Transgenic Sweetpotato Research Articles

Expression of Arabidopsis NDPK2 increases antioxidant enzyme activities and enhances tolerance to multiple environmental stresses in transgenic sweetpotato plants

Transgenic sweetpotato (Ipomoea batatas L. cv. Yulmi) plants expressing the Arabidopsis nucleoside diphosphate kinase 2 (AtNDPK2) gene under the control of an oxidative stress–inducible peroxidase (SWPA2) promoter (referred to as SN plants) were developed and evaluated for enhanced tolerance of SN plants under various abiotic stress conditions. The level of AtNDPK2 expression and NDPK activity in SN plants following methyl viologen (MV) treatment was positively correlated with the plant’s tolerance to MV. Interestingly, we observed that antioxidant enzyme activities such as peroxidase, ascorbate peroxidase, and catalase increased in MV-treated SN plants. In addition, SN plants showed enhanced tolerance to cold, high salinity, and drought stresses by an increase in the activity of H2O2 scavenging enzymes. These results indicate that overexpression of AtNDPK2 in sweetpotato might efficiently modulate oxidative stress from various environmental stresses.

Peroxiredoxin 유전자 발현 산화스트레스 내성 형질전환 고구마의 선발

Peroxiredoxin 유전자 발현 산화스트레스 내성 형질전환 고구마의 선발

Establishing a testing method for the aphid transmission of SPFMV and evaluating viral resistance in transgenic sweet potatoes

The sweet potato, Ipomoea batatas (L.) Lam., is the third most important root crop in the world after the potato and cassava. In particular, the sweet potato is not only an important crop in tropical, subtropical and temperate regions, but also an efficient biomass-producing plant for starch. The sweet potato is widely recognised as being prone to infection by sweet potato feathery mottle virus (SPFMV). Generally, SPFMV is transmitted by aphids (Myzus persicae), and the infected tuberous roots are used for vegetative propagation. However, neither the transmission of SPFMV using the aphid transmission test nor the aphid transmit theory itself has been established for sweet potato. The present study establishes a testing method for the aphid transmission of SPFMV and evaluates viral resistance in transgenic sweet potatoes. As a result of some examinations, we establish a testing method for resistance to SPFMV by aphid transmission in sweet potato. Furthermore, we evaluated the resistance to SPFMV in transgenic sweet potato using the improved aphid transmission method, and determined higher levels of resistance to SPFMVs in transgenic sweet potatoes. These results suggest that transgenic sweet potatoes show resistance to SPFMVs in the field.

Evaluation of resistance to complex infection of SPFMVs in transgenic sweet potato

Viral diseases of the sweet potato (Ipomoea batatas L. (Lam)) are highly prevalent and often cause serious damage to the plants, particularly the severe strain of the sweet potato feathery mottle virus (SPFMV-S) that causes ‘obizyo-sohi’ disease in Japan. To confer viral resistance to SPFMV using current biotechnology, a transgenic sweet potato has been developed by introducing SPFMV-S coat protein (CP) genes, which have shown significant resistance to SPFMV-S; however, ecological distribution in the field of SPFMVs is unclear. This study investigated the ecological distribution of SPFMVs in field-infected sweet potato, and virus resistance nearer to the field was evaluated in transgenic sweet potato. SPFMV was not capable of independent infection; rather, infection by SPFMVs was coincidentally complex under natural conditions. Furthermore, infection was by a dominant strain between complex infecting SPFMVs, and was differentiated by the area of infection. Transgenic sweet potato plants expressing the SPFMV-S CP gene were challenged by graft inoculation with field-infected SPFMVs. All of the transgenic sweet potato plants were highly protected in the long term against SPFMV complex infection compared to control plants. These results suggest that transgenic sweet potato can acquire resistance to SPFMVs in the field.

