Chemical and environmental growth regulation of sweetpotato (Ipomoea batatas (L.) Lam.) in vitro

The need for conservation of biotic diversity is well recognized. However, improved techniques for the efficient, cost effective-preservation of plant germplasm are needed. The conservation and distribution of plant germplasm in vitro is gaining acceptance. However, increased usage is dependent upon the ability of curators to minimize culture maintenance requirements. This report examines the effect of various levels of sucrose, photoperiod, temperature, sorbitol and mannitol on minimal growth storage of Ipomoea batatas (L.) Lam. Growth was reduced 50% with a temperature reduction of from 21.1 to 15.6°C. Sucrose concentrations of 15 and 20 g l^-1 resulted in reduced plant stature with few adverse effects on plantlet viability or morphology. Reduction of photoperiod from 16 to 4 h produced smaller, slightly chlorotic, but otherwise normal plants. The addition of sorbitol or mannitol to culture media generally produced undesirable effects on gross plant morphology and loss of apical dominance. Genotype x growth retarding treatment interactions were observed for all variables examined.Abbreviations PL plant introduction - f.w. fresh weight - SE standard error     

Interspecific somatic hybrids between wild potato Solanum acaule Bitt. and anther-derived dihaploid potato (Solanum tuberosum L.)

Solanum acaule Bitt. is a disomic tetraploid (4x) wild potato species which is resistant to several potato diseases. Introgression of disease resistance and abiotic stress tolerance to the tetrasomic tetraploid (4x) cultivated potato (S. tuberosum L.) gene pool via crossing has been limited due to the difference in the endosperm balance number. In the present study, protoplast fusion was applied to produce hexaploid (6x) somatic hybrids between the parental lines, tetraploid (4x) S. acaule and two anther-derived dihaploid (2x) lines of S. tuberosum cv. White Lady. One callus (0.4%) of a total of 229 calli obtained regenerated into shoots in the fusion combination S. acaule (+) White Lady 15.dh.8.2.2. All the regenerated shoots were confirmed to be interspecific somatic hybrids using species-specific RAPD markers. In another fusion combination, S. acaule (+) White Lady 7.dh.23.1.1, fifteen calli (5%) regenerated into a total of sixteen shoots from 289 calli. All the analysed somatic hybrids between S. acaule and S. tuberosum were hexaploid. The mean DNA content (2C value) of the combination S. acaule (+) White Lady 15.dh.8.2.2 somatic hybrids (4.55 pg), was approximately the sum (4.69 pg) of the DNA contents of the parental lines, S. acaule (2.95 pg) and S. tuberosum (1.74 pg). In the greenhouse, the two somatic hybrids analysed were normal in their morphological characteristics and more vigorous than their parental lines. Most of the morphological characteristics were closer to the tetraploid S. acaule than to the dihaploid S. tuberosum. The interspecific somatic hybrids are currently being tested for frost tolerance and glycoalkaloid composition. Received: 19 January 1998 / Revision received: 27 March 1998 / Accepted: 20 April 1998     

Auxin-regulated gene expression and embryogenic competence in callus cultures of sweetpotato, Ipomoea batatas (L.) Lam.

High levels of 2,4-dichlorophenoxyacetic acid (2,4-D, 10 µM) and sucrose (3%) are required for both the induction and maintenance of callus for somatic embryogenesis in sweetpotato. Newly inducted embryogenic callus lines in sweetpotato cv. White Star produce competent embryos that convert readily into plantlets. With age, these embryogenic callus lines produce a greater proportion of incompetent embryos with poor conversion potential. One hypothesis for this change is that auxin- and/or sugar-responsiveness may be altered with aging. A comparison of two older embryogenic lines (K592 and M892) to two new lines (K1194 and K195) addressed the relationship between extent of embryo conversion and relative abundance of mRNAs hybridizing with heterologous auxin- or sugar-responsive gene probes. The respective cDNAs utilized were the auxin-responsive pJCW1 and pJCW2 and the sugar-responsive Ivr2 and Sh1. Embryos from new callus lines formed more shoots, roots, and viable plantlets than embryos from older callus lines. In addition, new callus lines had greater relative levels of mRNAs hybridizing to auxin-responsive cDNAs. These sweetpotato mRNAs were themselves found to be 2,4-D-responsive in dosage analyses. In contrast, differences between young and old cultures were not evident for mRNAs hybridized to sugar-regulated genes. Our results support the suggestion that desensitization of auxin-responsiveness is a central feature of reduced embryogenic competence in callus lines following prolonged exposure to 2,4-D and elevated sucrose levels.     

