Effectiveness of Positive Selection in Managing Seed-Borne Potato Viruses (original) (raw)
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Potato Research
Smallholder farmers in Uganda commonly use seed potato tubers from the informal sector, especially by seed recycling over several generations. Therefore, seed tubers are highly degenerated with viruses and other pathogens, resulting in poor yield and quality of the produce. Over one cycle of multiplication, degeneration management by positive seed selection was found to be efficient in reducing virus diseases compared with the farmers' method of selection. The objective of this study was to assess to what extent positive selection over several seasons can reduce six different virus incidences in seed lots of different starting quality in southwestern Uganda. Multi-seasonal trials were carried out in three locations, with five seed lots from four sources and three cultivars. Detection of viruses was based on DAS-ELISA and Luminex xMAP technology. Analysis was carried out with analysis of variance (ANOVA) on angulartransformed percentages of virus incidence. Results showed fluctuations in some viruses over seasons with lower Potato leafroll virus (PLRV) and Potato virus X (PVX) incidences in lots from positive selection compared with lots from farmers' selection. In contrast, some seed lots were initially highly infected with Potato virus S (PVS) and Potato virus M (PVM) and showed no reduction in virus incidence through positive selection. In general, little infection with Potato virus Y (PVY) and Potato virus A (PVA) was found. Based on these results, it is recommended that smallholder farmers are trained in positive selection to opt for less virus-infected plants and tubers, thus increasing potato production.
Positive selection for the identification of virus-free potato planting material was evaluated in four locations in Cameroon. Leaves from asymptomatic plants were randomly collected, the plants marked and tubers collected four weeks later, and screened with DAS-ELISA for PLRV, PVY, PVA, PVX, PVS and PVM presence. Five viruses were prevalent in leaves while four prevalent in tubers. Potato virus M was highly prevalent in leaves and tubers while PVY was high only in leaves. Potato virus A was absent in both leaves and tubers while PVX was free only in tubers. A positive correlation was observed between virus prevalence in leaves and tubers (r=0.806). The prevalence of the six viruses in potato seed tubers from four seed stores was tested. Potato virus M was the most prevalent, while PLRV was the least. Small, medium and large tuber sizes were tested for the viruses, and infection rates decreased significantly the bigger the tuber size. Positive selection though not highly efficient can be recommended for resource-poor farmers, to control the economically important potato viruses. Tuber size can serve as a guide to identify healthy tubers, but must be combined with laboratory tests for effective use in selecting seeds for planting.
Improving potato tuber yields using genotypes with multiple virus resistance in Kenya
Agriculture and Biology Journal of North America, 2013
Potato (Solanumtuberosum L.) viruses play a major role in lowering yields and quality of ware and seed tubers in Kenya. This experiment was conducted to determine potential of potato clones with multiple virus resistance in minimizing virus related crop losses. The trials were conducted in two sites for four successive seasons of re-using seed tubers. The genotypes were exposed to natural sources of virus infection without spraying insecticides to control (aphids) virus vectors. Genotypes with multiple virus resistance experienced significant (P ≤ 0.05) lower rate of yield loss (21.2 %) compared to the major local varieties (68.4 %). There was successful identification of a higher yielding virus resistant clone (CIP396286.7) with significant (P ≤ 0.05) higher mean yield (30.3 T/ha) compared to the highest yielding local variety (24.3 T/ha), Tigoni. The number of tubers per plant was significantly (P ≤ 0.05) higher (12.1) in the virus resistant clones than in the local varieties (7.3). Reduced rate of yield loss, higher yield performance and higher number of tubers per plant in the tested clones was attributed to genetic contribution of multiple virus resistance. Virus related crop losses currently experienced by local farmers can be minimized with use of such virus resistant genotypes.
