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Khanal S, Gaire SP, Zhou XG. Kernel Smut and False Smut: The Old-Emerging Diseases of Rice-A Review. PHYTOPATHOLOGY 2023; 113:931-944. [PMID: 36441871 DOI: 10.1094/phyto-06-22-0226-rvw] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Kernel smut, caused by Tilletia horrida, is a disease characterized by the replacement of rice grains with black sooty masses of teliospores or chlamydospores. Kernel smut differs from rice false smut, caused by Ustilaginoidea virens, in the color of chlamydospores. False smut is characterized by globose, velvety spore balls ranging from orangish yellow to greenish black in color. Both kernel smut and false smut have been persistent but are considered minor diseases in many countries since they were discovered in the late 1870s to the 1980s due to their sporadic outbreaks and limited economic impacts. In recent years, however, kernel smut and false smut have emerged as two of the most economically important diseases in rice, including organic rice, in many countries, especially in the United States. The increased use of susceptible rice cultivars, especially hybrids, excessive use of nitrogen fertilizer, and short crop rotations have resulted in an increase in kernel smut and false smut, causing significant losses in grain yield and quality. In this article, we provide a review of the distribution and economic importance of kernel smut; our current understanding of the taxonomy, biology, and epidemiology of kernel smut; and the genomics of the kernel smut fungus as compared with false smut and its causal agent. We also provide an update on the current management strategies of pathogen exclusion, cultivar resistance, fungicides, biological control, and cultural practices for kernel smut and false smut of rice.
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Affiliation(s)
- Sabin Khanal
- Texas A&M AgriLife Research Center, Beaumont, TX 77713
| | | | - Xin-Gen Zhou
- Texas A&M AgriLife Research Center, Beaumont, TX 77713
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Kumari P, Azad C, Kumar RR, Kumari J, Aditya K, Kumar A. Defense Inducer Compounds Up-regulated the Peroxidase, Polyphenol Oxidase, and Total Phenol Activities against Spot Blotch Disease of Wheat. THE PLANT PATHOLOGY JOURNAL 2023; 39:159-170. [PMID: 37019826 PMCID: PMC10102565 DOI: 10.5423/ppj.oa.06.2022.0080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/01/2022] [Accepted: 11/24/2022] [Indexed: 06/19/2023]
Abstract
Spot blotch disease of wheat caused by Bipolaris sorokiniana (Sacc.) Shoem is considered as an economically important disease which affects all the growing stages of wheat crop. Therefore, it is important to search some effective management strategies against the spot blotch pathogen. Some synthetic elicitor compounds (salicylic acid, isonicotinic acid, and chitosan) and nano-particles (silver and aluminum) were tested against the pathogen to observe the change in biochemical activity and defense action of wheat plant against spot blotch disease. All the tested elicitor compounds and nano-particles showed a significant increase in activity of peroxidase, polyphenol oxidase (PPO), and total phenol over control. The highest increase in activity of peroxidase was recorded at 72 h from chitosan at 2 mM and 96 h from silver nano-particle at 100 ppm. Maximum PPO and total phenol activity were recorded from chitosan at 2 mM and silver nano-particle at 100 ppm as compared to pathogen-treated and healthy control. The lowest percent disease index, lowest no. of spots/leaf, and no. of infected leaves/plant were found in silver nano-particle at 100 ppm and chitosan at 2 mM, respectively. The use of defense inducer compounds results in significantly up-regulated enzymatic activity and reduced spot blotch disease. Therefore, chitosan and silver nano-particle could be used as alternative methods for the management of spot blotch disease.
