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Background and aims Legumes of the genus Lessertia have recently been introduced to Australia in an attempt to increase the range of forage species available in Australian farming systems capable of dealing with a changing climate. This study assessed the diversity and the nodulation ability of a collection of Lessertia root nodule bacteria isolated from different agro-climatic areas of the Eastern and Western Capes of South Africa. Methods The diversity and phylogeny of 43 strains was determined via the partial sequencing of the dnaK, 16srRNA and nodA genes. A glasshouse experiment was undertaken to evaluate symbiotic relationships between six Lessertia species and 17 rhizobia strains. Results The dnaK and 16S rRNA genes of the majority of the strains clustered with the genus Mesorhizobium. The position of the strains at the intra-genus level was incongruent between phylogenies with few exceptions. The nodA genes from Lessertia spp. formed a cluster on their own, separate from the previously known Mesorhizobium nodA sequences. Strains showed differences in their nodulation and nitrogen fixation patterns that could be correlated with nodA gene phylogeny. L. diffusa, L. herbacea and L. excisa nodulated with nearly all the strains examined while L. capitata, L. incana and L. pauciflora were more stringent. Conclusion Root nodule bacteria from Lessertia spp. were identified mainly as Mesorhizobium spp. Their nodA genes were unique and correlated with the nodulation and nitrogen fixation patterns of the strains. There were marked differences in promiscuity within Lessertia spp. and within strains of root nodule bacteria.

Lessertia frutescens (synonym Sutherlandia frutescens) is an important South African medicinal plant used traditionally to treat different human pathologies and is considered an adaptogenic plant. This study sought to isolate compounds from the plant and determine their protective potentials using SH-SY5Y cells and MPP+ (1-methyl-4-phenylpyridinium) to mimic Parkinson’s disease. The phytochemical analysis of a 70% aqueous methanolic extract of L. frutescens leaves resulted in the isolation and identification of 11 pure compounds (1–11), among which compounds 1 and 2 were identified as new metabolites. The new compounds were characterised using IR, UV, NMR, and HRESIMS and were given the trivial names lessertiosides A (1) and B (2). Additionally, the flavonoids 8-methoxyvestitol (7) and mucronulatol (8) were isolated for the first time from the plant. The biological actions show that the isolated compounds had negligible toxicity on SH-SY5Y cells and improved cell viability in the cells exposed to MPP+. Furthermore, as a mechanism of action, the compounds could sustain cellular ATP generation and prevent MPP+-induced apoptotic cell death. Our findings provide evidence for the neuroprotective properties of compounds isolated from L. frutescens in MPP+-induced neuronal damage for the first time and create an avenue for these compounds to be further investigated to elucidate their molecular targets.

Lessertia frutescens is a multipurpose medicinal plant indigenous to South Africa. The curative ability of the medicinal plant is attributed to its rich phytochemical composition, including amino acids, triterpenoids, and flavonoids. A literature review of some of the phytochemical compounds, particularly amino acids, in L. frutescens shows a steady decrease in concentration over the years. The reduction of the phytochemical compounds and diminishing biological activities may be attributed to drought and salt stress, which South Africa has been grappling with over the years. Canavanine, a phytochemical which is associated with the anticancer activity of L. frutescens, reduced slightly when the plant was subjected to salt stress. Like other legumes, L. frutescens forms a symbiotic relationship with plant-growth-promoting rhizobacteria, which facilitate plant growth and development. Studies employing commercial plant-growth-promoting rhizobacteria to enhance growth and biological activities in L. frutescens have been successfully carried out. Furthermore, alleviation of drought and salt stress in medicinal plants through inoculation with plant growth-promoting-rhizobacteria is well documented and effective. Therefore, this review seeks to highlight the potential of plant-growth-promoting rhizobacteria to alleviate the effect of salt and drought in Lessertia frutescens.

Lessertia frutescens (L.) Goldblatt & J.C.Manning (synonym Sutherlandia frutescens), commonly known as cancer bush, is one of the most prominently used South African medicinal plants, with a rich history of traditional uses among indigenous communities. Its phytochemical profile showed different metabolites such as amino acids, fatty acids, sugars, flavonoid glycosides, cycloartenol glycosides, and oleanane-type saponins. Moreover, several research studies have highlighted the promising therapeutic effects of L. frutescens in combating various cancer cell lines. Additionally, the plant demonstrated potent immunomodulatory, antioxidant, anti-inflammatory, antidiabetic, neuroprotective, antistress, and antimicrobial activities. These research findings highlight L. frutescens as a promising candidate for the development of new or complementary therapies for a range of diseases and conditions. This review analyses the chemical and biological properties of L. frutescens based on 154 articles identified through SciFinder. Of these, 78 articles, including two patents, met the inclusion criteria and were reviewed. Studies focused on agriculture and horticulture were excluded as they fell outside the scope of this research.

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.

