The tuber reaction to Phytophthora infestans was evaluated in individual genotypes of four diploid and four tetraploid potato families, their parents and standard cultivars. The genotypes were tested several times. Two testing methods were used, based on evaluation of tuber slices or whole tubers, respectively. All inoculations were done with MP 245, a fungus isolate with a broad virulence spectrum. If the reaction of tuber slices was evaluated, the distribution of genotypes in several families deviated considerably from a normal one. In some distributions more than one peak was detectable, indicating segregation of major genes. Genotypes transgressive in resistance were found in four families. If the reaction of whole tubers was evaluated, the distribution of genotypes did not deviate significantly from a normal one. Genotypes transgressive in resistance were found in one family. The tuber reaction to P. infestans depended to a large extent on testing conditions.
Potato has been known in Europe for the past 400 years. Potato breeding began after the global Phytophthora infestans epidemics in 1840 and 1841. The first breeding attempts were to increase the P. infestans resistance in cultivated potato. In the 21st century, new potato cultivars have been evaluated for more than 50 traits, both for disease and pest resistance, and significant tuber traits. Modern potato breeding requires biotechnology. Cell and tissue culture, genetic engineering and DNA-based molecular markers are the most promising areas of molecular biology for potato breeding. However, there are few reports indicating the actual use of biotechnology in potato breeding programs. Cisgenesis and DNA markers that reside within resistance genes or physically close to them and identified in a fully automated system are a chance for the progress in the future.
Solanum tuberosum, the potato a crop of the family Solanaceae, is cultivated in temperate and subtropical zones of the world.After wheat, rice and corn it occupies the fourth position in terms of world production per year.We summarize the work carried out in our department concerning the use of cellular and molecular techniques in potato breeding.
The influence of salicylic and salicylhydroxsamic acid on in vitro potato plants growth was examined. Both solutions in higher contentrations (10-6, 10-7 mol dcm-3 SAL and 2 x 10-6, 2 x 10-7 mol dcm-3 SHAM) inhibited the growth of the shoots and the number of the leaves and roots. Lower concentrations (10-8 and 2x10-8 mol dcm-3), however, stimulated these processes. The inhibition and stimulation effects on cultivar 'Irga' and 'Irys' were observed. The intensity of tuberization was lower on the medium with the studied acids than in the control cultures. The level of linolenic acid was higher in plants with tuberizing potatoes. It suggests the inhibition of biosynthesis of the jasmonic acid (the stimulus of tuberization) by linolenic acid.
Many of the wild species of Solanum possess high level of disease resistance to viruses, bacteria and pathogenic fungi that could be useful in potato breeding. Somatic hybridization technique enables introgression of those traits from related wild species into cultivated potato and appears to be very a useful means by which the sexual incompatibilities might be bypassed. The article discusses some aspects of potato somatic hybridization.
Erwinia chrysanthemi mutants, containing transcriptional fusion of one of the pectate lyase genes (pelA, pelB, pelC, pelD, pelE, pelI, pelL, pelZ) with the reporter gene encoding b-glucuronidase activity, were studied for their ability to cause disease symptoms and to synthesise pectinases after inoculation of potato tubers. The strains affected in pelI and pelL genes displayed a reduced virulence on potato tubers demonstrating the important role of these isoenzymes in soft rot disease. Analysis of the bacterial population showed an active multiplication of bacteria during the infection. Similar kinetics of growth were observed for all mutants and for the wild type strain. Comparison of the mutants and the wild type strain showed that the pelI, pelL and pelZ mutants synthesised reduced levels of Pels. The expression of pelA, pelE and pelZ is 5-fold higher in planta than in in vitro. In contrast, both pelI and pelL are highly (10-fold factor) induced in planta, which is characteristic of the plant-inducible pectate lyases.
The aim of the study reported here was to evaluate the performance and variability of transgenic potato clones. For the genetic transformation the Polish potato cultivar Irga was chosen in order to improve resistance to a necrotic strain of potato virus Y (PVYN ) by introducing to its genome a truncated gene coding PVYN replicase (in sense and antisense orientations). Transgenic plants and clones derived from them were propagated and the obtained tubers were planted in a replicated field trial. The several agronomic and morphological traits were evaluated and compared with measurements for non-transgenic control plants. The traits of transgenic clones showed a much greater variability than non-transgenic plants. The variability depended on the type of the introduced construct (in this case it was the orientation of the construct). None of the transgenic clones turned out to be completely true to type and resistant to PVYN, but some resistant clones expressed deviations in a small proportion of the traits. Usually, deviations were observed for those traits whose inheritance is characterised by a large environmental component. Genetic transformation is an effective method for introducing resistance. However, the method causes a great variability, which makes selection among transgenic clones a necessary step in breeding of an improved transgenic cultivar. Such selection has many similarities with selection done among traditionally obtained clones.
Inter-simple sequence repeat (ISSR) polymorphism was used for finding markers linked to the Ns gene, responsible for a resistance of potato (Solanum tuberosum L.) to potato virus S (PVS). The ISSR markers UBC811660 and UBC811950 were found to be linked to Ns. Linkage distances were estimated to be 2.6 cM and 6.6 cM, respectively. UBC811660 showed high accuracy for detection of PVS resistance in diploid potato clones. In tetraploids, among seventeen studied genotypes containing the resistance gene, this marker was revealed in eleven. UBC811660 can be a powerful tool for detection of genotypes carrying the Ns gene in diploid potato breeding programmes.
An asymmetric potato hybrid and its parental lines were cytogenetically examined. DAPI (4?-6-diamidino-2-phenylindole) staining was used to count chromosomes in all analysed lines and revealed the presence of minichromosomes in the hybrid genome. Fluorescent in situ hybridization (FISH) with rDNA sequence as a probe helped to determine the ploidy level of analysed lines and revealed that none of the minichromosomes contains rDNA repeats. CMA (chromomycin A3) band occurred to be a new chromosome marker that identifies potato chromosome No.1. It was possible to detect a deletion in one of four chromosomes No. 1 of the asymmetric potato hybrid. On the basis of these analyses a karyotype of the asymmetric hybrid was constructed.
In recent years a new subgroup of necrotic potato virus Y (PVY) isolates has spread in the Polish fields. To counter this infection, the PVY resistance was introduced into selected potato and tobacco cultivars. Plants were transformed by agroinfection with pROK2 derived binary plasmids, carrying an appropriate fragment of the PVY genome (patent applied for). Kanamycin resistant plants were screened by PCR for the presence of PVY cDNA inserts, positive transformants were tested for virus resistance by inoculation with sap from infected plants, followed by observations of disease symptoms and virus accumulation analysis. Several resistant potato and tobacco clones were identified and their phenotypes were preliminarily characterised.
The Ns gene confers resistance of potato to Potato virus S (PVS). Sixteen German and Dutch potato cultivars, all registered in Poland, were found to be susceptible to PVS infection. However, scoring of the cultivars for the presence of the Ns-linked SCAR marker SC811454 revealed additional amplicons with a similar electrophoretic migration rate as that of SC811454, which resulted in ambiguous determination of the genotype at the Ns locus. MboI or FokI treatment of the PCR products allowed to detect their Ns-unspecificity in PVS-susceptible potato cultivars.
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