Very high energy observations of the BL Lac objects 3C 66A and OJ 287

Using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), we have observed the BL Lac objects 3C 66A and OJ 287. These are members of the class of low-frequency-peaked BL Lac objects (LBLs) and are two of the three LBLs predicted by Costamante and Ghisellini to be potential sources of very high energy (>100 GeV) gamma-ray emission. The third candidate, BL Lacertae, has recently been detected by the MAGIC collaboration. Our observations have not produced detections; we calculate a 99% CL upper limit of flux from 3C 66A of 0.15 Crab flux units and from OJ 287 our limit is 0.52 Crab. These limits assume a Crab-like energy spectrum with an effective energy threshold of 185 GeV.Comment: 24 pages, 15 figures, Accepted for publication in Astroparticle Physic

Manual of Genebank Operations and Procedures

This manual of Genebank Operations and Procedures at ICRISAT provides information in 10 chapters regarding germplasm assembly, plant quarantine, seed processing and storage, germplasm distribution, monitoring, germplasm regeneration, characterization and preliminary evaluation, and taxonomic classification. We hope, this manual helps other genebank curators and researchers in their work for preserving plant biodiversity in ex situ collections. We welcome any suggestions to improve the manual in further editions

Marker applications in pearl millet

There are a multitude of potential applications of DNA marker technologies to the improvement of pearl millet (Pennisetum glaucum (L.) R. Br.). This presentation will delve into two major areas — the use of these molecular markers in pearl millet genetic diversity studies and the use of molecular markers for mapping quantitative trait loci (QTL) to facilitate marker-assisted (MA) breeding for economically important pearl millet traits having a large genotype ´ environment component to their phenotypic variation. The discussion of pearl millet genetic diversity studies builds on the general outline of this area presented earlier in this course by Dr. Bramel-Cox. The discussions of QTL mapping and MA breeding in pearl millet will be based largely on results obtained over the past nine years in a series of collaborative projects involving the International Crops Research for the Semi-Arid Tropics (ICRISAT), UK-based researchers supported by the Plant Sciences Programme (PSP) of the Department for International Development (DFID, formerly the Overseas Development Administration (ODA)) and based at the John Innes Centre for Plant Sciences Research (JIC, Norwich), the University of Wales (UW, Bangor), and the Institute of Grassland and Environmental Research (IGER, Aberystwyth), and several public-sector agencies involved in pearl millet improvement in India under the umbrella of the All-India Coordinated Pearl Millet Improvement Project (AICPMIP)

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity

Trait Associations in Introgressed Populations of Pearl Millet

Principal component analysis has been used in this study to describe the associations among 17 traits measured on progenies developed from matings of two adapted pearl millet inbreds with three exotic pearl millets. The exotic parents were a primitive I and race, a weedy relative, and a wild relative. The first three components were calculated for these matings and the associations defined. Correlations between these components and grain yield and growth rate were also determined. The first principal component described a hybrid index in five of the six matings, and a number of other complexes of traits were determined by this component or the other two. Some were common to several matings. The first three components accounted for only 50–60% of the total variability; thus no strong association of trans was found that would hinder recombination of parental types to select agronomically desirable segregates with high grain yield or growth rat

Gene diversity among botanical varieties in peanut (Arachis hypogaea L.)

For the first time, sufficient numbers of molecular markers that reveal polymorphism in cultivated peanut (Arachis hypogaea L.) have become available for diversity assessments. In this study, the amount and distribution of genetic variation within and among six peanut botanical varieties, as well as its partitioning among three continents of origin, was assessed at 12 simple sequence repeat (SSR) loci by means of 10 sequence-tagged microsatellite site (STMS) primers. Eighty-nine alleles were revealed, varying from 2 to 17 per locus with an average of 7.4 alleles per locus. Greater differentiation was observed between varieties (Fst = 0.33), compared with between continents (Fst = 0.016). However, maximum differentiation was observed among continents within varieties (Fst = 0.366) for three varieties. Rogers' modified distance among varieties revealed the similarity of three varieties of subspecies fastigiata Waldron, namely fastigiata, vulgaris C. Harz, and aequatoriana Krapov. & W.C. Gregory. It did not support the inclusion of var. peruviana Krapov. & W.C. Gregory in this grouping. In addition, the results suggest that subsp. hypogaea var. hypogaea and var. hirsuta Köhler are not closely related and therefore should not hold the same subspecific ranking. Discriminant function analysis reveals a high degree of accordance between variety delimitation on the basis of morphological and molecular characters. Landraces from Africa and Asia were more closely related to each other than to those from South America. Nei's unbiased estimate of gene diversity revealed very similar levels of diversity within botanical varieties. Landraces from South America had the highest diversity, and possessed 90% of alleles, compared with Africa (63%) and Asia (67%)

