Tuberous Roots Of Sweet Potato Research Articles

Cloning and characterization of sweetpotato MADS-box gene (IbAGL17) isolated from tuberous root

A new MADS-box gene, IbAGL17, was isolated from the tuberous root of sweetpotato (Ipomoea batatas (L.) Lam. cv. Kokei 14). IbAGL17 was expressed in vegetative tissues, especially root tissues; thickened pigmented root and tuberous root. On sequence alignment, IbAGL17 fell into the AGL17 subfamily composed of AGL16, AGL17, ANR1, NMHC5 and DEFH125, which share high sequence similarity. A transcript of IbAGL17 in root and petiole was found in the vascular tissues in tissue printing. These results suggest that expression pattern of IbAGL17 may lead to a higher proliferation potential of vegetative tissues and root development in sweetpotato.

The Effect of Calcium and its Distribution in Cell Wall Components of Sweet Potato (Ipomoea batatas Lam) Tuberous Roots

The Effect of Calcium and its Distribution in Cell Wall Components of Sweet Potato (Ipomoea batatas Lam) Tuberous Roots

Invertase inhibitors from sweet potato (Ipomoea batatas): purification and biochemical characterization.

Two proteinaceous invertase inhibitors, designated ITI-L and ITI-R, were purified to electrophoretic homogeneity. ITI-L was purified from acetone powder of sweet potato leaves through sequential steps entailing buffer extraction, acid treatment, DEAE-Sephacel ion-exchange chromatography, and Sephacryl S-100 gel filtration. ITI-R was purified from sweet potato tuberous roots by sequentially applying buffer extraction, Con A-Sepharose affinity chromatography, DEAE-Sephacel ion-exchange chromatography, Sephacryl S-200, and Superose 12 gel filtration. The optimal pHs for interaction between ITI-L and ITI-R and acid invertase from sweet potato leaves were 5.5 and 5.0, respectively. The molecular masses of ITI-L and ITI-R were 10 and 22 kDa, respectively, as estimated by both gel filtration and SDS-PAGE. Both inhibitors were thermostable (90% of the activity remained after incubation at 100 degrees C for 20 min), and Western blotting showed them to be immunologically related.

Structural and Immunocytochemical Characterization of the Synthesis and Accumulation of Starch in Sweet Potato (Ipomoea batatas Lam.) Tuberous Root

The structural changes in the plastid-amyloplast system in the parenchyma cells of sweet potato tuberous roots during thickening were examined by electron microscopy. In the tuberous roots, proplastids and plastids that contain starch granules propagated in young parenchyma cells adjacent to the meristem, but amyloplasts did not in parenchyma cells. It was suggested that the number of amyloplasts in a parenchyma cell is determined by the propagation of the proplastids and plastids. The form of amyloplasts and the number, size and form of starch granules in them were various. Tubular membranes containing the electron-dense substance were formed in plastids and extended from the envelope membranes of plastids to the starch granules. The electron-dense substance also existed around the starch granules. Tubular membranes are converted into membrane-bound inclusion bodies as a result of loading of the electron-dense substance into these tubes in the plastids. The inclusion bodies were also at the periphery of the amyloplasts. In this study, the functions of both tubular membrane and the inclusion were discussed. The localization of starch branching enzyme in tuberous roots was examined by immunogold electron microscopy. The label for branching enzyme was localized predominantly throughout the surface of each starch granule, suggesting that this is the branching for amylopectin synthesis, but not throughout the stroma in the plastid-amyloplast system. Small and round starch granules were often formed at parts of the periphery in the amyloplast. Dense labeling for the enzyme was detected around the granules. The increase of the number of starch granules in an amyloplast is certainly made by means of the formation of new starch granules at the periphery of the amyloplast. It is likely that the new granules are intensively formed there.

Absence of amylose in sweet potato [Ipomoea batatas (L.) Lam.] following the introduction of granule-bound starch synthase I cDNA

The full-length sense cDNA for sweet potato granule-bound starch synthase I (GBSSI) driven by the CaMV 35S promoter was introduced into the sweet potato by Agrobacterium tumefaciens-mediated transformation. Out of the 26 transgenic plants obtained, one plant showed the absence of amylose in the tuberous root as determined by the iodine colorimetric method. Electrophoresis analysis failed to detect the GBSSI protein, suggesting that gene silencing of the GBSSI gene occurred in the transgenic sweet potato plant. These results demonstrate that starch composition in the tuberous root of sweet potato can be altered by genetic transformation.