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Affiliation(s)
- Puja Kumari
- Department of Plant Pathology, Bihar Agricultural University, Sabour Bhagalpur 813210,
India
| | - Chandrashekhar Azad
- Department of Plant Pathology, Bihar Agricultural University, Sabour Bhagalpur 813210,
India
| | - Ravi Ranjan Kumar
- Department of Molecular Biology and Genetic Engineering, Bihar Agricultural University, Sabour Bhagalpur 813210,
India
| | - Jyoti Kumari
- Department of Plant Pathology, Bihar Agricultural University, Sabour Bhagalpur 813210,
India
| | - Kumar Aditya
- Department of Plant Pathology, Bihar Agricultural University, Sabour Bhagalpur 813210,
India
| | - Amarendra Kumar
- Department of Plant Pathology, Bihar Agricultural University, Sabour Bhagalpur 813210,
India
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Bishnoi SK, He X, Phuke RM, Kashyap PL, Alakonya A, Chhokar V, Singh RP, Singh PK. Karnal Bunt: A Re-Emerging Old Foe of Wheat. FRONTIERS IN PLANT SCIENCE 2020; 11:569057. [PMID: 33133115 PMCID: PMC7550625 DOI: 10.3389/fpls.2020.569057] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/09/2020] [Indexed: 05/18/2023]
Abstract
Wheat (Triticum aestivum L.) crop health assumes unprecedented significance in being the second most important staple crop of the world. It is host to an array of fungal pathogens attacking the plant at different developmental stages and accrues various degrees of yield losses owing to these. Tilletia indica that causes Karnal bunt (KB) disease in wheat is one such fungal pathogen of high quarantine importance restricting the free global trade of wheat besides the loss of grain yield as well as quality. With global climate change, the disease appears to be shifting from its traditional areas of occurrence with reports of increased vulnerabilities of new areas across the continents. This KB vulnerability of new geographies is of serious concern because once established, the disease is extremely difficult to eradicate and no known instance of its complete eradication using any management strategy has been reported yet. The host resistance to KB is the most successful as well as preferred strategy for its mitigation and control. However, breeding of KB resistant wheat cultivars has proven to be not so easy, and the low success rate owes to the scarcity of resistance sources, extremely laborious and regulated field screening protocols delaying identification/validation of putative resistance sources, and complex quantitative nature of resistance with multiple genes conferring only partial resistance. Moreover, given a lack of comprehensive understanding of the KB disease epidemiology, host-pathogen interaction, and pathogen evolution. Here, in this review, we attempt to summarize the progress made and efforts underway toward a holistic understanding of the disease itself with a specific focus on the host-pathogen interaction between T. indica and wheat as key elements in the development of resistant germplasm. In this context, we emphasize the tools and techniques being utilized in development of KB resistant germplasm by illuminating upon the genetics concerning the host responses to the KB pathogen including a future course. As such, this article could act as a one stop information primer on this economically important and re-emerging old foe threatening to cause devastating impacts on food security and well-being of communities that rely on wheat.
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Affiliation(s)
| | - Xinyao He
- International Maize and Wheat Improvement Center, Texcoco, Mexico
| | | | - Prem Lal Kashyap
- ICAR-Indian Institute of Wheat and Barley Research, Karnal, India
| | - Amos Alakonya
- International Maize and Wheat Improvement Center, Texcoco, Mexico
| | - Vinod Chhokar
- Department of Bio and Nanotechnology, Guru Jambheshwar University of Science and Technology, Hisar, India
| | | | - Pawan Kumar Singh
- International Maize and Wheat Improvement Center, Texcoco, Mexico
- *Correspondence: Pawan Kumar Singh,
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Pandey V, Gupta AK, Singh M, Pandey D, Kumar A. Complementary Proteomics, Genomics approaches identifies potential pathogenicity/virulence factors in Tilletia indica induced under the influence of host factor. Sci Rep 2019; 9:553. [PMID: 30679765 PMCID: PMC6346058 DOI: 10.1038/s41598-018-37810-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 12/05/2018] [Indexed: 12/21/2022] Open
Abstract
Karnal bunt disease of wheat is incited by quarantine fungal pathogen T. indica. Till date, there is little information on the pathogenic mechanisms involved in Karnal bunt. In order to understand the molecular mechanisms of disease pathogenesis, highly aggressive T. indica TiK isolate was cultured in the presence of host factor extracted from developing spikes of wheat variety WH-542. Modulation in protein profile of mycelial proteins and secretome from TiK cultured in the absence and presence of host factor was analyzed by 2-DE. Fifteen and twenty nine protein spots were up-regulated/differentially regulated in the proteome of mycelial and secreted proteins, respectively and identified using MALDI-TOF/TOF. Identified proteins are involved in suppression of host defense responses, lignin degradation of plant cell wall, penetration, adhesion of pathogen to host tissues, pathogen mediated reactive oxygen species generation, hydrolytic enzymes, detoxification of host generated reactive oxygen species. Further, integration of proteomic and genomic analysis has led to candidate pathogenicity/virulence factors identification. They were functionally annotated by sequence as well as structure based analysis. In this study, complementation of proteomics and genomics approaches resulted in novel pathogenicity/virulence factor(s) identification in T. indica.
