Research Journal of Recent Sciences _________________________________________________ ISSN 2277-2502 Vol. 3(ISC-2013), 248-255 (2014) Res. J. Recent. Sci. International Science Congress Association 248 Exploration and collection of cassava (Manihot esculenta Crantz) in Western Ghats and characterisation for industrial use Kanagarasu S.1#, Justinraj F., Prem Joshua J., Ganeshram S. and John Joel A.1 Dept. of Plant Genetic Resources, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, INDIA Horticultural Research Station, Tamil Nadu Agricultural University, Pechiparai-629 161, Tamil Nadu, INDIAAvailable online at: www.isca.in, www.isca.me Received 3rd September 2013, revised 9th January 2014, accepted 20th February 2014 AbstractIn India cassava (Manihot esculenta Crantz.) is extensively cultivated as an annual tuberous root crop for both food and industrial uses . Study was aimed to explore and collect the adapted landraces of cassava available in Western Ghats of Tamil Nadu and to characterise the existing variability with particular reference to amylose for industrial applications. A total of 52 landraces were collected from various parts of Western Ghats and significant variations for morphological, root and root quality traits were observed. Analysis on quality parameters revealed that, amylose content ranged from 14.4% to 30.4% with an average of 22.0%. Landraces Adukku Muttan and Ullii chigappan showed low amylose content (14.4%) which is highly amenable for paper, textiles and plywood industries. Landraces with yellow pulp had high carotenoids can be used for culinary purpose by the local peoples. Cluster analysis grouped the landraces into five clusters and the number of accessions varied from 2 to 26. Knowledge on the variability in amylose content and phenotypic diversity for root traits increases the efficiency of the cassava breeding programmes by way of utilising them for industrial purpose and also helps in developing core collections which makes handling of germplasm easy for plant breeders. Diversity in amylose content may help in finding appropriate industrial utility and to formulate efficient quality improvement programme. Keywords: Cassava, landraces, exploration, root morphology, diversity, amylose content. Introduction Cassava (Manihot esculenta Crantz.) is a perennial woody shrub of the Euphorbiaceae, native of South America that is extensively cultivated as an annual tuberous root crop in the tropical regions of Africa, Asia and Latin America as a subsistence crop on which more than 500 million people rely. Globally cassava is grown in an area of 18.57 million ha producing 230.27 million tones with 12.4 t/ha of productivity. Apart from its use as a high energy food, cassava starch has a wide range of applications in both food-related and nonfood-related industries. Cassava starch could be converted to maltotriose, maltose, glucose and other modified sugar and organic acid. Starch hydrolysate has been widely used as additive compound in food industries mainly in the preparation of candies, bread, canned food and frozen food. Outside of the food industry, cassava starch is used in the manufacture of paper, textiles and plywood, and more recently in the production of ethanol and biodegradable polymers. Low amylose starch has high granule melting temperature and less retrogradationand low amylase starch is highly amenable for non food industrial applications. India is one of the major Asian country growing cassava and it acquires significance in the global cassava scenario due to higher productivity in the world. Cassava cultivating area, production and productivity of India is 0.23 million ha, 8.06 million tones and 34.75 t/ha respectively. Global efforts have been taken to improve the cassava based on its varied utility. Hence, diverse genotype of cassava is essential to start any crop improvement