Synergy between an emerging monopartite begomovirus and a DNA-B component

In recent decades, a legion of monopartite begomoviruses transmitted by the whitefly Bemisia tabaci has emerged as serious threats to vegetable crops in Africa. Recent studies in Burkina Faso (West Africa) reported the predominance of pepper yellow vein Mali virus (PepYVMLV) and its frequent association with a previously unknown DNA-B component. To understand the role of this DNA-B component in the emergence of PepYVMLV, we assessed biological traits related to virulence, virus accumulation, location in the tissue and transmission. We demonstrate that the DNA-B component is not required for systemic movement and symptom development of PepYVMLV (non-strict association), but that its association produces more severe symptoms including growth arrest and plant death. The increased virulence is associated with a higher viral DNA accumulation in plant tissues, an increase in the number of contaminated nuclei of the phloem parenchyma and in the transmission rate by B. tabaci. Our results suggest that the association of a DNA-B component with the otherwise monopartite PepYVMLV is a key factor of its emergence.

Review of Dactylosternum Wollaston, 1854 from China and Japan (Coleoptera, Hydrophilidae, Sphaeridiinae)

The species of the genus Dactylosternum Wollaston, 1854 occurring in China and Japan are reviewed. Ten species are recognized to occur in China, two of which were also recorded from Japan. Four new species are described from China: Dactylosternum nanlingensis Mai et Jia, sp. nov. (Guangdong, Jiangxi) from fungal hyphae on fallen wood, D. songxiaobini Mai et Jia, sp. nov. (Guangxi) from fallen wood with termites, D. pseudolatum Mai et Jia, sp. nov. (Guangdong, Hubei, Hunan, Jiangxi, Fujian, Hainan, Yunnan) and D. frater Mai et Jia, sp. nov. (Yunnan) from banana trees. Dactylosternum latum (Sharp, 1873) and D. salvazai Orchymont, 1925 are reported for the first time from China, and species recorded previously (D. abdominale (Fabricius, 1792), D. corbetti Balfour-Browne, 1942, D. hydrophiloides (MacLeay, 1825) and D. pui Jia, 2002) are redescribed or diagnosed. Dactylosternum abdominale (Fabricius, 1792) is confirmed to occur in Japan. Dactylosternum latum is only known from Japan based on type specimens believed to be collected in Nagasaki by G. Lewis in late 19th century; since the species was never re-collected in Japan later, its distribution in Japan seems doubtful. Dactylosternum vitalisi Orchymont, 1925 is synonymized with D. latum (Sharp, 1873), the variability of the latter species is discussed. We moreover found that the type series of D. vitalisi contains two species, with some paratypes actually belonging to D. pseudolatum Mai et Jia, sp. nov. All species of Dactylosternum living in China and Japan are diagnosed and illustrated and a key allowing their identification is provided. We infer that the compact antennal club and paralleled body form are characters related to the life inside of plant tissues, while loose antennal club and rounded body form is present in free living Dactylosternum species. The combination of characters for distinguishing Dactylosternum from other genera of Coelostomatini is also provided.

Improved clearing method contributes to deep imaging of plant organs

Tissue clearing methods are increasingly essential for the microscopic observation of internal tissues of thick biological organs. We previously developed TOMEI, a clearing method for plant tissues; however, it could not entirely remove chlorophylls nor reduce the fluorescent signal of fluorescent proteins. Here, we developed an improved TOMEI method (iTOMEI) to overcome these limitations. First, a caprylyl sulfobetaine was determined to efficiently remove chlorophylls from Arabidopsis thaliana seedlings without GFP quenching. Next, a weak alkaline solution restored GFP fluorescence, which was mainly lost during fixation, and an iohexol solution with a high refractive index increased sample transparency. These procedures were integrated to form iTOMEI. iTOMEI enables the detection of much brighter fluorescence than previous methods in tissues of A. thaliana, Oryza sativa, and Marchantia polymorpha. Moreover, a mouse brain was also efficiently cleared by the iTOMEI-Brain method within 48 h, and strong fluorescent signals were detected in the cleared brain.

