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<jats:p>Sustainable agriculture practices involve the application of environment-friendly plant growth promoters and additives that do not negatively impact the health of the ecosystem. Stringent regulatory frameworks restricting the use of synthetic agrochemicals and the increase in demand for organically grown crops have paved the way for the development of novel bio-based plant growth promoters. In this context, microalgae biomass and derived agrochemicals offer novel sources of plant growth promotors that enhance crop productivity and impart disease resistance. These beneficial effects could be attributed to the presence of wide range of biomolecules such as soluble amino acid (AA), micronutrients, polysaccharides, phytohormones and other signaling molecules in microalgae biomass. In addition, their phototrophic nature, high photosynthetic efficiency, and wide environmental adaptability make them an attractive source of biostimulants, biofertilizers and biopesticides. The present review aims to describe the various plant growth promoting metabolites produced by microalgae and their effects on plant growth and productivity. Further, the effects elicited by microalgae biostimulants with respect to different modes of applications such as seed treatments, foliar spray and soil/root drenching is reviewed in detail. In addition, the ability of microalgae metabolites to impart tolerance against various abiotic and biotic stressors along with the mechanism of action is discussed in this paper. Although the use of microalgae based biofertilizers and biostimulants is gaining popularity, the high nutrient and water requirements and energy intensive downstream processes makes microalgae based technology commercially unsustainable. Addressing this challenge, we propose a circular economy model of microalgae mediated bioremediation coupled with biorefinery approaches of generating high value metabolites along with biofertilizer applications. We discuss and review new trends in enhancing the sustainability of microalgae biomass production by co-cultivation of algae with hydroponics and utilization of agriculture effluents.</jats:p>

<jats:p><jats:italic>Psathyrostachys huashanica</jats:italic>, which grows exclusively in Huashan, China, is an important wild relative of common wheat that has many desirable traits relevant for wheat breeding. However, the poorly characterized interspecific phylogeny and genomic variations and the relative lack of species-specific molecular markers have limited the utility of <jats:italic>P. huashanica</jats:italic> as a genetic resource for enhancing wheat germplasm. In this study, we sequenced the <jats:italic>P. huashanica</jats:italic> transcriptome, resulting in 50,337,570 clean reads that were assembled into 65,617 unigenes, of which 38,428 (58.56%) matched at least one sequence in public databases. The phylogenetic analysis of <jats:italic>P. huashanica</jats:italic>, Triticeae species, and Poaceae species was conducted using 68 putative orthologous gene clusters. The data revealed the distant evolutionary relationship between <jats:italic>P. huashanica</jats:italic> and common wheat as well as the substantial diversity between the <jats:italic>P. huashanica</jats:italic> genome and the wheat D genome. By comparing the transcriptomes of <jats:italic>P. huashanica</jats:italic> and Chinese Spring, 750,759 candidate SNPs between <jats:italic>P. huashanica</jats:italic> Ns genes and their common wheat orthologs were identified. Among the 90 SNPs in the exon regions with different functional annotations, 58 (64.4%) were validated as Ns genome-specific SNPs in the common wheat background by KASP genotyping assays. Marker validation analyses indicated that six specific markers can discriminate between <jats:italic>P. huashanica</jats:italic> and the other wheat-related species. In addition, five markers are unique to <jats:italic>P. huashanica</jats:italic>, <jats:italic>P. juncea</jats:italic>, and <jats:italic>Leymus</jats:italic> species, which carry the Ns genome. The Ns genome-specific markers in a wheat background were also validated regarding their specificity and stability for detecting <jats:italic>P. huashanica</jats:italic> chromosomes in four wheat–<jats:italic>P. huashanica</jats:italic> addition lines. Four and eight SNP markers were detected in wheat–<jats:italic>P. huashanica</jats:italic> 2Ns and 7Ns addition lines, respectively, and one marker was specific to both wheat–<jats:italic>P. huashanica</jats:italic> 3Ns, 4Ns, and 7Ns addition lines. These markers developed using transcriptome data may be used to elucidate the genetic relationships among <jats:italic>Psathyrostachys</jats:italic>, <jats:italic>Leymus</jats:italic>, and other closely-related species. They may also facilitate precise introgressions and the high-throughput monitoring of <jats:italic>P. huashanica</jats:italic> exogenous chromosomes or segments in future crop breeding programs.</jats:p>

<jats:p><jats:italic>Pleurospermum</jats:italic> is a taxonomically challenging taxon of Apiaceae, as its circumscription and composition remain controversial for morphological similarities with several related genera, leading to a dispute between <jats:italic>Pleurospermum</jats:italic> in the broad sense and strict sense. While evidence from previous molecular studies recognized plural branching lineages within the <jats:italic>Pleurospermum</jats:italic> s. l., it did not support the latest delimitation of <jats:italic>Pleurospermum</jats:italic> s. str. by only two closely related northern species. So far, no proper delimitation for <jats:italic>Pleurospermum</jats:italic> has come up, and many of the plural taxa in <jats:italic>Pleurospermum</jats:italic> s. l. remain unresolved, which may be due to poor phylogenetic resolution yielded barely from ITS sequences. Herein, we newly assembled 40 complete plastomes from 36 species of <jats:italic>Pleurospermum</jats:italic> s. l. and related genera, 34 of which were first reported and generated a well-resolved backbone phylogeny in a framework of the subfamily Apioideae. From the phylogeny with greatly improved resolution, a total of six well-supported monophyletic lineages within <jats:italic>Pleurospermum</jats:italic> s. l. were recognized falling in different major clades of Apioideae. Combining morphological characteristics with phylogenetic inference, we suggested to re-delimit the <jats:italic>Pleurospermum</jats:italic> s. str. by introducing nine species mainly from the Himalayan regions and proposed its boundary features; the remaining species were suggested to be excluded from <jats:italic>Pleurospermum</jats:italic> to incorporate into their more related taxa being revealed. On this basis, the plastome comparison revealed not only the high conservatism but also the mild differences among lineages in plastome structure and gene evolution. Overall, our study provided a backbone phylogeny essential for further studies of the taxonomically difficult taxa within <jats:italic>Pleurospermum</jats:italic> s. l.</jats:p>

