Establishing inoculum threshold levels for Bean common mosaic virus strain blackeye cowpea mosaic infection in cowpea seed

Bean common mosaic virus strain blackeye cowpea mosaic (BCMV-BlCM) is an important seed-borne virus infecting cowpea and is transmitted both by seeds and aphids. Infected cowpea seeds can act as primary source of inoculum for disease epidemics. Four field experiments were conducted during 2003 - 2006 to assess the role of different amounts of seed-borne inoculum in the dissemination of BCMVBlCM virus in cowpea under field conditions. The identity of BCMV-BlCM was confirmed by ELISA and IC-RT-PCR. Plants infected at an early growth stage appeared to serve as the primary source for subsequent virus spread by aphids. The mean disease incidence during four field experiments reached88-93% in plots sown with 10% infected seed. The disease incidence in plots sown with 5% infected seed recorded 46-63% while for plants raised from 3 and 2% BCMV-BlCM seed infection, disease incidence reached 32-49% and 17-23%, respectively. Mean yield losses in terms of seed yield per plant from four field experiments were 74 and 54% for initial seed infection of 10 and 5%, respectively. Seed infection of 2% BCMV-BlCM incidence resulted in an average of 24% mean seed yield loss/plant-1. The infection appeared to decrease the seed yield in terms of number and size. The BCMV incidence in harvested seed ranged from 0.3 - 19% for the different levels of initial seed infection. The field experiments demonstrated that sowing > 1% BCMV-BlCM infected seed can lead to significant losses in grain yield, while the spread of BCMV-BlCM infection resulting from sowing 1% infected seed did not significantly decrease seed yield. The role of establishing damage or inoculum thresholds from BCMVBlCM seed-borne infections is discussed in the present study.Keywords: Cowpea, potyvirus, seed-borne virus, thresholds, yield los

Context Matters: Intertextuality and Voice in the Early Modern English Controversy about Women

This dissertation examines three clusters of works from the early modern English controversy about women--the debate about the merits and flaws of womankind--in order to argue that authors in the controversy took advantage of the malleability of women's voices to address issues beyond the worth of women. I depart from standard treatments of the controversy by giving priority to the intertextual contexts among works that engage with one another. Attending to the intertextual elements of this genre reveals the metapoetic concerns of the authors and the way such authors fashion their feminine apologists as discursive agents in order to express those concerns. Chapter 1 examines Edward Gosynhyll's sixteenth-century works in tandem with Geoffrey Chaucer's The Legend of Good Women and "The Wife of Bath's Prologue and Tale," arguing that Gosynhyll's revisions of Chaucer--revisions embodied by the feminine apologists in the texts--are integral to his project of establishing the controversy genre as multivalent and dialectical. The resulting metacommentary examines in a new light the age-old rhetorical tradition of exemplarity, a persuasive tool used in diverse literary genres. Chapter 2 considers the way the anonymous play Swetnam the Woman-Hater uses cross-voicing and cross-dressing to establish the performative nature of controversy conventions. In doing so, the play argues for the social benefits of abandoning essentialist logic in favor of gender performance, as such performance makes the role of apologist available to men and women alike. This cluster reconsiders the very processes by which a person--male or female--can be known to others. Finally, I trace John Taylor's use of the marginal woman in his controversy works in order to demonstrate the extent to which Taylor makes these women instrumental in establishing his own poetic and social identity. This project contributes to studies on the English controversy as well as to the field of early modern women and women's writing by arguing that authors found the genre generally and the woman's voice specifically to be fit vehicles for articulating poetic agendas beyond the immediate task of debating the nature of womankind

Draft genome sequence of Sclerospora graminicola, the pearl millet downy mildew pathogen:Genome sequence of pearl millet downy mildew pathogen