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Affiliation(s)
- Vishakha Pandey
- Department of Molecular biology and Genetic Engineering, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India
| | - Atul Kumar Gupta
- Department of Molecular biology and Genetic Engineering, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India.
| | - Manoj Singh
- Department of Molecular biology and Genetic Engineering, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India
| | - Dinesh Pandey
- Department of Molecular biology and Genetic Engineering, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India
| | - Anil Kumar
- Department of Molecular biology and Genetic Engineering, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India.
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Ren T, Hu Y, Tang Y, Li C, Yan B, Ren Z, Tan F, Tang Z, Fu S, Li Z. Utilization of a Wheat55K SNP Array for Mapping of Major QTL for Temporal Expression of the Tiller Number. FRONTIERS IN PLANT SCIENCE 2018; 9:333. [PMID: 29599793 PMCID: PMC5862827 DOI: 10.3389/fpls.2018.00333] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 02/28/2018] [Indexed: 05/19/2023]
Abstract
Maximum tiller number and productive tiller number are important traits for wheat grain yield, but research involving the temporal expression of tiller number at different quantitative trait loci (QTL) levels is limited. In the present study, a population set of 371 recombined inbred lines derived from a cross between Chuan-Nong18 and T1208 was used to construct a high-density genetic map using a Wheat55K SNP Array and to perform dynamic QTL analysis of the tiller number at four growth stages. A high-density genetic map containing 11,583 SNP markers and 59 SSR markers that spanned 4,513.95 cM and was distributed across 21 wheat chromosomes was constructed. A total of 28 single environmental QTL were identified in the recombined inbred lines population, and among these, seven QTL were stable and used for multi-environmental and dynamic analysis. These QTL were mapped to chromosomes 2D, 4A, 4D, 5A, 5D, and 7D, respectively. Each QTL explained 1.63-21.22% of the observed phenotypic variation, with an additive effect from -20.51 to 11.59. Dynamic analysis showed that cqTN-2D.2 can be detected at four growth stages of tillering, explaining 4.92-17.16% of the observed phenotypic variations and spanning 13.71 Mb (AX-109283238-AX-110544009: 82189047-95895626) according to the physical location of the flanking markers. The effects of the stable QTL were validated in the recombined inbred lines population, and the beneficial alleles could be utilized in future marker-assisted selection. Several candidate genes for MTN and PTN were predicted. The results provide a better understanding of the QTL selectively expressing the control of tiller number and will facilitate future map-based cloning. 9.17% SNP markers showed best hits to the Chinese Spring contigs. It was indicated that Wheat55K Array was efficient and valid to construct a high-density wheat genetic map.