Regeneration of somatic hybrid plants formed between Lycopersicon esculentum and L. pennellii

Summary Somatic hybrid plants have been regenerated following polyethylene glycol mediated fusion of leaf mesophyll protoplasts from tomato and protoplasts from Lycopersicon pennellii callus. Three different cultivars of tomato were used as sources of protoplasts: Early Girl, Manapal, and UC82B. Fusions were performed between protoplasts of these tomato cultivars and protoplasts of L. pennellii, and between protoplasts of the cultivars and protoplasts of L. pennellii that had been exposed to 3 or 6 krads of gamma radiation. Somatic hybrid plants were identified on the basis of heterozygous isozyme banding patterns, and leaf and flower morphology. Somatic hybrid plants were regenerated following fusion of tomato protoplasts with either untreated or irradiated L. pennellii protoplasts. All were heterozygous for isozyme loci on five different chromosomes. Regenerated somatic hybrids showed inheritance of either or both parental chloroplast genomes, but predominantly the L. pennellii mitochondrial genome. The regenerated somatic hybrid plants exhibited reduced fertility, less than 20% viable pollen. A total of 34 somatic hybrid calli were identified. Of these, 21 regenerated shoots, and 7 produced seed following manual pollinations.     

Asymmetric somatic hybrids between Lycopersicon esculentum and irradiated Lycopersicon peruvianum

Summary Asymmetric somatic hybrids of Lycopersicon esculentum and Lycopersicon peruvianum were analysed for the retention of genes and alleles specific for L. peruvianum. The hybrids were obtained by fusion of protoplasts from L. esculentum with those of L. peruvianum (the donor), the latter having been irradiated before fusion with 50, 300 or 1,000 Gy of gamma-rays. The retention of three different types of genes or alleles was analysed. (1) The gene coding for kanamycin resistance, which is dominant and had been introduced in most of the L. peruvianum donor plants by transformation. It was present at one locus in 16 L. peruvianum donor plants and at two loci in one donor plant. (2) The genes coding for acid phosphatase, locus Aps-1, and glutamate oxaloacetate transaminase (GOT); different alleles of these genes are co-dominant and were detected by isozyme analysis. (3) Eighteen single gene morphological markers for which most of the L. esculentum genotypes used were homozygous recessive. Kanamycin resistance from donor plants with one locus was retained in about 50% of the asymmetric 30H-hybrids (the donor was irradiated with 300 Gy). L. peruvianum specific alleles of Aps-1 and GOT were present in at least 70% of the hybrids; the retention of donor alleles was lower in 30H- than in 5H-hybrids (donor irradiated with 50 Gy). On average, 73% of the L. peruvianum-specific alleles (one or both) of the morphological markers were detected in the 30H-hybrids. Several of the L. esculentum genotypes used were homozygous recessive for two morphological markers on the same chromosome; in 43% of the 30H-hybrids derived from them, only one of these markers was complemented by the L. peruvianum allele. This is an indication of frequent breakage of the L. peruvianum chromosomes. Several hybrid calli regenerated genotypically different shoots. On the whole, this analyses confirms the conclusion drawn from the cytogenetic and morphological analysis of these asymmetric hybrids, namely that irradiation prior to fusion eliminates the L. peruvianum genome to only a limited extent.     

A genetic linkage map of sweetpotato [Ipomoea batatas (L.) Lam.] based on AFLP markers

Amplified Fragment Length Polymorphism (AFLP) based genetic linkage maps were developed for hexaploid sweetpotato (Ipomoea batatas (L.) Lam., 2n = 6x = 90) using a segregating population derived from a biparental cross between the cultivars 'Tanzania' and 'Bikilamaliya'. A total of 632 ('Tanzania') and 435 ('Bikilamaliya') AFLPs could be ordered in 90 and 80 linkage groups, respectively. Total map lengths were 3655.6 cM and 3011.5 cM, respectively, with an average distance of 5.8 cM between adjacent markers. The genetic linkage analysis was performed in two steps. First a framework map was elaborated from the single dose markers. Interspersed duplex and double-simplex markers were used to detect homologous groups within and corresponding linkage groups among the parental maps. The type of polyploidy (autopolyploidy vs. allopolyploidy) was examined using the ratio of linkage in coupling phase to linkage in repulsion phase and the ratio of non-simplex to simplex markers. Our data support the predominance of polysomic inheritance with some degree of preferential pairing.     

