Antifungal Potential of Plant Growth Promoting Bacillus Species Against Blossom Blight of Rose

Blossom blight caused by Botrytis cinerea is one among the most devastating diseases that cause complete post-harvest loss in flower crops. The present study focuses on the development of effective bioformulation towards suppression of blossom blight and plant growth promotion in rose. Bacillus amyloliquefaciens (VB2) and Bacillus subtilis (AP) effectively inhibited mycelial growth of B. cinerea in vitro. Genome screening of VB2 and AP revealed the presence of antimicrobial peptide genes including, ituD, ipa14, bacA, bacD, srfA, sfP, spaC, spaS responsible for the biosynthesis of antibiotics such as iturin, bacilysin, bacillomycin, surfactin and subtilin. Further, the presence of volatile antifungal compounds in the bacterial secretome was identified through gas chromatography–mass spectrometry (GC/MS) analysis. Upon treatment, AP accelerated the metabolite profile of the plants and a rise in peak area of antifungal compounds such as, pentadecanoic acid, n-hexadecanoic acid, octadecanoic acid (stearic acid) and tetradecanoic acid was observed. In vitro, VB2 produced maximum indole acetic acid (9.17 µg/ml) and gibberellic acid (8.20 µg/ml) in nutrient broth. Under field conditions, foliar spray of VB2 at 0.5% (5 ml/l), four times at weekly interval suppressed blossom blight incidence (64% reduction over control) and also promoted yield. Future research towards development of an effective bioformulation with extended shelf life will aid in the management of various fungal, bacterial and viral diseases in different crop plants.

     

A small mobilizable IncP group plasmid vector packageable into bacteriophage lambda capsids in vitro

A mobilizable cosmid derivative of an IncP group plasmid was constructed by cloning the oriT region of RK2, a wide host-range plasmid, and the minimal DNA sequence of bacteriophage lambda required for efficient packaging in vitro. This cosmid is 13 kb in size and has unique restriction sites for EcoRI, XhoI, HindIII, and SalI. The XhoI and HindIII sites are within the kanamycin-resistance gene and the SalI site is in the tetracycline-resistance gene. This plasmid was mobilizable from an Escherichia coli donor to a number of diverse gram-negative bacteria at a frequency of 0.8 to 10 per 100 donors. This vector is one of the smallest of all wide host-range cosmids described in the literature. As part of this study, another mobilizable IncP group plasmid vector has also been constructed which, in addition to the sites listed above, has a unique BglII site, but which lacks the packager sequence.     

Growth-regulator Interactions in the Growth of the Shoot System of Avena sativa Seedlings: I. THE GROWTH OF THE FIRST INTERNODE

1. Segments, 3.5 mm. long, cut from the first internode of Avenasativa seedlings grown in complete darkness respond to bothauxins and gibberellic acid by accelerated extension. 2. The optimum concentration of indole-3-acetic acid (IAA) is10 p.p.m. and of gibberellic acid (GA) is 0.1 p.p.m. 3. The degree of stimulation relative to the growth of controlsegments is affected by the inclusion in the segement of thenode between the internode and coleoptile. Thus the gibberellineffect is greatly increased while the IAA effect is decreased.The optimal concentrations are not affected by inclusion ofthe node. 4. These results can best be explained in terms of the supplyby the node tissue of an endogenous auxin which is necessaryfor the expression of GA action. 5. Numerous factorial experiments demonstrated that there isno detectable interaction between applied IAA and GA in thepromotion of first-internode extension. This implies that thepostulated endogenous auxin which synergized GAA action in (4)is either an active form of IAA produced only in the node tissueor is a completely different auxin. 6. No synergism of growth-promotive action can be detected betweenGA and the two synthetic auxins I-naphthylacetic acid and 2,4-dichlorophenoxyaceticacid. 7. p-chlorophenoxy-iso-butyric acid (PCIB) anc 2,4,6-trichlorophenoxyaceticacid (2,4,6-T) act as weak auxins and thus antagonize competitivelythe promotive action of GA. 8. The anti-auxin -(I-naphythyl-methyl-sulphide)propionic acid(NMSP) antagonizes competitively the promotive action of bothIAA and GA. 9. The facts under (5)–(8) suggest that auxins and GAare acting at the same growth-promotion centres and may competefor them. 10. Growth inhibitions are induced by high concentrations ofPCIB, 2,4,6-T and NMSP. The inhibitions produced by PCIB and2,4,6-T are both synergized by supra-optimal concentrationsof IAA while that of NMSP is synergized by supra-optimal concentrationsof both IAA and GA. This similarity of the effects of IAA andGA suggests that their inhibition actions also are of a closelysimilar nature.     

