Diversity among landraces of Indian snapmelon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">momordica</Emphasis>)

Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew, Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base of melon germplasm available with the scientific community. N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors.     

Wild melon diversity in India (Punjab State)

We present here the first comprehensive genetic characterization of wild melon accessions from northern India. The genetic diversity among 43 wild melon accessions collected from the six agro-ecological regions of the Punjab State of India was assessed by measuring variation at 16 Simple Sequence Repeat (SSR) loci, morphological traits of plant habit and fruit morphological traits, two yield-associated traits, root nematode resistance and biochemical composition (ascorbic acid, carotenoids, titrable acidity). Variation among accessions was observed in plant habit and fruit traits and wild melon germplasm with high acidity and elevated carotenoid content and possessing resistance to Meloidogyne incognita was identified in the collection. A high level of genetic variability in wild melon germplasm was suggested by SSR analysis. Comparative analysis using SSRs of the genetic variability between wild melons from the north and other melons from the south and east regions of India and also reference accessions of cultivated melon from Spain, Japan, Korea, Maldives, Iraq and Israel, showed regional differentiation among Indian melon accessions and that Indian germplasm was not closely related to melon accessions from other parts of the world. A highly drought tolerant accession belonging to var. agrestis Naud. was also identified.     

Diversity among melon (Cucumis melo L.) landraces from the Indo-Gangetic plains of India and their genetic relationship with USA melon cultivars

We report here the first broad genetic characterization of farmer-developed landraces of melon (Cucumis melo L.) from the Indo-Gangetic plains of India, an area overlooked in previous melon genetic diversity analyses of Indian melon germplasm. Eighty-eight landraces from three melon Groups in two subspecies (C. melo subsp. agrestis Momordica Group, and C. melo subsp. melo Cantalupensis Group and Reticulatus Group) were collected from the four agro-ecological regions (six sub-regions) of two northern states of the Indo-Gangetic plains of India, Uttar Pradesh and Uttarakhand. Significant differences were found among the landraces and eight USA Reticulatus Group reference cultivars for 18 plant and fruit traits: no. of primary branches per plant, days to marketable maturity, sex expression, fruit shape, flesh colour, netting, no. of fruit per plant, fruit weight, shelf life, total soluble solids (°Bx), ascorbic acid (mg/100 g), titratable acidity (%), fruit length and diameter, seed cavity length and diameter, flesh thickness, and resistance to Cucumber mosaic virus. The three melon groups differed significantly for 10 of the plant and fruit traits. Cantalupensis Group and Reticulatus Group accessions were andromonoecious, and the Momordica Group was monoecious. Neighbour-joining (NJ) tree and factorial correspondence analysis (FCA) of simple sequence repeat loci also revealed a high level of genetic variability in this germplasm. The 96 melon genotypes clustered into five groups in the NJ tree analysis: the 16 Indian Reticulatus Group accessions and eight USA reference cultivars formed a distinct group; and the 60 Cantalupensis Group accessions clustered in four other groups with the 12 Momordica Group accessions in a distinct subgroup of one of the Cantalupensis groups. The FCA plot largely confirmed the NJ tree with three distinct groups, one for each melon group. The close affinity of the Indian and USA Reticulatus melons was not unexpected, but it is not clear whether it was inherent in the group and maintained as Reticulatus melons moved from India through Central Asia and Europe to North America, or the result of recent intercrossing of Indian landraces with the USA-derived cultivars and selection for a broad range of Reticulatus type melons.     

Molecular analysis of genetic diversity in melon landraces (<Emphasis Type="Italic">Cucumis</Emphasis><Emphasis Type="Italic">melo</Emphasis> L.) from Myanmar and their relationship with melon germplasm from East and South Asia

Genetic diversity of Myanmar melon was evaluated by analysis of 27 RAPD markers and morphological characters using 41 accessions of melon landraces of which 36 accessions were small-seed type. The gene diversity was 0.239, higher than for group Conomon from East Asia and equivalent to Indian melon populations. Melon accessions were classified into six major clusters. The largest cluster IV comprised mainly group Conomon which was closely related to cluster V consisting of mainly group Agrestis. Most of the accessions of group Cantalupensis were grouped into clusters II or VII and were distantly related to groups Conomon and Agrestis. The genetic relationship to melon accessions from neighboring countries was analyzed. The 24 accessions of clusters IV and V were mostly clustered together with small-seed type melon of India, but the 14 accessions of clusters VI and VII were mostly clustered together with large-seed type melon of India. These results indicated that the genetic diversity of Indian melon is conserved in Myanmar. Genetic introgression among melon groups through spontaneous hybridization was also indicated and was considered important to maintain or increase the genetic diversity in Myanmar.     

