16 17 As the world's population increases, demands on staple crops like rice (Oryza sativa L.) will also 18 increase, requiring additional fresh water supplies for irrigation of rice fields. Safe alternate wetting 19 and drying (AWD) is a water management technique that is being adopted across a number of 20 countries to reduce the water input for rice cultivation. The impact of AWD on plant growth, yield 21 and grain quality is not well understood. A field trial of AWD was conducted at Mymensingh, 22 Bangladesh over two boro (dry) seasons using eight field plots, four under AWD and four 23 continuously flooded (CF). This manuscript describes the results of check cultivar BRRI dhan28 which 24 was replicated in 35-40 rows per plot giving a total of 140-160 replicates per treatment. A study on 25 the soil solution concentration of many elements indicated that manganese, iron, zinc, and arsenic 26 were different under AWD conditions compared to CF on a number of sampling time points, but did 27 not show a pattern related to the AWD treatment. A survey of soil strength using a penetrometer 28 detected a small, but significant, hardening of the surface soil of the AWD plots. At harvest the shoot 29 and grain mass was significantly greater for the plants grown under AWD (9.0-9.4% and 12.0-15.4%, 30 respectively) with the plants grown under AWD having a greater number of productive tillers. 31Physiological examination in the first year showed that although AWD decreased (~21%) leaf 32 elongation rate (LER) of recently transplanted seedlings during the first drying cycle, subsequent 33 drying cycles did not affect LER, while tillering was slightly increased by AWD and there was evidence 34 of higher leaf abscisic acid (ABA) in AWD plants. In the second year analysis of six phytohormones 35 revealed that AWD increased plant foliar iso-pentenyladenine (iP) concentrations by 37% while leaf 36 trans-zeatin concentrations decreased (36%) compared to CF plants. The elemental composition of 37 the shoots and grains was also examined. In both years AWD decreased grain concentration of 38 sulphur (by 4% and 15%), calcium (by 6% and 9%), iron (by 11% and 16%), and arsenic (by 14% and 39 26%), while it increased the grain concentration of manganese (by 19% and 28%), copper (by 81% 40 and 37%), and cadmium (by 28% and 67%). These results indicate that plants grown under safe AWD 41 conditions at this site have an increased grain mass compared to plants grown under CF, and this 42 may be partly due to a high number of productive tillers. AWD decreases the concentration of 43 arsenic in the grains in this site, but it elevates the concentration of cadmium. 44 45 Key words: Rice, alternate wetting and drying, arsenic, cadmium, pore water 46 48 between 35-60% of their dietary calorie intake (Fageria, 2007). Irrigated lowland rice systems 49 produce ~75% of global rice (Fageria, 2007). Producing high yield under irrigated systems requires 50 large quantities of water (Bouman, 2009). It is estimated that to produce 1 kg of rice gra...

BackgroundCarotenoids are natural pigments with antioxidant properties that have important functions in human physiology and must be supplied through the diet. They also have important industrial applications as food colourants, animal feed additives and nutraceuticals. Some of them, such as β-carotene, are produced on an industrial scale with the use of microorganisms, including fungi. The mucoral Blakeslea trispora is used by the industry to produce β-carotene, although optimisation of production by molecular genetic engineering is unfeasible. However, the phylogenetically closely related Mucor circinelloides, which is also able to accumulate β-carotene, possesses a vast collection of genetic tools with which to manipulate its genome.ResultsThis work combines classical forward and modern reverse genetic techniques to deepen the regulation of carotenoid synthesis and generate candidate strains for biotechnological production of β-carotene. Mutagenesis followed by screening for mutants with altered colour in the dark and/or in light led to the isolation of 26 mutants that, together with eight previously isolated mutants, have been analysed in this work. Although most of the mutants harboured mutations in known structural and regulatory carotenogenic genes, eight of them lacked mutations in those genes. Whole-genome sequencing of six of these strains revealed the presence of many mutations throughout their genomes, which makes identification of the mutation that produced the phenotype difficult. However, deletion of the crgA gene, a well-known repressor of carotenoid biosynthesis in M. circinelloides, in two mutants (MU206 and MU218) with high levels of β-carotene resulted in a further increase in β-carotene content to differing extents with respect to the crgA single-null strain; in particular, one strain derived from MU218 was able to accumulate up to 4 mg/g of β-carotene. The additive effect of crgA deletion and the mutations present in MU218 suggests the existence of a previously unknown regulatory mechanism that represses carotenoid biosynthesis independently and in parallel to crgA.ConclusionsThe use of a mucoral model such as M. circinelloides can allow the identification of the regulatory mechanisms that control carotenoid biosynthesis, which can then be manipulated to generate tailored strains of biotechnological interest. Mutants in the repressor crgA and in the newly identified regulatory mechanism generated in this work accumulate high levels of β-carotene and are candidates for further improvements in biotechnological β-carotene production.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-016-0493-8) contains supplementary material, which is available to authorized users.

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Additional sex combs-like 1 (ASXL1) interacts with BRCA1-associated protein 1 (BAP1) deubiquitinase to oppose the polycomb repressive complex 1 (PRC1)mediated histone H2A ubiquitylation. Germline BAP1 mutations are found in a spectrum of human malignancies, while ASXL1 mutations recurrently occur in myeloid neoplasm and are associated with poor prognosis. Nearly all ASXL1 mutations are heterozygous frameshift or nonsense mutations in the middle or to a less extent the C-terminal region, resulting in the production of C-terminally truncated mutant ASXL1 proteins. How ASXL1 regulates specific target genes and how the C-terminal truncation of ASXL1 promotes leukemogenesis are unclear. Here, we report that ASXL1 interacts with forkhead transcription factors FOXK1 and FOXK2 to regulate a subset of FOXK1/K2 target genes. We show that the C-terminally truncated mutant ASXL1 proteins are expressed at much higher levels than the wild-type protein in ASXL1 heterozygous leukemia cells, and lose the ability to interact with FOXK1/K2. Specific deletion of the mutant allele eliminates the expression of C-terminally truncated ASXL1 and increases the association of wild-type ASXL1 with BAP1, thereby restoring the expression of BAP1-ASXL1-FOXK1/K2 target genes,