Isozyme modifications and plant regeneration through somatic embryogenesis in sweet potato (Ipomoea batatas (L.) Lam.)

Summary The potential of somatic embryogenesis was evaluated for 10 cultivars of sweet potato through extensive embryogenic response and isozyme analysis. Embryogenic callus was induced by incubating lateral buds on Murashige and Skoog medium containing 10 M 2,4-dichlorophenoxyacetic acid for 6–8 weeks. The frequency of embryogenic response was low, and varied with genotypes, ranging from 0 to 17%. Embryo to plantlet formation could be enhanced by the use of the combination of 2,4-dichlorophenoxyacetic acid with kinetin, both used at 0.01 M. Embryogenic callus with its potential of plantlet formation has constantly been maintained for over two years. However, after several subcultures, 0.5 to 12% of embryogenic callus reverted irreversibly into friable fast-growing non-embryogenic callus whose ability to regenerate shoots was then definitively lost. The isozymes of esterase, peroxidase, glutamate oxaloacetate transaminase and acid phosphatase investigated in this study were found appropriate to distinguish compact embryogenic from friable non-embryogenic callus in sweet potato. In fact, the callus reversion was associated with a loss of bands or a decline in isozyme activity. On the contrary, very small changes in isozyme activity or no specific changes at all were observed during the differentiation of embryogenic callus into globular embryos.Abbreviations Acp acid phosphatase - BAP 6-benzylaminopurine - cv cultivar - df degree of freedom - 2,4-D 2,4-dichlorophenoxyacetic acid - Est esterase - Got glutamate oxaloacetate transaminase - IAA indole-3-acetic acid - MS Murashige and Skoog (1962) medium - Prx peroxidase - Tris tris(hydroxymethyl)aminomethane     

甘薯与牵牛EST资源的SSR信息分析

为挖掘番薯（Ipomoea）属EST-SSR资源,从NCBI数据库下载23406条甘薯（Ipomoea batatas (L.) Lam.）EST和62282条牵牛（Ipomoea nil (L.) Roth）EST,利用生物信息学软件预处理、去冗余、拼接处理后得到12812条无冗余的甘薯EST（6.70 Mb）和28422条牵牛唯一序列（17.19 Mb）。对这些序列进行SSR搜索,在甘薯上获得328个SSR位点,发生频率为2.56%;牵牛上筛选到962个SSR位点,出现频率为3.38%。甘薯和牵牛EST-SSR具有多个共同特征：在SSR位点中,主要是二核苷酸重复类型,其次是三核苷酸重复;在二核苷酸重复中,出现最多的重复基序为AG/CT,其次是AT/AT;在三核苷酸重复中,主要基序是AAG/CCT;SSR位点的长度主要集中在20~22 bp。结果表明,这些搜索出的EST-SSR重复基序类型丰富、多态性潜能高,具有较高的开发和利用价值。     

The effect of replicate number and image analysis method on sweetpotato [Ipomoea batatas (L.) Lam.] cDNA microarray results

Microarray analysis makes it possible to determine the relative expression of thousands of genes simultaneously. It has gained popularity at a rapid rate, but many caveats remain. In an effort to establish reliable microarray protocols for sweetpotato [Ipomoea batatas (L.) Lam.], we compared the effect of replication number and image analysis software with results obtained by quantitative rela-time PCR (Q-RT-PCR). Sweetpotato storage root development is the most economically important process in sweetpotato. In order to identify genes that may play a role in this process, RNA for microarray analysis was extracted from sweetpotato fibrous and storage roots. Four data sets, Spot4, Spot6, Finder4 and Finder6, were created using 4 or 6 replications, and the image analysis software of UCSF Spot or TIGR Spotfinder were used for spot detection and quantification. The ability of these methods to identify significant differential expression between treatments was investigated. The data sets with 6 replications were better at identifying genes with significant differential expression than the ones of 4 replications. Furthermore when using 6 replicates, UCSF Spot was superior to TIGR Spotfinder in identifying genes differentially expressed (18 out of 19) based on Q-RT-PCR. Our study shows the importance of proper replication number and image analysis for microarray studies.     

