Genetic Diversity, Identification and Utilization of Novel Genetic Resources for Resistance to Meloidogyne incognita in Mulberry (Morus spp.)

Plant Disease ◽  
2021 ◽  
Author(s):  
Gondi S Arunakumar ◽  
Belaghihalli Nanjappa Gnanesh ◽  
Haniyambadi B Manojkumar ◽  
Doss S. Gandhi ◽  
Mogili Thallapally ◽  
...  

Mulberry (Morus spp.) is an important crop in the sericulture industry as the leaves constitute the primary feed for the silkworm. The availability of diverse genetic sources of resistance to root- knot nematode (RKN; Meloidogyne spp.) are very scanty and therefore, a set of 415 varied exotic and indigenous germplasm accessions were screened under glasshouse conditions. Twenty one accessions were identified as highly resistant and 48 were resistant, the highest numbers of highly resistant/resistant accessions were found in Morus alba. Further, thirty accessions based on rooting ability were evaluated for field resistance at four different locations with infested soil. Finally, eight germplasm accessions; BR-8, Karanjtoli-1, Hosur-C8, Nagalur Estate, Tippu, Calabresa, Thai Pecah and SRDC-3 were identified as potential genetic sources in RKN resistance breeding programs or as resistant rootstock for the establishment of mulberry gardens. Sixteen SSR markers analyzed among the 77 resistant and susceptible accessions, generated 55 alleles, ranging from 2 to 5 with an average of 3.43 alleles per locus. Principle coordinate analysis grouped the accessions on the basis of RKN susceptible and resistant to a greater extent. The RKN susceptible accessions exhibited higher variability as compared to resistant accessions and they were more dispersed. Analysis of molecular variance showed that maximum molecular variance (78%) within the population and 22% between populations. Results of this study indicate that SSR markers are reliable for assessing genetic variability among the RKN resistant and susceptible mulberry accessions.

2012 ◽  
Vol 10 (3) ◽  
pp. 258-260 ◽  
Author(s):  
Mohar Singh ◽  
Z. Khan ◽  
Krishna Kumar ◽  
M. Dutta ◽  
Anju Pathania ◽  
...  

Fusarium wilt caused by Fusarium oxysporum, Schlecht. emend. Snyd. & Hans. f. sp. ciceri is prevalent in most chickpea-growing countries and is a major devastating disease. Host plant resistance is the most practical method of disease management. Indigenous chickpea germplasm reveals a heterogeneous genetic make-up and the response of resistance to wilt is an unexplored potential source for disease resistance. There are 70 indigenous germplasm lines selected on the basis of their agronomic performance and diverse areas of collections in the country. Of these, four accessions had a highly resistant score of 1 and six had a score of 3 using a 1–9 rating scale, indicating their level of resistance to Fusarium wilt (race 4). Other germplasm accessions of chickpea were found to be moderately resistant to highly susceptible disease reaction. Likewise, the same set of germplasm was also screened for Meloidogyne incognita (race 1) using pot culture under controlled condition. Only one accession was found to be resistant to this pest. These resistant gene sources can be utilised effectively for race-specific chickpea wilt and root-knot resistance breeding programmes.


Author(s):  
O. O. Kalinina ◽  
O. D. Golyaeva ◽  
O. V. Panfilova ◽  
А. V. Pikunova

Powdery mildew is one of the most harmful fungal diseases that causes economically significant damage to berry plantations. The disease is common in all areas of currant cultivation in the Russian Federation. In this regard, in modern conditions of intensive berry growing, the problem of breeding cultivars that are highly resistant to diseases and pests becomes urgent. Breeders have a difficult task to combine the adaptive potential of the cultivar with its annual high productivity and resistance to biotic environmental factors. When studying the adaptability of introduced cultivars of red currant and selected forms of the Institute to local soil and climate conditions, the following cultivars were identified as sources of economic and useful characteristics and involved in selection: ‘Belaya Potapenko’ as a complex source of resistance powdery mildew and high marketable and taste qualities of berries; SS 1426-21-80 as a source of high productivity and long racemes (raceme length 11-13 cm; up to 20 berries in the raceme). On their base the selection family of red currant has been developed: Belaya Potapenko × ♂SS 1426-21-80. The study of data on the destruction of hybrid seedlings of the selection family by powdery mildew showed that in epiphytotic conditions, the percentage of intensity of the disease development varies over the periods of screening from 0.2% in May to 20.4% in June. Such indicators served as a prerequisite for conducting a comparative test of breeding material in the field under artificial infection with powdery mildew. After artificial infection on the background of epiphytosis, the rate of intensity of the disease development increased slightly and amounted to 35.6% for the family. There were 30 highly resistant seedlings in the family, 10 of which have remained stable and highly resistant since 2018. In these plants we can assume the presence of the so-called field resistance, controlled by polygens, each of which does not give a visible effect of stability, but with different combinations determines one or another of its degree. Highly resistant seedlings will be used in further breeding studies to identify new sources of resistance to powdery mildew.


