Changing roles for legumes in Mediterranean agriculture: developments from an Australian perspective

Pulse and pasture legumes have maintained productivity in Mediterranean agricultural systems since antiquity, providing biologically fixed nitrogen and helping to control pests, diseases and weeds. Throughout the last 500 years many species from the Mediterranean basin have been transferred either accidentally or deliberately to the new-world, and integrated into a multitude of farming systems. During the past 30 years biological, economic and environmental forces have caused failure/breakdown of some of these productive systems. This paper examines the factors influencing legume usage in Mediterranean agriculture and uses the changing focus on legumes in southern Australia to illustrate new roles for legumes in evolving farming systems. An essential factor in developing new roles for legumes is the matching of root-nodule bacteria to both legume hosts and soil conditions. New roles for annual and perennial pastures in Mediterranean-type agriculture are discussed in relation to an analysis of the role of root-nodule bacteria in maximising productivity in these systems

Ferroplasma cupricumulans sp. nov., a novel moderately thermophilic, acidophilic archaeon isolated from an industrial-scale chalcocite bioleach heap

A new species of Archaea was isolated from an industrial mineral sulphide bioleach heap. Strain BH2, a non-motile pleomorphic coccus, was capable of chemomixotrophic growth on ferrous sulphate and yeast extract. Growth was not supported in the absence of yeast extract. Phylogenetic analysis based on the 16S rRNA gene showed that strain BH2 was most closely related to the species Ferroplasma acidiphilum; however, it showed only 95% sequence similarity with this species. Strain BH2 had a temperature optimum of 53.6°C and a temperature range for growth between 22 and 63°C. Thus, it is the first moderately thermophilic member of the genus Ferroplasma. The optimum pH for the growth of the strain occurred between pH 1.0 and 1.2 and the lowest pH at which growth was observed was 0.4. Based on 16S rRNA gene sequence analysis and other physiological characteristics, strain BH2 constitutes a new species within the genus Ferroplasma. The name Ferroplasma cupricumulans is proposed for the new species and strain BH2 (DSM 16651) is proposed as the type strain

Overcoming non-selective nodulation of Lessertia by soil-borne rhizobium in the presence of inoculant mesorhizobium

Background and aims: Legumes of the South African genus Lessertia, along with their microsymbionts, were introduced into the Western Australia wheatbelt. They achieved poor establishment followed by weak summer survival. This was caused in part by low levels of nodulation with the inoculant strains, and by ineffective nodulation with naturalized strains -an example of non-selective nodulation. The aims of this work were to assess Lessertia spp. symbiotic promiscuity, to study the effect of increased doses of an effective inoculant strain (WSM3565) with L. herbacea, and to study the competitive ability and symbiotic performance of different Mesorhizobium strains nodulating L. diffusa. Methods: A glasshouse experiment was set up to evaluate the ability of L. diffusa, L. capitata, L. herbacea and L. excisa to nodulate with inoculants under current use in Western Australia. To assess competitive ability two field experiments were set up at Karridale, Western Australia. L. herbacea was inoculated with the strain WSM3565 at different doses and L. diffusa was inoculated with ten different Mesorhizobium strains. Rhizobia were re-isolated from nodules and their identity confirmed through PCR fingerprinting and sequencing of their partial dnaK. Results: There were differences in promiscuity between different Lessertia spp., where L. herbacea proved to be highly promiscuous under controlled conditions. Increasing the inoculation dose of L. herbacea with WSM3565 did not improve establishment and survival of the legume in the field. Although WSM3565 nodule occupancy improved from 28 to 54 % with higher doses of inoculation, none of the treatments increased L. herbacea yield over the inoculated control. The inoculation of L. diffusa with the strains WSM3598, 3636, 3626 and 3565 resulted in greater biomass production than the uninoculated control. These strains were able to outcompete resident rhizobia and to occupy a high (>60 %) proportion of lateral root nodules. The naturalised strains that achieved nodulation were identified as R. leguminosarum. Conclusion: The high numbers of resident rhizobia and their ability to rapidly nodulate Lessertia spp. are likely to be the main reasons for the low nodule occupancy achieved by some effective inoculant strains with L. diffusa and L. herbacea. Strains WSM 3636 and 3598 were very competitive on nodule occupancy and together with WSM 3565, WSM 3612 and WSM3626, effective on nodule formation and plant growth of L. diffusa despite the high numbers of resident soil rhizobia. These strains and L. diffusa have potential to be introduced as exotic legumes species and rhizobia strains to Western Australia