Sclerospora graminicola pathogen is one of the most important biotic production constraints of pearl millet worldwide. We report a de novo whole genome assembly and analysis of pathotype 1. The draft genome assembly contained 299,901,251 bp with 65,404 genes. Pearl millet [Pennisetum glaucum (L.) R. Br.], is an important crop of the semi-arid and arid regions of the world. It is capable of growing in harsh and marginal environments with highest degree of tolerance to drought and heat among cereals (1). Downy mildew is the most devastating disease of pearl millet caused by Sclerospora graminicola (sacc. Schroet), particularly on genetically uniform hybrids. Estimated annual grain yield loss due to downy mildew is approximately 10?80 % (2-7). Pathotype 1 has been reported to be the highly virulent pathotype of Sclerospora graminicola in India (8). We report a de novo whole genome assembly and analysis of Sclerospora graminicola pathotype 1 from India. A susceptible pearl millet genotype Tift 23D2B1P1-P5 was used for obtaining single-zoospore isolates from the original oosporic sample. The library for whole genome sequencing was prepared according to the instructions by NEB ultra DNA library kit for Illumina (New England Biolabs, USA). The libraries were normalised, pooled and sequenced on Illumina HiSeq 2500 (Illumina Inc., San Diego, CA, USA) platform at 2 x100 bp length. Mate pair (MP) libraries were prepared using the Nextera mate pair library preparation kit (Illumina Inc., USA). 1 ?g of Genomic DNA was subject to tagmentation and was followed by strand displacement. Size selection tagmented/strand displaced DNA was carried out using AmpureXP beads. The libraries were validated using an Agilent Bioanalyser using DNA HS chip. The libraries were normalised, pooled and sequenced on Illumina MiSeq (Illumina Inc., USA) platform at 2 x300 bp length. The whole genome sequencing was performed by sequencing of 7.38 Gb with 73,889,924 paired end reads from paired end library, and 1.15 Gb with 3,851,788 reads from mate pair library generated from Illumina HiSeq2500 and Illumina MiSeq, respectively. The sequences were assembled using various assemblers like ABySS, MaSuRCA, Velvet, SOAPdenovo2, and ALLPATHS-LG. The assembly generated by MaSuRCA (9) algorithm was observed superior over other algorithms and hence used for scaffolding using SSPACE. Assembled draft genome sequence of S. graminicola pathotype 1 was 299,901,251 bp long, with a 47.2 % GC content consisting of 26,786 scaffolds with N50 of 17,909 bp with longest scaffold size of 238,843 bp. The overall coverage was 40X. The draft genome sequence was used for gene prediction using AUGUSTUS. The completeness of the assembly was investigated using CEGMA and revealed 92.74% proteins completely present and 95.56% proteins partially present, while BUSCO fungal dataset indicated 64.9% complete, 12.4% fragmented, 22.7% missing out of 290 BUSCO groups. A total of 52,285 predicted genes were annotated using BLASTX and 38,120 genes were observed with significant BLASTX match. Repetitive element analysis in the assembly revealed 8,196 simple repeats, 1,058 low complexity repeats and 5,562 dinucleotide to hexanucleotide microsatellite repeats.publishersversionPeer reviewe

Chitin oligomers and polyunsaturated fatty acids act synergistically in inducing resistance in pearl millet against downy mildew disease

Several glycosidic components from the cellwall of pathogenic fungi have been implicated in inducing plant defense response in many host-pathogen systems. Chitin oligomers, released from fungal cellwalls by endochitinase act also as immuno-modulators. Polyunsaturated fatty acids (PUFAs) have been already developed specifically against oomycete pathogens. Downy mildew of pearl millet, caused by Sclerospora graminicola, is a devastating disease, resulting in considerable losses in the semi-arid regions of the world. The efficacy of two combinations of chitin oligomers and PUFAs was examined in vitro and also under epiphytotic conditions in inducing downy mildew resistance in pearl millet. When applied to seeds in greenhouse experiments, chitin oligomers and PUFAs induced 64 and 69% protection, resp. Chitin oligomers-supplemented with PUFAs when applied in combination to pearl millet seeds followed by foliar spray offered higher protection against downy mildew (73%). Plants raised from treated seeds and challenge inoculated at the tillering and inflorescence stages showed disease resistance, resulting in higher grain yield compared to untreated plants. Kinetic anal. of endochitinase elicitation by chitin oligomers and PUFA treatment resulted in increased chitinase activity. The enzyme activity was initiated 6h after the treatment and pathogen inoculation and was maximum at 24 h. The chitin oligomers and PUFAs have the potentiality to develop into future candidate mols. as ecofriendly pesticides in inducing resistance against downy mildew. Many biowastes are now being considered to obtain chitin and PUFA-based compounds to develop com. biopesticides for future plant disease management

Selection of downy mildew resistant somaclones, from a susceptible B line of pearl millet

Plants regenerated from seed-derived callus of a PNMS 6B line of pearl millet (Pennisetum glaucum (L.) R. Br.) were evaluated for their resistance induced by somaclonal variation for downy mildew disease caused by Sclerospora graminicola (Sacc.) Schroter. Among the 201 lines regenerated, only 3 lines consistently proved highly resistant (free from disease incidence) for up to 5 generations; whereas, 17 lines were resistant (disease incidence ranging from 1 to 9%). Resistance was confirmed by testing the plants under both laboratory and field conditions. The plants were evaluated for their agronomic traits