Morphological characterization of snake melon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">flexuosus</Emphasis>) populations from Palestine

Genetic diversity in 50 snake melon accessions collected from Palestine (West Bank) was assessed by examining variation in 17 phenotypic characters. These accessions belonged to four important landraces of Cucumis melo var. flexuosus: Green “Baladi” (GB), white Baladi (WB), green Sahouri (GS), and white Sahouri (WS). Principal component analysis (PCA) and a dendrogram were performed to determine relationships among populations and to obtain information on the usefulness of those characters for the definition of cultivars. PCA revealed that secondary fruit skin color, flesh color, primary fruit skin color, and secondary skin color pattern were the principal characters to discriminate melon accessions examined in the present study. According to the scatter diagram and dendrogram, landraces of C. melo var. flexuosus: GB, WB, GS, and WS formed different clusters. However, based on Euclidean genetic coefficient distances, GB and WB had the least degree of relatedness with GS and WS, indicating distantly related landraces (Baladi and Sahouri). On the other hand, the highest degree of relatedness was detected between WS on one hand, and both GS and WB on the other indicating closely related cultivars. Fruit traits variability among the different snake melon landraces was evaluated and discussed in this study. This evaluation of fruit trait variability can assist geneticists and breeders to identify populations with desirable characteristics for inclusion in cultivars breeding programs.     

Spanish melons (Cucumis melo L.) of the Madrid provenance: a unique germplasm reservoir

Melon (Cucumis melo L.) landraces of the Madrid provenance, Spain, have received national distinction for their high fruit quality and sensorial attributes. More specifically, a unique array of Group Inodorus landraces have been continuously cultivated and conserved by farmers in the municipality of Villaconejos since the 19th century. Their genetic relationships to other Group Inodorus and Flexuous melon market classes is not known, and, thus, a study was designed to determine their genetic relationships using 52 simple sequence repeat (SSR) markers, and then make genetic comparisons between these accessions and a previously published “Standard Reference Germplasm Array” (RA) containing Group Inodorus (14 Spanish and one USA), Flexuosus (1 Spanish), and Cantalupensis ( 2 USA) melon accessions. This subset consisted of 15 Spanish Group Inodorus landraces that circumscribed the genetic variation of major Spanish melon market classes (Groups Inodorus and Flexuosus), and USA commercial varieties (Groups Cantalupensis and Inodorus). Based on genetic distances, Villaconejos (Madrid) genotypes differed substantially from RA subset accessions, thus defining their genetic uniqueness. Principal component analysis (PCA) partitioned the accessions examined into four distinct groups revealing that Villaconejos black epidermis melons (landraces ‘Largo’, ‘Largo Negro Escrito’ and ‘Puchero’) were distinctly different from all other accessions examined, as cluster analysis separated Rochet market type Villaconejos’ accessions (landraces ‘Mochuelo’, ‘Mochuelo Tradicional’ and ‘Melón de Villaconejos’) from RA of the same market type. Genetic assessment of principal Spanish market classes revealed comparatively low intra-market heterogeneity in Piel de Sapo type accessions and high heterogeneity in Black and Yellow market type accessions. While a relatively high level of genetic introgression was detected between Yellow and Green market types, black epidermis market types were genetically unique. Given the uniqueness and high genetic diversity resident in Villaconejos landraces, this germplasm pool should be considered as a genetic source for broadening the comparatively narrow genetic base of Group Cantalupensis and Inodorus melon market types, especially standard commercial Spanish Group Inodorus market types (e.g., Piel de Sapo, Rochet, and Canari).     

Morpho-agronomic and simple sequence repeat-based diversity in colored rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) germplasm from peninsular India

Knowledge of the genetic diversity in the germplasm accessions is important for the efficient germplasm management. We studied 45 colored rice accessions, which had been earlier collected from peninsular India. The accessions were evaluated at two diverse locations for 12 morpho-agronomic traits and genotyped using 50 simple sequence repeat (SSR) markers. Significant genotypic variability was observed for all morpho-agronomic traits studied. Dendrogram and principal component analysis based on morpho-agronomic traits separated the accessions into three clusters. The first two principal components accounted for 82% of the total variation. The most discriminatory traits were number of grains per panicle, biomass yield, and days to flowering and maturity. The SSR analysis revealed high polymorphic information content value of 0.84. Though, Mantel test did not show a significant correlation, yet the classification based on phenotyping and genotyping data showed good agreement for the expression of morpho-agronomic traits in the formation of clusters. Five accessions had high concentration (> 100 μg/g) of Fe and one of Zn. Our study revealed the presence of large genetic variation among the colored rice accessions evaluated and moderate agreement between morpho-agronomic and SSR–based classifications and of these with geographic diversity.     

