Red Rot Resistance Research Articles

CoC 25–An early maturing high-yielding and red rot-resistant sugarcane variety suitable for the East Coast Zone of India

Aim: To develop early duration high-yielding sugarcane variety coupled with resistance or tolerant to major disease (red rot) and insect pests (borer complex). Methodology: CoC 25 was developed from two parents (Co 85002 and HR 83-144) and evaluated in station trials, state multi-location trials (five locations) and zonal varietal trials of AICRP (S) trials (IVT, AVT-I, AVT-II and AVT ratoon in five locations). Simultaneously, this clone was screened for major pest and diseases. Results: Based on the superiority performance of CoC 25 in cane yield (21.50% higher) and sugar yield (22.72% higher), it was observed in AICRP trials over the national check variety CoC 01061. Cane yield superiority was 12.75% compared to check variety observed in state multi-location trials. The CoC 25 was found moderately resistant (3.6%) to red rot disease and less susceptible to early shoot borer (9.42%) and inter-node borers. Interpretation: The results of this study revealed that CoC 25 is superior in terms of cane yield, CCS yield and resistance to red rot disease and it is less susceptible to borers. It was released by SVRC and notified for commercial cultivation in Tamil Nadu and Puducherry. Key words: Cane yield, CCS yield, Red rot resistance, Sugarcane

Identification of QTLs and Candidate Genes for Red Crown Rot Resistance in Two Recombinant Inbred Line Populations of Soybean [Glycine max (L.) Merr.]

Identification of QTLs and Candidate Genes for Red Crown Rot Resistance in Two Recombinant Inbred Line Populations of Soybean [Glycine max (L.) Merr.]

Deciphering Winter Sprouting Potential of Erianthus procerus Derived Sugarcane Hybrids under Subtropical Climates.

Winter sprouting potential and red rot resistance are two key parameters for successful sugarcane breeding in the subtropics. However, the cultivated sugarcane hybrids had a narrow genetic base; hence, the present study was planned to evaluate the Erianthus procerus genome introgressed Saccharum hybrids for their ratooning potential under subtropical climates and red rot tolerance under tropical and subtropical climates. A set of 15 Erianthus procerus derived hybrids confirmed through the 5S rDNA marker, along with five check varieties, were evaluated for agro-morphological, quality, and physiological traits for two years (2018-2019 and 2019-2020) and winter sprouting potential for three years (2018-2019, 2019-2020, and 2020-2021). The experimental material was also tested against the most prevalent isolates of the red rot pathogen in tropical (Cf671 and Cf671 + Cf9401) and subtropical regions (Cf08 and Cf09). The E. procerus hybrid GU 12-19 had the highest winter sprouting potential, with a winter sprouting index (WSI) of 10.6, followed by GU 12-22 with a WSI of 8.5. The other top-performing hybrids were as follows: GU 12-21 and GU 12-29 with a WSI of 7.2 and 6.9, respectively. A set of nine E. procerus-derived hybrids, i.e., GU04 (28) EO-2, GU12-19, GU12-21, GU12-22, GU12-23, GU12-26, GU12-27, GU12-30, and GU12-31, were resistant to the most prevalent isolates of red rot in both tropical and subtropical conditions. The association analysis revealed significant correlations between the various traits, particularly the fibre content, with a maximum number of associations, which indicates its multifaceted impact on sugarcane characteristics. Principal component analysis (PCA) summarised the data, explaining 57.6% of the total variation for the measured traits and genotypes, providing valuable insights into the performance and characteristics of the Erianthus procerus derived hybrids under subtropical climates. The anthocyanin content of Erianthus procerus hybrids was better than the check varieties, ranging from 0.123 to 0.179 (2018-2019) and 0.111 to 0.172 (2019-2020); anthocyanin plays a vital role in mitigating cold injury, acting as an antioxidant in cool weather conditions, particularly in sugarcane. Seven hybrids recorded a more than 22% fibre threshold, indicating their industrial potential. These hybrids could serve as potential donors for cold tolerance and a high ratooning ability, along with red rot resistance, under subtropical climates.

