Inheritance Of Resistance To Orobanche Cernua Loefl. In Six Sunflower Lines

Journal: Crop Science 39:674-678

ABSTRACT

Sunflower (Helianthus annuus L.) is severely affected by broomrape (Orobanche cernua Loefl.) in the main crop areas of the Old World. The appearance of new virulent broomrape populations has prompted the search for new sources of resistance. Objectives of this study were to elucidate the inheritance of sources of resistance from different origins and to determine allelic relationships between the resistance genes. Six resistant sunflower lines (one of them with resistance gene Or5), two susceptible lines, the F1 crosses between resistant and susceptible lines and resistant and resistant lines and the F2 and BC1 generations were evaluated for broomrape resistance using the widespread highly virulent population SE 194. Genetic ratios from segregating generations indicated that resistance to O. cernua in these lines was conferred by a single dominant gene. None of the crosses between resistant lines produced susceptible F2 or BC1 plants. However, the reaction of the resistant lines to broomrape populations from different areas and years showed differences to new highly virulent populations. Only two lines were resistant to all populations indicating that resistance in these lines was conferred by additional dominant alleles at the Or locus or by a cluster of very tightly linked non-allelic genes. The resistance found in the two cultivated lines against the new populations, which overcome the Or5 resistance gene, is an important finding to develop new resistant cultivars since the current resistant hybrids are based on this gene. Results from this study can also be used to establish differential lines against the new broomrape populations.

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Reproductive Behavior And Broomrape Resistance In Interspecific Hybrids Of Sunflower

Journal: Plant Breeding 117:279-285

ABSTRACT

Interspecific hybrids and backcross generations between the wild perennial species Helianthus resinosus, H. pauciflorus, H. laevigatus, H. nuttallii Subsp. nuttallii T. & G. and H. giganteus, resistant to broomrape (Orobanche cernua). and susceptible inbred lines were obtained to study crossability to cultivated sunflower and the transmission and expression of resistance to this parasitic weed. Conventional crosses with all the species tested were successful except for the crosses with diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F1 hybrids with hexaploid species and lowest for those with the diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F1 hybrids with hexaploid species and lowest for those with the diploid H. giganteus. We evaluated F1, BC1F1 some BC2 F1 plants and the wild and cultivated parents. The wild species and interspecific hybrids were resistant to broomrape infection except for H. nuttallii, which showed segregation, indicating that the resistance is dominant. The crossability and resistance of F1 and backcross generations of species with different ploidy levels indicate that the transfer of broomrape resistance to cultivated sunflower is feasible.

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Interspecific Hybridization Between Sunflower And Wild Perennial Helianthus Species Via Embryo Rescue

Journal: Euphytica 106:69-78

ABSTRACT

Interspecific crosses were made between the cultivated sunflower inbred line HA89 and accessions of the five wild perennial Helianthus species (H. giganteus L., H. laevigatus T.&G., H. resinosus Small., H. pauciflorus Nutt. and H. decapetalus L.) resistant to broomrape (Orobanche cernua Loefl.). Using the genetic male-sterile isogenic version of that line as female, successful reciprocal crosses were obtained with all the species except with H. decapetalus. Five-day-old hybrid embryos were excised and cultured in vitro. In all cases, few mature plants were obtained from embryos in early stages of development (early heart and globular) but up to 28 % mature plants were obtained from embryos in later stages of development. Very immature embryos were difficult to excise without damage. Hybrid embryos and mature plants were obtained from all the five wild species. Interspecific hybrid embryos from different wild species showed distinct developmental potentials, the proportion of hybrid embryos in different developmental stages varying among species. Differences in the proportion of hybrid embryos at the several developmental stages were also obtained for the reciprocal crosses (cultivated x wild), which showed higher proportion of fully developed embryos. Hybrids involving H. giganteus and cultivated sunflower were difficult to obtain without the use of embryo culture. Embryo culture proved to be an useful tool to overcome post-zygotic hybrid incompatibility in different Helianthus spp., and facilitated interspecific transfer of resistance to O. cernua.