Production of herbicide-resistant transgenic sweet potato plants through Agrobacterium tumefaciens method

Transgenic herbicide-resistant sweet potato plants [Ipomoea batatas (L.) Lam.] were produced through Agrobacterium-mediated transformation system. Embryogenic calli derived from shoot apical meristems were infected with Agrobacterium tumefaciens strain EHA105 harboring the pCAMBIA3301 vector containing the bar gene encoding phosphinothricin N-acetyltransferase (PAT) and the gusA gene encoding β-glucuronidase (GUS). The PPT-resistant calli and plants were selected with 5 and 2.5 mg l−1 PPT, respectively. Soil-grown plants were obtained 28–36 weeks after Agrobacterium-mediated transformation. Genetic transformation of the regenerated plants growing under selection was demonstrated by PCR, and Southern blot analysis revealed that one to three copies of the transgene were integrated into the plant genome of each transgenic plant. Expression of the bar gene in transgenic plants was confirmed by RT-PCR and application of herbicide. Transgenic plants sprayed with Basta containing 900 mg l−1 of glufosinate ammonium remained green and healthy. The transformation frequency was 2.8% determined by herbicide application which was high when compared to our previous biolistic method. In addition, possible problems with multiple copies of transgene were also discussed. We therefore report here a successful and reliable Agrobacterium-mediated transformation of the bar gene conferring herbicide-resistance and this method may be useful for routine transformation and has the potential to develop new varieties of sweet potato with several important genes for value-added traits such as enhanced tolerance to the herbicide Basta.

Inhibition of the gene expression for granule-bound starch synthase I by RNA interference in sweet potato plants

Granule-bound starch synthase I (GBSSI) is one of the key enzymes catalyzing the formation of amylose, a linear alpha(1,4)D-glucan polymer, from ADP-glucose. Amylose-free transgenic sweet potato plants were produced by inhibiting sweet potato GBSSI gene expression through RNA interference. The gene construct consisting of an inverted repeat of the first exon separated by intron 1 of GBSSI driven by the CaMV 35S promoter was integrated into the sweet potato genome by Agrobacterium tumefaciens-mediated transformation. In over 70% of the regenerated transgenic plants, the expression of GBSSI was inactivated giving rise to storage roots containing amylopectin but not amylose. Electrophoresis analysis failed to detect the GBSSI protein, suggesting that gene silencing of the GBSSI gene had occurred. These results clearly demonstrate that amylose synthesis is completely inhibited in storage roots of sweet potato plants by the constitutive production of the double-stranded RNA of GBSSI fragments. We conclude that RNA interference is an effective method for inhibiting gene expression in the starch metabolic pathway.

Expression of a Rice Chlorophyll a/b Binding Protein Promoter in Sweetpotato

Leaves are usually the target tissue for expressing transgenes conferring resistances to herbicides, pests, and diseases. To achieve leaf-specific expression, a light-harvest chlorophyll a/b binding protein (CAB) of photosystem-II (CAB2) promoter (CAB2-p) from rice (Oryza sativa L.) and the cauliflower mosaic virus 35S promoter were fused to the β-glucuronidase (GUS) reporter and subsequently evaluated in transgenic sweetpotato [Ipomoea batatas L. (Lam.)]. The 35S promoter-directed GUS activities varied from 46.0 to 61.2 nmol 4-methyl-umbelliferyl-β-D-glucuronide (4-MU) per minute per milligram of protein in leaf, stem, primary, and storage roots. In contrast, the CAB2-p directed an uneven distribution of GUS activities (4-MU at 1.1 to 12.6 nmol·min−1·mg−1 protein); GUS activity in mature leaves was ≈12-fold as high as that in storage roots. In addition, GUS assay in leaf tissues revealed that CAB2-p enabled a developmentally controlled and light-regulated GUS expression. These results indicate that the rice CAB2-p could be used to drive leaf-specific expression of linked genes in sweetpotato.

Selectionof nptll transgenic sweetpotato plants using G418 and paromomycin

We have used two aminoglycosides, G418 and paromomycin, to develop a reliable selection system fornptll transgenic sweet-potato (Ipomoea batatas (L.) Lam.). Embryogenic calli derived from shoot apical meristems were bombarded with gold particles coated with pCAMBIA2301, which contained thenptll andgusA genes. When compared on a kill curve that was based on calli proliferation and cell viability, G413-selection proved to be more efficient and had fewer escapes than kanamycin. These bombarded expiants were then selected on G418-containing media. The total time required from bombardment to plant establishment in soil was seven to nine months. Multiple copies of the transgene were integrated into the sweetpotato genome. Northern analysis confirmed transgene expression in the regenerated plants, and a paromomycin assay demonstrated that thenptll gene was functionally expressed in transformed sweetpotato. These molecular analyses and assays all showed that selection with G418 and paromomycin is reliable. So far, we have produced 69 transgenic events with this system, at a transformation frequency of approx. 1.1%. That efficiency is based on the number of transgenic plants obtained and the amount of calli bombarded. Thus, this selection method that combines G418 with paromomycin is now available for selectingnptll transgenic sweetpotato.

