through two cycles of modified phenotypic S 1 progeny recurrent selection. Treatments included three cycles of two locally adapted pearl millet populations, evaluated at three locations. Significant net genetic gain for grain yield (72 and 36%) were achieved in Lam and Omoda populations, respectively. This led to grain yield of 1,047 from 611 kg ha -1 in Lam population and 943 from 693 kg ha -1 in Omoda population. Significant improvement in rust resistance was achieved in the two populations, with a net genetic gain of -55 and -71% in Lam and Omoda populations, respectively. Rust severity reduced from 30 to 14% in Lam population and from 57 to 17% in Omoda population. Net positive genetic gains of 68 and 8% were also achieved for 1000- grain weight in Lam and Omoda, respectively. Traits with a net negative genetic gain in both populations were days to 50% flowering, days to 50% anthesis, days to 50% physiological maturity, flower-anthesis interval, plant height and leaf area. Key Words : Pennisetum glaucum, Puccinia substriata

QTL mapping of pearl millet rust resistance using an integrated DArT- and SSR-based linkage map

Rust, caused by the fungus Puccinia substriata var. indica, is one of the most important production constraints of pearl millet worldwide, leading to grain yield losses of up to 76 % as well as major losses in fodder yield and quality. Here, we report the development of a linkage map integrating Diversity Arrays Technology (DArT) markers and simple sequence repeat (SSR) markers, using this to identify quantitative trait loci (QTLs) for pearl millet rust resistance. Genotyping data from 256 DArT and 70 SSR markers on 168 F7 recombinant inbred lines from cross 81B-P6 × ICMP 451-P8 were used to construct a linkage map comprised of 286 loci (229 DArT and 57 SSR markers) spanning a total length of 740.3 cM (Haldane) with an average adjacent marker distance of 2.7 cM. Linkage group 7 (LG7) (153.5 cM) was the longest and LG6 the shortest (45.0 cM). The map was used to identify a major QTL for rust resistance with an LOD score of 27 on LG1, which explained 58 % of the observed phenotypic variation. In addition, two putative modifiers of small effect were detected, one each on LG4 and LG7. The novel rust resistance QTL identified on LG1 is thought to confer a durable slow-rusting phenotype, which is still effective in India more than 20 years after it was first deployed in the previously popular single-cross hybrid MH 179 (ICMH 451). The flanking markers reported here provide a framework for marker-assisted selection and possible future map-based cloning of this resistance gene.

English

Pearl millet (Pennisetum glaucum) is an important food and cash crop for many people living in the semi arid areas of Uganda. But information about the common diseases and their effect on yield is lacking yet it is important in designing a realistic and focused pearl millet breeding programme aimed at increasing yield. A disease survey was done in 2012 in the farmers&rsquo; fields in the predominantly pearl millet growing districts of Kumi and Katakwi in eastern and Kitgum and Lamwo in northern Uganda to identify the major diseases of pearl millet and establish their incidence, severity correlation and effect on grain yield. The aim of the study therefore was to identify the major pearl millet diseases that affect production in Uganda. In terms of incidence, rust (Puccinia substriata) (73.58%) was the most frequent disease followed by ergot (Claviceps fusiformis) (62.98%), then leaf blast (Pyricularia grisea) (61.25%) and smut (Moesziomyces penicillariae) (26.76%). However, in terms of severity, leaf blast (62.20%) was the most severe followed by rust (43.33%), ergot (29.46%) and smut (14.18%). Using SPSSv20, backward model reduction regression of disease parameters against grain yield, results show disease severities of rust, ergot, leaf blast and incidences of smut and rust were the most important in affecting grain yield. The correlation of disease severity with grain yield further indicated that ergot and rust severities were causes of the significant effect on yield. &nbsp; Key words: Pearl millet, diseases, severity, incidence, Uganda.

Salicylic acid confers resistance to a biotrophic rust pathogen, Puccinia substriata, in pearl millet (Pennisetum glaucum).

