Morphological Diversity of Bambara Groundnut [Vigna subterranea (L.) Verdc.] Landraces in Tanzania

A field experiment was conducted in Tanzania for two seasons to assess the genetic diversity of bambara groundnut landraces based on morphological characters. One hundred accessions collected from a wide range of agricultural zones in the country were evaluated in a 10 × 10 triple lattice block design at Maruku station in Bukoba, Tanzania. For the qualitative characters evaluated, considerable morphological variations were observed for growth habit, pod shape and pod colour. Quantitative morphological characters such as peduncle length, number of leaves per plant, terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant length, pod width, seed length, seed width, number of pods per plant, shelling percentage and days to 50% flowering showed significant variation among accessions for the two test seasons. Multivariate analysis for 15 quantitative morphological traits that showed significant variation indicated that the first four PCs with eigenvalues ≥1 accounted for 63.0 and 65.0% of the total variance among the accessions during the two test seasons, respectively. The most important loadings for PC1 and PC2 for the two seasons were terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant height and pod length, pod width, seed length, seed width, numbers of pods per plant. Cluster analysis grouped bambara groundnut accessions into three major groups with respect to their geographic origins. Based on this present study, bambara groundnut landraces from Tanzania displayed a considerable diversity for morphological and agronomic traits useful for germplasm management and utilization into crop improvement.     

Ecological stability of genetic diversity among landraces of little millet (<Emphasis Type="Italic">Panicum sumatrense</Emphasis>) in south India

Risk-prone agriculture by resource-poor tribal farmers in Kolli hills, south India is slowly giving way to commercial exploitation for paltry compensation thus eroding genetic diversity of millets. Cultivation and conservation of millets, particularly, little millet (Panicum sumatrense Roth ex Roem. et Schult.), called samai in the local language, Tamil are on the wane. Whether irregular and sparse cultivation of little millet by tribals has an impact on the current level of genetic divergence is also not clear. Therefore genetic divergence among 7 landraces and 1 check variety was evaluated based on morphometric traits at two sites over two seasons. The seven landraces formed six distinct groups with high inter-group distances. Days to maturity and flowering time contributed the most to genetic differentiation. Principal component analysis confirmed the results of divergence analysis. But a recent molecular analysis of diversity reported that the landraces were all genetically uniform and any observed diversity could be due environmental variation. An analysis of the contradictory results only emphasized the fact that lack of polymorphism need not imply lack of genetic divergence. The findings co evaluated with relevant published work highlight the value of morphometric analysis and reveal sustained genetic divergence in little millet.     

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.     

Diversity of common bean (Phaseolus vulgaris L.) germplasm from Portugal

Common bean (Phaseolus vulgarisL.) is a traditional crop in Portugal, where farmers growvarieties selected and maintained by themselves. A collection of 88landraces of common bean was evaluated for 17 quantitative andqualitative traits and the biochemical marker phaseolin to displaythe degree of variation of this germplasm. Agronomic data weresubjected to cluster analysis and several groups were identified,with three groups clustering most of the landraces. Regardingphaseolin variation the C and T banding patterns are the mostfrequent ones, so the origin of the Portuguese beans is thus probablythe Andean region of South America. These results give informationabout the origin, diversity and breeding value of the Portuguesegermplasm, that could be useful to widen the genetic base ofcurrently cultivated bean varieties in Europe.     

Collection and preliminary evaluation of small bitter gourds (<Emphasis Type="Italic">Momordica charantia</Emphasis> L.) a relict vegetable of Southern Peninsular India

Small-fruited bitter gourds, the “pavel” and “pandi-pavel” described in Hortus Malabaricus, is nearly an extinct crop in Kerala and rest of southern peninsular India. They are reported to have been cultivated extensively in the past. However, presently its cultivation is restricted to a few home gardens in remote forest areas consequent on its replacement by large-fruited cultivars over the last two centuries. Special traits like unique flavour, taste, medicinal properties and fruit fly tolerance have enabled the perpetuation of this relict vegetable still in a few homesteads. Eleven named landraces have been collected from South Western Ghats and Tamil Nadu plains and their seeds conserved in the genebank of NBPGR, New Delhi. Known as “uchie” in Northern India and “methipavai” in Tamil, these miniature bitter gourds have different landrace names in specific pockets of natural occurrence/cultivation.     

