Improved Tolerance of Three Saudi Pearl Millet Cultivars (<i>Pennisetum spicatum</i>) to Salt Stress by Mycorrhiza

Seeds of three Saudi pearl millet cultivars (Pennisetum spicatum) from three regions (Madinah, Khulais and Jaizan) were inoculated with arbuscular mycorrhizal fungus Glomus mosseae obtained from the Agriculture Research Center of Giza, Egypt to enhance their salt tolerance. Five different NaCl concentrations (0, 30, 60, 90, and 120 mM) were used for treating cultivars with and without mycorrhiza. Growth rates, chlorophyll content, chlorophyll fluorescence (Fv/Fm), proline content and gas exchange were measured to determine the effect of salinity on these cultivars. The results indicated that compared to cultivars without mycorrhiza, all cultivars with mycorrhiza had enhanced growth and physiological parameters including shoot and root length, area and number of leaves, fresh and dry weights of shoots and roots, chlorophyll contents and gas exchanges at 0 and 30 mM of salinity. In addition, the measurements of the different growth rates showed higher growth performance of the cultivars from Madinah and Khulais than the cultivar from Jaizan. However, all cultivars with and without mycorrhiza showed significant reductions in growth rates, chlorophyll contents and gas exchanges at a salinity of 60 mM than those grown at 0 and 30 mM. Moreover, the values of Fv/Fm were significantly reduced in all cultivars with and without mycorrhiza grown at 60 mM than in those grown at 0 mM and 30 mM. Proline contents indicated a progressive increase with the elevation of NaCl concentration stress. The proline contents in the mycorrhiza-inoculated cultivars were significantly higher than those in the non-inoculated cultivars. On the other hand, all cultivars with and without mycorrhiza underwent senescence within four weeks of growth at salinity concentrations of 90 mM and 120 mM. Therefore, relatively low salinity must be maintained to achieve high growth rates and gas exchanges of these inoculated cultivars.     

Synthesis and Absolute Configuration of Natural Gregatin B

(S)-(+)-Gregatin B and racemic gregatin B were synthesized from tetrahydro-2-methyl-5-oxo-2-furancarboxylic acid and the absolute configuration of natural gregatin B was determined as (S).     

Analysis of molecular genetic diversity in a representative collection of foxtail millet [Setaria italica (L.) P. Beauv.] from different agro-ecological regions of India

Foxtail millet [Setaria italica (L.) P. Beauv.], an important crop of East Asia is known for its drought tolerance and was once an indispensible crop of vast rainfed areas in semi-arid regions in India. In India it is cultivated in Andhra Pradesh, Karnataka, Maharashtra, Tamil Nadu, Rajasthan, Madhya Pradesh, Uttar Pradesh and north eastern states. The grain finds use in several local recipes such as roti (bread), jaula, singal, sirol. Foxtail millet grain contains 12.3 % protein, 4.7 % fat, 60.6 % carbohydrates, and 3.2 % ash. The present study was conducted to analyse the genetic diversity among foxtail accessions from different states of India and a few exotic accessions using RAPD and ISSR techniques and identify diverse accessions for use in variety improvement programmes. A set of 125 foxtail millet accessions selected from 11 different agro-ecological regions of India were analyzed using random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) marker techniques. A total of 146 (115 RAPD and 31 ISSR) scoreable markers were generated with 16 RAPD and four ISSR primers. The dendrogram generated using Nei’s genetic distances and principal component analyses revealed presence of two clusters and two subclusters in group I. The accessions from Andhra Pradesh, Karnataka, Maharashtra and Uttarakhand were more diverse since they were distributed in both the clusters. There was no clear geographical differentiation observable. The bootstrap support for the major groups identified was strong (above 80 %) indicating good statistical support. The average value of Nei and Li’s genetic distance was lowest (0.081) for accessions from West Bengal while the collections from Karnataka showed highest dissimilarity (average genetic distance = 0.239). The average genetic distance for all 125 accessions together was 0.177 indicating presence of only moderate genetic diversity in the collections. The analysis of molecular variance indicated that only 2.76 % variation was explained by variations among the groups and 11.55 % among populations within groups. However the percentage of variation observed within populations was high (85.68). The value of Fst was observed to be very low (0.028) indicating low differentiation of the accessions analysed. The population genetic analysis carried out indicates that highest number of alleles per locus (1.745 ± 0.438) was observed for Andhra Pradesh with 35 accessions. When four eco-geographic regions were considered, the southern region comprising AP, Karnataka and TN showed the highest number of alleles per locus (1.787 ± 0.411). The value of Gst was lowest for south (0.123) and highest for central west (0.455). This indicated that all the landraces from south share common alleles. The gene flow between the accessions from different regions was also observed to be high with the highest migration (3.557) recorded for south.     

