Native Lotus Research Articles

Lotus (Nelumbo nucifera G.) seed starch: Understanding the impact of physical modification sequence (ultrasonication and HMT) on properties and in vitro digestibility

Native lotus (Nelumbo nucifera G.) seed starch (LSS) was single- and dual-modified by heat-moisture treatment (HMT), ultrasonication (US), HMT followed by the US (HMT-US), and the US followed by HMT (US-HMT). The modified lotus seed starch (LSS) was evaluated for its physicochemical, pasting, thermal, and rheological properties and in vitro digestibility. All treatments decreased the swelling power (10.52–14.0 g/g), solubility (12.20–15.95 %), and amylose content (23.71–25.67 %) except for ultrasonication (17.67 g/g, 17.90 %, 29.09 %, respectively) when compared with native LSS (15.05 g/g, 16.12 %, 27.12 %, respectively). According to the rheological study, G′ (1665–4004 Pa) was greater than G″ (119–308 Pa) for all LSS gel samples demonstrating their elastic character. Moreover, gelatinization enthalpy (17.56–16.05 J/g) increased in all treatments compared to native LSS (15.38 J/g). Ultrasonication treatment improved the thermal stability of LSS. The digestibility results showed that dual modification using HMT and US significantly enhanced resistant starch (RS) and reduced slowly digestible starch (SDS) in LSS. Cracks were observed on the surface of the modified LSS granules. Peak viscosity decreased in all modified starches except for ultrasonication, suggesting their resistance to shear-thinning during cooking, making them ideal weaning food components. The results obtained after different modifications in this study could be a useful ready reference to select appropriate modification treatments to produce modified LSS with desired properties depending on their end-use.

Modified lotus seed starch and red turnip peel extract based pH responsive edible films

Starch obtained from lotus seed was physically modified through heat-moisture treatment to develop the starch-based biopolymer films. Three different types of films: native lotus seed starch (NLS)- carboxymethyl cellulose (CMC), heat moisture treated modified starch (HMLS)-CMC, and modified starch incorporated with red turnip peel extract (HMLS-RTE)-CMC films were developed. The different filmogenic solutions exhibited non-Newtonian behavior with the shear thinning property and showed weak gel-like and viscoelastic behavior. The three different films' tensile strength ranged from 14.97 ± 0.65–21.13 ± 0.41 MPa and elongation at break ranged from 32.87 ± 1.14–44.31 ± 0.82%. The water vapor permeability in NLS was 3.86 × 10−7 gm−1h−1Pa−1 and in HMLS-RTE film, the WVP was decreased to 2.58 × 10−7 gm−1h−1Pa−1. The findings revealed that the pH-sensitive HMLS-RTE film had higher thermal stability, improved mechanical and moisture barrier properties than the NLS films, making them suitable for the intelligent food packaging system.

Effect of Physical and Enzymatic Modifications on Composition, Properties and In Vitro Starch Digestibility of Sacred Lotus (Nelumbo nucifera) Seed Flour.

In this study, native lotus seed flour (N-LSF) was modified by different methods, namely, partial gelatinization (PG), heat–moisture treatment (HMT), or pullulanase treatment (EP). Their composition, functional properties, starch composition, and estimated glycemic index (eGI) were compared. PG contained similar protein, soluble dietary fiber, and insoluble dietary fiber contents to N-LSF, while those of HMT and EP differed from their native form. PG increased rapid digestible starch (RDS) but decreased resistant starch (RS); while HMT and EP increased amylose and RS contents to 34.57–39.23% and 86.99–92.52% total starch, respectively. Such differences led to the different pasting properties of the modified flours rather than PG, which was comparable to the native flour. HMT had limited pasting properties, while EP gave the highest viscosities upon pasting. The eGI of all samples could be classified as low (<50), except that of PG, which was in the medium range (60). It was plausible that lotus seed flour modified either with HMT or EP could be used as carbohydrate source for diabetes patients or health-conscious people.

