EFFECTS OF LATE BLIGHT RESISTANT POTATO CONTAINING RB GENE  ON THE SOIL MICROBES, PESTS AND PLANT DISEASES

Late blight caused by Phytophthora infestans is an important disease on potato. Several potato hybrids have been generated by crossing local varieties (Atlantic and Granola) with Katahdin SP951 which contains late blight resistance gene RB. Prior to release, these hybrids need to be evaluated for their environ-mental effects on non-target organisms and natural pests and diseases. The objectives of the study were to investigate the effect of LBR potato hybrids on beneficial soil microbes, pests and diseases. The trial was conducted in the confined field trial (CFT) in Lembang, West Java. The parental non-transgenic (NT) clones (Granola, Atlantic and Katahdin) and LBR hybrids (four clones of Atlantic x Katahdin SP951 hybrids; 10 clones of Granola x Katahdin SP951) were planted at a plant spacing of 30 cm x 70 cm. Fungicide applications were used as treat-ments (no spray, five and twenty times sprays). The experi-ment was arranged in a randomized completely block design with three replications. The parameters determined were popula-tions of N2 fixing and P solubilizing bacteria, soil C/N ratio as well as natural pests and diseases. The results showed that the transgenic LBR potato hybrids did not have negative effect on N fixing bacteria. The bacterial populations were around 1010-11 cells g-1 soil before planting, 1012 cells at 1.5 months after planting (MAP) and 108 cells after harvest. For P- solubilizing bacteria, their populations were 1010 cells before planting, 1012 cells at 1.5 MAP and 1011 cells g-1 soil after harvest. The soil C/N ratio of the transgenic plot was not statistically different compared to non-transgenic plot, i.e. 12-15 before planting, 10-11 at 1.5 MAP, and 10 after harvest in non-spray plot. Pests and diseases such as Alternaria solani, Liriomyza, potato tubber moth, aphid and mites on the transgenic and non-transgenic plots were statistically not different. The resistance score for A. solani was 7.2 (parental tansgenic) and 7.6 (parental non-transgenic); for Liriomyza it was 2.07 (parental transgenic) and 2.32 insect per plant (parental non-transgenic), the PTM was 0.63 (parental transgenic) and 0.73 insect per plant (parental non-transgenic), aphid and mites were 0.75 (parental transgenic) and 1.68 insects per plant (parental non-transgenic). The study indicated that LBR potato hybrids did not have any negative impacts on non-target organisms.

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Screening of Wild Potatoes Identifies New Sources of Late Blight Resistance

Plant Disease ◽

10.1094/pdis-06-20-1367-re ◽

2020 ◽

pp. PDIS-06-20-1367 ◽

Cited By ~ 2

Author(s):

Hari S. Karki ◽

Shelly H. Jansky ◽

Dennis A. Halterman

Keyword(s):

Late Blight ◽

Late Blight Resistance ◽

Wild Relatives ◽

Plant Diseases ◽

Clonal Lineage ◽

Wild Potato Species ◽

Detached Leaf ◽

Solanum Stoloniferum ◽

Cultivated Potatoes ◽

Excellent Source

Late blight (LB) of potato is considered one of the most devastating plant diseases in the world. Most cultivated potatoes are susceptible to this disease. However, wild relatives of potatoes are an excellent source of LB resistance. We screened 384 accessions of 72 different wild potato species available from the U.S. Potato GeneBank against the LB pathogen Phytophthora infestans in a detached leaf assay (DLA). P. infestans isolates US-23 and NL13316 were used in the DLA to screen the accessions. Although all plants in 273 accessions were susceptible, all screened plants in 39 accessions were resistant. Resistant and susceptible plants were found in 33 accessions. All tested plants showed a partial resistance phenotype in two accessions, segregation of resistant and partial resistant plants in nine accessions, segregation of partially resistant and susceptible plants in four accessions, and segregation of resistant, partially resistant, and susceptible individuals in 24 accessions. We found several species that were never before reported to be resistant to LB: Solanum albornozii, S. agrimoniifolium, S. chomatophilum, S. ehrenbergii, S. hypacrarthrum, S. iopetalum, S. palustre, S. piurae, S. morelliforme, S. neocardenasii, S. trifidum, and S. stipuloideum. These new species could provide novel sources of LB resistance. P. infestans clonal lineage-specific screening of selected species was conducted to identify the presence of RB resistance. We found LB resistant accessions in Solanum verrucosum, Solanum stoloniferum, and S. morelliforme that were susceptible to the RB overcoming isolate NL13316, indicating the presence of RB-like resistance in these species.

