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)

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

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

Shear Thinning Properties of Sorghum and Corn Starches

The paste viscosities of sorghum and corn starches were studied with a Brabender viscograph. Sorghum starches and the laboratory-prepared corn starch gave higher paste consistencies than did the two commercial corn starches. Considerable variation existed in shear thinning of starches. In general, sorghum starches shear-thinned more than corn starches, although certain sorghum starches gave low shear thinning. When the hot pastes were sheared at high speed, sorghum starches thinned more than corn starches. The gelatinization characteristics did not appear to be related to shear thinning of sorghum starches. Swelling power at 95 C was lower for corn starch than it was for sorghum starch. Solubility of both corn and sorghum starches at 95 C varied among the cultivars. The reasons for high shear thinning of certain sorghums requires further investigation

Factors Affecting the Color and Appearance of Sorghum Starch

Seven cultivars of grain sorghum with various seed colors were studied for the presence of light-absorbing substances in the grain and starch. A corn sample was used for comparison. Starch was isolated from both sorghum and corn. Corn starch was bright in appearance and had a yellowish tinge. Sorghum starch from the cultivars Dorado, UANL-1-V-187, and Blanco 88 was also bright in appearance and white; the seed color was pale yellow. Although Sorghum cultivar Dekalb 42Y had a pale yellow seed color, it yielded a dull-appearing starch. Kansas local, Bajio, and Tamaulipas cultivars had reddish-brown seed color and also yielded dull-appearing starch that had a reddish tint. It appears that the presence of certain alcohol-soluble components contributes to the dullness of some sorghum starches, because extraction of dull starch with methanol resulted in a brighter starch. Dehulling of the grain before starch isolation improved the appearance of starch. A simple alkali test on the grain was effective in predicting the dullness of starch

Preserving genetic resources

The mission of the U.S. National Plant Germplasm System (NPGS) is to effectively collect, document, preserve, evaluate, enhance, and distribute plant genetic resources for continued improvement in the quality and production of economic crops important to U.S. and world agriculture. Plant genetic resources in the NPGS are made freely available to all bona fide users fo r the benefit of humankind. The active collection is maintained and distributed by 19 national repositories, and the base collection is preserved at the National Seed Storage Laboratory (NSSL), U.S. Department o f Agriculture, Fort Collins, Colorado. The NPGS collections include 40,477 sorghum and 1,507pearl millet accessions. Of the 20,169 sorghum accessions in the base collection at NSSL, 80% are in conventional storage at about -18°C and 20% are in cryostorage in vapor phase above liquid nitrogen at about -16(fC; the pearl millet collection is in conventional storage. The International Crops Research Institute for the Semi-Arid Tropics (ICR1SAT) located at Patancheru, near Hyderabad, India, has assembled a collection o f35,643 sorghum and 21,195 pearl millet accessions, both ICRISAT mandate crops. All these accessions are maintained andpreserved in aluminum cans in the medium-term storage facility at about 4°C and 20% relative humidity. Freshly rejuvenated accessions with at least 90% viability and about 5% seed moisture content are being placed in moisture proof aluminum foil packets that are vacuum sealed and stored in long-term storage at -20°C. For these crops, 17% o f the sorghum collection and 23% o f the pearl millet collection have been transferred to long-term storage

A Pictorial Guide for the Identification of Mold Fungi on Sorghum Grain

Sorghum is one of the main staple food crops of the world's poorest and most food-insecure people. Approximately 90% of the world's sorghum areas are located in Africa and Asia. During 1992-94, 42% of the total sorghum produced worldwide was utilized for food, and 48% for animal feed. A preliminary study was conducted to understand the various storage conditions of sorghum grain, and the potential occurrence of mold fungi under such conditions. A total of 67 sorghum grain samples were collected from two surveys, 15 samples from the 1996 rainy season harvest, and 11 from the 1996/97 postrainy season harvest collected in June 1997, and 19 samples from the 1996/97 postrainy season and 22 from 1997 rainy season harvest collected in October 1997. Approximately 1 kg grain from each of the grain lots stored under various conditions (gunny bags, mud-lined baskets, metallic containers, polypropylene bags, and grains piled in a corner of a room) by farmers in rural India was collected. Each grain sample (200 grains treatment1) was examined to identify fungi up to the species level. Grains with and without surface sterilization were transferred separately to pre-sterilized petri dish humid chambers under aseptic conditions. The petri dishes were incubated for 5 days at 28±1 °C in an incubator with a 12-h light cycle. Under each treatment, 200 grains (25 grains dish-1) were examined for 49 mold fungi, including the species of Aspergillus and Penicillium. The major fungi observed on the grains included species of Alternaria, Curvularia, Drechslera, Fusarium, and Rhizopus. The frequency of occurrence of the various fungi on each grain sample under the various treatments was analyzed. This bulletin reports some new mold fungi on sorghum grain in India: Alternaria longipes, Bipolaris zeicola, Curvularia affinis, C. clavata, C. fallax, C. geniculata, C. harveyi, C. ovoidea, C. pallescens, C. tuberculata, Drechslera halodes, Gonatobotrys simplex, Nigrospora oryzae, Periconia macrospinosa, Spadicoides obovata, Torula graminis, and Trichothecium roseum

A Rapid Method of Evaluating Growth Rate in Pearl Millet and Its Weedy and Wild Relatives

Vegetative growth rate is a physiological trait that has been hypothesized to be useful in the improvement of grain yield in cereal crops. Usefulness of this physiological trait in a breeding program depends upon a rapid method that allows the evaluation of large numbers of lines. In this study, the objective was to determine if the rates of growth calculated from periodic samplings could be estimated by using only one or two dates of harvest relating to specific stages in the plant's development. Periodic samples of vegetative growth were made on 19 pearl millet (Pennisetum americanum) genotypes, plus three weedy (ssp. stenostachyum) and one wild (ssp. monodii) accession in two seasons once every 2 weeks starting at 21 days after emergence and continuing to maturity. With use of the rates calculated on these periodic samples as the actual growth rate, it was found that samples taken at either one or two dates of harvest could be used to adequately estimate this rate. The two dates of harvest were taken at either 10 days after flowering or at maturity. The rate was calculated as (vegetative dry weight at flowering + 10 days or at maturity)/(number of days to flowering + 10)

Population Improvement of Pearl Millet and Sorghum: Current Research, Impact and Issues for Implementation

Populations o f pearl millet and sorghum are being developed and improved fo r a variety o f purposes. In this paper, we present a global review o f current populations, their composition, and methods for improvement. The potential impact o f these programs is indicated by recent results regarding responses to recurrent selection and the linkages ofpopulation improvement with development o f lines and varieties in these two crops. Recent research on generating interpool populations and modeling responses to alternative recurrent selection methods are presented fo r population improvement o f pearl millet