Anti-oomycete compounds from ganoderma appalantum, a wood rot basidiomycete

Solvent extracts of 17 different basidiomycetes were tested for their ability to inhibit Sclerospora graminicola. Among those tested, only three basidiomycete crude extracts exhibited significant inhibition on pathogen sporulation, zoospore release and zoospore motility. In vitro, the chloroform extract of Ganoderma appalantum (3 mg mL-1) recorded a maximum sporangial inhibition of 52.5 and 82.0% zoospore release and 92.5% motility. Crude extracts of three different basidiomycete fungi were treated to pearl millet seeds and assessed for seed germination, seedling vigour and effectiveness against downy mildew disease under greenhouse conditions. None of the solvent extracts were found to be phytotoxic. Chloroform and petroleum ether extracts of G. appalantum (3 mg mL-1) proved to be the best by offering disease protection of 55.6 and 43.7%, respectively, followed by chloroform and petroleum ether extracts of Polyphorus spp., with 42.5 and 39.1% disease protection. The thin layer chromatography (TLC) spots that developed were eluted and tested for inhibition of S. graminicola zoosporangia. The partially purified compound from TLC chloroform extract of G. appalantum consistently showed good inhibitory effect against S. graminicola, which exhibited inhibition of sporangia (42.3%), zoospore release (76.7%) and zoospore motility (86.7%), compared to the chloroform control which offered only 1.9, 2.9 and 1.7% inhibition of sporangia, zoospore release and zoospore motility, respectively. The partially purified compound from petroleum ether extract of G. appalantum resulted in 38.0, 63.0 and 81.6% inhibition of sporangia, zoospore release and motility, respectively, compared to petroleum ether control. However, azoxystrobin 250 SC (2 g mL-1) and apron 35 SD (0.015 mg mL-1) treated on sporangial suspension showed the highest inhibition of S. graminicola pathogen compared to chloroform and petroleum ether TLC fractions

Cloning and development of pathotype-specific SCAR marker associated with sclerospora graminicola isolates from pearl millet

Downy mildew pathogen of pearl millet in India is associated with the spread of the highly virulent Sclerospora graminicola pathotype-1. Twenty-seven S. graminicola isolates were screened using 20 inter simple sequence repeats (ISSR). Dinucleotide repeat primer 17898A-(CA)(6) AC] amplified a similar to 600 bp fragment specific to five isolates of pathotype-1 (Sg 048, Sg 153, Sg 212, DM-11 and DM-90). The ISSR fragment linked with pathotype-1 was cloned successfully and sequenced. To convert ISSR fragments into pathotype-specific sequence characterised amplified region (SCAR) markers, PCR primers were designed using a sequence of the cloned DNA fragment. PCR amplification using SCAR primer pair (UOM3-Sg-Path1-F/R) amplified a single 284 bp band only in isolates of S. graminicola pathotype-1. This SCAR primer pair did not amplify the 284 bp product from the other five S. graminicola pathotypes or a negative control, which demonstrates primer specificity for pathotype-1. The SCAR primer pair (UOM3-Sg-Path1-F/R) obtained in this study will provide a valuable tool for rapid identification and specific detection of S. graminicola pathotype-1

Anti-oomycete compounds from Ganoderma appalantum, a wood rot basidiomycete

Solvent extracts of 17 different basidiomycetes were tested for their ability to inhibit Sclerospora graminicola. Among those tested, only three basidiomycete crude extracts exhibited significant inhibition on pathogen sporulation, zoospore release and zoospore motility. In vitro, the chloroform extract of Ganoderma appalantum (3 mg mL<SUP>−1</SUP>) recorded a maximum sporangial inhibition of 52.5 and 82.0% zoospore release and 92.5% motility. Crude extracts of three different basidiomycete fungi were treated to pearl millet seeds and assessed for seed germination, seedling vigour and effectiveness against downy mildew disease under greenhouse conditions. None of the solvent extracts were found to be phytotoxic. Chloroform and petroleum ether extracts of G. appalantum (3 mg mL<SUP>−1</SUP>) proved to be the best by offering disease protection of 55.6 and 43.7%, respectively, followed by chloroform and petroleum ether extracts of Polyphorus spp., with 42.5 and 39.1% disease protection. The thin layer chromatography (TLC) spots that developed were eluted and tested for inhibition of S. graminicola zoosporangia. The partially purified compound from TLC chloroform extract of G. appalantum consistently showed good inhibitory effect against S. graminicola, which exhibited inhibition of sporangia (42.3%), zoospore release (76.7%) and zoospore motility (86.7%), compared to the chloroform control which offered only 1.9, 2.9 and 1.7% inhibition of sporangia, zoospore release and zoospore motility, respectively. The partially purified compound from petroleum ether extract of G. appalantum resulted in 38.0, 63.0 and 81.6% inhibition of sporangia, zoospore release and motility, respectively, compared to petroleum ether control. However, azoxystrobin 250 SC (2 μg mL<SUP>−1</SUP>) and apron 35 SD (0.015 mg mL<SUP>−1</SUP>) treated on sporangial suspension showed the highest inhibition of S. graminicola pathogen compared to chloroform and petroleum ether TLC fractions