Optimised preparation and characterisation of lotus root starch oxidised with sodium hypochlorite (NaOCl) using response surface methodology

In this paper, response surface methodology (RSM) was used to study the optimised process conditions of lotus root starches modified by treatment with sodium hypochlorite (NaOCl). Based on the Box-Behnken design, quadratic models were developed to correlate the reaction variables. Analysis of variance (ANOVA) revealed that the active chlorine content was the most significant variable for the response. Under the experimental conditions in this paper, the calculated carboxyl content (CN&lt;sub&gt;COOH&lt;/sub&gt;) of obtained samples was approximately 0.98% ± 0.02% (n = 5). The spectra of Fourier transform infrared (FTIR) spectroscopy displayed that the formation of carboxyl groups successfully occurred on the oxidised lotus root starches. Scanning electron microscope (SEM) analysis showed that the oxidised lotus root starch (CN&lt;sub&gt;COOH&lt;/sub&gt;, 0.98%) granules were mostly spherical in shape and their surfaces were slightly rougher than those of native lotus root starch. This work may contribute to providing technical support and theoretical guidance for the production of oxidised lotus root starches using NaOCl as an oxidising agent.

Effect of γ-radiation on physico-chemical, morphological and thermal characteristics of lotus seed (Nelumbo nucifera) starch

Native and gamma (γ) irradiated lotus seed starches were studied for their physicochemical, thermal, pasting and morphological properties. Upon gamma irradiation of 5, 10, 15 and 20 kGy, amylose content of starches was decreased as the dose of irradiation was increased. Lotus seeds starch granules had bimodal size distribution varying in size from small to large. Observation under scanning electron microscope (SEM) showed that at low dose of irradiation (5, 10kGy), no significant changes were observed in shape and size. However, minor alterations were notice during treatment of 15kGy and 20 kGy, which included roughness. Irradiation significantly decreased the pasting properties (peak, trough, final and setback viscosities) of the starch. For native starch, To, Tp, and Tc of 137.44 °C, 138.29 °C and 143.21 °C and 169.51 °C, 169.72 °C, and 177.73 °C respectively was observed for first and second peak. Upon irradiation, the gelatinization temperatures were decreased. The irradiated starch showed no change in diffraction pattern compared to native lotus seed starch but a dose-dependent decrease in relative crystallinity was observed.

Physicochemical characterization of modified lotus seed starch obtained through acid and heat moisture treatment

Native Lotus seed (NLS) starch was independently subjected to two different modifications such as heat-moisture treatment (HMT) and citric acid treatment (CAT). The effect of the treatment on physical, chemical, morphological, thermal, pasting and gelling properties of native and modified starches were evaluated during the study. The results showed that the enthalpies of the HMT and the CAT samples along with the onset, peak, and conclusion temperatures of gelatinization were increased. The FTIR analysis revealed that HMT and CAT increased the degree of order and the degree of the double helix of the NLS. The gel elasticity and the adhesiveness of the HMT and the CAT starches were also greater than the NLS starch samples. The developed modified starches could be used for enhancement of different functional properties for applying as gelling, thickening, stabilizing and filling agents for developing starch-based food formulations.

Self-propulsion of dew drops on lotus leaves: a potential mechanism for self cleaning

This study shows that condensation on the hierarchically structured lotus leaf can facilitate self-propulsion of water droplets off the surface. Droplets on leaves inclined at high angles can be completely removed from the surface by self-propulsion with the assistance of gravity. Due to the small size of mobile droplets, light breezes may also fully remove the propelled droplets, which are typically projected beyond the boundary layer of the leaf cuticle. Moreover the self-propelled droplets/condensate were able to remove contaminants (eg silica particles) from the leaf surface. The biological significance of this process may be associated with maintaining a healthy cuticle surface when the action of rain to clean the surface via the lotus effect is not possible (due to no precipitation). Indeed, the native lotus plants in this study were located in a region with extended time periods (several months) without rain. Thus, dew formation on the leaf may provide an alternative self-cleaning mechanism during times of drought and optimise the functional efficiency of the leaf surface as well as protecting the surface from long term exposure to pathogens such as bacteria and fungi.