Enhanced tolerance of transgenic sweetpotato plants that express both CuZnSOD and APX in chloroplasts to methyl viologen-mediated oxidative stress and chilling

Oxidative stress is one of the major factors causing injury to plants exposed to environmental stress. Transgenic sweetpotato [Ipomoea batatas (L.) Lam. cv. Yulmi] plants with an enhanced tolerance to multiple environmental stresses were developed by expressing the genes of both CuZn superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) under the control of an oxidative stress-inducible SWPA2 promoter in the chloroplasts of sweetpotato plants (referred to as SSA plants). SSA plants were successfully generated by the particle bombardment method and confirmed by PCR analysis. When leaf discs of SSA plants were subjected to 5 μM methyl viologen (MV), they showed approximately 45% less damage than non-transformed (NT) plants. When 200 μM MV was sprayed onto the whole plants, SSA plants showed a significant reduction in visible damage compared to leaves of NT plants, which were almost destroyed. The expression of the introduced CuZnSOD and APX genes in leaves of SSA plants following MV treatment was significantly induced, thereby reflecting increased levels of SOD and APX in the chloroplasts. APX activity in chloroplast fractions isolated from SSA plants was approximately 15-fold higher than that in their counterparts from NT plants. SSA plants treated with a chilling stress consisting of 4°C for 24 h exhibited an attenuated decrease in photosynthetic activity (Fv/Fm) relative to NT plants; furthermore, after 12 h of recovery following chilling, the Fv/Fm of SSA plants almost fully recovered to the initial levels, whereas NT plants remained at a lower level of Fv/Fm activity. These results suggest that SSA plants would be a useful plant crop for commercial cultivation under unfavorable growth conditions. In addition, the manipulation of the antioxidative mechanism in chloroplasts can be applied to the development of various other transgenic crops with an increased tolerance to multiple environmental stresses.

Production of herbicide-resistant sweet potato plants transformed with the bar gene

Herbicide-resistant sweet potato plants were produced through biolistics of embryogenic calli derived from shoot apical meristems. Plant materials were bombarded with the vectors containing the beta-glucuronidase gene (gusA) and the herbicide-resistant gene (bar). Selection was carried out using phosphinothricin (PPT). Transformants were screened by the histochemical GUS and Chlorophenol Red assays. PCR and Southern-blot analyses indicated the presence of introduced bar gene in the genomic DNA of the transgenic plants. When sprayed with Basta, the transgenic sweet potato plants was tolerant to the herbicide. Hence, we report successful transformation of the bar gene conferring herbicide resistance to sweet potato.

Physicochemical properties of amylose-free and high-amylose starches from transgenic sweetpotatoes modified by RNA interference

The transgenic sweetpotatoes having amylose-free and moderately high-amylose starches have been obtained by RNA interferences of granule-bound starch synthase I (GBSSI) and starch branching enzyme II [SBEII (class A)] genes, respectively. In this study, the physicochemical properties of such sweetpotato starches were investigated. From the amylose-free starches, structural changes in the starch molecules were found by suppressing GBSSI expression: lack of amylose, lack of long chains with more than DP 100 in amylopectin, and a slight decrease in chains with DP 6 and 7 in amylopectin. These results suggest that GBSSI participates in not only the synthesis of amylose molecules, but also the characterization of amylopectin molecules. In the case of the high-amylose starches, complicated structural changes were found by suppressing SBEII expression: increase in amylose, increase in phosphate content, alteration of crystalline structure, decrease in long chains with more than DP 100 in amylopectin, decrease in chains around DP 6–11, and increase in chains around DP 12–15 and DP 24–33 in amylopectin. As the results of the structural changes, the amylose-free sweetpotato starches showed a very slow retrogradation and high digestibility by pancreatin, whereas the high-amylose sweetpotato starches showed a higher pasting viscosity, more rapid retrogradation and lower digestibility compared to normal starch.