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Affiliation(s)
- Tianheng Ren
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Yangshan Hu
- College of Life Science, Sichuan Agricultural University, Ya’an, China
| | - Yingzi Tang
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Chunsheng Li
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Benju Yan
- College of Life Science, Sichuan Agricultural University, Ya’an, China
| | - Zhenglong Ren
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Feiquan Tan
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Zongxiang Tang
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Shulan Fu
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Zhi Li
- College of Life Science, Sichuan Agricultural University, Ya’an, China
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A physiologically regulated multidomain cystatin of wheat shows stage-dependent immunity against Karnal Bunt (Tilletia indica). Appl Biochem Biotechnol 2012; 168:2344-57. [PMID: 23117416 DOI: 10.1007/s12010-012-9941-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Accepted: 10/05/2012] [Indexed: 10/27/2022]
Abstract
To identify novel components of basal resistance against the Tellitia indica of wheat, breeding for disease resistance was carried out on resistant and susceptible genotype of Karnal Bunt. The different members of wheat cystatin gene families were cloned, and their role in triggering differential resistance through co-expression was analyzed in our lab. The multidomain wheat cystatin (WCM) is a proteinase inhibitor characterized by cloning the gene from susceptible (WH542) and resistant genotype (HD 29). A WCM cDNA was isolated from both genotypes and sequenced. The WCM had a highly conserved N-terminal cystatin domain and a long C-terminal extension containing a second region, which exhibited similarity to the cystatin domain. The expression level was significantly (P > 0.001) higher in resistant compared to susceptible genotype at all the physiological stages of wheat spikes. In order to characterize the biochemical properties of WCM, the coding sequence was expressed in Escherichia coli using pET expression vector. The recombinant WCM was purified from soluble fraction of the cell extract by using affinity chromatography. WCM, with 23 KDa molecular mass, showed cysteine proteinase inhibitory activity against papain (Ki 3.039 × 10(-7) M) as determined by using BAPNA as substrate. Furthermore, it was able to arrest the fungal mycelial growth of T. indica. Hyphae growth was inhibited, and morphological changes such as swelling and fragmentation of the fungus were observed. Overall, these observations suggest an endogenous high expression of cystatin, possibly associated with the resistance of wheat against Karnal bunt.
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Gupta AK, Seneviratne JM, Joshi GK, Kumar A. Induction of MAP kinase homologues during growth and morphogenetic development of Karnal bunt (Tilletia indica) under the influence of host factor(s) from wheat spikes. ScientificWorldJournal 2012; 2012:539583. [PMID: 22547988 PMCID: PMC3322648 DOI: 10.1100/2012/539583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Accepted: 09/30/2011] [Indexed: 11/17/2022] Open
Abstract
Signaling pathways that activate different mitogen-activated protein kinases (MAPKs) in response to certain environmental conditions, play important role in mating type switching (Fus3) and pathogenicity (Pmk1) in many fungi. In order to determine the roles of such regulatory genes in Tilletia indica, the causal pathogen of Karnal bunt (KB) of wheat, semi-quantitative and quantitative RT-PCR was carried out to isolate and determine the expression of MAP kinase homologues during fungal growth and development under in vitro culture. Maximum expression of TiFus3 and TiPmk1 genes were observed at 14th and 21st days of culture and decreased thereafter. To investigate whether the fungus alters the expression levels of same kinases upon interaction with plants, cultures were treated with 1% of host factors (extracted from S-2 stage of wheat spikes). Such treatment induced the expression of MAPks in time dependent manner compared to the absence of host factors. These results suggest that host factor(s) provide certain signal(s) which activate TiFus3 and TiPmk1 during morphogenetic development of T. indica. The results also provides a clue about the role of host factors in enhancing the disease potential due to induction of MAP kinases involved in fungal development and pathogenecity.
