Biological control of bacterial wilt caused by Pseudomonas solanacearum in India with antagonistic bacteria

From among 125 strains of fluorescent and 52 strains of nonfluorescent bacteria initially screened in the laboratory for their antibiosis towards the bacterial wilt pathogen, Pseudomonas solanacearum, strain Pfcp of Pseudomonas fluorescens and strains B33 and B36 of Bacillus spp., were chosen and evaluated further in greenhouse and field tests. Pfcp treated banana (Musa balbisiana), eggplant and tomato plants were protected from wilt upto 50, 61 and 95% in greenhouse and upto 50, 49 and 36% respectively in field. Protection afforded by the Bacillus strains was lower. In bacteria-treated plants which were subsequently inoculated with P. solanacearum plant height and biomass values increased and were close to those of nontreated and noninoculated control plants.     

Genetic variability for esterase enzyme in Onobrychis species

Summary Understanding polymorphism at the enzyme level is basic to its use in population and genetic studies. However, no such information is available on the variability among different sainfoin (Onobrychis) species. Therefore, our objective was to study the existence of genetic polymorphism for esterase in 17 Onobrychis species and three cultivars of O. viciifolia Scop. Three regions of banding were observed in all the materials tested, with the number of bands varying from 0 to 3, 3 to 14, and 1 to 2 bands in each of these zones, which have been designated EST1, EST2, and EST3 respectively. All the materials studied had unique banding patterns, the only common feature being that all of them, except one species, had isozyme 1. Identification was possible only for four species (O. iberica, O. kachetica, O. transcaucasica, and O. bieberstenii) and one cultivar (Nova) based on the banding patterns. Large diversity was evident from the wide range of percent similarity values (0%–79%). Subsequent studies should be directed in using these isozyme banding patterns as markers to the desirable agronomic and quality traits of different germplasm lines.This work was supported by USDA Specific Cooperative Agreement No. 58-7MN1-8-143 from the Plant Stress and Water Conservation Unit, USDA-ARS, Lubbock, Texas. Joint contribution of the Texas Tech University, Lubbock, Texas and the USDA-ARS. TTU Journal no. T-4-302     

Stomatal response to humidity in sugarcane and soybean: effect of vapour pressure difference on the kinetics of the blue light response

Abstract. The effect of atmospheric humidity on the kinetics of stomatal responses was quantified in gas exchange experiments using sugarcane ( Saccharum spp. hybrid) and soybean ( Glycine max ). Pulses of blue light were used to elicit pulses of stomatal conductance that were mediated by the specific blue light response of guard cells. Kinetic parameters of the conductance response were more closely related to leaf-air vapour pressure difference (VPD) than to relative humidity or transpiration. Increasing VPD significantly accelerated stomatal opening in both sugarcane and soybean, despite an approximately five-fold faster response in sugarcane. In contrast, the kinetics of stomatal recovery (closure) following the pulse were similar in the two species. Acceleration of opening by high VPD was observed even under conditions where soybean exhibited a feedforward response of decreasing transpiration (E) with increasing evaporative demand (VPD). This result suggests that epidermal, rather than bulk leaf, water status mediates the VPD effect on stomatal kinetics. The data are consistent with the hypothesis that increased cpidermal water loss at high VPD decreases the backpressure exerted by neighbouring cells on guard cells. allowing more rapid stomatal opening per unit of guard cell metabolic response to blue light.     

中国特产雉类—褐马鸡,藏马鸡和蓝马鸡卵壳的电镜观察

迄今为止,在国内有关野生鸟类卵壳的超微结构报道尚少。我们对中国特产鸡类——三种马鸡卵壳的表皮、气孔、木栅层、锥体层、乳头结、壳膜和基帽进行了扫描巨镜观察,并对结果进行了比较、讨论。认为三种马鸡不同结构的形态,对研究它们的亲缘关系提供了新的价值。     

Effects of social conditions on Juvenile Hormone mediated reproductive development in Bombus terrestris workers

