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L-Ascorbic acid (AsA, vitamin C) is a key antioxidant and enzyme cofactor in plants. Ascorbate controls cell division, affects cell expansion, and plays an important role in modulating plant senescence. It protects plants against reactive oxygen species that are produced in response to abiotic and biotic stresses. Manual phenotyping indicated that Arabidopsis lines over-expressing enzymes in the myo-inositol pathway have elevated AsA, accumulate more biomass of both aerial and root tissues and are tolerant to abiotic stresses including salt, cold, heat, and environmental pollutants. However, manual phenotyping is time consuming, low throughput, subjective, and limited to the resolution of the human eye. In contrast, high throughput phenotyping technologies are accurate, non-destructive, and more sensitive, allowing the detection of subtle phenotypes. Therefore, we used a phenomics platform to phenotype our high AsA Arabidopsis lines with visible, fluorescence, and near infrared cameras. Based on this approach, high AsA lines grew faster, accumulated more biomass, and displayed healthier chlorophyll fluorescence and water content profiles than controls. By studying abiotic stress in a high throughout fashion using optimized protocols, we have also shown that these high AsA lines are tolerant to salt and water limitation stresses. In addition, we developed open source algorithms to analyze images and by comparing results obtained with a widely used commercial software against our algorithms, here we show that our method achieved good accuracy for all phenotypic parameters of interest including projected leaf area, rosette diameter (caliper length), compactness, and color classification.

Biosynthesis ofl-ascorbate (AsA) in plants is carried out by a complex metabolic network, which involvesd-mannose/l-galactose,d-galacturonate,l-gulose, andmyo-inositol as main precursors. Arabidopsis lines over-expressing enzymes in themyo-inositol pathway have elevated AsA, accumulate more biomass of both aerial and root tissues, and are tolerant to abiotic stresses as shown by manual and digital phenotyping. We crossedmyo-inositol oxygenase (MIOX4) over-expressers with two low-vitamin C mutants (vtc1-1 andvtc2-1) encoding enzymes involved ind-mannose/l-galactose route. The purpose of developing these crosses was to test MIOX4’s ability to restore the low AsA phenotype in mutants, and to assess the contribution of individual biosynthetic pathways to abiotic stress tolerance. We used a powerful high-throughput phenotyping platform for detailed phenotypic characterization of the Arabidopsis crosses with visible, fluorescence, near-infrared and infrared sensors. We combined digital phenotyping with photosynthetic parameters and soil water potential measurements. Our results show thatMIOX4is able to restore the AsA content of the mutants and the restored lines (vtc+MIOX4) show high AsA, enhanced growth rate, accumulate more biomass, and display healthier chlorophyll fluorescence and water content profiles compared to controls.HighlightsConstitutive expression of amyo-inositol oxygenase restored vitamin C deficient (vtcmutants). The restored lines have elevated ascorbate content and are tolerant to abiotic stresses. Under normal and abiotic stress conditions, the restored lines have enhanced biomass and increased water retention.

A higher minimum (night-time) temperature is considered a greater limiting factor for reduced rice yield than a similar increase in maximum (daytime) temperature. While the physiological impact of high night temperature (HNT) has been studied, the genetic and molecular basis of HNT stress response remains unexplored. We examined the phenotypic variation for mature grain size (length and width) in a diverse set of rice accessions under HNT stress. Genome-wide association analysis identified several HNT-specific loci regulating grain size as well as loci that are common for optimal and HNT stress conditions. A novel locus contributing to grain width under HNT conditions colocalized withFie1, a component of the FIS-PRC2 complex. Our results suggest that the allelic difference controlling grain width under HNT is a result of differential transcript-level response ofFie1in grains developing under HNT stress. We present evidence to support the role ofFie1in grain size regulation by testing overexpression (OE) and knockout mutants under heat stress. The OE mutants were either unaltered or had a positive impact on mature grain size under HNT, while the knockouts exhibited significant grain size reduction under these conditions. U.S. National Science FoundationNational Science Foundation (NSF) [1736192] Funding Source: Medline

Systems for collecting image data in conjunction with computer vision techniques are a powerful tool for increasing the temporal resolution at which plant phenotypes can be measured non-destructively. Computational tools that are flexible and extendable are needed to address the diversity of plant phenotyping problems. We previously described the Plant Computer Vision (PlantCV) software package, which is an image processing toolkit for plant phenotyping analysis. The goal of the PlantCV project is to develop a set of modular, reusable, and repurposable tools for plant image analysis that are open-source and community-developed. Here we present the details and rationale for major developments in the second major release of PlantCV. In addition to overall improvements in the organization of the PlantCV project, new functionality includes a set of new image processing and normalization tools, support for analyzing images that include multiple plants, leaf segmentation, landmark identification tools for morphometrics, and modules for machine learning.