Purification and Characterization of Sucrose Phosphate Synthase from Sweet Photato Tuberous Roots

Sucrose phosphate synthase (SPS) is one of the key enzymes in the sucrose biosynthesis pathway. SPS was purified 40 fold from crude extract of sweet potato tuberous roots by the methods of batch elution from DEAE-Sephacel, PEG precipitation, ω-aminohexyl Sepharose 4B affinity and Mono Q anion exchange chomatographies. The native- and SDS-PAGE analyses revealed SPS to have a native molecular mass of about 540kDa, and it may therefore be homotetramer composed of subunit with a mass of 130-140kDa. The isoelectric point of the purified enzyme as determined by IEF was 5.29. SPS from the sweet potato tuberous root, which differs from the SPS of photosynthetic tissues, was not allosterically regulated by G6P and Pi. The Km for F6P and UDPG was 5.3 and 31.3mM, respectively. The enzyme was activated by Mn (superscript 2+), Mg (superscript 2+), and Ca (superscript 2+), while being inhibited by Hg (superscript 2+). The nucleotides AMP, ADP, ATP, UMP, UDP, UTP, and TDP inhibited the enzyme about 30~50%. The enzyme was sensitive to sulfydryl reagents, but activity could be restored with DTT or β-ME. The enzyme was activated by glucose, glucosamine, maltose, and lactose, but was inhibited by δ-gluconolactone. SPS could also be inhibited by PCMBS and Cibacron blue F3G-A.

Effect of population density of Cylas formicarius(Fabricius)(Coleoptera: Brentidae) on the progeny populations.

Adults of the sweet potato weevil, Cylas formicarius, were allowed to lay eggs on a 150 g tuberous root of sweet potato for 3 days under conditions of 27°C, 60% RH, and 14L:10D. The number of progeny increased with the increase of parental density, and reached the saturation level. The number of progeny per parental female showed a peak at 30–100 pairs of parents. The density response mode of this insect characterizes it as the Allee type. At very low density, the mortality of eggs and larvae was high, which might have been due to the unfavorable conditions of the tuberous root, the quality of which had not yet been improved by the frano-inducing factor secreted during feeding by the larval and adult weevil. Comparatively more eggs were laid on the tuberous root conditioned by adult-feeding or oviposition. Size of adult progeny became smaller with the increase of parental density. The duration of their development was shortened, and variation of the time period until their emergence from the tuberous root became smaller with the increase of parental density. Optimal parental density for mass-rearing was found to be 65 pairs per tuberous root of 150 g for 3-days oviposition.

サツマイモ澱粉特性と品種ならびに栽培環境要因に関する研究

1. Starches were prepared from many kinds of sweet potatoes, which are mainly used for starch production, differing in variety, stage of development and tissue zone. Average granule size, amy lose content, gelatinization properties by differential scanning calorimetry and digestibility of raw starch by glucoamylase were compared. Digestibility by glucoamylase tended to be higher in the earlier stage of development and the cambium zone. Further, correlations among these starch properties were calculated to determine the factors relating to digestibility of raw starch by glucoamy lase. Negative correlations were observed between gelatinization heat and digestibility as well as average granule size and digestibility. 2. Starches were also prepared from many kinds of purple-and orange-fleshed sweet potatoes to investigate the effect of the cultivation conditions on starch properties. Earlier planting and harvesting dates apparently enhanced gelatinization temperature and tended to reduce the content of short chains of amylopectin. A major difference in starch properties, especially gelatinization temperature and amylopectin structure, occurs according to soil tem perature during the development of sweet potato tuberous roots. To elucidate the extensive variation in starch gelatinization properties within the same botanical origin for sweet potato, correlations were determined between gelatinization parameters and starch molecular characteristics. Starch with a lower gelatinization temperature had relatively abundant extremely shorter unit-chains of amylopectin.

Sweet potato β-amylase immobilized on chitosan beads and its application in the semi-continuous production of maltose

The present study is concerned with the immobilization of β-amylase from sweet potato tuberous roots on chitosan beads for the purpose of maltose production. Immobilized sweet potato β-amylase on Chitopearl BCW 3505 beads exhibited an activity of 142 U/g carrier. The optimum temperature of the immobilized β-amylase increased by 20°C, and thermostability was improved by about 10°C compared to free β-amylase. The additional effects of two types of the immobilized pullulanases on maltose formation were also investigated. The addition of pullulanase from Bacillus brevis gave a higher yield of maltose compared to that from Klebsiella pneumoniae. A semi-continuous production of maltose from a highly concentrated substrate (Pine-Dex #1, potato starch hydrolyzate) solution (40%, w/v) with the immobilized sweet potato β-amylase and Bacillus brevis pullulanase could be obtained at pH 6.0 and 60°C for 14 days at a higher yield (70.9%) using a horizontal rotary column reactor.