Recovering Portuguese Rice Landraces by Marker-Assisted Selection

Rice （Oryza sativa L.） was domesticated in Asia and brought to Europe （Mediterranean region） by returning members of Alexander the Great＇s expedition to India （324 B.C） （Khush, 1997）. In Portugal, rice was introduced by the Moors in the 10th century, and therefore has a long cultural tradition. Among the European countries, Portugal has the highest rice consumption per capita, with approximately 22.4 kg/capita/year, while the second country, Spain, only consumes 10.4 kg/capita/year （data from http：//www.fao.org referring 2004）. In 2005, the total rice area harvested was 23 060 hm2, distributed on the four main river beds： Mondego, Tejo, Sado and Sorraia. Presently Portugal produces nearly 56% of the internal demands, to meet the national needs, importation reached 6.8 xl07 kg in the year 2005 （data from http：//ania.pt）. About 80 percent of the rice area in Portugal is cultivated with japonica varieties and the rest is cultivated with indica-like varieties. These indica-like varieties are being cultivated particularly in the Southern regions, with much acceptance by the farmers due to their higher yields. Presently all Portuguese commercial varieties are either from Italy or from overseas.     

Comparison of black,purple, and yellow barleys

Many barley landraces are purple-or black-seeded, but the chemical composition of these purple-and black- seeded barley is rarely examined. Therefore, studies were conducted to determine if the chemical composition of purple and black barleys differs from that of yellow barleys. Four sets of genetic materials were used for these studies: 96 doubled-haploid (DH) lines, 10 near-isogenic lines, 40 landraces, and four F3 bulks. The results showed that purple DH lines contained a similar amount of lignin as yellow DH lines and that anthocyanin-containing isogenic lines did not differ from anthocyanin-free lines in lignin content. Therefore, these results suggest that anthocyanin biosynthesis is independent of lignin biosynthesis in barley. The results also showed that black barley contained more protein and more lignin than yellow barley in two crosses and that among the 40 landraces studied, the three with the highest concentration of lignin happened to be black seeded. Lignin content was not associated with seed weight except in defective endosperm lines. The presence of pigments and a relatively high concentration of lignin might help reduce the level of kernel blight severity in black barley. More studies are needed to determine the chemical composition and pest resistance associated with purple and black barleys.     

Protein heterogeneity in European wheat landraces and obsolete cultivars: Additional information

The objective of this study was to determine the composition of high molecular weight glutenin subunits of landraces and obsolete cultivars. Altogether glutenin profiles of 67 European wheats were analyzed by sodiumdodecylsulphate polyacrylamide gel electrophoresis. Nineteen of them were observed to be homogeneous, whereas 48 (71%) were heterogeneous in glutenin profiles. Heterogeneous accessions possessed from 2 to 9 different glutenin phenotypes. Seventeen high molecular weight (HMW)-glutenin subunits have been found, three belonged to Glu-1A, 11 to Glu-1B, and three to Glu-1D locus. The most frequented HMW-GS at the Glu-A1, Glu-B1, and Glu-D1 complex loci were 0, 7+9, and 2+12, respectively. However, allele low frequented in wheat such as 13+16, 20, 6, 7, 8, and 9 were observed also. Furthermore, other new alleles encoding HMW-GS at the locus Glu-1B with relative molecular weight 120 and 104 kDa have been found in one of the line of the Swedish cultivar Kotte. TheGlu-1 quality score in the examined accessions varied broadly with some lines reaching the maximum value of 10.     

Genotypic response of common bean to natural field populations of bean fly (Ophiomyia phaseoli) under diverse environmental conditions

Bean fly is a significant pest of common bean in semi-arid areas of East Africa. Apart from inadequate moisture in the dry land, bean fly simultaneously contributes negatively thereby adversely affecting bean productivity. The objectives of this study were to (1) identify sources of resistance to bean fly available in landraces, (2) confirm stability of host plant resistance in drought stress and (3) determine the effect of drought stress and seasonal variation on common bean genotypes in relation to bean fly attack for adaptability to the semi-arid areas of East Africa. Sixty four genotypes including landraces, bean fly resistant lines and local checks were evaluated for seed yield, 100-seed weight, days to maturity, plant mortality and pupae in stem in an alpha lattice design with two replications. This was under drought stressed (DS) and non-stressed (NS) environments and two treatments (insecticide sprayed and natural infestation) for three cropping seasons between 2008 and 2009. Genotypes differed in their reaction to natural bean fly attack under drought stressed (DS) and non-stressed (NS) environments over different cropping seasons. However, the effect of bean fly appeared to vary between the long rains (LR) and short rains (SR). It was observed that an increase in number of pupae per stem resulted in a higher plant mortality. The range of seed yield was from 345 to 1704 kg ha⁻¹ under natural infestation and from 591 to 2659 kg ha⁻¹ under insecticide protection. Seed yield loss ranged from 3 to 69%. The resistance of most of the bean fly resistant lines seemed to break down in presence of DS owing to their dismal performance. Screening of genetic resources in common bean to breed for host plant resistance to bean fly offers high potential of success if researchers take full advantage of the diversity available within the landraces.