Yield, Quality and Disease Resistance of Sugarcane Clones: A Field Evaluation

Evaluation and identification of sugarcane clones for different maturity groups is of paramount importance in sugarcane cultivation to get higher recoveries in sugar mills. A field experiment was conducted to evaluate the performance of early maturing sugarcane clones for red rot resistance, cane yield, CCS yield, and their contributing traits in order to idendify the superior clones. Observation on germination per cent, number of tillers (x1000/ha), number of millable cane (x1000/ha), stalk length (cm), stalk diameter (cm), single cane weight (kg), cane yield (t/ha), brix per cent, sucrose (%), purity (%), extraction CCS (%), and sugar yield (t/ha). From the results, it could be concluded that the early maturing clone, CoC 15336, was found to be the best among the test clones for sucrose per cent and sugar yield with resistance to red rot disease. Another clone, CoC 15340, was the next-best entry, with higher cane yield, CCS yield, and sucrose percent compared to the better standards. As a result, clones CoC 15338 and CoC 15336 were identified as the best promising entries and could be forwarded for further yield evaluation trials for release as a new sugarcane variety suitable for East Coast Zone of India.

Identification of <i>Rca2</i> and <i>Rpf1</i> resistance alleles in strawberry breeding forms of intervarietal hybrid origin

Background. The creation of varieties with genetic resistance to fungal pathogens is one of the most important directions in strawberry breeding. A promising direction of accelerated selection of valuable specimens is molecular screening for the presence in their genotype of diagnostic DNA markers, linked to target genes of agrobiological traits. Objectives of the work were determination of the allelic state of the Rca2 (resistance to anthracnose) and Rpf1 (resistance to red stele root rot) genes in selected strawberry forms to identify genotypes resistant to Colletotrichum acutatum Simmonds and Phytophthora fragariae var. fragariae Hickman.Material and methods. The object of research was breeding forms of strawberries of intervarietal hybrid origin. As a result of 22 crossing combinations, 61 selection forms were obtained, in which the allelic composition of resistance genes was studied. The Rca2 anthracnose resistance allele was identified by means of the STS-Rca2_240 marker. The Rpf1 red stele root rot resistance allele was identified with the help of SCAR-R1A marker. Results. At least one of the two genes was identified in 20 selected strawberry forms (32.8%). The STS-Rca2_240 marker was identified in 15 strawberry seedlings (22.9%) from six hybrid combinations ‘Vicoda’ × ‘Roxana’, ‘Florence’ × ‘Faith’, ‘Asia’ × ‘Aprica’, ‘San Andreas’ × ‘Monterey’, ‘Alisa’ × ‘Quicky’, ‘Quicky’ × ‘Olympia’). The SCAR-R1A marker was identified in five strawberry seedlings (8.2%) from four hybrid combinations (‘Privlekatelnaya’ × ‘Bylinnaya’, ‘Feyerverk’ × ‘Bylinnaya’, ‘Bylinnaya’ × ‘Feyerverk’, ‘Bylinnaya’ × ‘Olimpiyskaya nadezhda’). It has been established that all strawberry selected forms with identified marker fragments for resistance genes are characterized by a heterozygous combination of alleles.Conclusions. Promising sources of resistance alleles are strawberry selected forms: 2/1-24, 2/1-34 (‘Quicky’ × ‘Olympia’), 3/9-5 (‘Florence’ × ‘Faith’), 3/12-2, 3/12- 9 (‘Alisa’ × ‘Quicky’), 4/7-10, 4/7-19, 4/7-20 (‘Asia’ × ‘Aprica’), 5/2-26, 5/2-32 (‘San Andreas’ × ‘Monterey’), 9/ 1-11, 9/1-12, 9/1-13, 9/1-32, 9/1-37 ‘Vicoda’ × ‘Roxana’) in case of Rca2 gene; 72-24, 72-71 (Privlekatelnaya × Bylinnaya), 69-29 (‘Feyerverk’ × ‘Bylinnaya’), 62-41 (‘Bylinnaya’ × ‘Feyerverk’), 61-15 (‘Bylinnaya’ × ‘Olimpiyskaya nadezhda’) in case of Rpf1 gene.