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Affiliation(s)
- Atul K. Gupta
- Department of Molecular Biology and Genetic Engineering, College of Basic Sciences and Humanities, GBPant University of Agriculture and Technology, Pantnagar 263 145, India
| | - J. M. Seneviratne
- Department of Molecular Biology and Genetic Engineering, College of Basic Sciences and Humanities, GBPant University of Agriculture and Technology, Pantnagar 263 145, India
| | - G. K. Joshi
- Department of Biotechnology, HNB Garhwal University, Srinagar, Uttarakhand 246174, India
| | - Anil Kumar
- Department of Molecular Biology and Genetic Engineering, College of Basic Sciences and Humanities, GBPant University of Agriculture and Technology, Pantnagar 263 145, India
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Basal expression studies of cystatins during specific growth stages of wheat spikes for defining their possible role in differential and stage dependent immunity against Karnal bunt (Tilletia indica). Mol Biol Rep 2009; 37:1377-89. [PMID: 19347606 DOI: 10.1007/s11033-009-9520-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2008] [Accepted: 03/17/2009] [Indexed: 10/20/2022]
Abstract
Two genotypes showing differential immunity against Karnal bunt (Tilletia indica) were used to investigate the role of three members of cystatin gene family in growth stage dependent immunity in wheat (Triticum aestivum L.). Three members of cystatin gene family (WC1, WC2, and WC4) were cloned and sequenced. Analysis of sequenced data showed that there was 76-99% nucleotide and protein sequence identity between different genes of the wheat cystatin. In silico amino acid sequence analysis revealed the presence of a conserved signature pattern of residues and also the functional domains were presumed to be actively involved in imparting cysteine protease inhibition capability. The semi-quantitative and quantitative levels of these members were measured by means of RT-PCR, northern blotting, western blotting, and by ELISA techniques. The members of cystatin gene family were expressed in both resistant (HD 29) and susceptible genotypes (WH 542); however, the expression level was significantly (P < 0.001) higher in resistant compared to susceptible genotype at all the stages of wheat spikes. The patterns of expression of WC2, WC4 were similar except in the levels in S(1) and S(2) stages as it remained constant (P > 0.05) in contrary to WC1 family whose expression gradually increased from S(v) to S(2) stage. According to the intensity of the detected band in RT PCR, northern blot and western blot, WC1 family seems to be expressed more than the other gene families. The immunoassay results further showed that WC1 protein was abundantly expressed in resistant genotype and high expression was observed at the S2 stage as compared to susceptible genotype (P < 0.001) suggesting that low level of expression of WC1 in S2 stage is responsible for KB infection. The results of the present study clearly indicate the role of cystatin gene family in differential and stage dependent immunity against KB.
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Allen TW, Maples HW, Workneh F, Stein JM, Rush CM. Distribution and Recovery of Tilletia indica Teliospores from Regulated Wheat Fields in Texas. PLANT DISEASE 2008; 92:344-350. [PMID: 30769673 DOI: 10.1094/pdis-92-3-0344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Eight wheat fields from the Karnal bunt-regulated regions within Texas were grid sampled to gain a better understanding of the ecology and epidemiology of teliospores produced by the causal agent, Tilletia indica. Teliospores from 25-g aliquots of soil from each grid point were extracted using a size-selective sieving sucrose-centrifugation procedure. Teliospores were recovered from all eight fields and, in some cases, from every grid point within a field. Total teliospore numbers ranged from 0 to 1,305 per 25 g of soil. Over 70% of the total grid sampled points contained one or more teliospores. The relation between soil chemical and physical characteristics and teliospore numbers from each field was evaluated. In general, no consistent, significant trend could be made between soil factors and teliospore numbers. Geostatistics were used to analyze data from grid points and create contour maps. Teliospore distribution was aggregated in four of the fields, random in three of the fields, and discontinuous (neither random nor aggregated) in a single field. This is the first report of widespread distribution and high teliospore numbers from wheat field soils in the United States.