Development and adult survival of the sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae), during winter on Amami-Oshima Island, Japan.

We investigated the development and adult survival of Cylas formicarius (Fabricius) during winter on Amami-Oshima Island, Japan. Every developmental stage of the weevil (except for eggs, which were not examined) was found in sweet potato tuberous roots during winter, and adults and third instars were dominant. The weevils in sweet potato roots continued to develop during winter, although their development was delayed due to low temperatures. In addition, adult weevils continued to emerge from the host plants throughout winter. Most adult weevils were found under stones and fallen leaves on the ground surface and within the top 5 cm of soil in a sweet potato field during the daytime in winter, and scarcely dispersed from the host plants in winter. The adult weevils released in a sweet potato field and a field cage in December or later survived until the following late March or late April. The results suggest that most of the females that started to oviposit after overwintering came from eggs laid in the previous September and October.

Molecular characterization and expression of starch granule‐bound starch synthase in the sink and source tissues of sweet potato

In an effort to study regulation of starch synthesis in the source and sink tissues, a cDNA clone for starch granule‐bound starch synthase (GBSSI), which encodes a 67‐kDa protein, was isolated from a cDNA library prepared from tuberous roots of sweet potato (Ipomoea batatas Lam. cv. Tainong 62). This GBSSI protein contains a signal peptide of 77 amino acids, and the mature protein has a molecular mass of about 59 kDa. The mature protein shares 75–85% sequence identity with GBSSIs of dicotyledonous plants and about 70% identity with those of monocotyledons. The sequence of the signal peptide, on the other hand, differs substantially from those of the dicotyledons and monocotyledons studied, although their hydropathic profiles are all similar. This GBSSI gene was well expressed in tuberous roots, leaves, and stems, but not in roots. However, mechanisms involved in regulating the expression of this gene were different between tuberous roots and leaves. In tuberous roots, the synthesis of GBSSI transcript increased coordinately with tuberous root expansion; nevertheless, accumulation rates of GBSSI protein in starch granules remained constant regardless of tuberous root sizes, suggesting an involvement of post‐transcriptional regulation for the synthesis of this protein. The levels of GBSSI transcript were investigated in photosynthetic tissues during diurnal cycles, and the results suggest that the transcription of the GBSSI gene in leaves is controlled by the endogenous circadian rhythm.

B-16 Thickening of tuberous roots in sweet potato and 4-Chloroindole-acetic acid

B-16 Thickening of tuberous roots in sweet potato and 4-Chloroindole-acetic acid

Inhibitors of Protein Phosphatases 1 and 2A Block the Sugar-Inducible Gene Expression in Plants.

Genes coding for two major proteins of the tuberous root of sweet potato (Ipomoea batatas), namely, sporamin and [beta]-amylase, are inducible in leaves and petioles when they are supplied with high concentrations of sucrose or other metabolizable sugars, such as glucose and fructose, and the accumulation of a large amount of starch accompanies this induction. Three inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A), namely, okadaic acid, microcystin-LR, and calyculin A, strongly inhibited the sucrose-inducible accumulation of mRNAs for sporamin, [beta]-amylase, and the small subunit of ADP-glucose pyrophosphorylase in petioles. However, these inhibitors did not have any major effect on the steady-state levels of mRNAs for catalase and glyceraldehyde-3-phosphate dehydrogenase, and the sucrose-inducible increase in the level of sucrose synthase mRNA was enhanced by okadaic acid. Inhibitors of PP1 and PP2A also inhibited sucrose-inducible expression of a fusion gene, consisting of the promoter of the sweet potato gene for [beta]-amylase and the coding sequence for [beta]-glucuronidase (GUS), in leaves of transgenic tobacco (Nicotiana tabacum). The inhibition was not due to inhibition of uptake and cleavage of sucrose, since okadaic acid also inhibited induction of the fusion gene by glucose or fructose. Addition of okadaic acid to leaves that had been treated with sucrose for 6 h inhibited further increases in GUS activity. These results suggest that the continuous dephosphorylation of proteins is required in the transduction of carbohydrate metabolic signals to the transcriptional activation of at least some sugar-inducible genes in plant.

