Aquatic ecosystems are contaminated with heavy metals by natural and anthropogenic sources. Whilst some heavy metals are necessary for plants as micronutrients, others can be toxic to plants and humans even in trace concentrations. Among heavy metals, cadmium (Cd), arsenic (As), chromium (Cr), lead (Pb), and mercury (Hg) cause significant damage to aquatic ecosystems and can invariably affect human health. Rice, a staple diet of many nations, and other aquatic plants used as vegetables in many countries, can bioaccumulate heavy metals when they grow in contaminated aquatic environments. These metals can enter the human body through food chains, and the presence of heavy metals in food can lead to numerous human health consequences. Heavy metals in aquatic plants can affect plant physicochemical functions, growth, and crop yield. Various mitigation strategies are being continuously explored to avoid heavy metals entering aquatic ecosystems. Understanding the levels of heavy metals in rice and aquatic plants grown for food in contaminated aquatic environments is important. Further, it is imperative to adopt sustainable management approaches and mitigation mechanisms. Although narrowly focused reviews exist, this article provides novel information for improving our understanding about heavy metal accumulation in rice and aquatic plants, addressing the gaps in literature.

Streptomyces species can form beneficial relationships with hosts as endophytes, including the phytopathogen-inhibiting strain, Streptomyces griseoaurantiacusMH191, isolated from wheat plants. Using genomic characterization and untargeted metabolomics, we explored the capacity of strain MH191 to inhibit a range of fungal phytopathogens through the production of secondary metabolites. Complete genome assembly of strain MH191 predicted 24 biosynthetic gene clusters. Secondary metabolite production was assessed following culture on six different media, with the detection of 205 putative compounds. Members of the manumycin family, undecylprodigiosin, and desferrioxamine were identified as the predominant metabolites. Antifungal activity was validated for undecylprodigiosin and manumycin. These compounds were produced from different BGCs, which showed similarity to asukamycin, undecylprodigiosin, and FW0622 gene clusters, respectively. The growth of strain MH191 on different media illustrated the metabolic regulation of these gene clusters and the strain's extended chemical potential, with the asukamycin gene cluster alone, producing a variety of antifungal metabolites. The study highlights the extended chemical capability of strain MH191, which could be exploited as a biological control agent for designing future crop protection solutions.

Australian macadamia production is threatened by a disorder known as abnormal vertical growth (AVG), for which the etiology is unknown. AVG is characterized by vigorous upright growth and reduced lateral branching, flowering, and nut set that results in over 70% yield loss annually. Six commercial macadamia orchards were surveyed in 2012 and again in 2018 to examine spatiotemporal dynamics of the epidemic. Data were subjected to point-pattern and geostatistical analyses. AVG incidence in all orchards showed a better fit to the beta-binomial distribution than the binomial distribution. AVG incidence in the different orchards varied between 5 and 47% in 2012, and 13 and 55% in 2018 and the rate of spread was slow, averaging at about 2% increase in disease incidence per annum. Spatial patterns of AVG were highly aggregated on both survey years and spread was mainly between neighboring trees in a row or trees that were opposite to each other in different rows. Semivariograms showed large range values (approximately 15 to 120), indicating aggregation of AVG-affected trees beyond quadrat levels. Furthermore, clusters of disease were mainly at the edge of the orchard on the first survey date and the disease progressed toward the center of the orchard over time. It is concluded that AVG is caused by an infectious agent, and based on patterns of spread, we hypothesize that spread is facilitated by root grafting or root-to-root contact. Furthermore, a vascular-limited pathogen could be involved that modulates plant hormone production.

Date palm (Phoenix dactylifera L; Arecaceae) is one of a few fruit trees that can remarkably grow in dessert agroecosystems that are characterized by extreme temperature fluctuations. Due to increasing demands for dates in the global market and commercial cultivation in many countries, the tree is currently under extensive research in many countries, particularly to improve the germplasm using different molecular tools. Most molecular techniques largely depend on good quality DNA in significant quantities, which are highly compromised by the presence of various contaminants in DNA. The traditional cetyltrimethylammoniumbromide (CTAB) based method has failed to produce good quality DNA from date palm due to hard fibrous nature of tissue. On the basis of previous studies, commercial DNA extraction kits are not economical although they are very effective. Therefore, we have developed an improved DNA extraction protocol by modifying the original CTAB method to produce extra pure DNA in large quantities. The novel method has been validated using different quality testing approaches. This cost-effective method can be used successfully for DNA extraction from date palm. Moreover, this improved method may have potential for DNA extraction from other palms that have similar leaf texture to date palm leaves, but this method needs to be tested for other palms before being used. The improved method has following key modifications: • Grinding of plant tissue in liquid nitrogen and subsequent lysis of cells in CTAB buffer that has increased concentration of ß-mercaptoethanol • Repeated steps of chloroform: IAA extraction and ethanol washing • Addition of RNase A before the DNA precipitation step

Abnormal vertical growth (AVG) in macadamia is a syndrome that reduces flowering and alters tree architecture, resulting in significant yield losses. The epidemiological parameters suggest the cause is probably a biotic agent with the ability to modulate plant hormone production or signalling. To determine if a fungal pathogen is the cause of AVG, we compared the fungal profile of macadamia trees with or without AVG symptoms using conventional culturing and DNA metabarcoding techniques. A diverse range of fungi was isolated from leaf, root and stem samples of macadamia cultivars HAES 344 and A16. The abundance of the isolated fungi was at least three‐fold higher in trees with AVG symptoms than in trees at the non‐AVG site. Similar results were obtained using DNA metabarcoding. Although the fungal genus Sebacina was the most dominant in the DNA metabarcoding, whereas Diaporthe (>40%) was dominant using the culturing techniques, no unique fungal species was consistently associated with all AVG samples. Therefore, we conclude that it is unlikely that the cause of AVG in macadamia is a fungal pathogen.