Positive association between biotin and the abundance of root-feeding nematodes

Biotin is an essential micronutrient needed but not synthesized by animals. We performed a field experiment where we measured biotin levels and the community composition of nematodes in the rhizosphere of two legumes, the native Lotus corniculatus and an invasive alien, Lupinus polyphyllus. The relative abundance of root-feeding nematodes and the biotin concentration in nematodes were lower in the rhizosphere of the alien. We are the first to show that biotin levels in indigenous nematode populations are associated with the host plant species, and that the difference may affect nematode community.

Does the invasive Lupinus polyphyllus increase pollinator visitation to a native herb through effects on pollinator population sizes?

Invasive plants may compete with native species for abiotic factors as light, space and nutrients, and have also been shown to affect native pollination interactions. Studies have mainly focused on how invasive plants affect pollinator behaviour, i.e. attraction of pollinators to or away from native flowers. However, when an invasive plant provides resources utilized by native pollinators this could increase pollinator population sizes and thereby pollination success in natives. Effects mediated through changes in pollinator population sizes have been largely ignored in previous studies, and the dominance of negative interactions suggested by meta-analyses may therefore be biased. We investigated the impact of the invasive Lupinus polyphyllus on pollination in the native Lotus corniculatus using a study design comparing invaded and uninvaded sites before and after the flowering period of the invasive. We monitored wild bee abundance in transects, and visit rate and seed production of potted Lotus plants. Bumblebee abundance increased 3.9 times in invaded sites during the study period, whereas it was unaltered in uninvaded sites. Total visit rate per Lotus plant increased 2.1 times in invaded sites and decreased 4.4 times in uninvaded sites. No corresponding change in seed production of Lotus was found. The increase in visit rate to Lotus was driven by an increase in solitary bee visitation, whereas mainly bumblebees were observed to visit the invasive Lupinus. The mechanism by which the invasive increases pollinator visit rates to Lotus could be increased availability of other flower resources for solitary bees when bumblebees forage on Lupinus.

Spatial distribution of aquatic birds in Anavilundawa Ramsar wetland sanctuary in Sri Lanka

Biotic and abiotic factors that influence the avian distribution in a dry zone wetland was investigated by studying the distribution of Asian Openbill (Anastomus oscitans), Cotton Pygmy-goose (Nettapus coromandelianus) and Pheasant-tailed Jacana (Hydrophasianus chirurgus) in Anavilundawa Ramsar sanctuary in Sri Lanka in 2006. Their distribution was recorded in Anavilundawa, Suruwila and Maiyawa reservoirs, their catchments and respective paddy fields, through line transects. The floral cover of surface water was recorded by floating quadrates. Water lily (Nymphea spp.) was the dominant flora in Anavilundawa reservoir, invasive water hyacinth (Eichhornia crassipes) in Suruwila reservoir and a native lotus (Nelumbo nucifera) in Maiyawa reservoir, respectively. Anavilundawa area had a higher distribution of birds than in the other two areas. Among the three species observed, Asian Openbill distribution was mainly restricted to Anavilundawa whereas Pheasant-tailed Jacana was present in all three areas. Nesting of Asian Openbill occurred only in Anavilundawa while nesting of Pheasant-tailed Jacana was only observed in Maiyawa. Among the three species recorded, Cotton Pygmy-goose numbers were the least. Asian Openbill preferred dead trees and trees with no leaves for nesting and perching over live trees. It is concluded that the spread of invasives such as Water hyacinth and Salvinia (Salvinia molesta) forming mats over surface water have reduced the abundance of habitat specialists like Cotton Pygmy-goose.