The exploring of biostimulant sources is important for sustainable agriculture. Although all parts of the moringa plant (Moringa oleifera Lam.) are rich in phytohormones and phytochemicals which may be utilised as a potential plant growth enhancer, most attention has been placed on its leaves as a possible biostimulant for enhancing productivity of plants. Little has been reported on moringa seed extract (MSE) as a growth enhancer on medicinal plants. Thus, this study investigated the efficacy of MSE doses (water spray as control, MSE at 2, 4, 6 and 8%) on growth attributes, mineral content and phytochemical compositions of cancer bush plants (Lessertia frutescens L.) grown during the winter–spring and spring–summer seasons of 2021. A gradual increase in growth characteristics, chlorophyll content, phenols and flavonoid contents was recorded in all concentrations of MSE-treated plants compared with controls. Furthermore, all levels of MSE effectively enhanced the concentrations of macronutrients such as calcium, magnesium, phosphorus, nitrogen and potassium as well as micronutrients comprising copper, zinc, iron, manganese and sodium of cancer bush plants relative to untreated plants. Both 6 and 8% MSE concentrations showed high productivity, minerals and phytochemical constituents in cancer bush plants in comparison with 2 and 4% MSE treatments. Overall, the findings of this study demonstrated that, even at low concentrations, MSE can be successfully applied as a biostimulant to improve the growth and biochemical attributes of cancer bush plants.

Lessertia frutescens (L.) Goldblatt & J. C. Manning 2000 is an endemic species of Southern Africa with high medicinal and economic values. To facilitate exploration of its genetic resource, a complete chloroplast genome was determined using Illumina pair-end sequencing technology. The complete circular genome is 122,700 bp in length with overall 34.2% GC contents. It encodes a total of 110 genes, including 76 protein-coding genes, 30 tRNA, and four rRNA genes. The maximum-likelihood (ML) phylogenetic tree indicated that L. frutescens nested within the Papilionoideae and had a close relationship with Astragalus nakaianus and A. mongholicus. The newly sequenced complete chloroplast genome will help understanding the plastome evolution, genetic diversity and contribute to the genetic conservation of the natural population of L. frutescens.

Plant-beneficial microorganisms are determinants of plant health and productivity. However, the effects associated with secondary plant metabolism and interactions in the rhizosphere for Cancer bush Lessertia frutescens (L.) is unclear. The study was conducted to understand the mechanism of rhizobium inoculation for L. frutescens, variations in phytochemicals, soluble sugars, and soil–plant interactions in the rhizosphere. Four rhizobium inoculation levels (0, 100, 200, and 400 g) were evaluated under the field conditions to establish the antioxidant properties, soluble sugars, and rhizosphere soil microbial diversity at 150, 240, and 330 days after planting (d.a.p). Although inoculation did not significantly affect plant biomass and N2 fixation of L. frutescens, total phenolics and flavonoids were enhanced with the application of 200 g at 240 days after planting. The antioxidant values analyzed through FRAP (Ferric reducing power assay) were highest with 100 g inoculation at 240 days after planting. Water-soluble sugars such as fructose, sucrose, and glucose increased with the application of 400, 200, and 100 g rhizobium inoculation. The rhizosphere′s carbon source utilization profiles (CSUP) did not vary significantly, depicting the weaker ability in converting C, P, and N profiles. The lowest ß glucosidase activity was observed in the bulk soil with the lowest alkaline and acid phosphatase activities. Soil microbial populations present in the bulk sample demonstrated the smallest overall enzyme activities. The variation of different variables studied indicate the potential of rhizobium inoculation. However, further studies are required to ascertain the inoculation′s effectiveness for plant growth and rhizosphere microbial populations of L. frutescens.

Callus and suspension cell cultures were successfully developed from Sutherlandia frutescens (Fabaceae), an endemic medicinal plant of South Africa. Two callus cell lines, originating from hypocotyl and cotyledon explants of in vitro seedlings under both dark and light conditions, showed intensive fresh weight accumulation with growth index ranging from 4.6 to 5.9. Suspension cell cultures induced from two callus lines had similar growth profiles and their growth index (15–18), specific growth rate (0.15–0.16 day −1 ), productivity (0.83–0.96 g/(l day)) and maximum biomass accumulation (16–18 g/l) remained relatively high for Fabaceae cell cultures during 27 sub-cultivations. Callus and suspension cell cultures showed similar profiles of secondary metabolites that were, however, different from leaves of greenhouse plants. Isoflavones were predominant in both callus and suspension cell cultures while flavonoids (sutherlandins) and triterpene glycosides of the cycloartane group (sutherlandiosides) were mostly found in leaves. Nineteen fatty acids (FA), both short- and very-long-chained (up to C 25:0 ), were found in cell cultures. Linoleic and α-linolenic FA together comprised 60–64% out of total FA content in cell cultures followed by palmitic acid (18–25%). Extracts of suspension cell biomass exhibited antimicrobial activity against Staphylococcus aureus but were not effective against Pseudomonas aeruginosa. To the best of our knowledge, this is the first report on the induction, phytochemical composition and antimicrobial activity screening of S. frutescens suspension cell cultures which opens the door for their biotechnological application.

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 wheatbelt 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 Lessertìa 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.