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Optimizing Plant Disease Management in Agricultural Ecosystems Through Rational In-Crop Diversification

Frontiers in Plant Science ◽

10.3389/fpls.2021.767209 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yan-Ping Wang ◽

Zhe-Chao Pan ◽

Li-Na Yang ◽

Jeremy J. Burdon ◽

Hanna Friberg ◽

...

Keyword(s):

Late Blight ◽

Host Resistance ◽

Control Plant ◽

Late Blight Resistance ◽

Plant Diseases ◽

Crop Diversification ◽

Agricultural Ecosystems ◽

Potato Varieties ◽

Plant Disease Management ◽

Disease Epidemics

Biodiversity plays multifaceted roles in societal development and ecological sustainability. In agricultural ecosystems, using biodiversity to mitigate plant diseases has received renewed attention in recent years but our knowledge of the best ways of using biodiversity to control plant diseases is still incomplete. In term of in-crop diversification, it is not clear how genetic diversity per se in host populations interacts with identifiable resistance and other functional traits of component genotypes to mitigate disease epidemics and what is the best way of structuring mixture populations. In this study, we created a series of host populations by mixing different numbers of potato varieties showing different late blight resistance levels in different proportions. The amount of naturally occurring late blight disease in the mixture populations was recorded weekly during the potato growing seasons. The percentage of disease reduction (PDR) in the mixture populations was calculated by comparing their observed late blight levels relative to that expected when they were planted in pure stands. We found that PDR in the mixtures increased as the number of varieties and the difference in host resistance (DHR) between the component varieties increased. However, the level of host resistance in the potato varieties had little impact on PDR. In mixtures involving two varieties, the optimum proportion of component varieties for the best PDR depended on their DHR, with an increasing skewness to one of the component varieties as the DHR between the component varieties increased. These results indicate that mixing crop varieties can significantly reduce disease epidemics in the field. To achieve the best disease mitigation, growers should include as many varieties as possible in mixtures or, if only two component mixtures are possible, increase DHR among the component varieties.

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First signs of late blight resistance in traditional native potatoes of Pasco—Peru, a preliminary assay

Agriculture & Food Security ◽

10.1186/s40066-021-00330-9 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Edith Zevallos ◽

Josue Inga ◽

Fernando Alvarez ◽

Karina Marmolejo ◽

Rocio Paitan ◽

...

Keyword(s):

Late Blight ◽

Potato Crop ◽

Natural Infection ◽

Late Blight Resistance ◽

Relative Effect ◽

Subsistence Farmers ◽

Pests And Diseases ◽

Broad Variety ◽

Blight Disease ◽

Moderately Resistant

Abstract Background The native Andean potatoes, despite their low yield, have a large diversity that is conserved by subsistence farmers in Peru, due to their culinary characteristics and other qualities. However, this diversity is threatened by the impacts of climate change, which would directly affect the food security of these people, and eventually ours. Among its qualities of resistance to pests and diseases, there could be a genetic source of resistance to late blight, one of the most damaging diseases of the potato crop in the world. In this assay, 103 native landraces collected from local farmers in the Pasco region of Peru were subjected to natural infection conditions with Phytophthora infestans to identify potential resistant landraces within them. Results The 103 landraces assessed showed a broad variety of responses and were classified as “resistant” (22%), “moderately resistant” (57%), and “susceptible landraces” (21%). A relative effect of the disease in the yield is also shown, which is already low for commercial intentions. Conclusion Within this representative sample of the native potato diversity of the Pasco region, at least 23 local varieties grown by subsistence farmers have resistance qualities against eventual late blight disease.