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Temperature Effects On The Disease Reactions Of Sunflower To Infection By Orobanche Cernua

Journal: Plant Disease 85:553-556

ABSTRACT

Three virulent populations (CU194, SE193, and SE194) of the parasitic plant Orobanche cumana were inoculated onto four lines (KA-41, J-8281, HA-89, and RHA-273) of sunflower (Helianthus annuus L.). Pots were transferred to growth chambers set at 15, 19, 23, and 27°C. Emergence of broomrape plants and infection incidence were determinants of disease reaction. All broomrape populations were pathogenic to the sunflower lines KA-41, HA-89, and RHA-273, although differences in virulence were found. At 15 to 23°C, the populations of broomrape infected these three sunflower lines, but a delay in emergence of broomrape was found at 15°C; whereas, at 27°C, the level of infection was restricted. Only population CU194 infected the resistant line J-8281, with infection occurring mainly at 23 and 27°C, but few broomrape plants emerged. Our results suggest that the effect of temperature on the host-parasite relationship is complex. Additional keywords: differential lines, resistance genes.

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Screening of wild Helianthus species and derived lines for resistance to several populations of Orobanche cernua

Journal: Plant Disease. 80 (10): 1165-1169

ABSTRACT

Twenty-six different perennial species of Helianthus, 18 wild annual species of the some genus, and 29 lines tracing to wild species were evaluated for resistance to three highly virulent populations of broomrape (Orobanche cernua). Evaluations were carried out in pots containing soil mixture infested with broomrape seeds. Most of the perennial Helianthus species were immune to the populations of broomrape used in the tests. Some wild derived lines were resistant. The resistance found in the wild species, introgressed to cultivated sunflower, could provide unique resistance to the parasite.

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Scholarships and grants

FINAL REPORT

PROJECT TITLE: Identification And Characterization Of Resistance To Broomrape Of Sunflower

-Reference number: AIR-CT-93-6111
-Name of trainer: Serenella A. Sukno

-Summary of achievements and main conclusions.

We identify sources of resistance to highly virulent populations of Orobanche cernua, in both, from cultivated and from wild species of Helianthus. Immunity or a very high level of resistance to this population was observed. We characterize and transfer new sources of resistance to highly virulent races of broomrape from wild Helianthus species to cultivated sunflower .

The re-evaluations of our collection of wild Helianthus using a new highly virulent population of O. cernua confirm a high frequency of resistant entries among perennial wild species accessions in comparison to the annuals. In a previous work (Ruso et al., 1994) it was found that all the perennial entries tested were immune to two populations of broomrape. In the present study two accessions H. gracilentus and H. nuttallii ssp. nuttallii showed segregation for resistance. The results of evaluating annual species confirm the resistance of H. exilis and H. anomalus previously reported (Ruso et al.,1994). Moreover, another species, H. agrestis, not tested before was found to be resistant. The high levels of resistance found in many of the accessions, especially perennials, suggest the usefulness of wild sunflower species as sources of genes for resistance to O. cernua. The higher cross compatibility of the annuals with cultivated sunflower suggests these species are preferable in breeding programs. The resistance of the F1 plants between H. exilis and susceptible lines of cultivated sunflower indicate that the resistance to O. cernua, present in this species, is dominant. The segregation observed in one of the crosses suggests that all the resistance genes are not in homozygous condition in all the individuals of H. exilis. Unfortunately, the limited results of this study, do not allow us to interpret the segregation rate (19:3) found in the progeny of H. exilis 1 x P21. In order to elucidate it, backcrosses with the susceptible line are under testing. The results of the BC1 evaluation will determine the mode of inheritance of broomrape resistance found in this species.

The resistance found in H. exilis, could provide new genes of resistance against populations of O. cernua occurring in Spain as well as to new races overcoming current sources of resistance. The interspecific hybrids evaluated in our study indicate that it is possible to use this species to incorporate the resistance in H. exilis into cultivated sunflower. We conclude that it is possible to transfer broomrape resistance genes from wild annual species into cultivated lines in breeding programs for resistance to this disease. Interspecific hybridization has become important as a means of introducing resistant genes into the cultivated sunflower. This has been facilitated in wild perennials species by the use of embryo culture and chromosome doubling with colchicine to increase the fertility. We have obtained 9 interspecific hybrids with wild perennial sunflower including hybrids of the diploid species: H. gracilentus , H. nuttallii, H. giganteus, of the tetraploid H. hirsutus, and of the hexaploid species H. californicus, H. pauciflorus , H. resinosus. And the two supposed tetraploid that had been found hexaploid H. decapetalus and H. laevigatus, and the cultivated lines HA89 and P21. Four of them are resistant to broomrape and different generations of backcross are under testing. The other five interspecific hybrids, recently obtained, will be tested together with both parents (resistant and cultivated) in Spring of 1996. Our results like others suggest that seed set is higher when the wild specie is used as the pollen parent than when used as maternal parents. In this work we used the wild species as female. Although the cross is more difficult in this direction, the wild cytoplasm with its diversity is conserved. The introgression into cultivated sunflower of these genes of resistance could reduce genetic vulnerability to this disease and provide more genetic diversity to the narrow genetic base in cultivated material. For the long term future, introduction of boomrape resistance genes from perennial Helianthus species will hopefully alleviate the threat of the newly evolved virulent broomrape race.

