Rhizoctonia root and crown rot (RRCR) is an important disease in sugar beet production areas, whose assessment and control are still challenging. Therefore, breeding for resistance is the most ...practical way to manage it. Although the use of spectroscopy methods has proven to be a useful tool to detect soil-borne pathogens through leaves reflectance, no study has been carried out so far applying near-infrared spectroscopy (NIRS) directly in the beets. We aimed to use NIRS on sugar beet root pulp to detect and quantify RRCR in the field, in parallel to the harvest process. For the construction of the calibration model, mainly beets from the field with natural RRCR infestation were used. To enrich the model, artificially inoculated beets were added. The model was developed based on Partial Least Squares Regression. The optimized model reached a Pearson correlation coefficient (R) of 0.972 and a Ratio of Prediction to Deviation (RPD) of 4.131. The prediction of the independent validation set showed a high correlation coefficient (R = 0.963) and a root mean square error of prediction (RMSEP) of 0.494. These results indicate that NIRS could be a helpful tool in the assessment of Rhizoctonia disease in the field.
Abstract
Cryptococcus gattii, an environmental yeast isolated from plants, is one of the agents of cryptococcosis. Here, we aimed to develop a plant model to study C. gattii–plant interaction, since ...it is unclear how it affects the plant and the yeast. We tested three inoculation methods (scarification, infiltration, and abrasion) in three plant species: Arabidopsis thaliana, Nicotiana tabacum, and N. benthamiana. Cryptococcus gattii was able to grow in all three models, with a peak of yeast cell burden after 7 days, without any pathological effects. Furthermore, the fungal burden was reduced later, confirming that C. gattii is not a phytopathogen. Cryptococcus gattii proliferation was higher in N. benthamiana, which presented an increase in the hydrogen peroxide content, antioxidant system activity, and indoleacetic acid (IAA) production. Cryptococcus gattii colonies recovered from N. benthamiana presented lower ergosterol content, reduced capsule, and increased growth rate in vitro and inside macrophages. In vitro, IAA altered C. gattii morphology and susceptibility to antifungal drugs. We hypothesize that C. gattii can temporarily colonize plant living tissues, which can be a potential reservoir of yeast virulence, with further dissemination to the environment, birds, and mammals. In conclusion, N. benthamiana is suitable for studying C. gattii–plant interaction.
We demonstrate how the interaction of the fungus with the plant can alter its virulence.
Main conclusion
ABA and GA metabolism during incubation rather than hormone contents in dry seeds is the key to understanding secondary dormancy and germination of
Syngonanthus verticillatus
seeds.
...The mechanism of seed dormancy cycle, although very important for preventing germination during unfavorable periods for seedling establishment, is poorly understood in tropical species. Here, we used a perennial tropical species of the Brazilian
campo rupestre
,
Syngonanthus verticillatus
(Eriocaulaceae)
,
to investigate the involvement of ABA and GA in modulating secondary dormancy of seeds buried in situ over time and the dynamic of these hormones during the incubation of dormant and non-dormant seeds. Hormone analyses were carried out with freshly harvested seeds and on buried seeds exhumed after 3, 6 and 9 months. Dynamics of ABA and GAs in dormant and non-dormant seeds during incubation (0, 12, 24 and 36 h) under favorable conditions for germination (at 20 °C in the presence of light) were also investigated. In addition, the effects of GA
4
and fluridone were evaluated for overcoming secondary dormancy. Our results showed that changes in the contents of both ABA and GA
4
occurred after burial, suggesting they may be related to the modulation of secondary dormancy/germination of
S. verticillatus
seeds. The application of fluridone was more effective than GA
4
at overcoming secondary dormancy. We conclude that during incubation, de novo ABA synthesis and its consequent maintenance at high contents regulate the inhibition of germination in dormant seeds, while GA
4
synthesis and ABA catabolism modulate the germination of non-dormant seeds. ABA and GA metabolism during incubation of both dormant and non-dormant seeds rather than hormone contents of dry seeds in the field is thought to be the key to understanding secondary dormancy and germination.