Agro-morphological diversity of Spanish traditional melons (<Emphasis Type="Italic">Cucumis melo</Emphasis> L.) of the Madrid provenance

The variability of 14 landraces belonging to a Madrilean village historically specialized on melon cultivation, Villaconejos, was evaluated based on 58 quantitative and qualitative morphological traits. These landraces were compared to a reference array composed of 14 accessions which represented the main varieties cultivated in Spanish fields. Individual data related to plant, fruit, seed and phenology have been analysed using a multivariate analysis. This analysis showed intra- and inter-varietal diversity, as emphasized the most discriminant morphological traits in order to define similarities. Villaconejos accessions were morphologically distinct from the reference accessions (RA). Only the landraces belonging to Piel de Sapo market class showed common morphological affinities with the RA, grouping with them. The majority of Villaconejos traditional varieties clustered in five different groups, with no RA within, showing distinctive morphological singularities not described previously. Two of these groups showed some particularities in fruit traits, which are appreciated as quality marks for Spanish consumers. These results indicate that these accessions must be conserved as valuable genetic resources to enrich the Inodorus genetic bases for future breeding proposes worldwide. Furthermore, it should be considered the opportunity of promoting their cultivation under the shelter of a Protected Geographical Indication as a high quality melon. Finally, the discovering of such a high variability presented in a very small area, gives a clue for focusing, with an elevated probability of success, future surveys in similar ancestral European villages which in the past times, also supplied more populated cities with their farming products.     

Agromorphological genetic diversity of Spanish traditional melons

The variability of 62 Spanish landraces (and two hybrids used as reference) was described by analysing 39 morphological traits and eight SSR makers. Results showed that 81% of the examined genetic pool belonged to the inodorus type. Spanish traditional melons presented fruits from flattened and globular shapes to elliptical. Rind colour varied from pale green, almost white and yellow to dark green and almost black. Rind texture varied from smooth to intensely wrinkled. Spanish landraces also had larger fruits (average fruit weight ~2.6 kg) and longer vegetative cycles (117 days to maturity) compared to landraces from other geographical origins. Farmers seem to have focused on selection towards large fruits, which usually requires the longest production cycles. Fruit colour, size and shape seemed to have been determinant in varietal selection. Hierarchical clustering resulted in two main groups (climacteric and non-climacteric). The largest group was composed of 60 accessions of non-climacteric types, which includes the most demanded by national markets, ‘Piel de Sapo’, which fruits were characterized by an ovate or elliptical shape, a green rind, big spots and stains distributed over the whole fruit, a rounded blossom end shape and a very pointed stem end shape. The study demonstrates that the Spanish genetic pool is much more diverse. Wide variability was found in a geographical area with vast historical importance in melon farming. These evaluations has allowed the identification of several uniform groups of non-climacteric cultivars (‘Piel de Sapo’, ‘Mochuelo’, ‘Tendral’, Yellow/White, Winter and Black groups) and a set of highly variable climacteric ones. However, many accessions with singular properties remain unclassified, demonstrating the morphological variability of the studied collection. Melons in Spain have wide variability together with a vast historical importance on farms. Some fruit types, or at least some morphological characters reflected by painters during centuries, have reached the present. The present study confirmed the need to preserve these irreplaceable genetic resources and continue their study and evaluation for valuable traits which could enhance farmer’s opportunities for entering new markets.     

Characterization of Italian grasspea (<Emphasis Type="Italic">Lathyrus sativus</Emphasis> L.) germplasm using agronomic traits,biochemical and molecular markers

Genetic relationships among 13 grasspea (Lathyrus sativus L.) landraces mainly collected in Southern Italy were assessed using agronomic traits, biochemical and molecular markers. Field trials were carried out in two locations and revealed a high influence of field locations on yield, but a low genotype × environment interaction. Despite this, the agronomic data obtained provided useful information for the choice of the best grasspea landraces for southern Italian marginal areas. Seed storage proteins utilised as biochemical markers were not able to detect polymorphisms, on the contrary both classes of molecular markers used i.e. AFLP and SSR, provided useful information on genetic variation and relationships among landraces. Even though the number of polymorphic fragments detected by AFLP technique was low, it was sufficient to discriminate all the accessions. The use of SSR to detect polymorphic sites in grasspea showed that most landraces were clearly grouped in two sub-clusters. One comprised two landraces from most northern localities, while all the other landraces were clustered together at a very narrow genetic distance.     