QTL mapping and identification of candidate genes linked to red rot resistance in sugarcane.

The online version contains supplementary material available at 10.1007/s13205-023-03481-7.

Performance of Mid-late Sugarcane Clones in AICRP(S) Trials for Quality Traits and Red Rot Resistance

A field experiment was conducted to evaluate the performance of mid-late sugarcane pre-release clones for CCS yield and its contributing characters along with red rot disease resistance. Observation on brix per cent, sucrose (%), purity (%), extraction (%), fibre (%), CCS (%), cane yield (t/ha), and CCS yield (t/ha). From the results, it could be concluded that the mid-late maturing clone, CoC 14337, was found to be the best among the test clones for sucrose per cent and CCS yield along with resistance to red rot disease. Another clone, CoA 14323, was the next-best entry, with higher CCS yield, sucrose percent and red rot resistance, compared to the better standard. As a result, clones CoC 14337 and CoA 14323 were identified as the promising entries (clones) and could be forwarded for further yield evaluation trials before being released as a new sugarcane variety suitable for East Coast Zone of India.

Combining genomic selection with genome-wide association analysis identified a large-effect QTL and improved selection for red rot resistance in sugarcane.

Red rot caused by the fungus Colletotrichum falcatum is the main disease limiting sugarcane productivity in several countries including the major producer India. The genetic basis for red rot resistance is unclear. We studied a panel of 305 sugarcane clones from the Australian breeding program for disease response phenotype and genotype using an Affymetrix® Axiom® array, to better understand the genetic basis of red rot resistance. SNP markers highly significantly associated with red rot response (≤ 10-8) were identified. Markers with largest effect were located in a single 14.6 Mb genomic region of sorghum (the closest diploid relative of sugarcane with a sequenced genome) suggesting the presence of a major-effect QTL. By genomic selection, the estimated selection accuracy was ~0.42 for red rot resistance. This was increased to ~0.5 with the addition of 29 highly significant SNPs as fixed effects. Analysis of genes nearby the markers linked to the QTL revealed many biotic stress responsive genes within this QTL, with the most significant SNP co-locating with a cluster of four chitinase A genes. The SNP markers identified here could be used to predict red rot resistance with high accuracy at any stage in the sugarcane breeding program.

Analysis of the inheritance of the marker SCAR-R1A, linked to the Rpf1 red stele root rot resistance gene, in strawberry hybrid progeny

