Development Of Potato Cultivars Research Articles

Variation in Susceptibility to Potato Psyllid, Bactericera cockerelli (Hemiptera: Triozidae), among Solanum verrucosum Germplasm Accessions

Potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a key pest of potato and the vector of “Candidatus Liberibacter solanacearum,” the pathogen associated with zebra chip disease. Development of potato cultivars with genetic resistance to potato psyllid would enable cost-effective control of this pest with reduced use of insecticides. To facilitate the development of resistant cultivars, the objective of our study was to screen germplasm accessions of Solanum verrucosum for resistance to potato psyllid. The susceptibility of S. verrucosum germplasm accessions to potato psyllid was highly variable in choice prescreening assays and no-choice performance assays. Compared with the susceptible potato cultivar, ‘Russet Burbank,’ several S. verrucosum populations exhibited strong resistance to potato psyllid. The S. verrucosum accession, PI 195170 was highly resistant to potato psyllid, and is a potential source of genetic resistance for the development of resistant potato cultivars.

GENETIC STABILITY ANALYSIS OF RB GENE IN GENETICALLY MODIFIED POTATO LINES TOLERANT TO Phytophthora infestans

Development of potato cultivars with high levels of broad spectrum resistance is a key long-term management strategy against late blight disease caused by Phytophthora infestans. Six progeny lines of hybridization between transgenic potato Katahdin SP951 with non-transgenic Granola and Atlantic were selected based on agronomical characteristics and resistance to late blight disease. The study aimed to analyze the number of insertions and stability of inserted RB gene in the transgenic potato lines. The research was carried out through plant DNA extraction, southern blot analysis and polymerase chain reaction (PCR). Southern blot analysis was used to detect the number of inserts integrated into potato genome, while PCR analysis was used to detect stability of RB gene from generation to generation. The results showed that the progenies obtained from hybridization between Atlantic and transgenic Katahdin SP951 (lines No. 20 and 27) and between Granola and transgenic Katahdin SP951 (line No. 69) contained one copy number of RB gene, according to the probing of nptII. The result is similar to that of inserted RB gene found in the parental transgenic Katahdin SP951. The presence of RB gene in four different generations (G0, G1, G2 and G3) showed stable integration of the gene into the plant genome. The single copy number of RB gene will repress the occurrence of silencing gene expression. The stability analysis of RB gene can determine that the gene is still present in plant genome after several generations.

GENETIC STABILITY ANALYSIS OF RB GENE IN GENETICALLY MODIFIED POTATO LINES TOLERANT TO Phytophthora infestans

Development of potato cultivars with high levels of broad spectrum resistance is a key long-term management strategy against late blight disease caused by Phytophthora infestans. Six progeny lines of hybridization between transgenic potato Katahdin SP951 with non-transgenic Granola and Atlantic were selected based on agronomical characteristics and resistance to late blight disease. The study aimed to analyze the number of insertions and stability of inserted RB gene in the transgenic potato lines. The research was carried out through plant DNA extraction, southern blot analysis and polymerase chain reaction (PCR). Southern blot analysis was used to detect the number of inserts integrated into potato genome, while PCR analysis was used to detect stability of RB gene from generation to generation. The results showed that the progenies obtained from hybridization between Atlantic and transgenic Katahdin SP951 (lines No. 20 and 27) and between Granola and transgenic Katahdin SP951 (line No. 69) contained one copy number of RB gene, according to the probing of nptII. The result is similar to that of inserted RB gene found in the parental transgenic Katahdin SP951. The presence of RB gene in four different generations (G0, G1, G2 and G3) showed stable integration of the gene into the plant genome. The single copy number of RB gene will repress the occurrence of silencing gene expression. The stability analysis of RB gene can determine that the gene is still present in plant genome after several generations.

Effect of different test tube closure methods on growth and development of potato cultivars

The present study evaluates the effect of three different types of test tube closures (Cotton plugs, Poly-caps and Steri-stoppers) on in vitro performance of potato varieties Kufri Giriraj, Kufri Himalini and Kufri Himsona. Kufri Giriraj exhibited better rooting efficiency, leaf size and root length, while Kufri Himsona exhibited better leaf colour, stem thickness and number of nodes. Kufri Himalini showed better stem height and intermodal length. Overall all the varieties performed better with tubes closed with cotton plugs for leaf size, leaf colour and stem thickness. Kufri Himalini and Kufri Himsona produced longer intermodal length in test tubes closed with a poly-cap or a cotton plug. Kufri Giriraj, however, produced better result over the same trait in tubes closed with a cotton plug or a steri-stopper. Cotton plugs were superior over steri-stoppers and poly-caps providing better ventilation, thus promoting better plant morphogenesis and being economical for potato micro-propagation.

Development and Validation of a Real-Time PCR Assay for the Quantification of Verticillium dahliae in Potato.