Cryopreservation of sweet potato (Ipomoea batatas [L.] Lam.) shoot tips by vitrification

Summary Vitrification is a technically simple method for cryopreserving plant germplasm, requiring only the application of suitable cryoprotectants and rapid cooling rates. Sweetpotato (Ipomoea batatas [L.] Lam.) shoot tips obtained from in vitro plants survived liquid nitrogen (–196°C) exposure following a vitrification-inducing pretreatment. Shoot tips were treated in a stepwise manner with a vitrification solution containing 30% glycerol, 15% ethylene glycol and 15% dimethylsulfoxide in growth medium. Incubation of shoot tips for 1 to 2 h in low concentrations of the vitrification solution enhanced survival. Most surviving shoot tips developed callus, and a variable percentage subsequently formed shoots. Survival was not achieved using two-step cooling procedures. The percentage of shoot tips surviving vitrification and those subsequently forming a shoot varied widely among replications.Abbreviations BA N⁶-benzyladenine - IBA indole-3-butyric acid - EG ethylene glycol - DMSO dimethylsulfoxide - MS Murashige and Skoog (1962) minerals and vitamins - LN liquid nitrogen - PI plant introduction     

Sequence polymorphism and chromosomal localization of 5S rDNA of three cultivated varieties of sweetpotato (Ipomoea batatas (L.) Lam.)

The 5S rDNA of plant is organized into clusters of tandem repeat units which include a coding region of 5S rRNA gene and variable sequences of nontranscribed spacer (NTS). In this study, we investigated sequence polymorphism and chromosomal localization of 5S rDNA in three cultivated varieties of sweet potato (Ipomoea batatas Lam.). Two different PCR products of 5S rDNA were amplified from all three varieties, as approximately 0.25 kb and 0.34 kb with multiples. In sequence analysis, the 5S rDNA ofI. batatas were discriminated from four consensus sequences by in reasonable sizes and molecular informative factors. Four consensus sequences were divided into three short sequences, including 263, 253, and 243 – 283 bp by sequence variation between 160 and 186 bp in NTS region, and one long sequence with 340 bp. To identify molecular relationship among varieties, phylogenetic analysis was applied. A total of 35 sequenced clones in this study were classified into four groups in phylogenetic tree. Interestingly, two varieties included all four groups, but one variety only two groups. To localize the physical map of 5S rDNA, fluorescencein situ hybridization (FISH) was performed in metaphase chromosomes of each varieties. In 90 chromosomes ofI. batatas, 6 loci of 5S rDNA were detected in chromosomes for all varieties. Our results will help to further more understand the genomic relationship inI. batatas, to investigate molecular relationship among varieties.     

Optimisation of somatic embryogenesis in fourteen cultivars of sweet potato [Ipomoea batatas (L.) Lam.]

Culture procedures have been developed to facilitate the induction and maintenance of somatic embryogenic tissues in 14 out of 16 tested cultivars of sweet potato [Ipomoea batatas (L.) Lam]. Both the size of the axillary bud explant and the type of auxin were found to be critical for the successful induction of somatic embryogenesis. Of the five auxins screened 2,4-dichlorophenoxyacetic acid 2,4-D and 2,4,5-trichlorophenoxyacetic acid were the most effective, with use of the latter inducing the production of embryogenic tissues in 7 cultivars which responded poorly or not at all to 2,4-D. Procedures for secondary/cyclic embryogenesis, formation of mature embryos and their conversion to plants are also described. Received: 24 September 1996 / Revision received: 16 December 1996 / Accepted 27 January 1997     

Antimutagenicity of mono-, di-, and tricaffeoylquinic acid derivatives isolated from sweetpotato (Ipomoea batatas L.) leaf