Root-nodule bacteria of arid-zone legumes for use in rehabilitation in the Shark Bay World Heritage Area

The Shark Bay World Heritage Property (SBWHP) is a transition zone between the South West and Eremaean Biogeographic regions and was listed in 1991 due to its great geological, botanical and zoological importance (UNESCO, 2002). Shark Bay Salt is located within the SBWHP. Its lease area includes Useless Inlet and Useless Loop and there has been salt-mining production since 1965 (EPA, 1991). Over this time, borrow pits have been mined in areas surrounding the evaporation ponds, the majority of which were decommissioned over 15 years ago. Many of these pits remain in a highly disturbed state when compared to the surrounding undisturbed flora (Figure 1a, b)

Identification of tolerance to soil acidity in inoculant strains of Rhizobium leguminosarum bv. trifolii

The acid-soil tolerance of six strains (WU95, NA3001, WSM409, TA1, NA3025 and NA3039) of Rhizobium leguminosarum bv. trifolii was assessed in a three-year cross-row field experiment in an acid sandy soil of pH 4.2. Strains WSM409, NA3039 and WU95 were more acid-soil tolerant than strains NA3025, TA1 and NA3001. Strains WSM409 and NA3039 colonised and persisted in acid-soil to a greater degree than strains TA1 and NA3001. The data from this study clearly identified strain WSM409 as a strain with outstanding potential for improving the production of clovers on acid soils

Establishment and survival of the South African legume Lessertia spp. and rhizobia in Western Australian agricultural systems

Background and aims: The South African herbaceous legume species Lessertia capitata, L. diffusa, L. excisa L. incana and L. herbacea were introduced to Australia to assess plant establishment and survival, as well as the saprophytic ability of their root nodule bacteria (RNB). Methods: Five Lessertia spp., were inoculated with selected RNB strains and were sown in five different agroclimatic areas of the Western Australian wheat-belt during 2007 and 2008. Plant population and summer survival were evaluated in situ. Soil samples and nodules from host plants were also taken from each site. The re-isolated rhizobia were RPO1-PCR fingerprinted and their partial dnaK and nodA genes were sequenced to confirm their identity. Results: Plants achieved only poor establishment followed by weak summer survival. More than 83 % of the rhizobia re-isolated from Lessertia did not correlate with the original inoculants' fingerprints, and were identified as Rhizobium leguminosarum. The nodA sequences of the naturalised strains were also clustered with R. leguminosarum sequences, thus eliminating the likelihood of lateral gene transference from Mesorhizobium and suggesting a competition problem with indigenous rhizobia. Conclusion: The stressful soil conditions and high numbers of resident R. leguminosarum strains in Western Australian soils, and their ability to rapidly nodulate Lessertia spp. but not fix nitrogen are likely to preclude the adoption of Lessertia as an agricultural legume in this region

Genetic diversity and symbiotic effectiveness of Phaseolus vulgaris -nodulating rhizobia in Kenya

Phaseolus vulgaris (common bean) was introduced to Kenya several centuries ago but the rhizobia that nodulate it in the country remain poorly characterised. To address this gap in knowledge, 178 isolates recovered from the root nodules of P. vulgaris cultivated in Kenya were genotyped stepwise by the analysis of genomic DNA fingerprints, PCR-RFLP and 16S rRNA, atpD, recA and nodC gene sequences. Results indicated that P. vulgaris in Kenya is nodulated by at least six Rhizobium genospecies, with most of the isolates belonging to R. phaseoli and a possibly novel Rhizobium species. Infrequently, isolates belonged to R. paranaense, R. leucaenae, R. sophoriradicis and R. aegyptiacum. Despite considerable core-gene heterogeneity among the isolates, only four nodC gene alleles were observed indicating conservation within this gene. Testing of the capacity of the isolates to fix nitrogen (N2) in symbiosis with P. vulgaris revealed wide variations in effectiveness, with ten isolates comparable to R. tropici CIAT 899, a commercial inoculant strain for P. vulgaris. In addition to unveiling effective native rhizobial strains with potential as inoculants in Kenya, this study demonstrated that Kenyan soils harbour diverse P. vulgaris-nodulating rhizobia, some of which formed phylogenetic clusters distinct from known lineages. The native rhizobia differed by site, suggesting that field inoculation of P. vulgaris may need to be locally optimised