Eriocaulaceae occurs primarily in the Neotropics, diversifying mostly in mountainous areas in southeastern Brazil. They are popularly known as everlasting plants, because once dried, they retain the ...appearance of living structures, being widely used as ornamentals. Most of the commercialized species belong to the genus Comanthera L.B.Sm., which was reestablished from Syngonanthus Ruhland. Comanthera groups 41 species, 26 in Comanthera subg. Comanthera and 15 in C. subg. Thysanocephalus, all restricted to South America. Phylogenetic analyses show Syngonanthus and Comanthera, as well as both Comanthera subgenera, as monophyletic and sister groups. Seed coat ornamentation proved to be useful and informative to help in determining taxonomic relationships in many plant groups. This study aims to characterize the external morphology of the seed coat of Comanthera and its subgenera using scanning electron microscopy, and discuss its taxonomic and phylogenetic implications. Seeds from nine species of Comanthera were analyzed, seven of which belong to C. subg. Comanthera and two to C. subg. Thysanocephalus. The results were compared with four species of Syngonanthus and one of Leiothrix. In Comanthera and Leiothrix the external periclinal walls remain intact, whereas they degenerate in the remaining genera. However, seed coat ornamentation in Leiothrix and Comanthera has distinct origins, as in the former, it comes from projections of the external layer of the outer integument, forming a striate pattern, and in the latter, from projections of the inner layer, conferring a rough pattern. Comanthera subg. Comanthera shows a rugose undulatory pattern, whilst C. subg. Thysanocephalus has a rugose micropapillate pattern. The newly reported features of the seed coat provide support for the Comanthera subgenera, thus presenting taxonomic and phylogenetic value.
Key message
Storage changed carbohydrate and protein levels, which can be related to embryo viability. The fatty acid profile was constant, and the embryo composition was similar to the mesocarp, not ...the endosperm.
Macaw palm fruits have a diverse biochemical constitution, and there is significant commercial interest in this species among food, pharmaceutical, cosmetics, and bioenergy industries. We evaluated changes in the reserve compounds of macaw palm mesocarp and seeds from fruits stored for 1 year under three different conditions. Protein and carbohydrate levels were highest in the embryo than in the endosperm. Fatty acid profiles were very similar over time under all storage conditions and in each structure evaluated, with the embryo composition being very similar to the mesocarp. Macaw palm oil remained well preserved under all storage conditions tested, but seed reserves and seed viability are best maintained at room temperatures. The endosperm contained higher levels of saturated fatty acids than either the embryo or mesocarp, making seeds more resistant to oxidative deterioration than the mesocarp. The results showed that the composition of the mesocarp oil promises the production of high-quality biodiesel from this structure, and changes in carbohydrate and protein levels show that laboratory conditions are the most efficient for maintaining seed quality during storage.
•Germination temperature thresholds are related to moisture in the microhabitats.•ABA mediates interactions between light and temperature to germinate.•Most species from campo rupestre can form ...long-term persistent soil seed banks.•Cyclical dormancy is highly synchronized with the soil moisture seasonality.•Induction of secondary dormancy is related to low GA levels rather than high ABA.
Campo rupestre is a mountain tropical landscape occurring in Brazil. It is considered one of the most biologically diverse ecosystems in the world and a major center of endemism. This review addresses the particularities and crucial roles that environmental signaling plays in germination, longevity, and dormancy cycles of seeds of tropical species from campo rupestre vegetation. It also addresses how microhabitats can influence the hormonal and biochemical control of seed germination, longevity and dormancy, as well as how the interaction between soil humidity and temperature can modulate the acquisition and overcoming of secondary dormancy, affecting dormancy cycles of important groups of campo rupestre species. The available data show that most species of campo rupestre produce small seeds that germinate in a wide range of temperatures, require light to germinate and are able to form long-term persistent soil seed banks. Special attention should be given to seeds of Velloziaceae, which germinate in the dark at high temperatures with germination mediated mainly by abscisic acid, and to seeds of Eriocaulaceae and Xyridaceae, which have cyclical dormancy in fine synchrony with the seasonality of campo rupestre. Seasonal water availability, along with temperature, has shown to play a critical role in annual dormancy cycles, with the dynamics of gibberellins and abscisic acid levels driving the acquisition of secondary dormancy. This information is essential for understanding interactions between seeds and the environment and will provide useful contributions to the conservation and maintenance of campo rupestre vegetation and the preservation of this unique ecosystem.
•Dry storage and exogenous gibberellin (GA3) may lead to increase in germinablity.•Non-deep physiological dormancy is present in most of the species studied.•Differences in germination may be related ...to habitats and geographic distributions.
The genus Stachytarpheta (Verbenaceae) comprises numerous endemic species and taxa threatened with extinction and its main diversity center is the Espinhaço mountain chain in central-eastern Brazil. Although cases of seed dormancy are known from other genera of the family, there have been no reports of dormancy in Stachytarpheta. We investigated the viability and germination of recently harvested seeds of 12 species of Stachytarpheta evaluating the effects of light, alternating temperature, gibberellin and dry storage on germination. Seed sizes were measured and they were tested for viability (tetrazolium test) and germination at constant and alternating temperatures under 12-h photoperiod. Ten species were evaluated for the effects of GA3 on germination, and four species were dry stored for 12 months and their germination then evaluated. Results showed differences in germination among species that appeared to be related to their natural habitats and geographic distributions. Stachytarpheta seeds are small and most species showed low germination as well as light requirements for germination Incubating seeds under alternating temperatures resulted in germination increase of 30% of the species studied in relation to exposure to constant temperatures. Both dry storage (after-ripening) and application of GA3 resulted in significantly increases of germination of most of the investigated species. The responses to the treatments were not homogeneous among all of the species, indicating differences in their dormancy levels. Although no uniform pattern was identified for the genus, our results indicate that most of the taxa studied have non-deep physiological dormancy, which is commonly seen in species with restricted distributions.