programme. Existence of variability in quality parameters will aid in developing trait-specific cassava populations for use in food, feed and industrial purposes. India is the one of the richest biological diversity subcontinent in the world and Western Ghats regions retain its diversity due to its complex topography, high rainfall and relative inaccessibility. In the present study, we explored and collected the farmer-grown cassava landraces in Western Ghats of Tamil Nadu and assessed the extent of genetic diversity for root traits and amylose content to use them in cassava breeding programme for industrial applications. Material and Methods Exploration and maintenance of study material: An exploration was conducted during Sept-Oct. 2011 in the Western Ghats, covering the high altitude areas ranging from 250 to 2552 feet above MSL with the objective to collect and study the existing farmers-grown landrace diversity in cassava. The exploration was covered in 32 villages in the southern region of Western Ghats. The planning and logistics and the sampling procedure for the collection of germplasm was made as per the guidelines. A total of 51 landraces adapted to various rainfed situations with unique distinct morphological features were collected and planted with one improved commercial Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 3(ISC-2013), 1-8 (2014) Res. J. Recent. Sci. International Science Congress Association 249 hybrid, H226 at HRS, Pechiparai, Tamil Nadu as cassava clonal garden. Morphological characterisation using descriptors: Tuber samples from all the accessions were collected and it can be used for morphological characterization of roots as per the cassava descriptors. Seven morphological characters viz., root constriction, root shape, external colour of root, colour of the root pulp, colour of root cortex, cortex: ease of peeling and texture of root epidermis were recorded and converted into binary data. Estimation of Amylose Content: Amylose, the basic unit of the starch was determined using method10 for all the 52 genotypes and expressed as per cent on dry weight basis.Two determinations were made for each sample and mean values were used for grouping based on the amylose content as low (10-20%), medium (20-25%) and high amylose (25-30%) genotypes. Genetic diversity and cluster analysis: The binary data obtained for 52 cassava genotypes were used to generate similarity matrix using the SIMQUAL programme of NTSYS-pc software, version 2.02i11. The similarity coefficients were used for cluster analysis and dendrogram was constructed by the Unweighted Pair-Group method (UPGMA)12. Results and Discussion Variability at morphological level: In the present study, an attempt has been made to determine the extent of diversity using the seven evaluated traits and to characterise the amylose content among 52 cassava accessions studied (table 1). The easily observable root traits are useful for preliminary evaluation as they offer a fast and useful approach for assessing the extent of diversity in cassava. Analysis of variance revealed the presence of significant variability in the experimental material. Descriptors based root constriction study revealed that, 26 accessions were found to possess few to no constriction, 13 were found to possess some and 13 were found to possess many constrictions in roots. Tuber shape: 21 genotypes exhibited cylindrical, 14 conical-cylindrical, 21 irregular and 5 conical. For external skin colour of the storage root, 34 accessions were found to be of brown in colour, 15 were cream and 3 were of yellow in colour. Table-1 Details of cassava lines explored in Western Ghats of Tamil NaduSl. No. Cassava Landrace Ac. No. Collection site Observations Root Constriction Root Shape Root Skin colour Pulp colour Root cortex colour Cortex peeling Root texture Amylose content (%) 1 Ullii