<jats:p>Chloroplasts and mitochondria each contain their own genomes, which have historically been and continue to be important sources of information for inferring the phylogenetic relationships among land plants. The organelles are predominantly inherited from the same parent, and therefore should exhibit phylogenetic concordance. In this study, we examine the mitochondrion and chloroplast genomes of 226 land plants to infer the degree of similarity between the organelles’ evolutionary histories. Our results show largely concordant topologies are inferred between the organelles, aside from four well-supported conflicting relationships that warrant further investigation. Despite broad patterns of topological concordance, our findings suggest that the chloroplast and mitochondrial genomes evolved with significant differences in molecular evolution. The differences result in the genes from the chloroplast and the mitochondrion preferentially clustering with other genes from their respective organelles by a program that automates selection of evolutionary model partitions for sequence alignments. Further investigation showed that changes in compositional heterogeneity are not always uniform across divergences in the land plant tree of life. These results indicate that although the chloroplast and mitochondrial genomes have coexisted for over 1 billion years, phylogenetically, they are still evolving sufficiently independently to warrant separate models of evolution. As genome sequencing becomes more accessible, research into these organelles’ evolution will continue revealing insight into the ancient cellular events that shaped not only their history, but the history of plants as a whole.</jats:p>

<jats:p>Global climate warming and shifts in rainfall patterns are expected to trigger increases in the frequency and magnitude of drought and/or waterlogging stress in plants. To cope with water stress, plants develop diverse tactics. However, the adoption capability and mechanism vary depending upon the plant species identity as well as stress duration and intensity. The objectives of this study were to evaluate the species-dependent responses of alpine herbaceous species to water stress. Nine herbaceous species were subjected to different water stresses (including moderate drought and moderate waterlogging) in pot culture using a randomized complete block design with three replications for each treatment. We hypothesized that water stress would negatively impact plant growth and metabolism. We found considerable interspecies differences in morphological, physiological, and biochemical responses when plants were exposed to the same water regime. In addition, we observed pronounced interactive effects of water regime and plant species identity on plant height, root length, root/shoot ratio, biomass, and contents of chlorophyll a, chlorophyll b, chlorophyll (a+b), carotenoids, malondialdehyde, soluble sugar, betaine, soluble protein and proline, implying that plants respond to water regime differently. Our findings may cast new light on the ecological restoration of grasslands and wetlands in the Qinghai-Tibetan Plateau by helping to select stress-tolerant plant species.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>The above-ground parts of terrestrial plants are collectively known as the phyllosphere. The surface of the leaf blade is a unique and extensive habitat for microbial communities. Phyllosphere bacteria are the second most closely associated microbial group with plants after fungi and viruses, and are the most abundant, occupying a dominant position in the phyllosphere microbial community. Host species are a major factor influencing the community diversity and structure of phyllosphere microorganisms.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>In this study, six Populus spp. were selected for study under the same site conditions and their phyllosphere bacterial community DNA fragments were paired-end sequenced using 16S ribosomal RNA (rRNA) gene amplicon sequencing. Based on the distribution of the amplicon sequence variants (ASVs), we assessed the alpha-diversity level of each sample and further measured the differences in species abundance composition among the samples, and predicted the metabolic function of the community based on the gene sequencing results.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The results revealed that different Populus spp. under the same stand conditions resulted in different phyllosphere bacterial communities. The bacterial community structure was mainly affected by the carbon and soluble sugar content of the leaves, and the leaf nitrogen, phosphorus and carbon/nitrogen were the main factors affecting the relative abundance of phyllosphere bacteria.</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>Previous studies have shown that a large proportion of the variation in the composition of phyllosphere microbial communities was explained by the hosts themselves. In contrast, leaf-borne nutrients were an available resource for bacteria living on the leaf surface, thus influencing the community structure of phyllosphere bacteria. These were similar to the conclusions obtained in this study. This study provides theoretical support for the study of the composition and structure of phyllosphere bacterial communities in woody plants and the factors influencing them.</jats:p></jats:sec>

<jats:p>Height to crown base (HCB) is an important predictor variable for forest growth and yield models and is of great significance for bamboo stem utilization. However, existing HCB models built so far on the hierarchically structured data are for arbor forests, and not applied to bamboo forests. Based on the fitting of data acquired from 38 temporary sample plots of <jats:italic>Phyllostachys edulis</jats:italic> forests in Yixing, Jiangsu Province, we selected the best HCB model (logistic model) from among six basic models and extended it by integrating predictor variables, which involved evaluating the impact of 13 variables on HCB. Block- and sample plot-level random effects were introduced to the extended model to account for nested data structures through mixed-effects modeling. The results showed that bamboo height, diameter at breast height, total basal area of all bamboo individuals with a diameter larger than that of the subject bamboo, and canopy density contributed significantly more to variation in HCB than other variables did. Introducing two-level random effects resulted in a significant improvement in the accuracy of the model. Different sampling strategies were evaluated for response calibration (model localization), and the optimal strategy was identified. The prediction accuracy of the HCB model was substantially improved, with an increase in the number of bamboo samples in the calibration. Based on our findings, we recommend the use of four randomly selected bamboo individuals per sample to provide a compromise between measurement cost, model use efficiency, and prediction accuracy.</jats:p>