An increase in the stringency for higher quality potato tubers and restrictions on the use of soil fumigants, among other factors, has garnered renewed interest in Verticillium wilt, particularly in russet-skinned cultivars grown for processing. In response to the needs of producers, breeders have increased efforts in the development of potato cultivars with resistance to Verticillium dahliae Kleb., the primary cause of Verticillium wilt. These efforts have resulted in the release of numerous russet-skinned cultivars with purported resistance to the pathogen. However, because efficient and effective methods to screen germplasm for true resistance do not exist, breeders typically have reported resistance based on the development of wilt symptoms alone. The studies reported here demonstrate the efficiency and practicality of a QPCR method for quantification of V. dahliae in potato stem tissue. This method, developed to detect the target trypsin protease gene of the pathogen, was compared with traditional methods for V. dahliae quantification which involve plating stem tissue or sap onto semi-selective media, as well as to a recently developed QPCR assay which amplifies a region of the β-tubulin gene of V. dahliae. The QPCR assay developed in the studies reported here was demonstrated to be sensitive to 0.25 pg of DNA. Use of the duplex real-time PCR assay, utilizing the potato actin gene to normalize quantification, resulted in clearer differentiation of levels of resistance among eight russet-skinned potato cultivars inoculated in greenhouse trials when compared with traditional plating assays. However, relative levels of resistance among cultivars were similar between traditional plating and QPCR methods, resulting in correlation coefficients greater than 0.93. The assay described here also detected the pathogen in inoculated stem tissue at higher frequencies than both traditional plating assays and a previously developed QPCR assay. The QPCR assay developed here demonstrates rapid, efficient, and accurate quantification of V. dahliae, providing a tool amenable for use by breeding programs on large numbers of clones and selections, and will aid researchers evaluating other control strategies for Verticillium wilt.

Forecasting the impact of climate change on potato (Solanum tuberosum) productivity in Gujarat and relative adaptation strategies

A study was carried out in Gujarat to assess the impact of climate change on potato (Solanum tubersoum L.) productivity, using the WOFOST crop growth-simulation model. Three potato cultivars of different maturity, viz Kufri Badshah, Kufri Jyoti and Kufri Pukhraj, were selected as test varieties. The study was done for baseline scenario (2000) and for future climate scenarios (2020 and 2055) using A1FI scenario of temperature (SRES A1FI pathway) and atmospheric CO (based on the Bern-CC model for A1FI scenario). Potential production of potato 2 cultivars was estimated for 20 different locations across Gujarat. Under the baseline scenario, the mean productiv- ity of Kufri Badshah, Kufri Jyoti and Kufri Pukhraj was 40.0, 36.0 and 37.4 t/ha, respectively. The increase in temperature during 2020 and 2055, decreased the productivity ranging from 11.5 to 14.5% during 2020 and from 22.9 to 33.9% in 2055 climate scenarios. The corresponding increase in CO concentration enhanced the produc- 2 tivity ranging from 4.9 to 5.3% and 20.8 to 22.9% during 2020 and 2055 scenarios respectively. Overall, the com- bined effect of CO and temperature decreased the productivity of Kufri Badshah, Kufri Jyoti and Kufri Pukhraj 2 by 6.7, 9.4 and 9.5%, respectively, during 2020 and by 19.9, 23.3 and 25.6% for respective varieties during 2055. It was also found that rescheduling the date of planting and selecting suitable varieties can completely offset the impact of climate change on potato productivity during 2020 while it can reduce the decrease in yield from 22.3 to 9.7% during 2055. However, development of potato cultivars with high bulking period proportionate to their total crop duration are required to meet the challenges posed by climate change on potato crop in future.

A breeding method for accelerated development of cold chipping clones in potato

The development of potato cultivars having acceptable chipping quality after cold storage is important because it reduces costs to growers while ensuring continuity of supply to processors throughout the year. Over 5100 single-hill progenies were planted to select for cold chippers. A breeding procedure for selecting and evaluating these progenies for cold chipping ability was used, and 38 desirable genotypes were identified. These selections were increased in the second clonal generation and evaluated for yield, specific gravity, and seven chipping treatments of varying storage duration/temperature/reconditioning duration and were compared to standard chipping cultivars Atlantic, Monona, Norchip, and Snowden. Twenty-two selections yielded ≥ Norchip the highest yielding cultivar, while 15 selections had a specific gravity ≥ Atlantic, the highest specific gravity cultivar. Snowden was the best chipping cultivar overall and some selections were not significantly different than Snowden. Overall, nine selections combined high yield and specific gravity with the ability to produce attractive chips from 4° C. Single-hill selection for cold chipping could potentially save four years in the breeding process by the identification of good parents, the recycling of good parental cross combinations, and the evaluation of progeny for chipping earlier in the breeding program.