Cytidine Analogues and Stomatogenic Recovery in Amicronucleate Paramecium tetraurelia and Paramecium jenningsi

Removal of the micronuclei of Paramecium tetraurelia and Paramecium jenningsi by micropipetting generates amicronucleate cell lines. These cell lines go through a period of growth depression for several dozen fissions, but they gradually recover. Amicronucleate cells in the depression period characteristically exhibit abnormal oral development, particularly reduction in the length of the buccal cavity and an abnormal pattern of the oral membranelles. To test the notion that the macronucleus is involved in the recovery of amicronucleate cell lines, DNA demethylation drugs were administered to amicronucleates in the depression period. After at least 4 fissions, the treated amicronucleates were assessed for their progress in recovery by scoring the proportion of cells with normal oral membranelles. Cvtidine analogues which demethylate cytosine specifically at the 5 position, namely 5-azacytidine, 5-aza-2'- deoxycytidine and 5-fluoro-2'-deoxycytidine. promoted recovery of the amicronucleates. Cytidine, 6-azacytidine, 2'-fluoro-2'-deoxy-cytidine and cytosine-β-D-arabinofuranoside did not. These results suggest that (i) 5-methylcytosine is present in the macronucleus of these Paramecium species, probably in small amounts and (ii) recovery of amicronucleates involves demethylation of macronuclear DNA. This implies that in normal cells the micronuclei are involved in maintaining the macronuclear DNA in a methylated state and hence the inactivation of the macronuclear sequences that are to be employed for stomatogenic recovery. A general mechanism for the control of gene expression may therefore be employed for the regulation of specific sequences.     

Genetic studies of water buffalo blood markers. I. Red cell acid phosphatase,albumin, catalase,red cell α-esterase-3, group-specific component,and protease inhibitor

We have developed the methodologies for typing and family studies to establish the modes of inheritance of water buffalo red cell acid phosphatase (Acp), protease inhibitor (Pi), and group-specific component (Gc) on isoelectric focusing and albumin (Alb), red cell -esterase-3 (Est-3), and catalase (Cat) on polyacrylamide gel electrophoresis. Family studies showed that Pi, Gc, Alb, and Cat are coded by autosomal genes with two codominant alleles, while Est-3 is autosomal with two codominant alleles and a recessive null allele and Acp exhibits three codominant alleles.This project was funded by the Australian Centre for International Agricultural Research through Grant PN 8364 and the Malaysian programme for Intensification of Research in Priority Areas through Grant IRPA 1-07-05-057.     

A portable DNA sequence carrying the cohesive site (cos) of bacteriophage lambda and the mob (mobilization) region of the broad-host-range plasmid RK2: a module for the construction of new cosmids

A polylinker DNA sequence carrying the cos site of bacteriophage lambda and the mob (oriT) region of the IncP group plasmid RK2 was constructed. This composite polylinker has EcoRI sites at both termini and also unique sites for ClaI, HindIII, PstI and XbaI. The cos-mob region is portable with the use of EcoRI or a combination of EcoRI with ClaI, HindIII or XbaI. Another cos-mob cassette was also constructed from which the cos-mob region can be lifted with HindIII, ClaI or either of these enzymes in combination with others. These cos-mob cassettes can be used in constructing new cosmids that can be mobilized into a variety of Gram-negative bacteria. Using one of these cassettes we have constructed a small IncW group cosmid (11.1 kb) that was mobilizable into Escherichia coli, Rhizobium spp. and Alcaligenes eutrophus at high frequency.     

An Ultrastructural Investigation of 180°-Rotated Ciliary Meridians in Tetrahymena pyriformis*

SYNOPSIS. An ultrastructural investigation has been carried out on 180°-rotated ciliary meridians (inverted meridians) in Tetrahymena pyriformis temperature-sensitive mutant (mol^b/mol^b), syngen 1, strain B. The longitudinal, transverse and postciliary microtubular bands, the kinetodesmal fiber, and the parasomal sac, are shown to be disposed at a 180° angle to their normal positions or orientations. Other abnormalities are as folows: the first 2 basal bodies of the inverted meridian fail to organize into “couplets” and the inverted meridian intrudes into the anterior pole region; an extra longitudinal microtubular band is found in one of the cell lines.