Utilisation of wild relatives in the genetic improvement of Arachis hypogaea L.

Summary Cross-compatibility of species in section Arachis Krap. et Greg. nom. nud., and chromosome pairing and pollen fertility in their interspecific F₁ hybrids were studied to further understand the phylogenetic relationships among these species. Except those with A. batizocoi Krap. et Greg. nom. nud., hybrids between diploid species have near normal bivalent frequency (9.1–9.8) and moderate to high pollen fertility (60–91%). Hybrids between A. batizocoi and other species have low bivalent frequency (5.2–6.9) and very low pollen fertility (3–7%). These results confirm the earlier separation of these species into two groups based on karyomorphology and Mahalanobis D² calculated on arm ratios. These studies also provide a picture of relative affinities between A. batizocoi, the lone member of one cluster, and the other species, and among the rest of the species. They also indicate that the basic chromosome complement in the two groups of species is the same. Chromosome pairing in triploid hybrids, (A. hypogaea L. X diploid wild species), suggests that A. batizocoi is the closest diploid relative of A. hypogaea. It is closer to A. hypogaea subspecies fastigiata Waldron than to A. hypogaea subspecies hypogaea Krap. et. Rig. Other diploid species of the section Arachis are equidistant from A. hypogaea, and have the same genome which has strong homology to one of the genomes of A. hypogaea. Based on the present results, the two tetraploid species, A. monticola Krap. et Rig. and A. hypogaea can be recognised as two forms of the same species. Breeding implications have been discussed in the light of chromosome behaviour observed in hybrids of A. hypogaea X diploid species, and on the presumptions that A. hypogaea has an AABB genomic constitution, and that among the diploid species, the B genome is present in A. batizocoi while the A genome is common to the other diploid species of section Arachis.Submitted as Journal Article No. 328 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)     

Plant regeneration in callus and suspension cultures of Brassica campestris cv. Yellow Sarson

Prolific shoot bud differentiation was induced in callus and suspension cultures of hypocotyl origin in Brassica campestris cv. Yellow Sarson on MS medium supplemented with K (13.9–23.2 M) or BA (13.3–22.1 M). Plantlets were obtained by rooting the in vitro differentiated shoots. Histological studies revealed a unique mode of meristemoid formation.Abbreviations MS Murashige and Skoog (1962) - 2,4-D 2,4-dichlorophenoxyacetic acid - BA Benzyladenine - IAA Indole-3-acetic acid - IBA Indolebutyric acid - K Kinetin - NAA Naphthalene acetic acid     

Population dynamics ofFusarium spp. in pea rhizosphere as affected by soil amendments

In nonamended soil, vegetative growth and sporulation ofFusarium spp. were higher in the rhizosphere than in the soil. Sporulation was favoured by young plants and decreased with increasing plant age. Amendments with low C/N oil-cakes enhanced vegetative growth and sporulation in root-free soil. The extent of stimulation varied with the nature of organic matter used and the stage of its deoomposition. Sporulation was suppressed by castor cake and sawdust with urea amendments. Rhizosphere cf pea altered the effect of different amendments.     

Effect of soil moisture and clipping stresses on the nutrient (N,P and K) concentration,uptake and use efficiency in one temperate and two tropical grasses

Summary The concentration, uptake and element use efficiency of N, P and K in one C₃ annual (Polypogon monspeliensis) and two C₄ (Echinochloa colonum, an annual, andDichathium annulatum, a perennial) grasses were determined during winter and summer seasons in monocultures raised in field plots at three moisture levels,viz. full, half and one-fourth of field capacity. At each moisture regime the plants were clipped thrice at moderate and severe levels corresponding to 40 and 80% of live green. The concentration of these elements was characteristic of the growth habit of these plants;e.g. the build up of concentration was maximum in leaf of the annuals while it was comparable in crown and leaf of Dichanthium. The N level was maximum in Polypogon. The nutrient use effiency was comparable in the two annuals and maximum K and N use were obtained in Polypogon and Dichanthium, respectively.     

The configuration and location of the ribosidic linkage in the prosthetic group of citrate lyase (Klebsiella aerogenes).

The structure of the prosthetic group of citrate lyase (Klebsiella aerogenes) was studied by nuclear magnetic resonance and mass spectrometry. The spectra at 360 MHz of the nucleoside moiety (2'-ribosyladenosine) show the absence of 2'-hydroxyl proton, thus confirming the 2' position as the site of attachment of the second ribose moiety to the dephospho-CoA. This glycosidic linkage is found to be alpha(1" leads to 2') and is identical to that of poly(ADP-ribose). Studies of permethylation products by mass spectrometry support the above conclusion regarding the location of the ribosidic linkage.