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South American species Solanum alandiae Card. and S. okadae Hawkes et Hjerting as potential sources of genes for potato late blight resistance

PROCEEDINGS ON APPLIED BOTANY GENETICS AND BREEDING ◽

10.30901/2227-8834-2020-1-73-83 ◽

2020 ◽

Vol 181 (1) ◽

pp. 73-83

Author(s):

O. A. Muratova (Fadina) ◽

M. P. Beketova ◽

M. A. Kuznetsova ◽

E. V. Rogozina ◽

E. E. Khavkin

Keyword(s):

Late Blight ◽

Wild Species ◽

Potato Cultivar ◽

Late Blight Resistance ◽

Potato Late Blight ◽

South American ◽

South American Species ◽

Pests And Diseases ◽

Sequence Characterized Amplified Region ◽

Interspecific Potato Hybrids

For several decades, wild species of Solanum L. section Petota Dumort. have been involved in potato cultivar breeding for robust resistance to pests and diseases. Potato late blight (LB) is caused by oomycete Phytophthora infestans (Mont.) de Bary, and the genes for race-specific resistance to P. infestans (Rpi genes) have been introgressed into cultivated potatoes by remote crosses and trans- or cisgenesis, first from S. demissum Buk. and, more recently, from other wild species, such as S. bulbocastanum Dun., S. stoloniferum Schlechtd. et Bché, and S. venturii Hawkes et Hjerting (according to the nomenclature by Hawkes, 1990). Most wild species already involved in breeding for LB resistance came from North and Central Americas: series Bulbocastana (Rydb.) Hawkes, Demissa Buk. and Longipedicellata Buk., and some Rpi genes of these species have been already characterized in much detail. Rpi genes of South American species, including the series Tuberosa (Rydb.) Hawkes, have not been sufficiently investigated. Among the latter, this study focuses on the Rpi genes of S. alandiae Card. and S. okadae Hawkes et Hjerting. Four accessions of S. alandiae, one accession of S. okadae and 11 clones of interspecific potato hybrids comprising S. alandiae germplasm from the VIR collection were PCR-screened using specific SCAR (Sequence Characterized Amplified Region) markers for eight Rpi genes. SCAR amplicons of five Rpi genes registered in this study were validated by comparing their sequences with those of prototype genes deposited in the NCBI Genbank. Among the structural homologues of Rpi genes found in S. alandiae and S. okadae, of special interest are homologues of CC-NB-LRR resistance genes with broad specificity towards P. infestans races, in particular R2=Rpi-blb3, R8, R9a, Rpi-vnt1 and Rpi-blb2 (94–99, 94–99, 86–89, 92–98 and 91% identity with the prototype genes, respectively). Our data may help to better understand the process of Rpi gene divergence along with the evolution of tuberbearing Solanum species, particularly in the series Tuberosa.

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Response of Local Potato Cultivars to Late Blight Disease (Phytophthora infestans (Mont.) de Bary) under Field Conditions

Agro Bali: Agricultural Journal ◽

10.37637/ab.v3i1.464 ◽

2020 ◽

Vol 3 (1) ◽

pp. 28-37

Author(s):

Rishav Pandit ◽

Ravi Bhatta ◽

Pooja Bhusal ◽

Basistha Acharya ◽

Subash Subedi ◽

...

Keyword(s):

Late Blight ◽

Phytophthora Infestans ◽

Disease Incidence ◽

Block Design ◽

Potato Cultivar ◽

Late Blight Resistance ◽

Potato Cultivars ◽

Late Blight Disease ◽

Blight Disease ◽

Moderately Resistant

Developing host resistance is an economic and long-term approach to disease management; however, resistance reactions that differ depending on the genotypes. Potato late blight is the devastating disease caused due to Phytophthora infestans (Mont.) de Bary. In order to identify late blight resistance in potato genotypes, seven local potato cultivars (Bardiya Rato Local, Bardiya Seto Local, Cardinal, Deukhuri Rato Local, Deukhuri Seto Local, Kailali Local and Khumal Ujjowal) were evaluated in randomized complete block design (RCBD) with three replications during October 2018 to January 2019 on naturally infested soils in Deukhuri, Dang, Nepal. Results showed that significantly the highest disease incidence (99.17%), and the highest disease severity (88%) were found on Cardinal followed by Deukhuri Rato Local (64%), and Deukhuri Seto Local (60%). Potato cultivar namely Khumal Ujjowal was moderately resistant, whereas Deukhuri Rato local and Deukhuri Seto Local were susceptible to late blight disease. Significantly the highest yield (12.67 t ha-1) was produced by Khumal Ujjowal followed by Bardiya Rato Local (10.78 t ha-1) and Bardiya Seto Local (9.40 t ha-1). The disease incidence and Area under disease progressive curve (AUDPC) value was negatively co-related with the tuber yield. The potato cultivar Khumal Ujjowal followed by Bardiya Rato Local were found moderately resistant to late blight disease in Deukhuri conditions. This study suggests that potato cultivar Bardiya Rato Local can be grown for higher tuber production in Dang and similar topographic regions.