Background. Resistance to pathogens is an important breeding trait of a cultivar. Red stele root rot (Phytophthora fragariae var. fragariae Hickman) is a dangerous root disease. Revealing the patterns of resistance inheritance and identifying promising genotypes is an important stage in the development of strawberry cultivars resistant to red stele root rot. The purpose of the study was to identify patterns of inheritance for the SCAR-R1A marker, linked to the Rpf1 red stele root rot resistance gene, in the strawberry hybrid combinations.Materials and methods. The target materials were the strawberry cultivars ‘Bylinnaya’, ‘Olimpiyskaya Nadezhda’, ‘Privlekatelnaya’ and ‘Feyyerverk’, and hybrid seedlings of the cross combinations Bylinnaya × Olimpiyskaya Nadezhda, Bylinnaya × Feyyerverk, Olimpiyskaya Nadezhda × Bylinnaya, Privlekatelnaya × Bylinnaya, and Feyyerverk × Bylinnaya. The Rpf1 gene was identified with the marker SCAR-R1A.Results and conclusion. For the hybrid combination Bylinnaya × Olimpiyskaya Nadezhda, the percentage of seedlings with an Rpf1 resistance allele was 33.3%. For the combination Bylinnaya × Feyyerverk, their percentage was 37.2%; for Olimpiyskaya Nadezhda × Bylinnaya, 39.4%; for Privlekatelnaya × Bylinnaya, 39.6%; and for Feyyerverk × Bylinnaya, 36.2%. The average percentage of seedlings with an Rpf1 allele for the studied combinations was 37.1%. Assessment of the compliance between the observed segregation and theoretical one according to the χ2 criterion confirmed the monogenic character of the studied trait and the Mendelian ratio of inheritance frequencies for the marker fragments of the Rpf1 gene as 1 : 1. Therefore, all identified seedlings with an Rpf1 allele are characterized by a heterozygous genotype. Strawberry hybrids promising for breeding were identified: 62-41 (Bylinnaya × Feyyerverk), 65-17, 65-24 (Olimpiyskaya Nadezhda × Bylinnaya), and 69-29 (Feyyerverk × Bylinnaya).

Assessment of the adaptive potential of strawberry genotypes based on the development of endophytic microbiota and identified R-genes

The paper presents the results of a study of the strawberry genotypes (Fragaria L.) by characteristics of endophytic microbiota and genetic determinants of resistance to fungal pathogens. Highly adaptive genotypes were identified: F. virginiana Duch. ssp. platypetala, F. orientalis Los., F. ovalis Rydb., F. moschata Duch., 298-19-9-43, Urozhaynaya CGL, Flora, Privlekatelnaya and Troitskaya. These strawberry forms are characterized by a high frequency of testing of bacterial microbiota, which suppresses endophytic fungal pathogens. The wild strawberry F. virginiana Duch. ssp. platypetala is characterized by red stele root rot resistance (Rpf1 gene). Strawberry varieties Borovitskaya and Elianny are characterized by anthracnose resistance (Rca2gene).

English

The aim of this study was to screen the potential of locally grown sugarcane genotypes for red rot resistance and activity of native microbial strains against the pathogen. Field trials were conducted with 70 genotypes for consecutive years and results showed that only two genotypes viz., SSRI-1 and CO-0238 showed resistant behavior towards red rot of sugarcane. The red rot pathogen Colletotrichum falcatum Went was characterized and pathogenicity tests on two susceptible genotypes (NSG-59 and CPSG-2923) showed high virulence of SUCF04 isolate to develop severe disease lesions. The native rhizospheric microbiota was screened for microbial consortia exhibiting fine antifungal activity against the highly virulent pathogenic strain. The antagonism assay exposed that 10 bacterial isolates out of 46 showed great potential for antifungal activity. The selected bacterial isolates revealed 68–99% pathogen inhibition during the assay. The fungal strains with biological control potential inhibited the pathogen growth by 20–80% and a group of three strains with more than 50% antifungal activity were characterized. The molecular characterization of these microbes revealed that the isolates were belonging to Bacillus subtilus, Pseudomonas putida, Pseudomonas fluorescence, Trichoderma harzianum and several other important taxa. This study revealed that only two sugarcane genotypes were found as resistant against red rot pathogen, while most of the genotypes showed susceptible to moderately susceptible response. Moreover, the native residential microbiota associated with sugarcane exhibited great antifungal potential and can be utilized for disease protection and improved crop productivity. © 2021 Friends Science Publishers

Controlled Condition Testing (CCT): An Ideal High-Throughput Method for Screening of Pre-Release Clones and Progenies for Red Rot Resistance in Sugarcane

