Fusarium equiseti strain FCHE and Fusarium oxysporum strain FCHJ were isolated from the roots of wilting habanero pepper (Capsicum chinense Jacq.) seedlings with root rot. Toward developing a biorational control of these serious phytopathogenic strains, ethanolic (EE) and aqueous (AE) extracts of different vegetative parts of 40 tropical native plants of the Yucatán Peninsula were screened for antifungal activity. Extracts of six out of 40 assayed plants were effective, and the most inhibitory extracts were studied further. EEs from Mosannona depressa (bark from stems and roots), Parathesis cubana (roots), and Piper neesianum (leaves) inhibited mycelial growth of both strains. Each active EE was then partitioned between hexane and acetonitrile. The acetonitrile fraction from M. depressa stem bark (MDT-b) had the lowest minimum inhibitory concentration of 1000 µg/mL against both pathogens and moderate inhibitory concentration (IC₅₀) of 462 against F. equiseti and 472 µg/mL against F. oxysporum. After 96 h treatment with EE from M. depressa stem bark, both strains had distorted hyphae and conidia and collapsed conidia in scanning electron micrographs. Liquid chromatography–ultraviolet–high resolution mass spectrometry analysis revealed that the major component of the fraction was α-asarone. Its antifungal effect was verified using a commercial standard, which had an IC₅₀ of 236 µg/mL against F. equiseti and >500 µg/mL against F. oxysporum. Furthermore, the P. cubana hexane fraction and P. neesianum acetonitrile fraction had antifungal activity against both Fusarium pathogens. These compounds provide new options for biorational products to control phytopathogenic fungi.

A protocol for the induction of hairy roots on somatic embryos of rhizoclones from Typha domingensis seedlings grown in hydroponic rhizotron systems was established for the first time. Rhizogenesis was induced through the agrotransformation of somatic embryos in oblong and scutellar states of development using the K599, LBA9402, and A4 strains of Agrobacterium rhizogenes. The transfection to the embryos was performed by cocultivation of rhizoclones on a Murashige and Skoog mineral medium at 50% strength (MS0.5), in the dark, at 28 ± 2 °C for 72 h. In contrast to nontransformed embryos that did not exhibit any root tissue, transformed embryos presented hairy roots that varied in number, length, and density depending on the bacterial strain, and K599 was the most effective strain. After analysis via optical microscopy, the transformed embryos were collected and transferred to fresh culture media supplemented with 400 mg mL⁻¹ cefotaxime and 10 mg L⁻¹ ascorbic acid. The efficiency of transformation and survival of the oblong and scutellar embryos were similar among the three bacterial strains. The results show that agrotransformation of somatic embryos of rhizoclones from T. domingensis is a novel and viable strategy for the generation of genetic transformants of Typha that have potential applications in bioremediation technologies.

Background: Sustainable methods of propagation of Typha domingensis through somatic embryogenesis can help mitigate its current condition of ecological marginalization and overexploitation. This study examined whether differentiation up to coleoptilar embryos could be obtained in an embryogenic line proliferated with light and high auxin concentration. Methods: Murashige and Skoog medium at half ionic strength and containing 3% sucrose and 0.1% ascorbic acid was used for the three embryogenic phases. Induction started with aseptic 9-day-old germinated seeds cultured in 0.5 mg L⁻¹ 2,4-dichlorophenoxyacetic (2,4-D). Proliferation of the embryogenic callus was evaluated at 2,4-D concentrations ranging from 0 to 2 mg L⁻¹ in cultures maintained in the dark. The dominant embryogenic products obtained in each treatment were used as embryogenic lines in the third phase. Thus, maturation of the somatic embryos (SEs) was analyzed using four embryogenic lines and under light vs. dark conditions. Embryogenic differentiation was also monitored histologically. Results: Proliferation of the nine morphogenetic products was greater in the presence of 2,4-D, regardless of the concentration, than in the absence of auxin. Among the products, a yellow callus was invariably associated with the presence of an oblong SE and suspended cells in the 2,4-D treatments, and a brown callus with scutellar somatic embryos (scSEs) in the treatment without 2,4-D. During the maturation phase, especially the embryogenic line but also the light condition resulted in significant differences, with the highest averages of the nine morphogenetic products obtained under light conditions and the maximum concentration of auxin (YC3 embryogenic line). Only this line achieved scSE growth, under both light and dark conditions. Structurally complete coleoptilar somatic embryos (colSEs) could be anatomically confirmed only during the maturation phase. Discussion: In the embryogenic line cultured with the highest auxin concentration, light exposure favored the transdifferentiation from embryogenic callus to scSE or colSE, although growth was asynchronous with respect to the three embryogenic phases. The differentiation and cellular organization of the embryos were compatible with all stages of embryogenic development in other monocotyledons. The growth of colSEs under light conditions in the YC3 embryogenic line and the structurally complete anatomic description of colSEs demonstrated that differentiation up to coleoptilar embryos could be obtained. The diversity of embryogenic products obtained in the YC3 embryogenic line opens up the opportunity to synchronize histological descriptions with the molecules associated with the somatic embryogenesis of Typha spp.