Evaluating landraces of bread wheat <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. for tolerance to aluminium under low pH conditions

Bread wheat (Triticum aestivum L.) landraces held within ex situ collections offer a valuable and largely unexplored genetic resource for wheat improvement programs. To maximise full utilisation of such collections the evaluation of landrace accessions for traits of interest is required. In this study, 250 accessions from 21 countries were screened sequentially for tolerance to aluminium (Al) using haematoxylin staining of root tips and by root regrowth measurement. The staining test indicated tolerance in 35 accessions, with an intermediate response to Al exhibited in a further 21 accessions. Of the 35 accessions classified as tolerant, 33 also exhibited increased root length following exposure to Al. The tolerant genotypes originated from Bulgaria, Croatia, India, Italy, Nepal, Spain, Tunisia, and Turkey. AFLP analysis of the 35 tolerant accessions indicated that these represent diverse genetic backgrounds. These accessions form a valuable set of germplasm for the study of Al tolerance and may be of benefit to breeding programs for expanding the diversity of the gene pool from which tolerant cultivars are developed.     

Extent and Pattern of Genetic Diversity for Morpho-agronomic Traits in Ethiopian Highland Pulse Landraces II. Faba Bean (<Emphasis Type="Italic">Vicia faba</Emphasis> L.)

A field experiment was conducted in 2001 at Holetta and Kulumsa, Ethiopia, to study genetic diversity in Ethiopian faba bean (Vicia faba L.) landraces. One hundred sixty random germplasm accessions were grown in an alpha lattice design with two replications. Data on 12 traits were collected and analyzed. Significant differences were observed among the accessions for most of the traits (except number of pods/podding nodes) at each location even though differences pooled over location were mostly non-significant. Cluster analysis distinguished seven diversity classes of different sizes. Accessions from the northern half of the country (North and South Wello, North Gonder and North Shewa) were closely related while those from the southern part of the country (Arsi) were highly diverse. Cumulative effects of a number of characters dictated differentiation of the accessions into clusters. Some overlapping were encountered between accessions from the northern and those from the southern parts of the country. The study revealed that accessions from different regions might have similar genetic background and those from the same origin might also have different genetic background. Therefore, geographic diversity should not necessarily be used as an index of genetic diversity and parental selection should be based on a systematic study of genetic diversity in a specific population. Genetic distances between most of the clusters were significant that crosses between parents selected out of them are expected to generate desirable progenies. Future germplasm collection, conservation and utilization strategies should put more focus not only on inter-regional diversity in the country as a whole but also on intra-regional diversity in Arsi.     

Temporal variation of diversity in Italian durum wheat germplasm

The aim of this work is to analyse the temporal change of genetic diversity in Italian durum wheat germplasm. The germplasm deployed in this study (158 accessions), belonging to 5 different historical classes, was characterised for its microsatellite and gliadin markers. The level of genetic diversity (He), based on gliadin and SSR markers results – on average – greater in indigenous landraces present in Italy before 1915, with the exception of pure line material which had been selected from landraces (showing highest level of heterozigosity for gliadin markers). Genotypes obtained from crosses or mutagenesis (referring to the 1950–1960 period) along with those resulting from crosses between CIMMYT lines and old materials (1970s and beyond) were also genetically more diverse. Forty-nine percent of indigenous landraces were genetically heterogeneous. Nine out of 53 landrace accessions were able to capture 4 different SSR private alleles. It is speculated that the reduction of allele richness is an indicator of the genetic erosion of the pre-breeding germplasm and it is pointed out that the implementation of appropriate methods of genetic conservation of this germplasm is a priority for breeding and food safety.     

Development of Core Collection in Pigeonpea [<Emphasis Type="Italic">Cajanus cajan</Emphasis> (L.) Millspaugh] using Geographic and Qualitative Morphological Descriptors

Pigeonpea is an important pulse crop grown by smallholder farmers in the semi-arid tropics. Most of the pigeonpea cultivars grown to date are selections from the landraces, with a narrow genetic base. With the expansion of the crop to newer areas, problems of local importance are to be addressed. Hence, an economically feasible and faster germplasm evaluation mechanism, such as a core collection, is required. This article describes the development of core collection from 12,153 pigeonpea accessions collected from 56 countries and maintained at ICRISAT, Patancheru, India. The germplasm accessions from 56 countries were placed under 14 clusters based primarily on geographic origin. Data on 14 qualitative morphological traits were used for cluster formation by Ward’s method. From each cluster ≈10% accessions were randomly selected to constitute a core collection comprising 1290 accessions. Mean comparisons using Newman–Keuls test, variances’ comparisons by Levene’s test, and comparison of frequency distribution by χ²-test indicated that the core collection was similar to that of the entire collection for various traits and the genetic variability available in the entire collection is preserved in the core collection. The Shannon–Weaver diversity index for different traits was also similar for both entire and core collection. All the important phenotypic associations between different traits available in the entire collection were preserved in the core collection. The core collection constituted in the present study facilitates identification of useful traits economically and expeditiously for use in pigeonpea improvement.     