New use of broomcorn millets for production of granular cultures of aphid-pathogenic fungus Pandora neoaphidis for high sporulation potential and infectivity to Myzus persicae

Glutinous broomcorn millets from the crop Panicum miliaceum were first used as substrate to produce granular cultures of Pandora neoaphidis, an obligate fungal pathogen specific to aphids. Carrying a water content of 36.5% after being steamed in a regular autoclaving procedure, millet grains of each 15 g (dry weight) in a 100-ml flask were mixed with 3 ml modified Sabouraud dextrose broth containing half a mashed colony of P. neoaphidis grown on egg yolk milk agar and then incubated at 20 degrees C and a light/dark cycle of 12 h/12 h for 21 days. Based on individually monitoring conidial production potential of 20 millet grains sampled from an arbitrarily taken flask at 3-day intervals, the millet cultures incubated for 6-15 days were capable of producing 16.8-23.4 x 10(4) conidia per millet grain with conidial ejection lasting for up to 6 days. The cultured millet grains individually produced significantly more conidia than apterous adults of Myzus persicae killed by P. neoaphidis (8.4 x 10(4) conidia per cadaver) and sporulated twice longer. The modeling of time-dose-mortality data from bioassays on M. persicae apterae exposed to conidial showers from the cultured millet grains and the mycelial mats produced in liquid culture resulted in similar estimates of LC(50) (millets: 21.4, 7.3, and 4.9 conidia mm(-2) on days 5-7 after exposure; mycelial mats: 22.1, 10.6, and 7.7 conidia mm(-2)) although the LT(50) estimated at a given conidial concentration was slightly smaller for the millet cultures than for the mycelial mats. This indicates that the millet grains cultured with P. neoaphidis produced conidia as infective as or slightly more infective to M. persicae than those from the mycelial mats. Based on the sporulation potential, infectivity, and ease and cost of the millet cultures, the method developed in this study highly improved in vitro cultures of P. neoaphidis and may adapt to culturing other entomophthoralean fungi for microbial control of insect pests.     

Genetic analysis of reciprocal differences in the inheritance of in vitro characters in pearl millet

Reciprocal differences persist in nature because of the unequal contribution of cytoplasmic determinants from male and female gametes to the zygote. The inheritance of genetic differences is an important factor that influences various traits, including somatic embryogenesis and regeneration in vitro. In this report, we estimate the cytoplasmic and maternal effects in pearl millet and their adequacy in describing the observed reciprocal differences based on an in depth study of the parents, F₂s and reciprocal backcross progenies needed for fitting genetical models. Our study revealed that of the two characters examined, embryogenic callus quantity and regeneration frequency, the former showed a greater proportion of cytoplasmic nuclear interaction whereas the latter showed a greater role of nuclear factors. Additive-maternal effects influenced total callus quantity and dominance-maternal effects influenced total callus quantity, embryogenic callus quantity and regeneration frequency. Dwarfing was associated with the production of large quantities of embryogenic callus that had visually recognizable characteristics. The phenotypic nature of dwarf parents (green dwarf with long narrow leaves) with a genetic basis for a given character controlled by nuclear and cytoplasmic determinants can be exploited for other breeding programs.     

Extraction of a salt-insoluble α-glucosidase from Sorghum vulgare grain

Sorghum grain α-glucosidase may be either insoluble in sodium chloride under alkaline conditions, or partially soluble, depending upon the sorghum variety. A good correlation was found between the degree of sodium chloride insolubility of the grain α-glucosidase and the degree of water-insolubility of the malt amylases. Peptone, in the presence of sodium chloride, was effective in liberating sodium chloride insoluble α-glucosidase from grain. Similarly, the water-insoluble amylases of malt were solubilized by peptone in water. Maximum liberation of grain ga-glucosidase was only achieved, however, by using a combination of 8 M urea, 0·1 M sulphite, 5% peptone and 1% Triton. It is suggested that the insolubility in both enzymes is caused by insoluble tannin-enzyme complexes.     

Potential of Sahelian Native Shrub Materials to Suppress the Spiral Nematode Helicotylenchus dihystera

Pearl millet (Pennisetum glaucum) is a drought-tolerant cereal commonly grown for grain and fodder in arid areas throughout the world. Senegalese millet fields are infested with Helicotylenchus. The native evergreen woody shrub Piliostigma reticulatum is widely distributed in sub-Saharan Africa. Its coppiced residues are used by small farmers as mulch in crop fields. The shrub’s nematicidal effect on the spiral nematode Helicotylenchus dihystera was evaluated in a pearl millet pot experiment. The abundance of nematodes decreased by 64% after application of either leaf powder or a pulverized mixing of leaves and stems, suggesting the use of aboveground materials of P. reticulatum as a potential nematicide. The results show promise for use of a local resource by subsistence farmers in the Sahel. Further research is needed on application to fully develop this approach as a biopesticide.     

Role of seed flow on the pattern and dynamics of pearl millet (<Emphasis Type="Italic">Pennisetum glaucum</Emphasis> [L.] R. Br.) genetic diversity assessed by AFLP markers: a study in south-western Niger

We studied the regional genetic diversity and seed exchange dynamics of pearl millet landraces in south-western Niger. The genetic study was based on AFLP markers. We found significant genetic differentiation between landraces in different geographical areas of south-western Niger. However, the degree of differentiation was low insofar as only 1.9% of the total molecular diversity was due to regional differentiation, suggesting a relatively high gene flow. Anthropologic studies on farming practices have suggested that seed exchanges between farmers on a large geographical scale probably make a considerable contribution to this result. In order to test this hypothesis, the effects of seed exchange on the genetic diversity of landraces was analyzed on seed samples from two distant villages in contrasting areas of south-western Niger. Seeds imported by farmers into the southern village of Sina Koara did not differ significantly from locally grown landraces. By contrast, in the northern village of Alzou, several samples were genetically different from locally grown landraces and closer to southern accessions. These data suggest that the seed flow is preferentially from south to north, i.e. from an area with more favorable rainfall conditions. The potential consequences for the genetic diversity and adaptation of northern pearl millet landraces are discussed.