The caffeoylquinic acid derivatives, 3-mono-O-caffeoylquinic acid (chlorogenic acid, ChA), 3,4-di-O-caffeoylquinic acid (3,4-diCQA), 3,5-di-O-caffeoylquinic acid (3,5-diCQA), 4,5-di-O-caffeoylquinic acid (4,5-diCQA) and 3,4,5-tri-O-caffeoylquinic acid (3,4,5-triCQA), and caffeic acid (CA) were isolated from the sweetpotato (Ipomoea batatas L.) leaf. We examined the antimutagenicity of these caffeoylquinic acid compounds to promote new uses of the sweetpotato leaf. These caffeoylquinic acid derivatives effectively inhibited the reverse mutation induced by Trp-P-1 on Salmonella typhimurium TA 98. The antimutagenicity of these derivatives was 3,4,5-triCQA > 3,4-diCQA = 3,5-diCQA = 4,5-diCQA > ChA in this order. There was no difference in the antimutagenicity of all dicaffeoylquinic acid derivatives. A comparison of the activities and structures of these compounds suggested that the number of caffeoyl groups bound to quinic acid played a role in the antimutagenicity of the caffeoylquinic acid derivatives. The sweetpotato leaves contained distinctive polyphenolic components with a high content of mono-, di-, and tricaffeoylquinic acid derivatives and could be a source of physiological functions.     

Effects of shading on the photosynthetic capacity,endogenous hormones and root yield in purple-fleshed sweetpotato (Ipomoea batatas (L.) Lam)

A field experiment was conducted to examine the effects of shading on the photosynthetic capacity, endogenous hormones and root yield in purple-fleshed sweetpotato [Ipomoea batatas L. cv. Jishu18 and Ayamuraski (Aya)]. Sweetpotato plants were treated with two shading levels, 40 and 70 % shading, with full radiation used as a control. The results showed that the photosynthetic rate, adenosine triphosphatase activity, Ribulose 1,5-bisphosphate carboxylase activity and soluble sugar content decreased under both shading treatments. Leaf indole-3-acetic acid (IAA) and abscisic acid content increased, whereas leaf gibberellic acid content, zeatin riboside (ZR) content, root IAA, and ZR content decreased in the plants under both shading treatments. Shading also altered the production of sweetpotato storage root, including reductions in the root yield and dry matter accumulation, increase in the top/root (T/R) ratio, and the difference between the treatments and control for the T/R value and storage root yield was significant. Therefore, the responses of the photosynthetic parameters and endogenous hormones to shading were closely correlated with the variation in the storage root yield of the different cultivars. In response to shading, the reduction of root ZR contents, the fresh dry weight of the above-ground parts and the root yield for Jishu18 were higher than that for cv. Aya, indicating that cv. Jishu18 might be more sensitive to weak light than cv. Aya.     

Efficient plantlet regeneration from protoplasts isolated from suspension cultures of poplar (Populus alba L.)

We developed an efficient plant regeneration system from protoplasts for poplar (Populus alba L.). Protoplasts were isolated from 4-day-old suspension cultures derived from seed-induced calli with a yield of 6.96× 10⁶ cells/g fresh weight cells and then cultured at a concentration of 2.5×10⁵ cells/ml in NH₄NO₃-free Murashige and Skoog (MS) medium supplemented with 5 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 0.05 μM thidiazuron (TDZ) and 0.5 M glucose as a osmoticum. The plating efficiency of the cultured protoplasts was calculated at 26.5% at day 7 and 31.7% at day 14. Cell colonies were observed after culturing for 4 weeks. Regenerated colonies were propagated through subculture in liquid MS medium supplemented with 5 μM 2,4-D. Buds were induced from regenerated calli on MS medium containing 10 μM kinetin or 1 μM TDZ. Regenerated shoots were rooted on half-strength MS medium, and the plantlets were transplanted in soil. Randomly amplified polymorphic DNA analysis did not detect any DNA polymorphism among the regenerated plants. Received: 7 March 1997 / Revision received: 16 June 1997 / Accepted: 5 July 1997     

Regeneration of somatic hybrid plants formed between Lycopersicon esculentum and Solatium rickii

Summary A single somatic hybrid callus clone was identified following the fusion of Lycopersicon esculentum protoplasts and Solanum rickii suspension culture protoplasts. The hybrid nature of the callus and the plants regenerating from it was determined by assaying phosphoglucomutase-2 isozyme expression. The chloroplast genome present in four somatic hybrid plants was characterized by probing digests of total DNA with nick translated L. esculentum chloroplast DNA(cpDNA). All four somatic hybrid plants had inherited S. rickii cpDNA. Two clones of plant mitochondrial DNA (mtDNA), soybean 18S and 5S rDNA and maize cytochrome oxidase subunit II were used to characterize the mtDNA present in total DNA digests of four somatic hybrid plants. In both cases, the somatic hybrid plants had inherited most but not all of the S. rickii specific fragments, but none of the L. esculentum specific fragments.     