Water quality indicators have been tied to natural or man-made surface hydraulic connection (SHC) conditions. Among these, temporally connected lakes (TCL) are hydraulic intermediates between isolated (IL) and permanently connected lakes (PCL). Therefore, the aim of this study is to answer if water quality indicators can estimate the possible overlap between the two opposed conditions of SHC (IL and PCL) with the intermediate one (TCL) in lakes with similar modifications in the water level regulation at the basin level. Among nine water variables sampled in six lakes with the three SHC conditions mentioned, chlorophyll a (Chl-a), Secchi disk (SD), and total phosphorus (TP) were identified as quality water indicators through principal component analysis. Furthermore, said indicators were used to measure their overlap and trophic state index deviations. The Chl-a, SD, and TP values in TCL showed a 0.72 overlap of PCL and IL. TP surplus measured in all the lakes was meaningful in urbanized ILs and lessened in a rural lake (PCL6) with submerged rooted macrophytes. The estimated overlap of trophic indicators between TCL, IL, and PCL in this study must be verified at a global representative scale for predictive and preventive use in the conservation of tropical coastal plain lakes.

Plant extracts are a valuable alternative for the control of phytopathogenic fungi in horticultural crops. In the present work, the in vitro antifungal effect of ethanol and aqueous extracts from different vegetative parts of 40 native plants of the Yucatan Peninsula on Curvularia lunata ITC26, a pathogen of habanero pepper (Capsicum chinense), and effects of the most active extracts on postharvest fruits were investigated. Among these, the ethanol extracts of Mosannona depressa (bark from stems and roots) and Piper neesianum (leaves) inhibited 100% of the mycelial growth of C. lunata. The three extracts were partitioned between acetonitrile and n-hexane. The acetonitrile fraction from M. depressa stem bark showed the lowest mean inhibitory concentration (IC₅₀) of 188 µg/mL against C. lunata. The application of this extract and its active principle α-asarone in the postharvest fruits of C. chinense (500 µg/mL) was shown to inhibit 100% of the severity of the infection caused by C. lunata after 11 days of contact. Both samples caused the distortion and collapse of the conidia of the phytopathogen when observed using electron microscopy at 96 h. The spectrum of M. depressa enriched antifungal action is a potential candidate to be a botanical fungicide in the control of C. lunata in cultivating habanero pepper.

Nutrient enrichment is an environmental stress factor involved in the decline of submerged vegetation. However, the physiological or toxicological sensitivity of the genotypes varies due to microbiotic interactions and physicochemical imbalance of water, which have been studied through a reductionist approach and controlled experiments. The objective of the study was to evaluate, in an in vitro culture model of Vallisneria americana, the increase of different sources and concentrations of N on the survival and growth of leaves and roots. Juvenile plants in vitro grew at concentrations of 500 to 2 000 mu g L-1 of total N with sources of NH4, NO3 and NH4:NO3 (1:1) in a factorial design 4 x 3, in short- and medium-term evaluations. Survival was inversely proportional to symptoms of chlorosis, necrosis, or tissue rupture. The first foliar elongation was measured with a non-destructive method. While at 25 days, the individual and average length of leaves and roots, number of regenerated leaves and number of total roots were quantified. The plants did not show symptoms of vulnerability. NH4 in all its concentrations inhibited the growth of the nine parameters analyzed. In contrast, NH4:NO3 caused two inhibitions at the leaf level and NO3 stimulated leaf and root growth. The growth prediction proved promising to discriminate stress factors on the submerged vegetation of the Pantanos de Centla.