2011 ◽  
Vol 1 (1) ◽  
pp. 36-42
Author(s):  
K.K. Chaudhary ◽  
R. K. Kaul

Chilli (Capsicum annuum L.) crop is highly susceptible for the root knot nematode Meloidogyne incognita and every year this nematode causes great loss to the crop. The present study investigated the cumulative effect of two biocontrol agents viz. Pasteuria penetrans and Paecilomyces lilacinus against M. incognita. Two doses of P. penetrans i.e. 50g/Kg and 100g/Kg infested soil were applied either alone or in combination with two doses of P. lilacinus i.e. 4g spore culture/Kg and 6g spore culture/Kg of soil. Application of P. penetrans with P. lilacinus resulted into relatively better improvement in various growth attributes of chilli when compared with the individual application. Amongst the various treatments tested combined application with the higher dose of both bioagents (i.e. 100g P. penetrans infested soil with 6g of P. lilacinus/Kg) showed maximum improvement in fresh and dry weight of shoot and root over the nematode check and it was almost at par with that of the absolute check. The combined application of both the bioagents at higher dose resulted in 139 and 84% increase in dry weight of shoot and root over the nematode check respectively. The combined application of both the bioagents was also observed to cause higher reduction in gall number and nematode population than their individual application except for the treatment having lower dose of the P. penetrans with P. lilacinus where reduction in both the parameters was observed to be at par with that of the either dose of P. penetrans or higher dose of P. lilacinus. Combined application with higher dose of P. penetrans and P. lilacinus showed maximum reduction of 62.6 and 82.2% in gall numbers and nematode population over the nematode check.


2013 ◽  
Vol 11 (2) ◽  
pp. 131-139 ◽  
Author(s):  
D. Carputo ◽  
D. Alioto ◽  
R. Aversano ◽  
R. Garramone ◽  
V. Miraglia ◽  
...  

The evolutionary diversity of wild potato species makes them excellent materials for improving the narrow genetic basis of the cultivated potato Solanum tuberosum. Understanding their genetic diversity is important not only to choose the best parents for breeding, but also to design proper crossing schemes and selection strategies. The objectives of this study were to determine the resistance response to Ralstonia solanacearum, Potato virus Y and low temperatures of 21 clones of 12 potato species, and to determine their genetic diversity through simple sequence repeat (SSR) markers. Sources of resistance have been found for all the investigated traits, with high resistance variability not only between but also within species. Combined resistances were also identified, with positive implications for efficient breeding. SSR analysis allowed the detection of 12 loci and 46 alleles across all genotypes, with an average value of 3.8 alleles per locus. Both unique and rare alleles useful for marker-assisted selection were found. SSR-based cluster analysis revealed that resistant genotypes were distributed among all clusters, suggesting that genetically different resistant genotypes were identified. The information obtained in this study is discussed from a breeding perspective.


2019 ◽  
Vol 56 (1) ◽  
pp. 30-41 ◽  
Author(s):  
N. Thligene ◽  
G. N. Mezzapesa ◽  
D. Mondelli ◽  
A. Trani ◽  
P. Veronico ◽  
...  

