Tracing the evolution of the arbuscular mycorrhizal symbiosis in the plant lineage

The Arbuscular Mycorrhizal (AM) symbiosis is formed by ~80% of land plants with a specific group of soil fungi, the AM fungi. Through this symbiosis, plants obtain nutrients that they otherwise would not be able to access. Based on data from fossils and extant plants, it has been predicted that the AM symbiosis evolved in early land plants. Research in the past two decades utilising angiosperm model plant species has identified several plant genes that regulate the AM symbiosis. These studies have also revealed that these symbiosis genes are highly conserved in the angiosperms but whether this conservation extends to the non-flowering plants has not been explored. In the present study, a comprehensive phylogenetic analysis of the symbiosis genes was conducted, using genomic and transcriptomic data from the non-flowering plant lineages, to gain insights into the evolution of these genes in plants. The results of this analysis indicate that these genes evolved in a stepwise fashion. While some genes appeared in the algal ancestors of the charophytes, others appeared in the early land plant ancestors of liverworts. To further study the AM symbiosis in the non-flowering plants, key methods and genomic resources were established for the liverwort Marchantia paleacea to enable its use as a model plant for the study of the evolution of the AM symbiosis. Using the resources established, phylogenomic comparisons were conducted between M. paleacea and a related liverwort species, M. polymorpha, that is predicted to have lost the ability to engage in the AM symbiosis. These analyses revealed that the homologs of angiosperm symbiosis genes are required for functional symbioses in the liverworts. The findings presented here provide insights into the processes that contributed to the evolution and maintenance of this ancestral symbiosis in the plant lineage

A combination of chitooligosaccharide and lipochitooligosaccharide recognition promotes arbuscular mycorrhizal associations in Medicago truncatula.

Plants associate with beneficial arbuscular mycorrhizal fungi facilitating nutrient acquisition. Arbuscular mycorrhizal fungi produce chitooligosaccharides (COs) and lipo-chitooligosaccharides (LCOs), that promote symbiosis signalling with resultant oscillations in nuclear-associated calcium. The activation of symbiosis signalling must be balanced with activation of immunity signalling, which in fungal interactions is promoted by COs resulting from the chitinaceous fungal cell wall. Here we demonstrate that COs ranging from CO4-CO8 can induce symbiosis signalling in Medicago truncatula. CO perception is a function of the receptor-like kinases MtCERK1 and LYR4, that activate both immunity and symbiosis signalling. A combination of LCOs and COs act synergistically to enhance symbiosis signalling and suppress immunity signalling and receptors involved in both CO and LCO perception are necessary for mycorrhizal establishment. We conclude that LCOs, when present in a mix with COs, drive a symbiotic outcome and this mix of signals is essential for arbuscular mycorrhizal establishment

Mutagenesis of Puccinia graminis f. sp. tritici and selection of gain-of-virulence mutants

Wheat stem rust caused by the fungus Puccinia graminis f. sp. tritici (Pgt), is regaining prominence due to the recent emergence of virulent isolates and epidemics in Africa, Europe and Central Asia. The development and deployment of wheat cultivars with multiple stem rust resistance (Sr) genes stacked together will provide durable resistance. However, certain disease resistance genes can suppress each other or fail in particular genetic backgrounds. Therefore, the function of each Sr gene must be confirmed after incorporation into an Sr-gene stack. This is difficult when using pathogen disease assays due to epistasis from recognition of multiple avirulence (Avr) effectors. Heterologous delivery of single Avr effectors can circumvent this limitation, but this strategy is currently limited by the paucity of cloned Pgt Avrs. To accelerate Avr gene cloning, we outline a procedure to develop a mutant population of Pgt spores and select for gain-of-virulence mutants. We used ethyl methanesulphonate (EMS) to mutagenize urediniospores and create a library of > 10,000 independent mutant isolates that were combined into 16 bulks of ~658 pustules each. We sequenced random mutants and determined the average mutation density to be 1 single nucleotide variant (SNV) per 258 kb. From this, we calculated that a minimum of three independently derived gain-of-virulence mutants is required to identify a given Avr gene. We inoculated the mutant library onto plants containing Sr43, Sr44, or Sr45 and obtained 9, 4, and 14 mutants with virulence toward Sr43, Sr44, or Sr45, respectively. However, only mutants identified on Sr43 and Sr45 maintained their virulence when reinolculated onto the lines from which they were identified. We further characterized 8 mutants with virulence toward Sr43. These also maintained their virulence profile on the stem rust international differential set containing 20 Sr genes, indicating that they were most likely not accidental contaminants. In conclusion, our method allows selecting for virulent mutants toward targeted resistance (R) genes. The development of a mutant library from as little as 320 mg spores creates a resource that enables screening against several R genes without the need for multiple rounds of spore multiplication and mutagenesis

Crossing boundaries:bras, lingerie and rape myths in postcolonial urban middle-class India