BEYOND THE ECOLOGICAL: BIOLOGICAL INVASIONS ALTER NATURAL SELECTION ON A NATIVE PLANT SPECIES

Biological invasions can have strong ecological effects on native communities by altering ecosystem functions, species interactions, and community composition. Even though these ecological effects frequently impact the population dynamics and fitness of native species, the evolutionary consequences of biological invasions have received relatively little attention. Here, I show that invasions impose novel selective pressures on a native plant species. By experimentally manipulating community composition, I found that the exotic plant Medicago polymorpha and the exotic herbivore Hypera brunneipennis alter the strength and, in some instances, the direction of natural selection on the competitive ability and anti-herbivore defenses of the native plant Lotus wrangelianus. Furthermore, the community composition of exotics influenced which traits were favored. For example, high densities of the exotic herbivore Hypera selected for increased resistance to herbivores in the native Lotus; however, when Medicago also was present, selection on this defense was eliminated. In contrast, selection on tolerance, another plant defense trait, was highest when both Hypera and Medicago were present at high densities. Thus, multiple exotic species may interact to influence the evolutionary trajectories of native plant populations, and patterns of selection may change as additional exotic species invade the community.

Evaluation of the quality of lotus seed of Nelumbo nucifera Gaertn from outer space mutation

Lotus seeds from outer space mutation, named as No. 36 space lotus seed, have been used for 6 years in Jianou county, Fujian province, China and compared to the native counterpart. The proximate composition (ash, moisture, protein, lipid, alcohol extract, 100-seed weight, carbohydrate) and nutritional components (amino acids, vitamins B1, B2, B6, C, E, phospholipids) of No. 36 space lotus seed and native lotus seed embryos were compared. The results indicate that the profiles of proximate composition and nutritional components of No. 36 space lotus seed and native lotus seed embryos were similar; however, most chemical contents were significantly higher ( P < 0.05) in the former. This result was also confirmed by the HPLC fingerprint. The quality of No. 36 space lotus seed was better than that of native lotus seed and the results support the use of this seed as a food and a herbal medicine product.

EVOLUTIONARY RESPONSES OF NATIVE PLANTS TO NOVEL COMMUNITY MEMBERS

Both ecological and evolutionary processes can influence community assembly and stability, and native community members may respond both ecologically and evolutionarily as additional species enter established communities. Biological invasions provide a unique opportunity to examine these responses of native community members to novel species additions. Here, I use reciprocal transplant experiments among naturally invaded and uninvaded environments, along with experimental removals of exotic species, to determine whether exotic plant competitors and exotic insect herbivores evoke evolutionary changes in native plants. Specifically, I address whether the common native plant species Lotus wrangelianus has responded evolutionarily to a series of biological invasions by adapting to the presence of the exotic plant Medicago polymorpha and the exotic insect herbivore Hypera brunneipennis. Despite differences in selection regimes between invaded and uninvaded environments and the presence of genetic variation for traits relevant to the novel competitive and plant-herbivore interactions, these experiments failed to reveal evidence that Lotus has responded evolutionarily to the double invasion of Medicago followed by H. brunneipennis. However, when herbivory from H. brunneipennis was experimentally reduced, Lotus plants from source populations invaded by Medicago outperformed plants from uninvaded source populations when transplanted into heavily invaded destination environments. Therefore, Lotus showed evidence of adaptation to Medicago invasion but not to the newer invasion of an exotic shared herbivore. The presence of this exotic insect herbivore alters the outcome of evolutionary responses in this system and counteracts adaptation by the native Lotus to invasion by the exotic plant Medicago. This result has broad implications for the conservation of native communities. While native species may be able to adapt to the presence of one or a few exotics, a multitude of invasions may limit the ability of natives to respond evolutionarily to the novel and frequently changing selection pressures that arise with subsequent invasions.