Studies were undertaken to assess the induction of defence response pathways in pearl millet (Pennisetum glaucum) in response to infection with the leaf rust fungus Puccinia substriata. Pretreatment of pearl millet with salicylic acid (SA) conferred resistance to a virulent isolate of the rust fungus, whereas methyl jasmonate (MeJA) did not significantly reduce infection levels. These results suggest that the SA defence pathway is involved in rust resistance. In order to identify pearl millet genes that are specifically regulated in response to SA and not MeJA, and thus could play a role in resistance to P. substriata, gene expression profiling was performed. Substantial overlap in gene expression responses between the treatments was observed, with MeJA and SA treatments exhibiting 17% co-regulated transcripts. However, 34% of transcripts were differentially expressed in response to SA treatment, but not in response to MeJA treatment. SA-responsive transcripts represented genes involved in SA metabolism, defence response, signal transduction, protection from oxidative stress and photosynthesis. The expression profiles of pearl millet plants after treatment with SA or MeJA were more similar to one another than to the response during a compatible infection with P. substriata. However, some SA-responsive genes were repressed during P. substriata infection, indicating possible manipulation of host responses by the pathogen.

Rust and Downy Mildew Resistance in Pearl Millet (Pennisetum glaucum) Mediated by Heterologous Expression of the afp Gene from Aspergillus giganteus

The cDNA encoding the antifungal protein AFP from the mould Aspergillus giganteus was introduced into two pearl millet (Pennisetum glaucum) genotypes by particle bombardment. Stable integration and expression of the afp gene was confirmed in two independent transgenic T0 plants and their progeny using Southern blot and RT-PCR analysis. In vitro infection of detached leaves and in vivo inoculation of whole plants with the basidomycete Puccinia substriata, the causal agent of rust disease, and the oomycete Sclerospora graminicola, causal agent of downy mildew, resulted in a significant reduction of disease symptoms in comparison to wild type control plants. The disease resistance of pearl millet was increased by up to 90% when infected with two diverse, economically important pathogens. This is the first report of genetic enhancement of Pennisetum glaucum against fungal infections.

Description of the Life-cycle of the Pearl Millet Rust Fungus–Puccinia substriata var. penicillariae with a Proposal of Reducing var. indica to a Synonym

Pearl millet (Pennisetum glaucum) is a major staple food crop in the drier parts of the old world, like Africa and India. Recently, its cultivation became more widespread in no-tillage crop farming systems in central Brazil, but it is also being used for cultivation during the dry season in other areas in Brazil. An emerging problem for the wider adoption of this crop in Brazil is the damage caused by the rust Puccinia substriata. This fungal disease is among the worst limitations for this crop worldwide. The rust occurring in Brazil was initially identified as the P. substriata var. penicillariae, but little information on the taxonomy and life-cycle of this rust is available in Brazil. The life-cycle of this rust variety remains somewhat obscure and the connection between the telial stage on pearl millet and the aecial stage on Solanaceae has never been experimentally demonstrated. Natural infection and inoculations under controlled conditions allowed for a complete description of all stages of this rust and the elucidation of its life-cycle, confirming that Solanum aethiopicum and Solanum melongena are aecial hosts. This coincidence for the alternate host and the limited and ambiguous morphological basis for the distinction of the varieties penicillariae and indica support the view that they are synonyms. Var. indica should be regarded as a late synonym of var. penicillariae.

Natural Infection of Eggplant by Puccinia substriata var. indica in the United States.

Eggplant (Solanum melongena) and other Solanum spp. are aecial hosts for Puccinia substriata var. indica, the rust pathogen of pearl millet (Pennisetum glaucum) (2). Although long suspected to be important in epidemic initiation (1), natural infection of eggplant has never been documented in the United States. All previous observations have been the result of deliberate inoculations. Eggplant (cv. Santana) seedlings with sporulating aecia were identified in the inventory of a vegetable transplant producer near Ty Ty, GA, on 22 April 1997. Flats of seedlings were being grown in a greenhouse with adjustable sides for creating an open-air environment for temperature control. Disease incidence was approximately 1.5% in the lot of 10,000 seedlings. Lesions were found most frequently on the first true leaf or less frequently on cotyledons. Aeciospores from 15 arbitrarily selected leaves were used to inoculate pearl millet seedlings in the greenhouse. Each leaf was used to inoculate pearl millet cultivars with no known resistance, and with the Rr1 resistance gene. Infection was obtained on all cultivars with no resistance genes, verifying pathogen identification. Fourteen isolates infected pearl millet with Rr1, revealing that virulence to Rr1 was common in this sample. The nearest point source of exposed pearl millet debris that could serve as a source of basidiospores was located approximately 9.7 km away from the eggplant.