chigappan CL1 Pechiparai Many Conical-cylindrical Light brown Yellow Pink Easy Smooth 25.4 2 Laxhmi vellai CL2 Tiruvarambu Some Cylindrical Cream Yellow Cream Difficult Rough 20 3 Karialai porian CL3 Pechiparai Many Cylindrical Light brown Yellow Pink Easy Rough 24.4 4 Ottai moodu CL4 Koruvakkuzhi Few to none Conical Light brown Yellow Pink Difficult Intermediate 23.4 5 Karialai porian CL5 Thanikunndu Some Conical-cylindrical Light brown Yellow Pink Easy Intermediate 21.2 6 Karialai porian CL6 Mothiramalai Few to none Irregular Light brown Yellow Pink Easy Intermediate 30.4 7 Karialai porian CL7 Vazhi battu kadavu Some Conical Cream White Cream Easy Intermediate 25.4 8 Karialai porian CL8 EB.Pachiparai Some Irregular Dark brown Cream Pink Easy Intermediate 22.4 9 Dwarf vellai CL9 Maramalai Some Cylindrical Cream White Cream Easy Intermediate 22.4 10 Dwarf Ullii chigappan CL10 Naval kadu Some Irregular Cream White Cream Easy Intermediate 25.4 11 Kattu (NT) CL11 Koruvakkuzhi Some Irregular Light brown Yellow Pink Difficult Intermediate 17.2 12 Ullii chigappan CL12 Koruvakkuzhi Some Irregular Light brown White Pink Easy Intermediate 14.4 13 Kerala thadi muttan CL13 Pathanamthittai Many Conical-cylindrical Cream Cream Pink Easy Smooth 18.4 14 Ullii chigappan CL14 Thanikunndu Many Conical-cylindrical Cream Cream Pink Easy Intermediate 15.2 15 Adukku muttan CL15 Thanikunndu Many Conical-cylindrical Cream Yellow Cream Easy Rough 14.4 16 Karialai porian CL16 Mookirakall Many Conical Cream Yellow Pink Difficult Rough 15.3 17 Laxhmi vellai CL17 Mallamuthan karai Many Conical Cream Cream Cream Easy Intermediate 17.2 18 Tall-kattu CL18 Mallamuthan Many Cylindrical Dark White Yellow Difficult Smooth 16.1 Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 3(ISC-2013), 1-8 (2014) Res. J. Recent. Sci. International Science Congress Association 250 karai brown 19 Tall-Chilly kallan CL19 Mallamuthan karai Many Irregular Cream White Cream Easy Intermediate 16 20 Tall- Karialai porian CL20 Mallamuthan karai Many Irregular Cream Yellow Cream Easy Rough 20 21 Adukku muttan CL21 Mallamuthan karai Some Conical-cylindrical Cream White Cream Easy Intermediate 26.4 22 Yeathan chivalai CL22 Vaiyana challai Many Conical-cylindrical Cream Cream Pink Easy Intermediate 15.2 23 Pachai konntai CL23 Koruvakkuzhi Many Cylindrical Dark brown White Cream Easy Smooth 16 24 Nadan karialai CL24 Chittar Few to none Cylindrical Light brown Cream Cream Easy Intermediate 20.4 25 - CL25 Allan chollai Few to none Conical-cylindrical Dark brown Cream Pink Easy Intermediate 16 26 Laxhmi vellai CL26 Chittar Some Conical-cylindrical Dark brown Yellow Yellow Easy Intermediate 25.4 27 Kaichi kuttai CL27 Chittar dam Some Cylindrical Dark brown Yellow Pink Easy Intermediate 30.4 28 Nooru muttan CL28 Allan chollai Few to none Conical-cylindrical Dark brown Yellow Pink Easy Intermediate 20.4 29 Aana karialai CL29 Neduman kaadu Few to none Cylindrical Dark brown Cream Cream Difficult Intermediate 22.4 30 Kailady CL30 Valia yela Few to none Cylindrical Light brown Cream Pink Easy Intermediate 19.4 31 Black karialai CL31 Valia yela Some Irregular Light brown Yellow Pink Easy Intermediate 26.4 32 - CL32 Mantharam puthur Few to none Irregular Dark brown Yellow Yellow Easy Intermediate 27.4 33 - CL33 Kottaram Few to none Irregular Dark brown Cream Pink Easy Intermediate 22.4 34 - CL34 Kottaram Few to none Cylindrical Dark brown Yellow Pink Easy Intermediate 14.9 35 - CL35 Achan kulam Few to none Conical-cylindrical Dark brown Cream Pink Easy Intermediate 24.4 36 Arriam vellai CL36 Kaata vilai Many Irregular Light brown Cream Pink Easy Intermediate 25.4 37 Tall-muttan CL37 Kaata vilai Few to none Irregular Dark brown Yellow Pink Easy Intermediate 20.4 38 Karun karialai CL38 Mudavan pottai (Hill) Few to none Cylindrical Light brown Cream Pink Easy Intermediate 20.4 39 Chengambai CL39 