EVOLUTIONARY RESPONSES OF NATIVE PLANTS TO NOVEL COMMUNITY MEMBERS

Both ecological and evolutionary processes can influence community assembly and stability, and native community members may respond both ecologically and evolutionarily as additional species enter established communities. Biological invasions provide a unique opportunity to examine these responses of native community members to novel species additions. Here, I use reciprocal transplant experiments among naturally invaded and uninvaded environments, along with experimental removals of exotic species, to determine whether exotic plant competitors and exotic insect herbivores evoke evolutionary changes in native plants. Specifically, I address whether the common native plant species Lotus wrangelianus has responded evolutionarily to a series of biological invasions by adapting to the presence of the exotic plant Medicago polymorpha and the exotic insect herbivore Hypera brunneipennis. Despite differences in selection regimes between invaded and uninvaded environments and the presence of genetic variation for traits relevant to the novel competitive and plant-herbivore interactions, these experiments failed to reveal evidence that Lotus has responded evolutionarily to the double invasion of Medicago followed by H. brunneipennis. However, when herbivory from H. brunneipennis was experimentally reduced, Lotus plants from source populations invaded by Medicago outperformed plants from uninvaded source populations when transplanted into heavily invaded destination environments. Therefore, Lotus showed evidence of adaptation to Medicago invasion but not to the newer invasion of an exotic shared herbivore. The presence of this exotic insect herbivore alters the outcome of evolutionary responses in this system and counteracts adaptation by the native Lotus to invasion by the exotic plant Medicago. This result has broad implications for the conservation of native communities. While native species may be able to adapt to the presence of one or a few exotics, a multitude of invasions may limit the ability of natives to respond evolutionarily to the novel and frequently changing selection pressures that arise with subsequent invasions.

INSECT HERBIVORES DRIVE IMPORTANT INDIRECT EFFECTS OF EXOTIC PLANTS ON NATIVE COMMUNITIES

Exotic plant species can affect native plant species both directly via competition and indirectly by modifying native species' interactions with other organisms in the community. Both direct and indirect effects can have strong fitness impacts on the native species and can result in cascading effects throughout the invaded community. Many exotic plant species escape from the herbivores with which they co-evolved, but in our study system, the exotic Egyptian alfalfa weevil (Hypera brunneipennis) has been introduced to California and is able to feed both on the exotic plant Medicago polymorpha and on the California native Lotus wrangelianus. Because these two plant species share this common herbivore, the possibility of strong herbivore-mediated indirect interactions between these introduced and native plant species is plausible. We used observational studies and manipulative field experiments to determine whether exotic Medicago affects herbivory on the native Lotus and whether Medicago reduces the fitness of Lotus through direct competitive effects and/or herbivore-mediated indirect effects. Both observational and experimental data indicate that Medicago increases weevil herbivory on the native Lotus. Additionally, Medicago reduced Lotus fitness through direct as well as indirect mechanisms. In 2002, Medicago reduced Lotus fitness even when herbivores were experimentally reduced, suggesting direct competitive effects of Medicago on the native Lotus. In contrast, in 2003, Medicago reduced Lotus fitness only in the presence of herbivores, indicating that the fitness effects in that year were largely indirect and mediated by herbivores. Our results demonstrate that the net fitness consequences of indirect and direct effects of exotic plant species on native plants can vary temporally, depending on the abundance of members of the herbivore community. Also, rather than limiting the success of exotics, introduced herbivores that feed on exotic plants may provide additional, indirect avenues through which exotic plants can reduce the fitness of native species.

The Biology of the American Lotus, Nelumbo lutea (Wild.) Pers

Small (1933) in his Manual of the Southeastern Flora designated the American or yellow lotus as Nelumbo lutea (Willd.) Pers. Synonyms include Nelumbium luteutm Willd., Nelumbo lutea Pers., Nelumbium pentapetalum Walt., Nelumbo pentapetala, and Nelumbium codophyllum Raf. The latter name was given 'by Robin (1817) to the lotus plants in Louisiana which were said to be much larger than those of Nelumbium luteunt. Examination of lotus colonies in Louisiana suggests that the larger size is to be attributed to the richer soils and longer growing season. The concensus among botanists seems to be that there is only one species of native lotus in America.