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FINAL REPORT

PROJECT TITLE: Characterization Of Resistance To Broomrape Of Sunflower

-Reference number: FAIR-CT-96-5028
-Name of trainee: Serenella A. Sukno

-Summary Of Achievements:

Six cultivated sunflower (H. annuus L.) sources from different origins resistant to O. cernua Loefl., one carrying the gene of resistance Or5 and two susceptible lines, along with the F1 crosses (resistant x susceptible and resistant x resistant) and segregating generations (F2 and BC1F1) were studied to characterize the gene number and mode of inheritance of resistance to broomrape. Segregation ratios of F2 and backcross generations indicate one major dominant gene controlling resistance. The lack of segregation in the F2 and BC1 F1 generation between resistant lines indicate that the gene for resistance in the different resistant lines is allelic to or closely linked to Or5 gene. Further evaluations of all the resistant lines of this study to other new more virulent inoculum, which overcome resistance given by Or5 gene were carry out. Two of the resistant lines used in this study, JB-2 and Kavk showed resistance to the new population (SE296). These results suggest that these lines may have a allele or gene different from the Or5 which was not possible to distinguish with inoculum SE194. This resistance to the new virulent broomrape population SE296, is an important finding since resistance of current sunflower cultivars is based on Or5 gene.

The results of segregating generations of an interspecific hybrid of a wild annual sunflower resistant species, H. exilis and a cultivated susceptible line suggested that two genes could be involved in the resistance of this species and that they are different from Or 5. This was an interesting possibility since the resistance of Or5 was starting to be overcome by new virulent races.

Interspecific hybrids and backcross generations between the resistant wild perennial species Helianthus resinosus Small, H. pauciflorus Nutt., H. laevigatus T.&G., H. nuttallii nuttallii T.&G. and H. giganteus L., H. hirsutus, H. californicus and H. gracilentus and the broomrape susceptible H. annuus L. cultivated inbred line HA89 were made to study the behavior of hybrids and backcrosses on the transmission and expression of resistance to this parasite. The resistance of the F1 plants between the wild perennial species and HA89 indicated that the resistance is dominant in this species, thus facilitating its transfer in backcross programs. In the case of the diploid H. giganteus and H. nuttallii, resistant plants with 34 chromosomes, the diploid number of cultivated sunflower, were obtained whereas in the case of BC1F1 of hexaploid perennials x H. annuus, the resistant plants had 51 chromosomes. Segregation for susceptible and resistant individuals indicated that the transfer of resistance found in these species with different ploidy levels into cultivated sunflower was feasible.

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Presentation At Profesional Meetings

Proceedings: Sixth Parasitic Weed Symposium, Cordoba, Spain, 1996

Evaluation Of Wild Helianthus Germplasm For Resistance To Highly Virulent Races Of Orobanche Cernua Loefl. And Transfer To Cultivated Sunflower

SUKNO, S* ; RUSO, J; MELERO-VARA, J. AND FERNANDEZ-MARTINEZ, J.
CSIC, Instituto de Agricultura Sostenible. Apdo. 4084, 14080 Cordoba, Spain.

ABSTRACT

Twenty six different wild perennial species of sunflower and 16 wild annual species of the same genus were evaluated for susceptibility to Orobanche cernua under artificial conditions in 1994, using one of the most virulent populations of broomrape from southern Spain. Most of the evaluated perennial wild species except H. gracilentus and H. nuttallii were immune to Orobanche. In contrast, wild annual species were susceptible to that population of Orobanche except H. agrestis, H. anomalus and H. exilis, which showed a resistant reaction. On the basis of these results, we made crosses between H. exilis, a known resistant annual sunflower species, and susceptible cultivated lines, as well as with the latter and a resistant line carrying the resistance gene Or5, which is used in the production of hybrids in Spain. Current work is aimed at determining which genes for resistance to Orobanche are present in these species.