Extent and Pattern of Genetic Diversity for Morpho-agronomic Traits in Ethiopian Highland Pulse Landraces: I. Field Pea (<Emphasis Type="Italic">Pisum sativum</Emphasis> L.)

An experiment was conducted in 2001 at Holetta and Kulumsa, Ethiopia, to study the extent and pattern of genetic diversity in Ethiopian field pea (Pisum sativum L.) landraces. One hundred forty-eight germplasm accessions were grown in an alpha lattice design with 2 replications. Data on 12 traits were collected and analyzed. Differences among the accessions were significant for most of the traits (except number of seeds/ pod) at each location even though differences pooled over location were mostly non-significant. The accessions were grouped into five clusters of different sizes. Accessions from the southern part of the country (Arsi) distributed overall clusters while those from the northern half (North and South Wello, North Gonder and North Shewa) fell into clusters C₁ to C₃. Cumulative effects of a number of characters dictated differentiation of the accessions into clusters. There was no definite relationship between geographic diversity and genetic diversity as overlapping was encountered in clustering pattern among accessions from different parts of the country. Accessions from different regions might have similar genetic background and those from the same origin might also have different genetic background. Therefore, geographic diversity should not necessarily be used as an index of genetic diversity and parental selection should be based on a systematic study of genetic diversity in a specific population. Genetic distances among most of the clusters were significant that crosses between parents selected out of them are expected to generate desirable genetic recombination. Selection should also consider the special advantages of each cluster and each accession within a cluster. Future germplasm collection, conservation and breeding efforts should focus not only on inter-regional diversity but also on intra-regional diversity.     

Thermal and Functional Characterization of Starch from Argentinean Corn

Screening accessions in a germplasm bank aids in the identification of plants with unusual properties ranging from agronomic traits to functional and compositional traits of the seed itself. Results from this study confirm the presence of a wide variation in the thermal and functional properties of starch from several landraces of corn in the Argentinean germplasm. Thermal properties of starch measured using differential scanning calorimetry (DSC) identified several corn landraces with properties of potential commercial interest. The pasting and textural properties of gels obtained from starch of different corn landraces also exhibited considerable variability. The degree of variation in thermal and functional properties of corn reported in this study is comparable to the thermal properties of starch from several other crop species. These corn races show promise for further regeneration to create inbred lines with unusual traits. The potential for further improvement of corn races exists not only based on thermal properties, but directly for specific functional attributes as well. Correlation analyses suggest that the variability in thermal and functional attributes are a function of amylose content, granule size distribution and, possibly, differences in the structural makeup of amylose and amylopectin. The strong correlation observed between the thermal properties and pasting and textural properties will allow for the estimation of starch properties from small sample sizes.     

Genetic resources of Chironji (<Emphasis Type="Italic">Buchanania lanzan</Emphasis> Spreng.): a socio-economically important tree species of central Indian tribal population

Buchanania lanzan Spreng. (Chironji) is a socio-economically important underutilized fruit and life support species of tribal populations of north, west and central India. A survey and germplasm collection programme undertaken in the Indian states of Rajasthan, Gujarat and Madhya Pradesh observed that B. lanzan is found as natural wild in the forest, marginal lands and occasionally in farmer’s fields. A total of 72 diverse accessions of this important tree species were collected from the diversity–rich areas of India having wide range of variation in agro-morphological traits among the accessions. This species has high socio-economic value providing livelihood to tribal population of these areas and has high potential as commercial horticulture species. Fresh ripen fruits and extracted seed kernels have several nutritional and medicinal properties. Seed kernel and extracted kernel oil is used for the preparation of several Indian dishes. Traditional indigenous knowledge revealed immense importance of almost all parts of plant like roots, leaves, fruits, seeds and gum for various medicinal applications like cure for blood disorder, fever, ulcers, burning sensation of body, diarrhoea, dysentery, asthma, snakebite, etc. Due to direct harvesting of economically important parts of tree from natural habitat, genetic resources of B. lanzan are facing severe threat of extinction and need immediate conservation efforts.