Effects of Temperature and Light on Germination of Urediniospores of the Pearl Millet Rust Pathogen, Puccinia substriata var. indica.

Germination of urediniospores of Puccinia substriata var. indica was evaluated after 2, 4, 6, and 8 h of incubation in petri dishes containing 2% water agar under 10, 16, 20, 25, 30, and 35°C in light (1650 lux, cool white fluorescent), dark, alternate light-dark, and alternate dark-light. Less than 1% germination occurred at 35°C. At 30°C, percent germination did not significantly change after 4 h. At 10°C, percent germination increased with longer incubation. Under all illumination conditions, percent maximum germination after 4 to 8 h occurred at 20-25°C. Response surface analysis indicated that under all four illumination regimes, urediniospore germination greater than 90% occurs between 19 and 22°C after 6-7 h of incubation. Two hours of continuous light appeared to significantly delay germination, but exposure to light during the first hour of incubation was stimulatory when followed by 1 h dark.

Disease Resistance in WildPennisetumSpecies

Ninety-eight accessions of wild Pennisetum glaucum from the primary gene pool (1 o Pennisetums) and 27 species from the tertiary gene pool (3 o Pennisetums) of P. glaucum were evaluated for disease resistance. The 1 o Pennisetums were also evaluated for morphologic traits to further differentiate the accessions. The 1 o Pennisetums were evaluated for resistance to Pyricularia grisea, Puccinia substriata var. indica, and Moesziomyces penicillariae and also for height, diameter of the fifth internode, number of nodes, heading date, and panicle length and morphology (.)

Infection of and Colony Development within Leaves of Susceptible and Resistant Pearl Millet and Two Nonhosts by the Rust Fungus Puccinia Substriata Var. Indica

The rust fungus Puccinia substriata var. indica produced germ tubes, appressoria, and substomatal vesicles on seedling and mature leaves of susceptible and resistant pearl millet as well as two nonhost plants, corn and peanut. Lack of directional germ tube growth on peanut leaves appeared to affect the ability of germ tubes to successfully locate stomates. In seedling leaves of the susceptible cultivar Tift 23DB, the fungus produced an extensive system of intercellular hyphae and sporulated abundantly. In seedling leaves of the moderately resistant cultivar 86–8770, necrosis of host cells in response to fungal infection occurred by 2 days post-inoculation. Colonies gradually expanded in size and were associated with macroscopic necrotic flecks with sporulation occurring at 15% of the infection sites. In seedling leaves of the highly resistant cultivar Tift 85DB, fungal colonies were extremely limited in growth and did not sporulate. They were associated with intensely autofluorescent, necrotic host cells. Mature leaves of each cultivar were more resistant to fungal colonization than seedling leaves. Some colonies in mature leaves of Tifit 23DB were completely encompassed by necrotic cells and did not expand further. No sporulation was noted in mature leaves of 86–8770 or Tift 85DB. Fungal colonies were not successfully established in either nonhost. Thickening of plant cell walls at sites of attempted infection was noted in corn. In peanut, guard cells underneath fungal appressoria became autofluorescent.

Infection of and Colony Development within Leaves of Susceptible and Resistant Pearl Millet and Two Nonhosts by the Rust Fungus Puccinia substriata var. indica

Infection of and Colony Development within Leaves of Susceptible and Resistant Pearl Millet and Two Nonhosts by the Rust Fungus Puccinia substriata var. indica

Fungal development and host cell responses to the rust fungus Puccinia substriata var. indica in seedling and mature leaves of susceptible and resistant pearl millet