Cross Talk Between Zinc-Solubilizing Bacteria and Plants: A Short Tale of Bacterial-Assisted Zinc Biofortification

A contemporary approach to bacterially mediated zinc (Zn) biofortification offers a new dimension in the crop improvement program with better Zn uptake in plants to curb Zn malnutrition. The implication of Zn solubilizing bacteria (ZSB) represents an inexpensive and optional strategy for Zn biofortification, with an ultimate green solution to enlivening sustainable agriculture. ZSB dwelling in the rhizospheric hub or internal plant tissues shows their competence to solubilize Zn via a variety of strategies. The admirable method is the deposition of organic acids (OAs), which acidify the surrounding soil environment. The secretion of siderophores as a metal chelating molecule, chelating ligands, and the manifestation of an oxidative–reductive system on the bacterial cell membrane are further tactics of bacterially mediated Zn solubilization. The inoculation of plants with ZSB is probably a more effective tactic for enhanced Zn translocation in various comestible plant parts. ZSB with plant growth-enhancing properties can be used as bioelicitors for sustainable plant growth via the different approaches that are crucial for plant health and its productivity. This article provides an overview of the functional properties of ZSB-mediated Zn localization in the edible portions of food crops and provides an impetus to explore such plant probiotics as natural biofortification agents.

Chitosan nanoparticles as a new technique in gene transformation into different plants tissues

The utilization of chitosan nanoparticles is a novel technique for gene transformation into plant tissues. It takes a few minutes to transform gene to plant. UidA gene was detected in <i>Escherichia coli</i> (K12 strain) using polymerase chain reaction analysis by UidA-specific primers. The gene was transformed into the explants of two different plant species (<i>Solanum tuberosum</i> and <i>Paulownia tomentosa</i>). These plants have different natures as crop and woody plants respectively. Therefore, they have different abilities to express the UidA gene. The gene is expressed into blue color in plant tissues due to the formation and expression of the GUS enzyme. The transformation of the UidA gene was detected morphologically by the formation of blue color; and molecular using PCR. Chitosan nanoparticles were characterized by UV/Visible spectroscope and photographing with a transmission electron microscope (TEM). As a result of this research, it is suggested that chitosan nanoparticles be used in gene transformation into plant tissues. Because it is safe, quick, and inexpensive, as well as biocompatible and biodegradable.

Identification in silico and expression analysis of a β-1-4-endoglucanase and β-galactosidase genes related to ripening in guava fruit

Background Guava fruit softening is a crucial process during ripening and this process involves a number of enzymes that modifies the cell wall. Two of the enzymes that regulate this process are (a) the β-1, 4-endoglucanase 17 (BEG) which hydrolyze β-1, 4 bonds from cellulose and hemicellulose, and (b) β-galactosidase (BGA) that hydrolyzes pectin chains. Bioinformatics and expression analysis information on these genes is limited in guava fruit. Results A fragment of a β-1, 4-endoglucanase 17 (PgE17), and another of a β-galactosidase (PgGa1) were identified. These sequences have a similarity of more than 85% with those reported in the NCBI database. In the guava genome, one homologous sequence was found for PgE17 in Chr 4 and two homologous to PgGa1: one in Chr 3 and the other one in Chr 6. Putative protein PgE17 contains part of the glyco_hydro_9 domain. Putative protein PgGa1 has a part of the glyco_hydro_35 domain. Phylogenetic analysis of PgE17 and PgGa1 revealed that both are highly conserved inside the Myrtaceae family. In silico expression analysis showed that both PgE17 and PgGa1 work in a coordinated way with other cell wall modifier enzymes. Expression of these genes was found in all the guava samples analyzed. However, the highest expression was found in the fruit in the breaking and ripe states. Conclusions A β-1, 4-endoglucanase 17, and β-galactosidase 1 sequences were identified. PgE17 and PgGa1 are expressed in all the plant tissues, and fruit ripening states. Although, the highest expression was on breaker and ripe states.