Resistance to red rot, a fungal disease caused by Colletotrichum falcatum is an important trait in sugarcane varietal development and commercial release. All the varieties in the advanced varietal trials are artificially screened for red rot resistance in the field on standing canes following plug method. However, rejection of the varieties at this stage due to red rot susceptibility causes huge losses in the selection process for 5–6 years. Hence, there was a need to screen progenies at an early stage of selection to overcome the rejection of promising sugarcane clones due to red rot susceptibility at later stages. ICAR-SBI has developed controlled condition testing (CCT), a rapid screening method to identify more number of red rot-resistant clones before the advanced varietal trial. In this study, we compared the effectiveness of plug and CCT methods in categorizing about 654 sugarcane clones over a period of 10 years. In both the methods, the clones were categorized into resistant (R), moderately resistant (MR), moderately susceptible (MS), susceptible (S) and highly susceptible (HS) and the frequencies were 3.52%, 44.50%, 26.45%, 13.46% and 12.08% in the plug method and 13.91%, 41.44%, 17.28%, 20.80% and 6.57% in the CCT method, respectively. The clones showed similar reactions of 56.52, 57.73, 27.17, 51.14 and 34.18% in both the methods, respectively. In general, the plug method favoured more MR reactions whereas the CCT method showed more of R reactions. In about 500 population from bi-parental crosses, both the methods had shown similar categorization for red rot reactions and the results are encouraging and favoured the usage of CCT method for rapid screening of large populations during early stages of sugarcane varietal development programme. The utilization of CCT method hastens the selection process for red rot resistance and indirectly increases the selection frequency of good quality varieties.

Expression Analyses of Resistance-Associated Candidate Genes During Sugarcane-Colletotrichum falcatum Went Interaction

Sugarcane, the essential sugar and biofuel crop cultivated in tropics and subtropics worldwide, faces uncertainty in sustainable production and yield due to various biotic and abiotic factors. Among them, the fungal disease red rot (Colletotrichum falcatum) is a devastating disease that results in loss to farmers' economic livelihood and elimination of cultivated varieties due to severe disease epidemics. Development of resistant varieties is a viable option for a sustainable crop cultivation. Studies in the past explored the sugarcane resistance mechanism that helped to understand the host defense and associated gene transcripts. In lieu of developing suitable markers associated with red rot resistance, we studied the temporal expression of nine selected red rot resistance-associated candidate gene transcripts in sugarcane × C. falcatum interaction on a set of sugarcane varieties after the pathogen challenge. The resulted expression analyses of the selected resistance-associated gene transcript showed differential expression during compatible and incompatible interactions. In the resistant variety, it showed efficient defense responses as early recognition and defense response to the red rot pathogen compared to the susceptible one. Further, the selected resistance-associated gene transcripts have the potential to be explored for use in screening sugarcane varieties for red rot resistance traits.

Use of RAPD and SCAR markers for identification of strawberry genotypes with red stele resistance genes Rpf1 and fruit rot resistance genes Rca2 in the hybrid progenies

ISHS IX International Strawberry Symposium Use of RAPD and SCAR markers for identification of strawberry genotypes with red stele resistance genes Rpf1 and fruit rot resistance genes Rca2 in the hybrid progenies

Exploring the Sources of Red Rot Resistance Available in National Breeding Gene Pool and their Potential Utilization for Sugarcane Improvement in India

The breeding gene pool maintained in ICAR-SBI, Coimbatore serves as the prime source for generating genetic variability for sugarcane varietal development in India. About 417 parents from five different zones of sugarcane cultivation in India, exotic hybrids and interspecific hybrids, were initially tested for their resistance against the tropical (mixed inoculums of the tropical pathotypes CF06 [Cf671] and CF12 [Cf94012]) of Colletotrichum falcatum, followed by the subtropical pathotype CF08 (Cf64) in order to identify stable red rot resistant parents. Among them, mixed inoculums of CF 06 and CF 12 were found more virulent than CF 8. The highest number (48 of 155) of resistant (R) or moderately resistant (MR) parents to the mixed virulent inoculums was from North West Zone (30.97%) followed by North Central and North East Zone (18 of 37), Peninsular Zone (16 of 134) and East Coast Zone (2 of 34). Only one exotic parent (CP 61–23) among the 18 was found to be MR to all the tested pathotypes of C. falcatum. Overall, the subtropical parents had higher proportion of R types due to high accumulation of stress tolerant genes, while the tropical parents had more susceptible types. In case of interspecific hybrids, nine out of 39 were moderately resistant to the subtropical pathotypes. Among the 417 parents screened, 83 parents were stable in their resistance against tropical and subtropical pathotypes. Since selection for red rot resistance may lead to low sucrose content, the potential parents having high sucrose combining red rot resistance were identified from different sources and efforts were made to collect other characters of breeding importance of these stable resistance parents. Red rot resistant parents identified in this study have a greater potential in breeding for red resistance in the sugarcane improvement in the country.