The rust fungus Puccinia substriata var. indica established a compatible relationship with host cells, characterized by large numbers of haustoria and an extensive system of intercellular hyphae, in seedling leaves of the susceptible pearl millet cultivar Tift 23DB. At some infection sites, however, necrotic host cells and papillae formed by plant cells adjacent to infection hyphae or haustorial mother cells were noted. In seedling leaves of the moderately resistant cultivar 86-8770, the initial interaction between host cells and the pathogen was quite variable and included successful haustorium formation as well as papilla deposition. Necrosis of host cells apparently developed as a gradual disorganization of the cytoplasm of invaded and surrounding host cells and occurred at all infection sites by 2 days postinoculation. In seedling leaves of the highly resistant cultivar Tift 85DB, haustoria were established at early stages of development, followed by a rapid necrosis response at 1 day postinoculation. Host cell disintegration was noted both before and after abnormalities in haustoria were observed. In mature leaves of all three cultivars, wall deposits were quite extensive at 12 h postinoculation. In addition, necrotic plant cells appeared rapidly in both susceptible and resistant cultivars. Both of these factors may have contributed to the increased resistance to fungal colonization observed in mature leaves. Key words: Puccinia substriata var. indica, pearl millet rust, host resistance, ultrastructure.

Disease Resistance and Morphologic Traits of Pearl Millet Landraces from South Burkina Faso

Disease resistance and morphologic traits of 106 landraces of pearl millet [Pennisetum glaucum (L.) R. Br.] collected in south Burkina Faso were evaluated to distinguish potentially different sources of resistance. Selfed (S1) plants were inoculated with isolates of Pyricularia grisea (Cooke) Sacc. (leaf spot), Puccinia substriata Ellis &amp; Barth. var. indica (rust), and Moesziomyces penicillariae (Bref.) Vánky (smut) collected in Georgia. Height and flowering dates of greenhouse‐grown S0 plants, S1 seed characteristics, and frequencies of chlorophyll‐deficient S1 seedlings were evaluated. Among landraces, the frequency of plants resistant to Py. grisea ranged from 51.9 to 99.1% (x = 82.5%). Frequencies of plants resistant to Pu. substriata ranged from 0 to 44.2% (x = 10.1%). Differences in resistance to M. penicillariae existed among the landraces. Percent smutted florets ranged from 0.8 to 8.4% (x = 4.2%). Seed set in the smut evaluation averaged 24.3% and was correlated with smut infection. In the greenhouse, S0 plant height and days to flowering averaged 2.3 m and 60.4 d, respectively. Seed color was generally light gray; seeds were typhoides shaped, with a mean 100‐seed weight of 1.20 g. Five clusters of phenotypic diversity were identified among the landraces by principal component and cluster analyses, and several potentially different sources of disease resistance were identified. Nine pairs of the landraces and an additional landrace clustered with one of the pairs may be duplicate accessions.

Diversity Among Pearl Millet Landraces Collected in Central Burkina Faso

Evaluation of genetic diversity within germplasm collections is important to plant breeders who desire sources of genes for particular traits. The S1 bulks of 103 landraces of pearl millet [Pennisetum glaucum (L) R. Br.] collected in central Burkina Faso, West Africa were evaluated for morphologic characteristics in an attempt to differentiate among the landraces. Seed shape, seed color, and 100 seed weight were evaluated. Maturity and height of field‐grown plants were assessed in 1987 and 1988, and panicle length and diameter were measured in 1988. Frequencies of chlorophyll‐deficient seedlings were determined. These descriptors, in addition to previously reported data of their resistance to Pyricularia grisea (Cke.) Sacc., Puccinia substriata Ell. &amp; Barth vat. indica Rach. &amp; Cumin., and Moesziomyces penicillariae (Bref.) Vanky, and seed set after inoculation with M. penicillariae were analyzed by Ward's cluster analysis. The landraces could be grouped into ten dusters of phenotypic diversity. There was some correspondence between the geographic collection sites of landraces and their inclusion in particular clusters. Analysis of morphologic and disease resistance descriptors was useful for identifying likely duplicates within the collection, and will facilitate identification of potentially different sources of desired traits.

A new variety of Puccinia substriata from Nigeria

Puccinia substriata var. decrospora nov.var. on Pennisetum americanum from Nigeria is described and illustrated.