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Association of seedcoat mottling with plant reactions to soybean mosaic virus and peanut mottle virus

S. Sukno, Q. Yang, P. Chen, G. Buss and S. Tolin.

ABSTRACT

Soybean mosaic virus (SMV) and peanut mottle virus (PMV) cause yield loss and seed quality deterioration including seedcoat discoloration. Reports of the relationship between seedcoat mottling and virus infection are inconsistent. Research was conducted to examine the response of soybean genotypes when inoculated with SMV or PMV and to study the association of virus infection with the degree of seedcoat mottling. The effect of inoculation with PMV at 2 growth stages was also studied. Preliminary results of this research indicated a strong association between symptoms expression of virus infection and seed coat mottling with both virus. SMV infection produced more severe disease symptoms and greater reductions in plant height, but lower percentages of mottled seeds and less severity of mottling than did PMV infection. Early PMV infection produced higher percentages of mottled seeds and greater reductions in seed size than did late infection. A few genotypes showed no leaf symptoms of virus infection but produced some mottled seeds. This observation needs further investigation.

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Use od Molecular Markers for Population Studies of the Blue Mold Pathogen, Peronospora tabacina. 39th Tobacco Worker’s Conference. Colonial Williamsburg, Virginia. January 10-13.

Sukno, S, Taylor, A., Nesmith, W. and Farman, M. 2000.

ABSTRACT

Peronospora tabacina Adam is an oomycete that casues blue mold (downy mildew) a common and potentially severe desease of tabacco in kentucky and other states. This desease has caused significant crop losses in the United States every year since 1979. It has been hypothesized that the 1979 epidemic was due to a race change in the pathogen population (Lucas, 1980) but in the absence of methods to reliably characterize the pathogen population, this hypothesis was untestable. Molecular markers based on Restriction Fragment Length Polymorphisms (RFLPs) were developed using low copy, middle and highly repetitive DNA probes. These markers will enable identification and tracking of Peronospora tabacinapopulations. Results obtained using these markers to characterize US Blue Mold Populations will be described.

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RFLP markers for population studies of the blue mold pathogen, Peronospora tabacina. Phytopathology 90:S75.

S. SUKNO, A. Taylor and M. Farman. 2000.

ABSTRACT

Blue mold of tobacco, caused by the oomycete, Peronospora tabacina, is an economically important disease. To examine the genetics and population biology of this organism RFLP markers were developed using low copy, middle copy and highly repetitive DNA probes isolated from partial genomic DNA libraries. Preliminary analysis of 9 blue mold strains indicates that most isolates are geneticallysimilar. However, DNA from 2 isolates failed to hybridize to several probes. These preliminary data suggest that although there is more than one genetic form of blue mold in the US, a single clone predominates. This hypothesis will be tested by RFLP analysis of a more comprehensive collection of isolates. Some DNA probes produced inconsistent and/or irreproducible hybridization patterns in different DNA preps of a single isolate. Based on DNA sequence analysis, we conclude that these probes were derived from bacteria. These could be either associated with P. tabacina infections or they might be endosymbionts. Regardless, the unavoidable presence of contaminating bacterial DNA indicates that results from PCR-based analyses of P. tabacina maybe unreliable.

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Analysis of genetic variation in Peronospora tabacina using RFLPs. XXI Fungal Genetis Conference, Asilomar CA.

S. SUKNO and M. Farman. 2001.

ABSTRACT

Peronospora tabacina Adam is the causal agent of blue mold of tobacco and belongs to the Oomycetes, a diverse group of fungus-like organisms that cause a wide range of destructive and economically important diseases on plants. The inability to identify and track specific P. tabacina populations hamper efforts to control blue mold. Such information is vital to the successful implementation of durable disease management strategies in US. To examine the genetics and population biology of this obligate biotrophic parasite, three Pst-I genomic DNA libraries were constructed from DNA of three isolates that originated from Kentucky, USA. In preparation for a broader population study, 10 strains representing populations from Kentucky, Florida, Texas, Georgia, Pennsylvania, and Connecticut, were selected for an initial survey of RFLPs markers. Pst-I and Dra-I digested DNA were hybridized to 10 probes. Preliminary analysis indicates that there is a low level of genetic variation among the US populations. Two polymorphic probes were identified and seven different haplotypes could be differentiated among 10 isolates. Experiments are currently under way to evaluate the somatic stability of single spore lineages of one isolate and variability among individuals in a population. Results of the studies will be presented.