Large-scale comparative transcriptomic analysis of temperature-responsive genes in Arabidopsis thaliana

Key message Comparative transcriptomic analysis provides broad and detailed understandings of transcriptional responses to a wide range of temperatures in different plant tissues, and unique regulatory functions of temperature-mediating transcription factors. Abstract Climate change poses a great threat to plant diversity and food security. It is thus of necessity to understand the molecular mechanisms for perceiving and responding to adverse temperature changes, to develop the cultivars that are resilient to these environmental stresses. Making use of publicly available datasets, we gathered and re-analyzed 259 individual transcriptomic profiles from 139 unique experiments of Arabidopsis thaliana’s shoot, root, and seedling tissues, subjected to a wide variety of temperature conditions, ranging from freezing, cold, low and high ambient temperatures, to heat shock. Despite the underlying differences in the overall transcriptomic profiles between the plant tissues, we were able to identify distinct sets of genes whose transcription patterns were highly responsive to different types of temperature conditions, some were common among the tissues and some were tissue-specific. Interestingly, we observed that the known temperature-responsive genes such as the heat-shock factor (HSF) family, were up-regulated not only in response to high temperatures, but some of its members were also likely involved in the cold response. By integrating the DNA-binding specificity information of the key temperature transcription factor (TF) HSFA1a, PIF4, and CBFs, we elucidated their distinct DNA-binding patterns to the target genes that showed different transcriptional responses. Taken together, we have comprehensively characterized the transcription patterns of temperature-responsive genes and provided directly testable hypotheses on the regulatory roles of key temperature TFs on the expression dynamics of their target genes.

A Historic Perspective of Endophytes in Vascular Plants and Their Role in Environmental Sustainability

The term “endophyte” comes from words “endo” meaning within and “phyton” meaning plant. In 1866, De Bary first defined an endophyte as any organism that resides in the tissues of plants but not causing any harm. Thus, endophytes can be a microorganism, usually fungi or bacteria, that colonizes plants parts. The plant tissues/parts where endophytes grow include healthy leaves, petioles, stems, twigs, bark, roots, fruits, flowers, and seeds. They are found virtually in every one of the 300,000 species of vascular plants. Many endophytes co-exist in a single plant host with their populations ranging from one to hundreds of bacterial/fungal species. This chapter outlines a historical perspective of endophytes including ethnobotanical approach to drug discovery. Also, this chapter provides upto date information on the emerging role of endophytes in the sustainability of pasture and economy of agriculture, thereby contributing to the environmental sustainability.

Clohesyomyces symbioticus sp. nov., a fungal endophyte associated with roots of water smartweed (Persicaria amphibia)

The widespread aquatic plant Persicaria amphibia (water smartweed, Polygonaceae) occurs in both flooded aquatic habitats and moist terrestrial environments. Its physiological versatility and wide geographic range highlight its resilience to stress and make the species intriguing for the study of fungal endophytes. Endophytes occur within living plant tissues and are known from diverse aquatic, marine, and terrestrial plants, where they often mitigate plant responses to stress. As part of a study evaluating endophyte communities associated with aquatic plants in lentic waters of Arizona, USA, we isolated a distinctive clade of endophytes from healthy, living roots of seasonally inundated P. amphibia, which we describe here on the basis of morphology and evidence from four loci as new species Clohesyomyces symbioticus (Lindgomycetaceae, Pleosporales, Dothideomycetes, Ascomycota). Clohesyomyces has long been considered a monotypic genus comprising the saprobic species C. aquaticus, presently known from submerged wood in freshwater systems in Asia and Australia. Description of Clohesyomyces symbioticus highlights the occurrence of endophytism in this genus and expands its geographic scope to the western hemisphere.