Knock-down of glucose transporter and sucrose non-fermenting gene in the hemibiotrophic fungus Colletotrichum falcatum causing sugarcane red rot.

Red rot caused by Colletotrichum falcatum, is one of the economically important disease of sugarcane and breeding for resistant varieties is considered to be the major solution to manage the disease. However, breakdown of red rot resistance become usual phenomenon due to development of newer races by culture adaptation on newly released varieties. Hence it is needed to characterize the genes responsible for pathogen virulence in order to take care of host resistance or to manage the disease by other methods. The transcript studies gave foundation to characterize the huge number of pathogenicity determinants and their role in pathogenesis. Here we studied role of two important genes viz., Glucose Transporter (GT) and Sucrose Non-Fermenting1 (SNF1) during pathogenesis of C. falcatum, which said to be involved in carbon source metabolism. Sugar metabolism has a vital role in disease progression of C. falcatum by regulating their cell growth, metabolism and development of the pathogen during various stages of infection. The present study was aimed to find out the role of GT and SNF1 genes in response to pathogenicity by RNA silencing (RNAi) approach. Knock-down of the target pathogenicity gene homologs in standard C. falcatum isolate Cf671 was carried out by amplifying sense and antisense fragments of targets individually using pSilent-1 vector. The expression cassette was cloned into the binary vector pCAMBIA1300 followed by fungal transformation through Agarobacterium mediated transformation. Resulted mutants of both the genes showed less virulence compared to wild type isolate. Simultaneously, both the mutants did not produce spores. Moreover, the molecular confirmation of the mutants displayed the expression of hygromycin gene with reduced expression of the target gene during host-pathogen interaction. Knockdown of the pathogenicity related genes (GT and SNF1) by RNAi approach corroborate the possible role of the genes in causing the disease.

English

Resistance of sugarcane varieties to red rot disease is essential for their successful commercial cultivation in Pakistan. Evaluation of sugarcane germplasm for red rot resistance is a basic component of the varietal development system in Punjab. The studies on varietal screening against red rot disease of exotic sugarcane germplasm were conducted at the research farm of the Sugarcane Research Institute, Faisalabad from 2008–2009 to 2010–2011. The screening test was carried out at different varietal development stages including sugarcane nursery-2, nursery-3, semi-final varietal trial, final varietal trial and National Uniform Yield Trial by using plug method of inoculation. In three years, 724 sugarcane genotypes were examined in screening test against red rot disease, which were developed from germplasm (fuzz), imported from different sugarcane breeding organizations of the world. Fuzz is a true seed of sugarcane used to develop new sugarcane variety(ies) through repeated selection in any varietal development program. The results of three years experimentation revealed that 425 genotypes were resistant, 141 moderately resistant, 48 moderately susceptible and 110 susceptible to red rot disease. It was also concluded that sugarcane germplasm belongs to the USA, proved to be superior for resistance to red rot disease with 91% genotypes followed by Brazil and Australia with 86 and 68% genotypes, respectively, which were classified in resistant and moderately resistant category. © 2021 Friends Science Publishers