Enhanced Resistance of Transgenic Sweetpotato (Ipomoea batatas Lam.) Plants to Multiple Environmental Stresses Treated with Combination of Water Stress, High Light and High Temperature Stresses

Ecophysiological parameters of non-transgenic sweetpotato (NT) and transgenic sweetpotato (SSA) plants were compared to evaluate their resistance to multiple environmental stresses. Stomatal conductance and transpiration rate in NT plants decreased markedly from Day 6 after water was withheld, whereas those values in SSA plants showed relatively higher level during this period. Osmotic potential in SSA plants was reduced more negatively as leaf water potential decreased from Day 8 after dehydration treatment, while such reduction was not shown in NT plants under water stressed condition. SSA plants showed less membrane damage than in NT plants. As water stress and high light stress, were synchronously applied to NT and SSA plants maximal photochemical efficiency of PS II () in NT plants markedly decreased, while that in SSA plants was maintained relatively higher level. This trend of changes in between SSA plants and NT plants was more conspicuous as simultaneously treated with water stress, high light and high temperature stress. These results indicate that SSA plants are more resistive than NT plants to multiple environmental stresses and the enhanced resistive characteristics in SSA plants are based on osmotic adjustment under water stress condition and tolerance of membrane.

Rapid genetic transformation of sweetpotato (Ipomoea batatas (L.) Lam) via organogenesis

An efficient and rapid Agrobacterium-mediated transformation method based on de novo (via callus) organogenesis has been developed from petioles with leaf for sweetpotato (Ipomoea batatas (L.) Lam). Stable transgenic sweetpotato plants cv. Jewel were obtained in six to ten weeks after infection with Agrobacterium tumefaciens hyper-virulent strain EHA105 harboring a binary vector pCIP45 bearing the nptII gene conferring resistance to kanamycin and a gene of interest. PCR and Southern analyses confirmed stable integration of both genes into the sweetpotato genome. The expression of the nptII gene was assessed by reverse-transcribed PCR and callus development in a high kanamycin medium. A two-step organogenesis regeneration using media containing 4-fluorophenoxyacetic acid (4-FA) and zeatin was used in two independent transformation experiments yielding 20% and 10% transformation efficiency, respectively. When using indolacetic acid (IAA) in regeneration media, the transformation efficiency dropped to 4.0%. It indicated an auxin to cytokinin treatment could improve the regeneration of transgenic calluses. This rapid organogenesis-based transformation strategy represents an important improvement over existing methods and will facilitate producing large-scale transgenic sweetpotato plants the genetic improvement of a crop that is reputed to be difficult to transform.

TRANSGENIC SWEETPOTATO WITH AMYLOSE-FREE STARCH

In the storage roots of sweetpotato (Ipomoea batatas (L.) Lam. cv. 'Kokei 14'), the starch consists of 18 to 20% of amylose and the other major component is amylopectin. Granule-bound starch synthase I (GBSSI) is one of the key enzymes to catalyze the formation of amylose. Amylose-free transgenic sweetpotato plants were successfully obtained by inhibition of the sweetpotato GBSSI gene expression through RNA interference. The gene construct consisting of an inverted repeat of the first exon separated by the first intron of GBSSI and driven by the CaMV 35S promoter was integrated into the sweetpotato genome by Agrobacterium tumefaciens-mediated transformation. About 73% of transgenic plants were inactivated by the expression of GBSSI, resulting in the storage roots containing only amylopectin but no amylose. The results clearly demonstrate that the amylose synthesis is completely inhibited in roots of sweetpotato plants which constitutively synthesized double stranded RNA of GBSSI. The RNA interference is very effective in inhibiting the gene expression in the starch metabolic pathway in sweetpotato.