With the processes of modernization, urbanization and the entry of women in the formal labour market in Indian metropolitan spaces, this paper examines how the modern middle-class woman’s sartorial choices become enmeshed in popular rape myths (false beliefs) that serve to blame her for the wearing of western clothing. The paper articulates the ways in which middle-class women’s social realities are shaped by historical, colonial and nationalist ideologies of modernization, constructed and mediated through moral codes of dressing. By drawing upon original and contemporary empirical narratives from the urban spaces of Delhi and Mumbai, we emphasise how everyday sartorial choices, in relation to particularly the bra and lingerie, can reveal the nuanced ways in which Urban Indian Professional Women (UIPW) seek to understand, negotiate, and resist patriarchal power. Our findings shed light on conflicting and contradictory spatial experiences, where some women internalize and negotiate moral codes of dressing, out of fear, and others who transgress are subject to sanctions. Given the paucity of scholarly literature in this area, the paper makes an important theoretical and empirical contribution with its focus on postcoloniality and everyday discursive material spaces of gendered and sexualized dress practices. It argues for the consciousness raising of everyday urban geographies of dress that reveal complicated structures of power that are often deemed hidden

Standards for plant synthetic biology: A common syntax for exchange of DNA parts

© 2015 New Phytologist Trust. Inventors in the field of mechanical and electronic engineering can access multitudes of components and, thanks to standardization, parts from different manufacturers can be used in combination with each other. The introduction of BioBrick standards for the assembly of characterized DNA sequences was a landmark in microbial engineering, shaping the field of synthetic biology. Here, we describe a standard for Type IIS restriction endonuclease-mediated assembly, defining a common syntax of 12 fusion sites to enable the facile assembly of eukaryotic transcriptional units. This standard has been developed and agreed by representatives and leaders of the international plant science and synthetic biology communities, including inventors, developers and adopters of Type IIS cloning methods. Our vision is of an extensive catalogue of standardized, characterized DNA parts that will accelerate plant bioengineering

The Chara Genome: secondary complexity and implications for plant terrestrialization

Land plants evolved from charophytic algae, among which Charophyceae possess the most complex body plans. We present the genome of Chara braunii; comparison of the genome to those of land plants identified evolutionary novelties for plant terrestrialization and land plant heritage genes. C. braunii employs unique xylan synthases for cell wall biosynthesis, a phragmoplast (cell separation) mechanism similar to that of land plants, and many phytohormones. C. braunii plastids are controlled via land-plant-like retrograde signaling, and transcriptional regulation is more elaborate than in other algae. The morphological complexity of this organism may result from expanded gene families, with three cases of particular note: genes effecting tolerance to reactive oxygen species (ROS), LysM receptor-like kinases, and transcription factors (TFs). Transcriptomic analysis of sexual reproductive structures reveals intricate control by TFs, activity of the ROS gene network, and the ancestral use of plant-like storage and stress protection proteins in the zygote

Standards for plant synthetic biology: a common syntax for exchange of DNA parts.

Inventors in the field of mechanical and electronic engineering can access multitudes of components and, thanks to standardization, parts from different manufacturers can be used in combination with each other. The introduction of BioBrick standards for the assembly of characterized DNA sequences was a landmark in microbial engineering, shaping the field of synthetic biology. Here, we describe a standard for Type IIS restriction endonuclease-mediated assembly, defining a common syntax of 12 fusion sites to enable the facile assembly of eukaryotic transcriptional units. This standard has been developed and agreed by representatives and leaders of the international plant science and synthetic biology communities, including inventors, developers and adopters of Type IIS cloning methods. Our vision is of an extensive catalogue of standardized, characterized DNA parts that will accelerate plant bioengineering.Biotechnological and Biological Sciences Research Council (BBSRC). Grant Numbers: BB/K005952/1, BB/L02182X/1 Synthetic Biology Research Centre ‘OpenPlant’ award. Grant Number: BB/L014130/1 Spanish MINECO. Grant Number: BIO2013‐42193‐R Engineering Nitrogen Symbiosis for Africa (ENSA) The Bill & Melinda Gates Foundation US Department of Energy, Office of Biological and Environmental. Grant Number: DE‐AC02‐05CH1123 COST Action. Grant Number: FA100

Varicella vaccination in children with acute lymphoblastic leukemia: Experience from a pediatric cancer centre in India

Background: Varicella infection in children with Acute Lymphoblastic Leukemia (ALL) is associated with significant morbidity and mortality. Immunisation against varicella infection is not mandatory as per the national immunisation program in India and therefore the majority of children with ALL are unimmunised and are at an increased risk of infection. Methods: The present study retrospectively analysed the case records of patients with ALL diagnosed between January 2013 and May 2017 and received the varicella vaccine. Patients with ALL who had no previous history of varicella infection or immunisation and were in remission were given a single dose of live attenuated varicella vaccine prior to the start of the maintenance phase of treatment. Results: The study included 125 patients with a median age of 6 years and 57% patients were males. Fifty-two patients (41%) developed vaccine-induced varicella. The median time to develop vaccine-induced varicella was 21 days (range: 10–35 days). The median duration of fever was 2 days (range; 1–8) and 5 patients developed febrile neutropenia. Maintenance chemotherapy was withheld in symptomatic patients for a median duration of 7 days (range: 3–15 days). Breakthrough varicella infection after vaccination was seen in 2 patients. There was no mortality due to vaccine-induced varicella. Conclusion: Varicella immunisation is safe and efficacious in children with ALL and should be considered in countries where varicella immunisation is not routinely practiced. Vaccine-induced varicella is commonly seen; however, it is self-limiting. Keywords: Varicella, ALL, Immunisatio