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Affiliation(s)
- T W Allen
- Texas Agricultural Experiment Station, Bushland 79012-0010
| | - H W Maples
- Texas Agricultural Experiment Station, Bushland 79012-0010
| | - F Workneh
- Texas Agricultural Experiment Station, Bushland 79012-0010
| | - J M Stein
- Plant Science Department, South Dakota State University, Brookings 57007
| | - C M Rush
- Texas Agricultural Experiment Station, Bushland
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Goates BJ, Jackson EW. Susceptibility of Wheat to Tilletia indica During Stages of Spike Development. PHYTOPATHOLOGY 2006; 96:962-966. [PMID: 18944051 DOI: 10.1094/phyto-96-0962] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ABSTRACT Karnal bunt of wheat is caused by the fungus Tilletia indica, which partially converts kernels into sori filled with teliospores. Despite minor overall yield and quality losses, the disease is of considerable international quarantine concern. Plant development stages reported susceptible to infection vary considerably. A study was designed to better define the susceptibility period by inoculating wheat spikes at different growth stages with naturally liberated secondary sporidia under optimal conditions for disease development. Spikes of a resistant and susceptible cultivar were inoculated at eight growth stages from awns emerging to soft dough. Spikes became susceptible only after emerging from the boot and continued to be susceptible up to soft dough stage at which low levels of disease occurred. Disease severity in both cultivars peaked when spikes were inoculated after complete emergence, but before the onset of anthesis. Disease levels tapered off gradually in spikes inoculated after anthesis. The results broaden the known susceptibility period of wheat to T. indica to include stages long after anthesis, and indicate that infection from airborne inoculum is not possible during boot or awns emerging stages, which are commonly referred to as the most susceptible stages.
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Carris LM, Castlebury LA, Goates BJ. Nonsystemic bunt fungi--Tilletia indica and T. horrida: a review of history, systematics, and biology. ANNUAL REVIEW OF PHYTOPATHOLOGY 2006; 44:113-33. [PMID: 16480336 DOI: 10.1146/annurev.phyto.44.070505.143402] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The genus Tilletia is a group of smut fungi that infects grasses either systemically or locally. Basic differences exist between the systemically infecting species, such as the common and dwarf bunt fungi, and locally infecting species. Tilletia indica, which causes Karnal bunt of wheat, and Tilletia horrida, which causes rice kernel smut, are two examples of locally infecting species on economically important crops. However, even species on noncultivated hosts can become important when occurring as contaminants in export grain and seed shipments. In this review, we focus on T. indica and the morphologically similar but distantly related T. horrida, considering history, systematics, and biology. In addition, the controversial generic placement and evolutionary relationships of these two species are discussed in light of recent molecular studies.
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Affiliation(s)
- Lori M Carris
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, USA.
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Rush CM, Stein JM, Bowden RL, Riemenschneider R, Boratynski T, Royer MH. Status of Karnal Bunt of Wheat in the United States 1996 to 2004. PLANT DISEASE 2005; 89:212-223. [PMID: 30795341 DOI: 10.1094/pd-89-0212] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
| | - Jeffrey M Stein
- Plant Science Department, South Dakota State University, Brookings
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Garrett KA, Bowden RL. An Allee Effect Reduces the Invasive Potential of Tilletia indica. PHYTOPATHOLOGY 2002; 92:1152-1159. [PMID: 18944239 DOI: 10.1094/phyto.2002.92.11.1152] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ABSTRACT The Karnal bunt pathogen, Tilletia indica, is heterothallic and depends on encounters on wheat spikes between airborne secondary sporidia of different mating types for successful infection and reproduction. This life history characteristic results in reduced reproductive success for lower population densities. Such destabilizing density dependence at low population levels has been described for a range of animals and plants and is often termed an Allee effect. Our objective was to characterize how the Allee effect might reduce the invasive potential of this economically important pathogen. We developed a simple population model of T. indica that incorporates an Allee effect by calculating the probability of infection for different numbers of secondary sporidia in the infection court. An Allee effect is predicted to be important at the frontier of an invasion, for establishment of new foci by a small population of teliospores, and when the environment is nonconducive for the production of secondary sporidia. Using estimated model parameter values, we demonstrated a theoretical threshold population size below which populations of T. indica were predicted to decline rather than increase. This threshold will vary from season to season as a function of weather variables and their effect on the reproductive potential of T. indica. Deployment of partial resistance or use of fungicides may be more useful if they push population levels below this threshold.
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