Purification and some properties of starch branching enzyme (Q‐enzyme) from tuberous root of sweet potato

The pattern of isoforms of starch branching enzyme II or Q‐enzyme II in the tuberous root of sweet potato was distinct from those of other organs; altogether 7 isoforms of QEII were contained in the sweet potato plant. The QEIIf isoform, one of the two major QEII isoforms in the tuberous root, was purified to homogeneity by using a variety of HPLC columns. The purified QEIIf was a monomeric protein with a molecular mass of about 85 kDa. Western blot analysis showed that the polyclonal antibodies raised against the purified QEIIf was significantly reactive to the rice endosperm QEI, but not to the rice endosperm QEIIa. Furthermore, the sweet potato QEIIf reacted with the antiserum raised against the rice endosperm QEI, but not with that against the rice endosperm QEIIa. The results suggest that the sweet potato QEIIf is more similar to the rice endosperm QEI than to the rice endosperm QEIIa.

Purification and some properties of starch branching enzyme (Q-enzyme) from tuberous root of sweet potato

Purification and some properties of starch branching enzyme (Q-enzyme) from tuberous root of sweet potato

In Vitro Formation of Tuberous Roots in Sweet Potato.

In Vitro Formation of Tuberous Roots in Sweet Potato.

Cloning and characterization of a cDNA encoding the cytosolic copper/zinc-superoxide dismutase from sweet potato tuberous root

A full-length cDNA clone encoding a putative copper/zinc-superoxide dismutase (SOD) of sweet potato, Ipomoea batatas (L.) Lam. cv Tainong 57, was isolated from a cDNA library constructed in lambda gt10 from tuber root mRNA. Nucleotide sequence analysis of this cDNA clone revealed that it comprises a complete open reading frame coding for 152 amino acid residues. The deduced amino acid sequence showed higher homology (78-86%) with the sequence of the cytosolic SOD than that of the chloroplast SOD from other plant species. The residues required for coordinating copper and zinc are conserved as they are among all reported Cu/Zn-SOD sequences. In addition, it lacks recognizable plastic or mitochondrial targeting sequences. These data suggest that the isolated sweet potato clone encodes a cytosolic Cu/Zn-SOD.

Rooting of Cut-Sprouts and Formation and Thickening of Tuberous Roots in Sweet Potato

Rooting of Cut-Sprouts and Formation and Thickening of Tuberous Roots in Sweet Potato

Relationship between Starch Content and Activity of Starch Synthase and ADP-glucose Pyrophosphorylase in Tuberous Root of Sweet Potato.

Relationship between starch content and the activity of starch synthase and ADP-glucose pyrophos-phorylase in tuberous roots of sweet potato was investigated using several cultivars. No correlation was observed between soluble starch synthase activity and dry matter content and between total starch synthase activity and starch content of tuberous root. ADP-glucose pyrophosphorylase activity per fresh weitht of tuberous root correlated positively to starch content of cultivars. And the changes in the activity of this enzyme during growth were similar to those in the starch content. From these results, it is thought that ADP-glucose pyrophosphorylase is one of the key enzymes in starch accumulation in tuberous root of sweet potato.

Potato Tuber-Inducing Activity of the Extracts of Some Root and Tuber Crops.

塊根茎作物の貯蔵器官形成のメカニズム解明に資するため, バレイショ茎断片培養法を生物検定系として用い, 我が国への新規導入が期待される塊根茎作物を含め9種の植物の抽出物の塊茎形成活性を調査・比較した. 供試した植物の地上部抽出物の内, バレイショの塊茎形成を誘導する活性が強かったのは, サツマイモの水溶性分画と酸性酢酸エチル(AE)分画, キクイモのAE分画, ヤーコンのAE分画, スギナのAE分画で, キャッサバのAE分画も比較的強い活性を示した. 一方, 食用カンナ, コンニャク, サトイモや塊根を形成しないサツマイモ近縁野生種では, いずれの分画も活性は低かった. 強い活性を示した分画の内, サツマイモのAE分画に存在する活性物質は精製の結果, ジャスモン酸と同定した. また, スギナのAE分画に存在する活性にはABAが関与しているものと思われた. 地下貯蔵器官の抽出物では, AE分画にバレイショ塊茎形成活性を示すものが見られ, キクイモの塊茎で特に活性が強く, キクイモのふく枝, ヤーコンの塊茎や塊根, サツマイモの塊根, キャッサバの塊根も比較的高い活性を示した. 一方, 食用カンナの肥大茎, コンニャクの球茎, サトイモの塊茎では活性が弱く, コンニャクの吸枝では全く活性は認められなかった. 上記のバレイショ塊茎形成活性を指標にして, 地下貯蔵器官形成の生理的機構のバレイショとの類似性という視点で塊根茎作物を比較・類別すると, 塊茎作物の内キクイモ, ヤーコンは類似性が高く, 塊根作物のサツマイモ, キャッサべでも一定の類似性を持っているが, サトイモ, 食用カンナ, コンニャクではバレイショとの類似性は低いと思われた.