돼지 유행성 설사병 바이러스의 스파이크 유전자 발현 형질전환 고구마

Porcine epidemic diarrhea virus (PEDV)는 돼지의 급성장염을 유발하여 설사 증상을 일으키는 바이러스이다. 본 연구에서는 고구마 저장뿌리 고발현 sporamin 프로모터 및 CaMV 35S promoter를 이용하여 PEDV 항원단백질을 생산하는 고구마 식물체를 개발하고자 하였다. 형질전환 벡터를 제작하기 위하여 PEDV에서 항원성이 알려진 스파이크 단백질의 일부분을 암호화하는 유전자를 PCR로 합성하였다. 고구마 [Ipomoea batatas (L.) Lam] 율미 품종의 배발생 캘러스를 재료로 하여 Agrobacterium tumefaciens을 매개로 형질전환하였다. 선발배지 (MS medium, 1 mg/L 2,4-D, 100 mg/L kanamycin, and 400 mg/L claforan)에서 배발생 캘러스를 3주 간격으로 4개월 동안 계대배양하여 카나마이신 저항성 캘러스를 선발하였다. 선발된 배발생 캘러스를 호르몬을 제거한 배지로 옮겨 체세포배를 유도하였으며 이후 shoot과 뿌리가 형성되었다. 재분화된 소식물체를 대상으로 PCR 분석으로 카나마이신 저항성 재분화 개체의 50% 이상이 도입 유전자를 가지고 있었으며 이들 식물체를 대상으로 Southern blot 분석하여 PEDV 유전자가 고구마 식물체의 게놈으로 안정적으로 도입되었음을 확인하였다. 형질전환 식물체에서 도입유전자의 발현을 RT-PCR로 분석한 결과 PEDV의 spike 유전자가 높은 수준으로 발현하였다. Porcine epidemic diarrhea virus (PEDV) causes acute enteritis in pigs of all ages and is often fatal for neonates. In order to develop sweetpotato plants expressing PEDV antigen, we constructed the vector expressing spike gene of PEDV under the control of sweetpotato sporamin promoter or constitutive CaMV 35S promoter. The spike protein region of PEDV was synthesized by PCR and linked to each promoter, Transgenic sweetpotato [Ipomoea batatas (L.) Lam. cv. Yulmi] plants were developed from embryogenic calli following Agrobacterium tumefaciens-mediated transformation. The co-cultured embryogenic calli transferred to selective MS medium containing 1 mg/L 2,4-D, 100 mg/L kanamycin, and 400 mg/L claforan. These embryogenic calli were subcultured to the same selection medium at 3 weeks interval. Kanamycin-resistant calli transferred to hormone-free MS medium with kanamycin gave rise to somatic embryos and then converted into plantlets in the same medium. Southern blot analysis confirmed that the spike gene of PEDV was inserted into the genome of the sweetpotato plants. RT-PCR revealed that the spike gene of PEDV was highly expressed in transgenic sweetpotato plants.

엽록체 항산화기구 대사조절에 의한 환경스트레스 내성 식물

Injury caused by reactive oxygen species (ROS), known as oxidative stress, is one of the major damaging factors in plants exposed to environmental stress. Chloroplasts are specially sensitive to damage by ROS because electrons that escape from the photosynthetic electron transfer system are able to react with relatively high concentration of in chloroplasts. To cope with oxidative stress, plants have evolved an efficient ROS-scavenging enzymes such as superoxide dismutase (SOD) and ascorbate peroxidase (APX), and low molecular weight antioxidants including ascorbate, glutathione and phenolic compounds. To maintain the productivity of plants under the stress condition, it is possible to fortify the antioxidative mechanisms in the chloroplasts by manipulating the antioxidation genes. A powerful gene expression system with an appropriate promoter is key requisite for excellent stress-tolerant plants. We developed a strong oxidative stress-inducible peroxidase (SWPA2) promoter from cultured cells of sweetpotato (Ipomoea batatas) as an industrial platform technology to develop transgenic plants with enhanced tolerance to environmental stress. Recently, in order to develop transgenic sweetpotato (tv. Yulmi) and potato (Solanum tuberosum L. cv. Atlantic and Superior) plants with enhanced tolerance to multiple stress, the genes of both CuZnSOD and APX were expressed in chloroplasts under the control of an SWPA2 promoter (referred to SSA plants). As expected, SSA sweetpotato and potato plants showed enhanced tolerance to methyl viologen-mediated oxidative stress. In addition, SSA plants showed enhanced tolerance to multiple stresses such as temperature stress, drought and sulphur dioxide. Our results strongly suggested that the rational manipulation of antioxidative mechanism in chloroplasts will be applicable to the development of all plant species with enhanced tolerance to multiple environmental stresses to contribute in solving the global food and environmental problems in the 21st century.

Virus Resistant Transgenic Sweet Potato with the CP Gene : Current Challenge and Perspective of its Use