Valayamthukki Few to none Conical-cylindrical Dark brown Cream Cream Easy Rough 22.4 40 Pachai konda CL40 Valayamthukki Few to none Cylindrical Yellow Cream Cream Easy Smooth 24.4 41 Vellai porian CL41 Valayamthukki Few to none Conical-cylindrical Yellow Yellow Pink Easy Intermediate 23.4 42 Karialai porian CL42 Kayarkarai Few to none Cylindrical Dark brown Yellow Pink Easy Intermediate 26.4 43 Adukku muttan CL43 Kkayarkarai Few to none Conical-cylindrical Dark brown Cream Cream Easy Intermediate 24.4 44 Chengambai CL44 Kayarkarai Few to none Cylindrical Dark brown Yellow Cream Easy Intermediate 26.4 45 Pachai konda CL45 Kkayarkarai Few to none Cylindrical Cream Yellow Pink Easy Intermediate 24.4 46 Karialai porian CL46 Kayarkarai Few to none Cylindrical Dark brown Yellow Pink Easy Rough 28.4 47 Karialai porian CL47 Kayarkarai Some Cylindrical Yellow Cream Pink Easy Intermediate 24.4 48 Karialai porian CL48 Verkilambi Few to none Cylindrical Dark brown Yellow Pink Easy Intermediate 28.4 49 Adukku muttan CL49 Arasan seri Few to none Cylindrical Dark brown Yellow Yellow Easy Intermediate 24.4 50 - CL50 Mathur Few to none Conical Light brown Yellow Pink Easy Intermediate 28.4 51 Ullii chigappan CL51 Mathur Few to none Cylindrical Dark brown Cream Pink Easy Intermediate 28.4 52 White rose CL52 Salem Few to none Cylindrical Cream Cream Cream Easy Intermediate 28.5 Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 3(ISC-2013), 1-8 (2014) Res. J. Recent. Sci. International Science Congress Association 251 Regarding the pulp colour, 18 accessions were found to possess pulp cream and 25 were possessing yellow pulp. In the case of root cortex colour, 32 accessions were having the pink colour, 17 were of cream colour and 3 accessions were to be of yellow colour. With respect to peeling of cortex, 46 accessions were peeled easily and 6 accessions were found difficult to peel. Regarding the tuber surface texture, 4 accessions were of smooth, 41 accessions were of intermediate and 7 accessions found to possess rough surface (table 2. and figure-1). Descriptor based root diversity study revealed the presence of enormous diversity for tuberous root colour, cortex colour, pulp colour as well as tuberous root shape and texture. The reason may be, a farmer very rarely discards even a low-yielding variety, but maintains it at a low frequency for its other quality or adaptability traits. This corresponds to a strategy of risk management in uncertain farming conditions, but the practice is also motivated by social or cultural reasons because diversity is prized for its own sake. This much variability would have been created through volunteer cassava or through exchange of clones within the community, or with other villages. The present study revealed the existence of high level of morphological diversity among the cassava genotypes as reported earlier in cassava13, providing scope for improvement through hybridization and selection. Table-2 Cassava variability for root morphological traits and amylose content Sl.No. Characters No. of Genotypes 1 Root constrictions Few to none 26 Some 13 Many 13 2 Root shape Conical 5 Conical-cylindrical 14 Cylindrical 21 Irregular 12 3 External skin colour of root White or cream 15 Yellow 3 Light brown 13 Dark brown 21 4 Colour of root pulp White 9 Cream 18 Yellow 25 5 Colour of root cortex White or cream 17 Yellow 3 Pink 32 6 Cortex: ease of peeling Easy 46 Difficult 6 7 Texture of root epidermis Smooth 4 Intermediate 41 Rough 7 8 Amylose content (%) Low (10-20) 18 Medium (20-25) 18 High (�25) 16 Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 3(ISC-2013), 1-8 (2014) Res. J. Recent. Sci. International Science Congress Association 252 Figure-1 Variation in root morphological characters in cassava Diversity in amylose content: Estimation of amylose content in the 52 genotypes revealed that the