Host-pathogen interaction in sugarcane and red rot pathogen: exploring expression of phytoalexin biosynthesis pathway genes

Sugarcane crop, the major source of sugar is a high value commercial crop. The importance of the crop is growing as it has the potential to boost the green fuel production and various other eco-friendly products. The fungal disease, red rot (Colletotrichum falcatum) is a dreadful one and studying the dynamics of host-pathogen interaction is essential to develop disease resistant varieties. Earlier, the role of 3-deoxyanthocyanidin phytoalexins in red rot resistance was established. Further studies were made to assess antifungal activities of these compounds against C. falcatum through in vitro assays. Since phenyl propanoid biosynthesis pathway is the major secondary metabolite producing pathway which leads to production of flavonoids, isoflavonoids and lignin, studies were made to explore expression dynamics in major gene transcripts involved in anthocyanidin pathway by qRT-PCR. Our studies showed antifungal nature of the sugarcane phytoalexins 3-deoxy anthocyanidin compounds, apigeninidin and luteolinidin along with differential expression of transcripts involved in the phytoalexin biosynthesis pathway during compatible and incompatible interactions.

Red rot of sugarcane (Colletotrichum falcatumWent)

AbstractRed rot of sugarcane was recorded more than 100 years before in Java, India, Argentina, USA and other countries, and it is one of the most devastating diseases of sugarcane. Since the cultivated sugarcane (Saccharum officinarum) has failed across the countries, systematic inter-specific hybridization betweenS. officinarumand the wild speciesS. spontaneumreferred as ‘nobilization’ was done to develop resistant varieties and the disease was managed in most of the countries. However, in the countries especially in Asia, varietal breakdown to red rot caused severe epiphytotics, by which the resistant varieties failed in the field at regular intervals. New pathogenic strains ofColletotrichum falcatumwith higher virulence were found responsible for varietal breakdown in sugarcane. Extensive cultivation of a single variety over large areas led to extensive crop damages due to ‘vertifolia’ effect in different decades in India. The current epiphytotic on the ruling variety Co 0238 has caused loss of more than one billion US dollars in the current season in the country. Detailed studies were done on pathogenic variation, epidemiology, screening methods, disease resistance mechanism, identifying effectors, pathogenicity determinants, antifungal genes and transgenics. Recently, complete genome and transcriptomes ofC. falcatumwere sequenced and pathogenicity hot spots and candidate secreted effector proteins were identified and this will further help to identify the candidate genes for further genetic manipulation. In spite of poor understanding on inheritance of resistance toC. falcatumin sugarcane, new varieties with red rot resistance were developed and deployed after each of the epiphytotic to save the crop. Further, other management practices including bioagents, chemicals and inducers were attempted and improved efficacy by mechanized sett treatment showed promising results to manage the disease under field conditions.

Marker controlled screening of resistant to red stele root rot (Rpf1 gene) strawberry selected forms

The results of the analysis of allelic polymorphism of the Rpf1 red stele root rot resistance gene in strawberry hybrid forms using diagnostic DNA markers were shown. The recessive homozygous genotype (rpf1rpf1) was identified in strawberry seedlings 932-29 (F. virginiana subsp. platypetala (Rydb.) Staudt × Feyerverk), 933-4 (F. virginiana subsp. platypetala (Rydb.) Staudt × Rubinovyy kulon), 62-7, 62-23 (Bylinnaya × Feyerverk), 65-2, 65-15 (Olimpiyskaya nadezhda × Bylinnaya) and 35-16 (922-67 × Maryshka). The heterozygous state of the Rpf1 gene was identified in strawberry forms 69-29 (Feyerverk × Bylinnaya), 62-41 (Bylinnaya × Feyerverk), 72-24, 72-71 (Privlekatelnaya × Bylinnaya), 65-17, 65-24 (Olimpiyskaya nadezhda × Bylinnaya), which allows them to be used in breeding for resistance to P. fragariae var. fragariae as valuable initial forms.