Virus diseases of sweet potato are very prevalent and often seriously damage to the plants. Especially sweet potato feathery mottle virus severe strain (SPFMV-S) causes russet crack disease in Japan. In order to confer virus resistance against SPFMV using current biotechnology, we have produced transgenic sweet potato with an expression vector plasmid harboring the coat protein (CP) gene as well as hygromycin phosphotransferase gene (HPT). The plasmid was introduced into mesophyll protoplasts of a sweet potato breeding line, Chikei 682-11 (Ipomoea batatas L.(Lam.)) by electroporation. Protoplatsts were further cultured in the presence of hygromycin. Some of the hygromycin resistant calli were grown to form adventitious shoots. Southern blot analysis with CP and HPT genes showed that these genes were integrated into the chromosomes in four lines. Expression of the CP gene was confirmed by Northern and dot immuno blot analyses. Each line was grafted with the SPFMV-S infected morning glory (I. nill) to reveal any virus resistance conferred. After three months from the graft-inoculation, these transgenic plants were used for ELISA test in order to know any virus infection. There was no significant differences of ELISA values between the inoculated-transgenic and the non inoculated-virus free plants, suggesting that these transgenic plants were not infected with the virus. They produced storage roots, from which the young shoots were again found to be virus-free by ELISA. We concluded that these transgenic plants were highly resistant to the virus. Concerns about the releasing transgenic plants that contain genes from other species include the potential weediness of the plants as well as the potential flow of the transgenic genes to other plants through normal outcrossing. Usually sweet potato is a vegetatively propagated and hardly flowers during growing seasons in Japan. Under these circumstances it might be safe to release these transgenic plants. One concern unique to virus resistant transgenic plants is that a viral sequence from transgene may be potentially incorporated by RNA recombination into a virus that may infect the transgenic plants. There is no useful information available on the occurrence of recombinant virus under the very high level of resistance. From the point; whether or not the frequency of recombination in the transgenic plants greater than that in plants with two or more viruses, it would be at least much lower in these highly virus resistant transgenic plants.

Production of mouse adiponectin, an anti-diabetic protein, in transgenic sweet potato plants

Adiponectin is a 30kDa protein exclusively produced and secreted from adipocytes and as a cytokine has been found to link obesity, insulin resistance, and type 2 diabetes. Production of biologically active adiponectin in large scale is desirable for pharmaceutical applications. Mouse adiponectin cDNA was used for developing transgenic sweet potato plants via Agrobacterium-mediated transformation. The presence of the transgene was verified by PCR and DNA gel blot analysis. Further investigated were five independent transgenic lines, all of which expressed high levels of adiponectin mRNA. Immuno blot analysis with a mouse adiponectin antiserum revealed that, in addition to a 29 kDa-protein which co-migrates with the adiponectin protein produced in Escherichia coli cells, a 31 kDa-protein was produced, indicative of a post-translational modification of the protein. The transgenic plants did not show obvious differences in growth rate and morphology in response to adiponectin production.

BIOAVAILABILITY OF CALCIUM FROM SWEETPOTATO AND SOY FLOUR SUPPLEMENTED DIETS IN HAMSTERS

The bioavailability of calcium from two varieties of sweetpotatoes and supplementation of sweetpotatoes with soy flour was investigated in hamsters using plasma calcium concentration and femur calcium content as indicators. Five different diets were fed to five groups of animals for 28 days. There was no significant difference in plasma calcium concentrations of hamsters in all the diet groups. However, the femur calcium content of hamsters with transgenic sweetpotato flour (TSPF) and parent nontransgenic (from which transgenic was produced) sweetpotato flour (NTSPF) diets was significantly higher than that of the transgenic sweetotato flour supplemented with soy flour (TSPF+SF) and parent nontransgenic sweetpotato flour supplemented with soy flour (NTSPF+SF) diets. The relative bioavailability of calcium from the control (100%), TSPF+SF (30%), NTSPF+SF (23%), TSPF (57%) and NTSPF (46%) indicated that sweetpotatoes could be the better source of calcium, however, supplementation with soy flour might reduce the bioavailability of calcium.

Inheritance and stability of the virus‐resistant gene in the progeny of transgenic sweet potato

AbstractViral diseases of sweet potato are very prevalent and often seriously damaging to the plants. In particular, the severe strain of the sweet potato feathery mottle virus (SPFMV‐S) causes ‘obizyo‐sohi’ disease in Japan. In order to confer viral resistance against SPFMV using current biotechnology, a transgenic sweet potato has been produced, introducing hygromycin‐resistant (hpt) and SPFMV‐S coat protein (CP) genes, which have shown a significant resistance to SPFMV‐S. In the breeding programme, it is important to confirm that the viral resistance conferred in T0 plants can be inherited by their progeny. In the present study, progeny were obtained from crosses between the transgenic T0 and a non‐transgenic variety of sweet potato. The results showed that the CP gene was inherited by the next generation and that the stability of viral resistance was also confirmed. Thus, this production system for the virus‐resistant transgenic sweet potato is useful in practical breeding.