Characterization of chromosome instability in interspecific somatic hybrids obtained by X-ray fusion between potato (Solanum tuberosum L.) and S. brevidens Phil

Summary Asymmetric somatic hybrids between Solanum tuberosum L. and S. brevidens Phil. have been obtained via the fusion of protoplasts from potato leaves and from cell suspension culture of S. brevidens. The wild Solanum species served as donor after irradiation of its protoplasts with a lethal X-ray dose (200 Gy). Selection of the putative hybrids was based on the kanamycin-resistance marker gene previously introduced into the genome of Solanum brevidens by Agrobacterium-mediated gene transfer. Thirteen out of the 45 selected clones exhibited reduced morphogenic potential. The morphological abnormalities of the regenerated plantlets were gradually eliminated during the extended in vitro culture period. Cytological investigations revealed that the number of chromosomes in the cultured S. brevidens cells used as protoplast source ranged between 28–40 instead of the basic 2n=24 value. There was a high degree of aneuploidy in all of the investigated hybrid clones, and at least 12 extra chromosomes were observed in addition to the potato chromosomes (2n=48). Interand intraclonal variation and segregation during vegetative propagation indicated the genetic instability of the hybrids, which can be ascribed to the pre-existing and X-ray irradiation-induced chromosomal abnormalities in the donor S. brevidens cells. The detection of centromeric chromosome fragments and long, poly-constrictional chromosomes in cytological preparations as well as non-parental bands in Southern hybridizations with restriction fragment length polymorphism (RFLP) markers revealed extensive chromosome rearrangements in most of the regenerated clones. On the basis of the limited number of RFLP probes used, preferential loss of S. brevidens specific markers with a non-random elimination pattern could be detected in hybrid regenerants.     

Characterization of somatic hybrids of potato by use of RAPD markers and isozyme analysis

Electrofusion of mesophyll protoplasts from two male sterile dihaploid Solanum tuberosum genotypes. DHAK-11 and DHAK-33, was performed. Selection of putative fusion products was based on vigorous callus growth. Regeneration of rooted putative hybrid plants was scored 14 weeks after fusion. Characterization of hybrids was performed by use of morphological assessment, random amplified polymorphic DNA (RAPD), and cytological and isozyme analysis. The rate of regenerated hybrids from callus was ca 6%. Of the putative hybrids, 45% were confirmed as true hybrids. Morphological assessment of the putative hybrids revealed that tetraploid and neartetraploid hybrids were vigorous plants with intermediate characteristics between the two parental phenotypes in respect to internode length, leaf size and shape, and purple pigmentation on the abaxial side of the leaves. Near-hexaploid hybrids were slender plants with small leaves and short petioles. Selected RAPD primers showed unique marker bands for the two parental genotypes. Hybrid plants revealed the unique marker bands from both parents. A total of 53 randomly chosen decamer primers were tested and 26 primers (49%) detected polymorphism between the two dihaploid parentals. Two primers revealed that one parental marker band was missing in two aneuploid hybrids. However, of 51 putative hybrids, a double test with two independently chosen primers showed unequivocally the hybrid character of 23 plants. The ploidy level of the hybrids was analysed by chromosome numbers in root tip cells and by number of guard cell chloroplasts. A strong correlation between the chromosome number and the number of chloroplasts was obtained. The hybrid nature of all RAPD-verified hybrids was confirmed by isozyme analysis with malate dehydrogenase.     

Assessment of sweet potato [Ipomoea batatas (L.) Lam] for bioethanol production in southern Italy

The potential of sweet potato as an alternative crop for bioethanol production has been assessed. We evaluated the amount of soluble sugars, starch and cell wall polysaccharides in tubers of three sweet potato cultivars characterized by different pulp and peel colouration: “Yellow yam” with yellow flesh and brown peel, “White yam” with white flesh and white peel and “Orange yam” with orange flesh and brown peel. The results confirm the high concentration of carbohydrates in sweet potato tubers, especially “Yellow yam”, mainly in the form of starch (67%) and soluble sugars (26%). “Yellow yam”, which is the most widespread cultivar in Salento, appeared the best choice as biomass for bioethanol production. It is characterized by high productivity (20–40 tons/ha year). Results also suggest that “Yellow yam” cultivar has great potential as a bioethanol source in southern Italy with an estimated agroindustrial production yield higher than 2032 l/ha year.