SummaryPlant parasitic nematodes (PPN) are important pests of numerous agricultural crops especially vegetables, able to cause remarkable yield losses correlated to soil nematode population densities at sowing or transplant. The concern on environmental risks, stemming from the use of chemical pesticides acting as nematicides, compels to their replacement with more sustainable pest control strategies. To verify the effect of aqueous extracts of the agro-industry waste coffee silverskin (CS) and brewers’ spent grain (BSG) on the widespread root-knot nematode Meloidogyne incognita, and on the physiology of tomato plants, a pot experiment was carried out in a glasshouse at 25 ± 2 °C. The possible phytotoxicity of CS and BSG extracts was assessed on garden cress seeds. Tomato plants (landrace of Apulia Region) were transplanted in an artificial nematode infested soil with an initial population density of 3.17 eggs and juveniles/mL soil. CS and BSG were applied at rates of 50 and 100 % (1L/pot). Untreated and Fenamiphos EC 240 (nematicide) (0.01 μL a.i./mL soil) treated plants were used as controls. Reactive oxygen species (ROS) and chlorophyll content of tomato plants were estimated during the experiment. CS extract, at both doses, significantly reduced nematode population in comparison to the untreated control, although it was less effective than Fenamiphos. BSG extract did not reduce final nematode population compared to the control. Ten days after the first treatment, CS 100 %, BSG 50 % and BSG 100% elicited the highest ROS values, which considerably affected the growth of tomato plants in comparison to the untreated plants. The control of these pests is meeting with difficulties because of the current national and international regulations in force, which are limiting the use of synthetic nematicides. Therefore, CS extracts could assume economic relevance, as alternative products to be used in sustainable strategies for nematode management.


Weed Science ◽  
2020 ◽  
Vol 68 (2) ◽  
pp. 125-133 ◽  
Author(s):  
Erik W. Ohlson ◽  
Michael P. Timko

AbstractCowpea witchweed [Striga gesnerioides (Willd.) Vatke] is a primary constraint of cowpea [Vigna unguiculata (L.) Walp.] production in West Africa. Previously, seven S. gesnerioides races were classified based upon host specificity and genotypic profiling. Because race number and distribution are dynamic systems influenced by gene flow, genetic drift, and natural selection, a thorough investigation of S. gesnerioides diversity and the effectiveness of known sources of resistance in cowpea is needed to develop varieties with durable and broad-spectrum Striga resistance. In this study, we screened seven cowpea lines against 58 unique S. gesnerioides populations collected from across nine West African countries. Individuals from 10 S. gesnerioides populations were genotyped with simple sequence repeat (SSR) markers. We identified six races of S. gesnerioides based on their parasitism of the seven cowpea lines with known differential resistance genotypes. No cowpea line was resistant to all 58 Striga populations and none of the Striga populations were able to overcome the resistance of all seven lines. A novel race, SG6, of the parasite collected from Kudu, Nigeria, was found to overcome more cowpea resistance genes than any previously reported race. SSR analysis indicates that Striga populations are highly differentiated and genetic relatedness generally corresponds with geographic proximity rather than their host compatibility. Due to the dearth of broad-spectrum resistance found among Striga-resistant cowpea lines, there exists a need to stack multiple Striga resistance genes in order to confer broad-spectrum and durable resistance.


1999 ◽  
Vol 89 (8) ◽  
pp. 613-617 ◽  
Author(s):  
N. R. Walker ◽  
T. L. Kirkpatrick ◽  
C. S. Rothrock

Controlled environments were used to study the relationship between the root-knot nematode (Meloidogyne incognita) and Thielaviopsis basicola on cotton. Temperature treatments were continuous 20, 24, and 28°C or two cyclic linear regimes with ranges of 14 to 32 or 18 to 28°C over 24 h. Cotton seeds were planted in fumigated soil infested with T. basicola, M. incognita, or both. After 42 days, pathogen effects on plant growth and pathogen development were evaluated. Histology was conducted on roots collected 14, 28, and 42 days after planting in the continuous 24°C treatment. Reductions in plant height-to-node ratio and total fresh weight were observed for soils infested with both pathogens compared with the control or with soils infested with either pathogen, except for M. incognita-infested soil at 28°C. T. basicola reduced root galling and reproduction of the nematode at all temperatures. Vascular discoloration caused by T. basicola was greater in the presence of M. incognita compared with that by T. basicola alone. At 2 and 4 weeks, histological studies showed that plants grown in all T. basicola-infested soils contained chlamydospore chains on the root surface and in cortical cells. The fungus was not observed inside the vascular cylinder. Roots from 4-week-old plants from soils infested with T. basicola and M. incognita showed fungal sporulation in vascular tissue and localized necrosis of vascular tissue adjacent to the nematodes. At 6 weeks, plants grown in soil infested with T. basicola alone exhibited no remaining cortical tissue and no evidence of vascular colonization by the fungus. Six-week-old plants grown in T. basicola + M. incognita-infested soils exhibited extensive vascular necrosis and sporulation within vascular tissue. These studies suggest that coinfection expands the temperature ranges at which the pathogens are able to cause plant damage. Further, M. incognita greatly increases the access of T. basicola to vascular tissue.