Abstract. During the annual life cycle of the bumble bee Bombus terrestris (L.) colony, there is a stage characterized by worker reproduction in the presence of the queen. It has been proposed that this is a result of a decrease in queen inhibition. This hypothesis was examined by studying the effects of queens taken from colonies at different stages of development on several aspects of worker physiology and behaviour: rates of Juvenile Hormone (JH) release in vitro , ovary development, and behaviour associated with reproduction. After optimizing and validating the radiochemical assay for JH release for bumble bee workers, we found that queenless workers had significantly more developed ovaries and higher rates of release of JH than did queenright workers, confirming and extending previous findings that suggest that bumblebee ovarian development is under JH control. Mated queens, separated from their colony and brood, can have the same inhibitory effect on the reproductive development of callow workers. In contrast, workers confined with virgin queens or in queenless groups demonstrated a significantly higher rate of release of JH, overt aggression and threatening behaviours. However, there were no differences in rates of release of JH between workers confined in groups in the laboratory with queens taken from colonies either before or after the onset of worker reproduction. Furthermore, overt aggression and threatening behaviours were similar and low in both types of groups. These results gave no support to the hypothesis that a decrease in queen inhibition is associated with the onset of worker reproduction. We also show that young workers reared in colonies either before or after worker reproduction occurs, or in queenless colonies, all demonstrated similar, low rates of release of JH. These results suggest that older workers may inhibit the corpora allata of younger workers in queenless colonies.     

Characterization of a cDNA encoding cysteine proteinase inhibitor from Chinese cabbage (Brassica campestris L. ssp. pekinensis) flower buds

A cDNA encoding a new phytocystatin isotype named BCPI-1 was isolated from a cDNA library of Chinese cabbage flower buds. The BCPI-1 clone encodes 199 amino acids resulting in a protein much larger than other known phytocystatins. BCPI-1 has an unusually long C-terminus. A BCPI-1 fusion protein expressed in Escherichia coli strongly inhibits the enzymatic activity of papain, a cysteine proteinase. Genomic Southern blot analysis revealed that the BCPI gene is a member of a small multi-gene family in Chinese cabbage. Northern blot analysis showed that it is differentially expressed in the flower bud, leaf and root.     

Alnus rubra nodulation capacity of soil under five species from harvested forest sites in coastal British Columbia

Nodulation of Alnus rubra seedlings after inoculation with soil from under A. rubra, Betula papyrifera. Rubus lacianutus, R. spectabilis, and R.ursinus on 2 recently harvested sites was compared. Nodulation capacity was low compared to other published reports, ranging from 0 to 18.9 infective units cm^-3 of soil and was significantly affected by the site and plant species. Nodulation capacity of soil under alder was significantly higher than under all other species except R. spectabilis, regardless of site. The lowest nodulation capacity was found in soil under B. papyrifera.Joint appointment with Dept. of Soil Science, Faculty of Agricultural Sciences     

Production of hybrids, amphiploids and backcross progenies between a cold-tolerant wild species, Erucastrum abyssinicum and crop brassicas

Three intergeneric hybrids were produced between a cold-tolerant wild species, Erucastrum abyssinicum and three cultivated species of Brassica, B. juncea, B. carinata and B. oleracea, through ovary culture. The hybrids were characterized by morphology, cytology and DNA analysis. Amphiploidy was induced in all the F₁ hybrids through colchicine treatment. Stable amphiploids and backcross progenies were obtained from two of the crosses, E. abyssinicum x B. juncea and E. abyssinicum x B. carinata. The amphiploid, E. abyssinicum x B. juncea was successfully used as a bridge species to produce hybrids with B. napus, B. campestris and B. nigra. These hybrids and backcross progenies provide useful genetic variability for the improvement of crop brassicas.     

MORBILLIVIRUS INFECTION IN BOTTLENOSE DOLPHINS: EVIDENCE FOR RECURRENT EPIZOOTICS IN THE WESTERN ATLANTIC AND GULF OF MEXICO

Morbillivirus infection is widespread among odontocetes of the western Atlantic and Gulf of Mexico. Serologic evidence of infection in bottlenose dolphins, Tursiops truncatus , was first detected during an epizootic along the mid-Atlantic coast in 1987. Here, we report recurrent epizootics in the coastal dolphin population since at least the early 1980s based on serological surveys and regional stranding frequencies. The first observed epizootic of this series occurred in the Indian and Banana Rivers in 1982 and was followed by others on the mid-Atlantic coast in 1987–1988 and in the Gulf of Mexico between 1992 and 1994. This temporal pattern of infection is likely facilitated by the population size and its fragmentation into relatively discrete coastal communities. Introduction of morbillivirus into a community with a sufficient number of naive hosts may precipitate an epizootic, depending on the potential for transmission within the group. Propagation of an epizootic along the coast is probably determined by frequency of contact between adjacent communities and seasonal migrations.
Morbillivirus antibodies were also detected in serum from offshore bottlenose dolphins. The sero-prevalence in the latter may be higher than in coastal dolphins because of their close association with enzootically infected pilot whales ( Globicephala spp.). Occasional contact between offshore and coastal dolphins may provide an epizootiologic link between pilot whales and coastal dolphin communities.