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Response of Local Potato Cultivars to Late Blight Disease (Phytophthora infestans (Mont.) de Bary) under Field Conditions

Agro Bali: Agricultural Journal ◽

10.37637/ab.v3i1.556 ◽

2020 ◽

Vol 3 (1) ◽

pp. 28-37

Author(s):

Rishav Pandit ◽

Ravi Bhatta ◽

Pooja Bhusal ◽

Basistha Acharya ◽

Subash Subedi ◽

...

Keyword(s):

Late Blight ◽

Phytophthora Infestans ◽

Disease Incidence ◽

Block Design ◽

Potato Cultivar ◽

Late Blight Resistance ◽

Potato Cultivars ◽

Late Blight Disease ◽

Blight Disease ◽

Moderately Resistant

Developing host resistance is an economic and long-term approach to disease management; however, resistance reactions that differ depending on the genotypes. Potato late blight is the devastating disease caused due to Phytophthora infestans (Mont.) de Bary. In order to identify late blight resistance in potato genotypes, seven local potato cultivars (Bardiya Rato Local, Bardiya Seto Local, Cardinal, Deukhuri Rato Local, Deukhuri Seto Local, Kailali Local and Khumal Ujjowal) were evaluated in randomized complete block design (RCBD) with three replications during October 2018 to January 2019 on naturally infested soils in Deukhuri, Dang, Nepal. Results showed that significantly the highest disease incidence (99.17%), and the highest disease severity (88%) were found on Cardinal followed by Deukhuri Rato Local (64%), and Deukhuri Seto Local (60%). Potato cultivar namely Khumal Ujjowal was moderately resistant, whereas Deukhuri Rato local and Deukhuri Seto Local were susceptible to late blight disease. Significantly the highest yield (12.67 t ha-1) was produced by Khumal Ujjowal followed by Bardiya Rato Local (10.78 t ha-1) and Bardiya Seto Local (9.40 t ha-1). The disease incidence and Area under disease progressive curve (AUDPC) value was negatively co-related with the tuber yield. The potato cultivar Khumal Ujjowal followed by Bardiya Rato Local were found moderately resistant to late blight disease in Deukhuri conditions. This study suggests that potato cultivar Bardiya Rato Local can be grown for higher tuber production in Dang and similar topographic regions.

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Soil response to chemicals used in a field experiment

International Agrophysics ◽

10.2478/v10247-012-0080-0 ◽

2013 ◽

Vol 27 (2) ◽

pp. 151-158 ◽

Cited By ~ 6

Author(s):

S. Jezierska-Tys ◽

A. Rutkowska

Keyword(s):

Alkaline Phosphatase ◽

Enzymatic Activity ◽

Field Experiment ◽

Soil Microorganisms ◽

Block Design ◽

Soil Samples ◽

Alkaline Phosphatases ◽

Soil Response ◽

Negative Effect ◽

Set Up

Abstract The effect of chemicals (Reglone 200 SL and Elastiq 550 EC) on soil microorganisms and their enzymatic activity was estimated. The study was conducted in a field experiment which was set up in the split-block design and comprised three treatments. Soil samples were taken six times, twice in each year of study. The results showed that the application of chemicals generally had no negative effect on the number of soil microorganisms. The application of Reglone 200 SL caused an increase of proteolytic and ureolytic activity and affected the activity of dehydrogenases, acid and alkaline phosphatases in the soil. The soil subjected of Elastiq 550 EC was characterized by lower activity of dehydrogenases, protease, urease and alkaline phosphatase.