ABA and GA metabolism during incubation rather than hormone contents in dry seeds is the key to understanding secondary dormancy and germination of Syngonanthus verticillatus seeds. The mechanism of ...seed dormancy cycle, although very important for preventing germination during unfavorable periods for seedling establishment, is poorly understood in tropical species. Here, we used a perennial tropical species of the Brazilian campo rupestre, Syngonanthus verticillatus (Eriocaulaceae), to investigate the involvement of ABA and GA in modulating secondary dormancy of seeds buried in situ over time and the dynamic of these hormones during the incubation of dormant and non-dormant seeds. Hormone analyses were carried out with freshly harvested seeds and on buried seeds exhumed after 3, 6 and 9 months. Dynamics of ABA and GAs in dormant and non-dormant seeds during incubation (0, 12, 24 and 36 h) under favorable conditions for germination (at 20 °C in the presence of light) were also investigated. In addition, the effects of GA
and fluridone were evaluated for overcoming secondary dormancy. Our results showed that changes in the contents of both ABA and GA
occurred after burial, suggesting they may be related to the modulation of secondary dormancy/germination of S. verticillatus seeds. The application of fluridone was more effective than GA
at overcoming secondary dormancy. We conclude that during incubation, de novo ABA synthesis and its consequent maintenance at high contents regulate the inhibition of germination in dormant seeds, while GA
synthesis and ABA catabolism modulate the germination of non-dormant seeds. ABA and GA metabolism during incubation of both dormant and non-dormant seeds rather than hormone contents of dry seeds in the field is thought to be the key to understanding secondary dormancy and germination.
Swietenia macrophylla have been considered for the treatment of various diseases, including anticancer activity. This study aimed to investigate the anticancer activity of S. macrophylla leaves ...extract and its isolated compound towards human colorectal cancer cell line.
Hexanic extract of S. macrophylla leaves demonstrated relevant cytotoxicity only against colon cancer cell line HCT116.
Our results showed significant DNA damage and apoptosis after treatment with the hexanic extract of S. macrophylla. Moreover, no toxicity was noticed for the animal model. The isolated compound limonoid L1 showed potent cytotoxicity against cancer cell lines with IC50 at 55.87 μg mL−1. Limonoid L1 did not trigger any cell membrane rupture in the mice erythrocytes suggesting no toxicity. The antiproliferative effect of L1 was confirmed in colorectal cancer cells by clonogenic assay, inducing G2/M arrest, apoptosis, and DNA damage in cancer-type cells.
L1 reduced BCL2 and increased ATM, CHK2, TP53, ARF, CDK1, CDKN1A, and CASP3 in the colorectal cancer cell line. These findings suggest that limonoid L1 isolated from S. macrophylla can be a promising anticancer agent in managing colorectal cancer.
species are appreciated for their edible fruits and are known as having anticonvulsant, antimicrobial and insecticidal actions.
The plant material was collected in the southeastern Pará state of ...Brazil and submitted to hydrodistillation. GC-MS analyzed the oils, and their antioxidant and cytotoxic activities were evaluated by the DPPH and MTT assays.
The main components identified in the
oils were 5-hydroxy-
-calemene, (2
,6
)-farnesol, (2
,6
)-farnesol, caryophylla-4(12),8(13)-dien-5α-ol-5β-ol,
-γ-bisabolene, β-bisabolene, germacrene D, and ishwarane. The oil of
showed the most significant antioxidant activity (216.5 ± 11.6 mg TE/mL), followed by the oils of
(122.6 ± 6.8 mg TE/mL) and
(111.2 ± 12.4 mg TE/mL).
oils were cytotoxic to HCT-116 (colon cancer) cells by the MTT assay, where the most active was the oil of
(10.3 µg/mL), followed by the oils of
(13.9 µg/mL) and
(16.4 µg/mL). The oils of
and
showed the highest toxicity for MRC5 (human fibroblast) cells, with values of 14.0 µg/mL and 18.1 µg/mL, respectively.
These results suggest that
oils could be tested in future studies for the treatment of colon cancer and oxidative stress management.
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