Core collection of sorghum: I. stratification based on eco-geographical data

ICRISAT conserves a large (36 719 entries) collection of sorghum [Sorghum bicolor (L.) Moench] accessions in India. This collection comprises cultivated and wild sorghums acquired over the past 25 years from 90 countries. However, it is difficult to characterize and assess a large collection with limited time and resources. To facilitate maintenance, assessment, and utilization of the collection, we considered the establishment of a core collection using stratified sampling strategies. Results from a study of the morpho-agronomic diversity were used to describe the genetic structure of the collection. Morphological traits, including days to flowering and plant height, can be affected by daylength variation. These two characters were highly correlated with latitudinal and racial distributions of landraces. Thus, stratifying the entire collection for response to photoperiod, estimated by flowering date and plant height, was indicative of a major source of specific adaptation within the collection. This stratification resulted in four clusters, which described the sensitivity of genotypes to photoperiod within the latitudinal range where selection was carried out by farmers. These four clusters may serve as the basis for a random stratified sampling to establish cores in this collection

Core collection of sorghum: II. comparison of three random sampling strategies

Since 1972, the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) has maintained a large collection of sorghum in India. The collection size has continuously increased, and the total number of accessions at present conserved in the gene bank has reached about 36 000 accessions. The need to help management was considered, and this study was conducted to establish core collections. This sorghum collection was earlier stratified into four clusters according to the photoperiod sensitivity. Then, considering the core collection strategy, we used three random sampling procedures to determine the specific accessions to be included in the core, i.e. a constant portion (Core C), a proportional (Core P), and a proportional to the logarithm (Core L), of the photoperiod group size sampling strategy. Both the Core C and L were significantly different from the landrace collection with better representation of the smallest groups, such as landraces insensitive to photoperiod. Despite differences between the three core collections, estimates of global diversity through the Shannon-Weaver Diversity Indices were of the same magnitude as the landrace collection. When compared, the Core C and L were significantly different. Core L sampled better for the characters, the race, and the latitudinal classes that were related to the photoperiod-sensitive landraces. Thus, for establishing a core collection with the widest range of adaptation to photoperiod, we propose the use of a logarithmic sampling strategy, which identifies a broadly adapted set of genotypes

Very high-energy observations of the two high-frequency peaked BL Lac objects 1ES 1218+304 and H 1426+428

We present results of very-high-energy gamma-ray observations (E > 160 GeV) of two high-frequency-peaked BL Lac (HBL) objects, 1ES 1218+304 and H 1426+428, with the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). Both sources are very-high-energy gamma-ray emitters above 100 GeV, detected using ground-based Cherenkov telescopes. STACEE observations of 1ES 1218+304 and H 1426+428 did not produce detections; we present 99% CL flux upper limits for both sources, assuming spectral indices measured mostly at higher energies

Development of a chickpea core subset using geographic distribution and quantitative traits

Chickpea (Cicer arietinum) is a major food legume and an important source of protein in many countries in Asia and Africa. Crop productivity continues to be low (0.78 t ha-1). A very small number of the 16 991 accessions in the ICRISAT germplasm collection that contain a high level of genetic variability have been used in the chickpea improvement programme. The objective of our research was to develop a core collection of chickpea that will enhance utilization of these resources in improvement programmes and simplify their management. Germplasm accessions were stratified by country of origin and the data on 13 quantitative traits were used for clustering by Ward's method. From each cluster, _10% of the accessions were randomly selected to constitute a core subset of 1956 accessions. A comparison of mean data using Newman-Keuls test, variance using Levene's test, distribution using the chi2 test, and Wilcoxon's rank-sum non-parametric test for different traits indicated that the genetic variation available for these traits in the entire collection had been preserved in the core subset. The important phenotypic correlations among different traits, which may be under the control of co-adapted gene complexes were also preserved in the core subset. This core subset will be a point of entry to the proper exploitation of chickpea genetic resources for the improvement of the crop