amylose content ranged from 14.4% (Ullii chigappan from Koruvakkuzhi) to 30.4% (Karialai porian from Mothiramalai) with an average of 22.0% (table 1). Amylose content in cassava genotypes were grouped as high (25.4%–30.4%), intermediate (20.4%–24.4%) and low (14.4%–20.0%). Among the 52 accessions, 18 cassava accessions had low amylose content, 18 were medium and 16 genotypes possessed high amylose content (table 2). Estimation of amylose content indicates the existence of variation among the landraces studied (figure-2). The extreme amylose lines can be used in cassava breeding programme to develop high or low amylose genotypes that has wider applications in food processing industry and paper and textile industries respectively. Principal component analysis: The Principal Component Analysis was performed using the observations recorded for seven root morphological traits and amylose content. The values of the Eigen vectors and their contribution to total variation are presented in table 3. The first three principal components accounted for 61.8% of the total variance. The first principal component (PC1) accounted for 30.23% of total variance and had high contributing factor loadings from root skin colour, pulp colour and root cortex colour. The second principal component (PC2) accounted for 17.95% variation and had high contributing factor loadings from traits namely pulp colour, cortex peeling and root texture. The third principal component (PC3) accounted to 13.6% of the total variation, with high factor loadings for root cortex colour. The contribution of maximum variability to total variation by root skin colour, pulp colour, cortex peeling and root cortex colour were reported earlier13,14Table-3 Principal components analysis showing the contribution of root morphological traits in cassava Variables PC1 PC2 PC3 Root constrictions -0.794 0.115 0.336 Root shape 0.131 -0.400 0.277 External skin colour of root 0.783 -0.214 0.190 Colour of root pulp 0.511 0.685 0.172 Colour of root cortex 0.489 0.197 0.713 Cortex: ease of peeling -0.164 0.466 0.161 Texture of root epidermis 0.037 0.694 -0.378 Amylose content -0.794 0.106 0.395 EIGEN VALUE 2.419 1.436 1.088 % VARIANCE 30.2 18.0 13.6 CUMULATIVE % VARIANCE 30.2 48.2 61.8 Figure-2 Variation in amylose content among the cassava genotypes Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 3(ISC-2013), 1-8 (2014) Res. J. Recent. Sci. International Science Congress Association 253 Cluster analysis: The similarity coefficients generated in the SIMQUAL programme of NTSYS-pc 2.02i were used to construct the hierarchical clusters and resulting dendrogram is presented in figure 3. The 52 cassava accessions formed 5 clusters at similarity index of 0.71. The details of five clusters along with the accessions and average amylose content were presented in table 4. Among the different clusters, the cluster size varied from 2 to 26. The cluster II possessed a maximum of 26 genotypes with intermediate amylose and less root constrictions. A minimum of two genotypes with low amylose represented in cluster V. Cluster I contains 10 genotypes and the tubers possessed light brown colour outer skin. Four accessions with characters like yellow pulp and rough texture were grouped in Cluster III. Ten accessions having unique characters like cylindrical tuber shape, white pulp and smooth texture were grouped in Cluster IV. Similar studies have been carried out previously15-18 for the estimation of genetic diversity in cassava based on morphological traits and reported high degree of genetic variability among 94 cassava accessions of Brazilian origin14 and African and Latin American accessions19. This trait based clustering will be helpful in handling large populations and to develop core collections and trait based collections for the breeders to develop a working germplasm. Also, cassava hybrid breeding