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Development of contamination-free RFLP probes for the obligate biotrophPeronospora tabacina, an oomycete causing blue mold of tobacco.

S. SUKNO, A. Taylor and M. Farman. 2001.

Journal: Phytophatology 92:1227-1235

ABSTRACT

Peronospora tabacina is an obligate parasitic oomycete that causes blue mold, a devastating disease of tobacco. To generate molecular markers for this organism, sporangiospores were collected from infected tobacco leaves, DNA was extracted and cloned in a plasmid vector. The resulting clones were then used to probe DNA from a collection of P. tabacina isolates to survey for polymorphisms. Most probes gave unexpected hybridization patters with signal intensities that varied significantly from one DNA sample to another. In addition, signals varied between different DNA preparations of the same isolate. These results gave an indication that some probes were derived from contaminating organisms present in the spore suspensions. Therefore, we characterized the inserts of several recombinant plasmids to determine their origins. Sequence analysis revealed that several of the inserts encoded peptides with similarity to bacterial proteins, suggesting that they were derived from bacterial contaminants. Of the remaining clones, five exhibited similarity to retroelements, one resembled eukaryotic helicase genes, and nine had no similarity to sequences in the databases. These were postulated to be true P. tabacina DNA clones. Verification of the origin of each probe was achieved by filtering a spore suspension, extracting DNA from the retentate and filtrate and probing Southern blots of these DNA samples. Theses experiments confirmed the probe origins predicted by the sequencing analysis. This study resulted in the generation of 28 confirmed P. tabacina probes, thereby providing reliable molecular markers for population studies of the blue mold organism.

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Genetic uniformity among isolates of Peronospora tabacina, the Tobacco Blue mold pathogen

S. SUKNO, A. Taylor and M. Farman. 2002.

Journal: Phytophatology. 92:1227-1235

ABSTRACT

We used a collection of random genomic DNA fragments from Peronospora tabacina to survey for restriction Fragment Lengh Polymorphisms(RFLPs) in DNA from a representative collection of isolates from Nicotiana tabacum in the Unites States. Also included in the study were isolates from the wild tobacco species N. rapanda. In a preliminary survey using DNA from 10 pathogen isolates, no polymorphisms were detected at 6 single-copy DNA loci, using 22 probe-enzyme combinations. Moderately-repetitive and highly-repetitive regions of the genome were also remarkably similar between isolates, with only 6 out of 15 different probes identifying genetic differences. Some of the polymorphic probes were then used to analyze a larger collection of isolates. This resulted in the identification of very few additional polymorphisms. Together, these results indicate that the US population of P. tabacina is genetically very homogeneous. Two of the RFLP markers gave hybridization patterns that were consistent with P. tabacina being diploid. Frequencies of alleles at these loci and linkage desequilibrium between different marker loci indicated that genetic recombination does not occur frequently in the US population of P. tabacina. DNA polymorphisms that were identified in this study enabled us to differentiate the pathogen population into at least 10 haplotypes. One isolate was analyzed in detail and was shown to be genetically stable through several rounds of single spore isolation and pathogenic growth.

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The activity of truncated Arabidopsis thaliana Cel1 endo 1,4 B glucanese promoter deletions and effects of AtCel1 antisense expression during plant-nematode interactions.

....
Journal: Plant Molecular Biology, submitted

ABSTRACT

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The promoter of the A. thaliana (Cel1) Endo1,4-B, glucanase gene is differentially expressed in plant feeding cells induced by cyst and root-knot nematodes.

Journal: Molecular Plant Pathology 5: 175-181

ABSTRACT

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Copyright © 2004 S Sukno


Sukno, S., McCuiston, J., Wang, X., Hussey, R., Baum, T. and Davis, E. 2004. Towards functional analysis of putative parasitism genes in Heterodera glycines using RNA Interference. 2004. 96 nd. American Phytopathological Society, Annual Meeting. CA, USA. August 1-5. Abstract

Sukno, S., Shoseyov, O., Wang, X., McCuiston, J., Shimerling, O. and Davis, E. Expression of truncated Arabidopsis thaliana Cel1 promoter during compatible plant-nematode interactions. 2003. 95nd. American Phytopathological Society, Annual Meeting. NC, USA.