Improving Seed Health and Seed Performance by Positive Selection in Three Kenyan Potato Varieties
American Journal of Potato Research, 2012
Selecting seed potatoes from healthy-looking mother plants (positive selection) was compared with common Kenyan farmer practice of selection from the harvested bulk of potatoes (farmer selection) in 23 farmer-managed trials. Positive selection assured lower incidences of PLRV (39%), PVY (35%) and PVX (35%). Positive selection outyielded farmer selection irrespective of the agro-ecology, crop management, soil fertility, variety and quality of the starter seed, with an overall average of 30%. Regression analysis showed a relation between lower virus incidence and higher yield for the varieties. The paper discusses the consequences for seed system management in African countries. Furthermore possible additional effects of positive selection are discussed and further research is suggested. The paper concludes that positive selection can benefit all smallholder potato producers who at some stage select seed potatoes from their own fields, and should thus be incorporated routinely in agricultural extension efforts.
Agriculture and Biology Journal of North America, 2013
Potato virus Y (PVX) and potato virus X (PVX) are among the most important viruses of the potato (Solanum tuberosum L.) crop worldwide. The use of virus resistant varieties is considered the most effective and sustainable long term way of minimizing crop losses associated with the viruses. In Kenya, major potato varieties grown do not have effective host resistance to the two viruses. Among the different types of virus resistances available, extreme resistance has been found to be durable and most effective. This type of resistance protects the plant against all strains of the virus and has been found particularly for PVY and PVX. Nature of inheritance of extreme resistance genes make it easy to transfer to cultivated varieties through conventional cross breeding. Screening for the two viruses is cheap, simple and straight forward due to the fewer number of genes involved. In major potato breeding programmes around the world, this type of resistance has been incorporated in many cultivated potato varieties with reported reduction in yield losses. Focus on sourcing of suitable parents, hybridization and screening for the two viruses can make a significant contribution in management of the two locally important viruses while reducing virus related crop losses.
Horticultural and Viral Studies for Improving Local Potato Seeds Production
ABSTRACT Two experiments were carried out to study the possibility of production of improved potato seeds under Egyptian conditions. The first experiment was conducted in fall season to compare between improved seeds produced from three imported varieties (Diamant, Spunta and Lady Rosetta) in summer seasons (2012 and 2013) under control in Kaha research station and seeds produced by farmers in Kafr El-Zayat (KZ). The second experiment was performed in summer season (2013 and 2014) to compare the improved seeds produced from three varieties in previous summer seasons (2012 and 2013) with imported seeds. Detection of the most important potato viruses (potato leafroll virus; PLRV, potato virus Y; PVY, potato virus X; PVX and alfalfa mosaic virus; AMV) were carried out on potato leaves and tubers using ELISA and RT-PCR for the detection of these viruses. Specific primer pairs designed to amplify the coat protein gene of each virus (627 bp for PLRV, 801 bp for PVY, 714 bp for PVX and 666 bp for AMV) were successfully applied. The obtained data indicated that virus- infection incidence percentage was increased in KZ potato seeds. Most vegetative growth and yield characteristics were significantly higher in Spunta cultivar. Meanwhile, Diamant cultivar gave the highest value for leaf number per plant, number of tuber/plant, number of main stems at 75 DAP and number of tubers per plant at harvest time. Conversely, Lady Rosetta gave the highest dry matter percentage of tubers for both fall seasons. Improved seeds which produced under Kaha Research Station were significantly superior in emergence percentage, leaves number, leaf area per plant, total dry weight, tuber fresh and number of tubers/plant in both seasons. In summer season, the potato seeds produced from seeds produced in previous summer season under control (Kaha, local) showed increase in viral infection percentage which aggravated by using the cut seeds in plantation compared to the imported seeds. Spunta gave the lowest significant average tubers number per plant, on the contrary, produced the highest average tuber fresh weight, total yield per plant and feddan comparing with Diamant and Lady Rosetta. Imported potato seed tubers which were planted as complete tubers yielded the highest significant total tuber yield per plant and feddan compared to other seed sources. As well as, using whole local tubers seed increased yield per plant and feddan compared to all divided tubers seed. On the other hand, divided local seeds gave the lowest value of total yield per plant and feddan in the two growing seasons. KEYWORDS: Potato - Diamant - Lady Rosetta - Spunta - Imported seeds - local seeds - Potato virus Y- Potato virus X - Potato leafroll virus - alfalfa mosaic virus.