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Effects of Vector Maturation Time on the Dynamics of Cassava Mosaic Disease

Bulletin of Mathematical Biology ◽

10.1007/s11538-021-00921-4 ◽

2021 ◽

Vol 83 (8) ◽

Author(s):

F. Al Basir ◽

Y. N. Kyrychko ◽

K. B. Blyuss ◽

S. Ray

Keyword(s):

Time Delay ◽

Plant Density ◽

Plant Viruses ◽

Mosaic Disease ◽

Plant Diseases ◽

Cassava Mosaic Disease ◽

Maturation Time ◽

Negative Effect ◽

Dynamical Regimes

AbstractMany plant diseases are caused by plant viruses that are often transmitted to plants by vectors. For instance, the cassava mosaic disease, which is spread by whiteflies, has a significant negative effect on plant growth and development. Since only mature whiteflies can contribute to the spread of the cassava mosaic virus, and the maturation time is non-negligible compared to whitefly lifetime, it is important to consider the effects this maturation time can have on the dynamics. In this paper, we propose a mathematical model for dynamics of cassava mosaic disease that includes immature and mature vectors and explicitly includes a time delay representing vector maturation time. A special feature of our plant epidemic model is that vector recruitment is negatively related to the delayed ratio between vector density and plant density. We identify conditions of biological feasibility and stability of different steady states in terms of system parameters and the time delay. Numerical stability analyses and simulations are performed to explore the role of various parameters, and to illustrate the behaviour of the model in different dynamical regimes. We show that the maturation delay may stabilise epidemiological dynamics that would otherwise be cyclic.

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Growth and flowering of young cocoa plants is promoted by organic and nitrate-based fertiliser amendments

Experimental Agriculture ◽

10.1017/s0014479720000320 ◽

2020 ◽

pp. 1-21

Author(s):

Smilja Lambert ◽

Hussin bin Purung ◽

Syawaluddin ◽

Peter McMahon

Keyword(s):

Growth Rates ◽

Block Design ◽

Calcium Nitrate ◽

Agricultural Practices ◽

Aluminium Toxicity ◽

Gliricidia Sepium ◽

Available P ◽

Average Growth ◽

Organic Fertiliser ◽

Soil C

Summary Cocoa (Theobroma cacao) farmers in Sulawesi, Indonesia typically use subsidised, ammonium-based rice fertilisers that in combination with poor agricultural practices have resulted in soil acidification, loss of organic matter, aluminium toxicity and lower soil fertility. As a result, these soils are only marginally appropriate for replanting cocoa to boost production. A field experiment was performed to test alternative soil amendments for successful replanting of cocoa on these deficient soils. In a trial with a randomised block design, 6-month old seedlings, top-grafted with the local MCC02 clone, were planted under light Gliricidia sepium shade and after 3 months treated quarterly with two options of mineral fertilisers: either a customised fertiliser, consisting of Nitrabor (a combination of calcium nitrate and boron), dolomite, rock phosphate and KCl or a NPK/urea mix used by farmers, each supplied with or without ‘micronutrient’ rock salt, organic fertiliser and beneficial microorganisms or their culture medium, a mixture of chitin and amino acids (a total of 20 treatments). Over a 4-year period, the marginal mean rates of stem diameter increment and flowering score were higher in customised fertiliser than NPK/urea treatments. The average growth rate was highest in the first year and was increased by supplying organic fertiliser. A significant correlation (r = 0.22, p < 0.05) occurred between growth and available P, but concentrations of available P were higher in the NPK/urea plots, which also had lower mean growth rates. Combined supply of organic fertiliser and microbes increased available P, as well as growth rates, in both the customised and NPK/urea treatments. In contrast, NPK/urea-treated plots without these amendments demonstrated very low growth rates. The customised formulation was more effective with or without added organic fertiliser or inoculated microbes. Micronutrient supply stimulated flowering. Growth rates in trees supplied with NPK/urea were also promoted by micronutrients. Leaf flush production occurred in regular cycles and was unaffected by the nutrient amendments. After 3 years, the customised and organic fertiliser application increased soil pH and exchangeable Ca and Mg concentrations, although they remained below recommended levels for cocoa production. These treatments had little impact on soil C content (about 1.3%) which was also deficient. Exchangeable Al and total Zn concentrations were higher in soils amended with NPK/urea. The results of the trial provide evidence that utilisation of organic fertiliser in combination with customised nitrate-based formulations improves cocoa establishment, growth and soil properties and should be recommended as a replacement for the NPK/urea fertilisers traditionally used by farmers.

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