programme involving parents from diverse amylose content clusters will be useful in exploiting and fixing heterosis. Sequencing of candidate gene: Molecular breeding program has been initiated by retrieving the Expressed Sequence Tag (EST`s) sequences for cassava (Manihot esculenta Crantz.) granule bound starch synthase gene 1 (GBSS 1) (X74160.1) along with the amino acid sequences from the gene bank database of NCBI and primers were designed. Using the primers the candidate gene was sequenced through primer walking strategy and gene model was developed. Gene model for GBSS gene revealed it has 13 exons and 12 introns (figure- 4). It was in accordance with the GBSS 1 gene model of potato20 and sweet potato21. Comparing the sequence difference in two extreme genotypes is underway. After sequencing, it can be compared to explore the sequence differences between them and to develop functional markers which may be used in marker based screening of genotypes in molecular breeding programme. Table-4 Cluster composition of cassava accessions for root morphological traits and amylose content Sl.No. Clusters No. of Genotypes Mean amylose content (%) Code No. 1 I 10 23.1 CL1, CL3, CL4, CL5, CL6, CL8, CL11, CL12, CL31, CL36 2 II 26 23.1 CL24, CL25, CL26, CL27, CL28, CL29, CL30, CL32, CL33, CL34, CL35, CL37, CL38, CL39, CL40, CL41, CL42, CL43, CL44, CL45, CL46, CL47, CL48, CL49, CL50, CL51 3 III 4 17.5 CL2, CL15, CL16, CL20 4 IV 10 21.0 CL7, CL9, CL10, CL13, CL14, CL17, CL19, CL21, CL22, CL52 5 V 2 16.1 CL18, CL23 Figure-3 Dendrogram showing relationship among 52 cassava genotypes based on seven morphological data Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 3(ISC-2013), 1-8 (2014) Res. J. Recent. Sci. International Science Congress Association 254 Figure-4 Gene model for the candidate gene GBSS I Conclusion Farmers are the saviours of cassava on farm diversity in Western Ghats region of Tamil Nadu by way of acquiring and maintaining local landraces which are productive even under unfavourable conditions. Cassava farmers enjoy diversity and eagerly acquire new landraces. They rarely discard unproductive landraces, retaining them, even if at low frequencies, arguing that they can become productive under different climatic conditions. The other reason for diversity is the occurrence of natural introgression through gene flow and growing volunteer seedlings. We also argue that recombination and gene flow play a major role in the dynamics of genetic diversity of cassava in traditional farming systems. Diversity analysis and clustering of genotypes for morphological and biochemical traits helps in developing core collections which makes handling of large germplasms easy for plant breeders. Knowledge on the variability in amylose content may help in finding appropriate industrial utility and to formulate efficient quality improvement programme. Developing knowledge on the sequence diversity for GBSS 1 gene will help in formulating molecular breeding programme to meet industrial needs. References 1.Thro A.M., Taylor N., Raemakers C.J.J.M., Puonti-Kaerlas J., Schopke C., Visser R.G.F., Iglesias C., Sampaio M.J., Fauquet C., Roca W. and Potrykus I., Maintaining the cassava biotechnology network, Nature Biotechnol.,16,428-430 (1998) 2.FAO., FAO statistics http://apps.fao.org: Food and Agricultural Organization of the United Nations, Rome, Italy, (2010)3.Sudarmonowati E., Hartati N.S. Hartati and SukmariniL., Amylose Content Variation of Indonesian Cassava Genotypes and its Correlation with RAPD and AFLP Markers, Pro. Intl. Meeting Cassava Breed, Biotechnol. Ecol., 85-95 (2007) 4.Visser R.G.F., Suurs C.J.M., Steeneken P.A.M. and Jacobsen E., Some physicochemical properties of amylose-free potato starch, Starch,49, 443-448 (1997)5.Raji A.A., Ladeinde T.A.O. and Dixon A.G.O., Agronomic traits and tuber quality attributes of farmer