2014 ◽  
Vol 15 ◽  
pp. 128-138
Author(s):  
Bal K Joshi ◽  
Hari P Bimb ◽  
Gopal Parajuli ◽  
Bedanand Chaudhary

Molecular markers tightly linked to target gene have been identified in different chromosomes to impose the genetic selection. This paper summarizes the progress and achievement made in breeding for blast resistance rice based on DNA markers. At least 40 genes conferring resistance to blast isolates with multiple alleles have been described. Both dominant and recessive resistance alleles have been found in many rice landraces. Highly polymorphic and easily detectable SSR markers are being used in breeding for blast resistance. Bulked segregant analysis (BSA) is the simple method for tagging resistance gene by SSR markers. Quantitative trait loci (QTLs) have also been mapped and most of them are linked to qualitative genes. Simple sequence repeat (SSR) markers linked to the gene are being used to select plants possessing the desired trait and markers throughout the genome are being used to select plants that are genetically similar to recurrent parent. Using SSR markers it may be possible to select blast resistance genotypes at any stage of crop development from any small part of crop, to conduct many round of selection, to select without inoculums, without scoring, and without testing in hot spot or artificial inoculation. Molecular based blast resistance breeding work is necessary to initiate in Nepal focusing on resistance gene tagging in Nepalese rice landraces and utilization.


Plant Disease ◽  
2019 ◽  
Vol 103 (11) ◽  
pp. 2884-2892 ◽  
Author(s):  
Maria I. Purnamasari ◽  
William Erskine ◽  
Janine S. Croser ◽  
Ming Pei You ◽  
Martin J. Barbetti

Sclerotinia sclerotiorum and Leptosphaeria maculans are two of the most important pathogens of many cruciferous crops. The reaction of 30 genotypes of Camelina sativa (false flax) was determined against both pathogens. C. sativa genotypes were inoculated at seedling and adult stages with two pathotypes of S. sclerotiorum, highly virulent MBRS-1 and less virulent WW-1. There were significant differences (P < 0.001) among genotypes, between pathotypes, and a significant interaction between genotypes and pathotypes in relation to percent cotyledon disease index (% CDI) and stem lesion length. Genotypes 370 (% CDI 20.5, stem lesion length 1.8 cm) and 253 (% CDI 24.8, stem lesion length 1.4 cm) not only consistently exhibited cotyledon and stem resistance, in contrast to susceptible genotype 2305 (% CDI 37.7, stem lesion length 7.2 cm), but their resistance was independent to S. sclerotiorum pathotype. A F5-recombinant inbred line population was developed from genotypes 370 × 2305 and responses characterized. Low broad-sense heritability indicated a complex pattern of inheritance of resistance to S. sclerotiorum. Six isolates of L. maculans, covering combinations of five different avirulent loci (i.e., five different races), were tested on C. sativa cotyledons across two experiments. There was a high level of resistance, with % CDI < 17, and including development of a hypersensitive reaction. This is the first report of variable reaction of C. sativa to different races of L. maculans and the first demonstrating comparative reactions of C. sativa to S. sclerotiorum and L. maculans. This study not only provides new understanding of these comparative resistances in C. sativa, but highlights their potential as new sources of resistance, both for crucifer disease-resistance breeding in general and to enable broader adoption of C. sativa as a more sustainable oilseed crop in its own right.


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