Response of Selected Potato Genotypes to Natural Virus Infection in the Field
Asian Journal of Research in Crop Science, 2019
Potato viruses are one of the major biotic factors causing high yield losses in potato production fields. In contrast to other disease causing pathogens, potato viruses' lack well documented chemical control strategy and hence difficult to control once established in the field. The aim of the study was to assess the reaction of different potato genotypes to natural virus infection in the field. The present study was carried out on 12 potato genotypes (7 CIP clones and 5 commercial varieties) at the Field Station of the University of Nairobi, Upper Kabete campus Kenya in two potato growth seasons. A Randomized Complete Block Design (RCBD) of 4 replications was adopted with 12 treatments. Data was collected on percent crop emergence, disease incidence, growth and yield performance. At the end of season 2, tubers were sampled randomly per genotype and tested for presence of viruses using CIP DAS-ELISA kit. Analysis of variance on different parameters revealed varied response of each genotype to virus infection in the field in both seasons. Four potato viruses: PVS (67%), PVY (20%), PLRV (12%) and PVM (7%), were detected infecting tested potato tubers Original Research Article Okeyo et al.; AJRCS, 3(2): 1-13, 2019; Article no.AJRCS.45364 2 either as single or as multiple infections. The results revealed that four clones: 392797.22, 393371.157, 398190.200 and 397073.7 had high levels of tolerance to virus infection. Therefore further studies should be done to understand whether they possess quantitative or qualitative resistant traits to specific potato viruses and other biotic factors.
Assessment of prevalence and distribution of potato viruses in Ethiopian seed systems
Viruses are among the significant biotic constraints burdening global potato production, particularly in developing countries where seed certification is not common and production, availability and accessibility to quality seed potato is a big hindrance. Virus infection in seed potato reduces yield, and the problem is exacerbated when an early-generation seed is affected. The prevalence of six key potato viruses, PVY, PVX, PLRV, PVA, PVS, and PVM, was assessed among decentralized seed multipliers such as individuals, farmer seed group cooperatives, private companies, and agricultural research center that produce early generation seed in six major potato growing districts in Ethiopia. A total of 262 leaf samples were randomly collected from potato plants and analyzed using a double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for potato viruses. Potato virus prevalence was calculated as the proportion of samples that tested positive for the viruses against the tota...
Potato (Solanum tuberosum L.) is an important cash-food crop, which is widely grown in three of the five agro-ecological zones of Cameroon. A study was carried out to determine the prevalence of PVA, PLRV, PVM, PVS, PVX and PVY in 1175 sprouted potato seed tubers of different diameters collected from four seed stores in the North West Region of Cameroon. The study also sorts to ascertain variations in virus incidence in small, medium and large size sprouted tubers prior to planting. The DAS-ELISA method was used to test for the presence of these viruses. Results showed significant differences in the prevalence of the six viruses with PVM being the most prevalent (92%), while PLRV was least prevalent (35%) in all the four seed stores sampled. Upper-Farm store registered the highest relative prevalence (82%), with PVM detected in all the tubers while samples from Rock-Farm store showed the least relative incidence (55%) with no PLRV detected. Viruses were significantly most prevalent in small size tubers (71%) and least in large size potato tubers (63%). Our results suggest that tuber size can serve as a guide to identify healthy (virus-free) tubers. Farmers could therefore use large size potato tubers for planting.
Management Of Potato Viruses In Seed Potato Production Using Border Crops
2013
Field experiments were conducted over two cropping seasons to investigate the effectiveness of border crops in managing potato aphids and the associated viruses in seed potato production. Potato plots were surrounded with maize, sorghum and wheat borders. Aphid population was monitored on leaves and on yellow sticky traps. Other data collected included virus disease incidence and tuber yield. The border crops reduced aphid population on leaves compared to non-bordered potato plots. More alate aphids were caught on yellow sticky traps placed inside potato plots than on traps placed inside the border crops. In addition, virus disease incidence was reduced in all plots surrounded by the border crops. However, plots surrounded by border crops had reduced tuber yield, although the yield of seed grade was increased. The results indicated that use of border crops would be beneficial in the management of virus diseases in small-holder seed potato production.