grown cassava landraces in Nigeria, J. Tropical Agric., 45(1-2), 9-13 (2007)6.Engels J.M.M., Arora R.K. and Guarino L., An introduction to plant germplasm exploration and collecting: planning, methods and procedures, follow-up. In: Collecting plant genetic diversity. Technical guidelines.Guarino L., V. Ramanatha Rao and R. Reid (eds.). CAB International, Wallingford, United Kingdom, 31-63, (1995)7.Brown A.H.D. and Marshall D.R., A basic sampling strategy: theory and practice. In: Collecting plant genetic diversity. Technical guidelines. Guarino, L., Ramanatha Rao, V. and Reid R. (eds.) CAB International, Wallingford, United Kingdom 75-91 (1995)8.Fukuda W.M.G., Guevara C.L., Kawuki R. and FergusonM.E., Selected morphological and agronomic descriptors for the characterization of cassava. International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, (2010)9.Benesi I.R.M., Native starch evaluation and analysis of genetic distance using AFLP of elite cassava (Manihot esculenta Crantz.) genotypes from Malawi. MSc Thesis, Department of Plant Sciences, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein, South Africa, (2002)10.Juliano B.O., A simplified assay for milled rice amylase, Cereal Sci., 16, 334-338 (1971)11.Rohlf F.J., NTSYS-pc. Numerical Taxonomy and Multivariate Analysis System, Version 2.02. Exeter Software, Setauket, New York, (1998) 12.Sneath I.H.A. and Sokal R.R., Numerical taxonomy. W. H. Freeman and Company, San Francisco, Theor. Appl. Genet., 93, 613-617 (1973)13.Raghu D., Senthil N., Saraswathi T., Raveendran M., Gnanam R., Venkatachalam R., Shanmugasundaram, P. and Mohan C., Morphological and simple sequence repeats (SSR) based finger printing of south Indian cassava germplasm, Intl. J. Integrative Biol.,1(2), 141-148, (2007)14.Carvalho L.C.B. and Schaal B.A., Assessing genetic diversity in the cassava (Manihot esculenta Crantz) germplasm collection in Brazil using PCR-based markers, Euphytica,120, 133-142 (2001) 15.Pereira A.V., Vencovsky R. and Cruz C.D., Selection of botanical and agronomical descriptors for the characterization of cassava (Manihot esculenta Crantz.) germplasm, Revista Brasileira De Genetica, 15, 115-124 (1992) Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 3(ISC-2013), 1-8 (2014) Res. J. Recent. Sci. International Science Congress Association 255 16.Cury R., Dinamica evolutiva e caracterizaçao de germoplasma de mandioca (Manihot esculenta Crantz.) na agricultura autoctone do sul do Estado de Sao Paulo. MSc Thesis, ESALQ (Escola Superior de Agricultura Luiz de Queiroz), USP, Piracicaba, SP, Brasil, (1993)17.Cordeiro C.M.T., Morales E.A.V., Ferreira P., Rocha D.M.S., Costa I.R.S., Valois A.C.C. and Silva S., Towards a Brazilian core collection for cassava. In: Core Collections of Plant Genetic Resources. Hodgkin, T., Brown, A.D.H., van Hintun, T.J.L. and Morales, E.A.V. (eds.). International Plant Genetic Resources Institute (IPGRI). John Wiley & Sons, New York. 155-169, (1995)18.Fregene M.A., Bernal A., Duque M., Dixon A.G.O. and Tohme J., AFLP analysis of African cassava (Manihot esculenta Crantz.) germplasm resistant to the cassava mosaic disease (CMD), Theor. Appl. Genet., 100, 678-685, (2000)19.Chavez A.L., Sanchez T., Jaramillo G., Bedoya J.M., Echeverry J., Bolanos A., Ceballos H. and Iglesias C.A., Variation of quality traits in cassava roots evaluated in landraces and improved clones, Euphytica, 143, 125-133 (2005)20.van der Leij F.R., Visser R.G.F., Ponstein A.S., Jacobsen E. and Feenstra W.J., Sequence of the structural gene for granule-bound starch synthase of potato (Solanum tuberosum L.) and evidence for a single point deletion in the amf allele, Mol. Genet.,228, 240-248 (1991)\21.Kimura T., Ideta O. and Saito A., Identification of the gene encoding granule-bound starch synthase I in sweet potato Ipomoea batatas (L.) Lam.), Plant Biotechnol., 17, 247-252 (2000)