Host–strain mediated selection for an effective nitrogen-fixing symbiosis between Trifolium spp. and Rhizobium leguminosarum biovar trifolii

We have previously reported significant strain–host incompatibility between the microsymbiont Rhizobium leguminosarum biovar trifolii and Trifolium spp. related to geographic and phenological barriers. Additionally, we have shown that an effective symbiosis between strains of R. l. trifolii and clover was established despite the soil harbouring ineffective R. l. trifolii capable of nodulating the host. We termed this “selection” for effective symbiosis. This paper reports glasshouse-based experiments to validate and further explore this in situ selection phenomenon. The effect of cell density and strain ratio at the time of inoculation, as well as soil pH, were investigated on two hosts (Trifolium purpureum and Trifolium polymorphum) that were each exposed to one microsymbiont capable and one incapable of N2 fixation. In co-inoculation experiments at a cell density of 104 cells/mL, each host nodulated solely with its effective strain, even when this strain was outnumbered 100-fold by the ineffective strain. However, the selection process ceased when the effective strain was outnumbered 1000-fold. At higher basal cell concentrations of 105–108 cells/mL, selection for WSM1325 to form effective nodulation on T. purpureum was evident, but was significantly reduced as the ratio of ineffective cells in the inoculum increased above 4-fold. The results indicate that the selection mechanism is highly dependent on the basal rhizobial cell density. Soil pH did not significantly alter the process, and both strains grew at similar rates and formed nodules at similar rates. A preliminary investigation into the genetic backgrounds of WSM1325 and WSM2304 revealed that although their 16S rRNA sequences were identical, they have considerable differences in their symbiotic and chromosomal replicons through examination of atpD, GSII and nodD sequences

Unemployment and psychological distress one year after childbirth in France

STUDY OBJECTIVE—To analyse the relation between unemployment and the psychological distress of mothers one year after childbirth.
DESIGN—Multicentric survey concerning births occurring between September 1993 and July 1994.
SETTING—In France: two maternity units in the Parisian area and one in Champagne-Ardennes, in the east of France, comprising both urban and rural areas.
PARTICIPANTS—Primipara and secondipara women were interviewed three times: at birth by a face to face interview, five months and 12 months after the birth, by postal questionnaires, with a 83% response rate for the two postal questionnaires. The analysis includes 632 women who answered all three stages of the survey.
MEASUREMENTS—Psychological distress was mainly assessed one year after birth by the 12-item General Health Questionnaire.
RESULTS—After adjustment for unwanted pregnancy, marital conflicts, marital status, hospitalisation of the baby during the last year, lack of confiding relationship, depressive or anxious troubles before pregnancy, age, educational level and parity, unemployed women had an excess of psychological distress compared with employed women (OR = 1.87; 95%CI = 1.12, 3.13). The ratios for housewives were very close to those of employed women. Among the unemployed women, 60% had recently been without a job, since a few months before or after the birth. An excess of psychological distress among unemployed compared with employed women was observed in all social groups defined by the current or last occupation, but with various extents. Psychological distress was specially linked to the employment status in the group of women with the more qualified occupations.
CONCLUSION—Even after a birth, when women are very much involved in their maternal role, those seeking a job have worse mental health than those in a stable situation, either employed or housewives. In France, the unemployment rate among young women is high. It is specially important that social regulations protecting employment during and after pregnancy are adequately applied. Employers, legislators, such as medical doctors, have to be aware to this situation.


Keywords: psychological distress; unemployment; childbirth; women's healt