Aboveground biomass density models for NASA's Global Ecosystem Dynamics Investigation (GEDI) lidar mission

NASA's Global Ecosystem Dynamics Investigation (GEDI) is collecting spaceborne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This paper presents the development of the models used to create GEDI's footprint-level (similar to 25 m) AGBD (GEDI04_A) product, including a description of the datasets used and the procedure for final model selection. The data used to fit our models are from a compilation of globally distributed spatially and temporally coincident field and airborne lidar datasets, whereby we simulated GEDI-like waveforms from airborne lidar to build a calibration database. We used this database to expand the geographic extent of past waveform lidar studies, and divided the globe into four broad strata by Plant Functional Type (PFT) and six geographic regions. GEDI's waveform-to-biomass models take the form of parametric Ordinary Least Squares (OLS) models with simulated Relative Height (RH) metrics as predictor variables. From an exhaustive set of candidate models, we selected the best input predictor variables, and data transformations for each geographic stratum in the GEDI domain to produce a set of comprehensive predictive footprint-level models. We found that model selection frequently favored combinations of RH metrics at the 98th, 90th, 50th, and 10th height above ground-level percentiles (RH98, RH90, RH50, and RH10, respectively), but that inclusion of lower RH metrics (e.g. RH10) did not markedly improve model performance. Second, forced inclusion of RH98 in all models was important and did not degrade model performance, and the best performing models were parsimonious, typically having only 1-3 predictors. Third, stratification by geographic domain (PFT, geographic region) improved model performance in comparison to global models without stratification. Fourth, for the vast majority of strata, the best performing models were fit using square root transformation of field AGBD and/or height metrics. There was considerable variability in model performance across geographic strata, and areas with sparse training data and/or high AGBD values had the poorest performance. These models are used to produce global predictions of AGBD, but will be improved in the future as more and better training data become available

PAMPS/MMT composite hydrogel electrolyte for solid-state supercapacitors

PAMPS/MMT composite electrolytes with high ionic conductivities were prepared by solution-casting method. The influences of Na-MMT contents on the ionic conductivities and mechanical properties of PAMPS hydrogel electrolyte were characterized and the electrochemical properties of supercapacitor with PAMPS/MMT composite electrolytes were investigated. The addition of Na-MMT can increase the ionic conductivities, tensile strength of PAMPS. PAMPS/MMT composite electrolyte has the superior integrated performance of ionic conductivities and tensile strength when the mass fraction of Na-MMT is about 5–7%, the ionic conductivity is 5.91 × 10−2 S cm−1 and the tensile strength is 8.9 MPa. The capacitor exhibits ideal behavior for the electronic double-layer capacitance. The specific capacitance and the cycling stability of PAMPS/MMT composite electrolytes are enhanced in comparison with that of PAMPS. Thus it provides a promising composite polyelectrolyte for supercapacitor

A high-throughput DNA extraction method from rice seeds

Rapid and inexpensive preparation of genomic DNA from rice seeds for marker-assisted selection and seed purity estimation is a major bottleneck for plant breeders. Here, we describe a high-throughput method that provides DNA at sufficient quantity and quality for these applications. Optimization of buffer composition and individual protocol stages allow processing of 384 samples within 2 h, yielding templates that reliably support downstream polymerase chain reaction of single copy amplicons up to 1.2 kb

Grain Shape Genes: Shaping the Future of Rice Breeding

The main goals of rice breeding nowadays include increasing yield, improving grain quality, and promoting complete mechanized production to save labor costs. Rice grain shape, specified by three dimensions, including grain length, width and thickness, has a more precise meaning than grain size, contributing to grain appearance quality as well as grain weight and thus yield. Furthermore, the divergence of grain shape characters could be utilized in mechanical seed sorting in hybrid rice breeding systems, which has been succeeded in utilizing heterosis to achieve substantial increase in rice yield in the past decades. Several signaling pathways that regulate rice grain shape have been elucidated, including G protein signaling, ubiquitination-related pathway, mitogen-activated protein kinase signaling, phytohormone biosynthesis and signaling, microRNA process, and some other transcriptional regulatory pathways and regulators. This review summarized the recent progress on molecular mechanisms underlying rice grain shape determination and the potential of major genes in future breeding applications

WGCNA Analysis Identifies the Hub Genes Related to Heat Stress in Seedling of Rice (Oryza sativa L.)

Frequent high temperature weather affects the growth and development of rice, resulting in the decline of seed–setting rate, deterioration of rice quality and reduction of yield. Although some high temperature tolerance genes have been cloned, there is still little success in solving the effects of high temperature stress in rice (Oryza sativa L.). Based on the transcriptional data of seven time points, the weighted correlation network analysis (WGCNA) method was used to construct a co–expression network of differentially expressed genes (DEGs) between the rice genotypes IR64 (tolerant to heat stress) and Koshihikari (susceptible to heat stress). There were four modules in both genotypes that were highly correlated with the time points after heat stress in the seedling. We further identified candidate hub genes through clustering and analysis of protein interaction network with known–core genes. The results showed that the ribosome and protein processing in the endoplasmic reticulum were the common pathways in response to heat stress between the two genotypes. The changes of starch and sucrose metabolism and the biosynthesis of secondary metabolites pathways are possible reasons for the sensitivity to heat stress for Koshihikari. Our findings provide an important reference for the understanding of high temperature response mechanisms and the cultivation of high temperature resistant materials

Comparative Analysis of Heat-Tolerant and Heat-Susceptible Rice Highlights the Role of <i>OsNCED1</i> Gene in Heat Stress Tolerance

To elucidate the mechanism underlying the response of rice to heat stress (HS), the transcriptome profile of panicles was comparatively analyzed between the heat-tolerant line 252 (HTL252) and heat-susceptible line 082 (HSL082), two rice recombinant inbred lines (RILs). Our differentially expressed gene (DEG) analysis revealed that the DEGs are mainly associated with protein binding, catalysis, stress response, and cellular process. The MapMan analysis demonstrated that the heat-responsive (HR) genes for heat shock proteins, transcription factors, development, and phytohormones are specifically induced in HTL252 under HS. Based on the DEG analysis, the key gene OsNCED1 (Os02g0704000), which was induced under HS, was selected for further functional validation. Moreover, 9-cis-epoxycarotenoid dioxygenase (NCED) is a key rate-limiting enzyme in the ABA biosynthetic pathway. Overexpression of OsNCED1 improved the HS tolerance of rice at the heading and flowering stage. OsNCED1-overexpression plants exhibited significant increases in pollen viability, seed setting rate, superoxide dismutase (SOD) and peroxidase (POD) activities, while significantly lower electrolyte leakage and malondialdehyde (MDA) content relative to the wild type (WT). These results suggested that OsNCED1 overexpression can improve the heat tolerance of rice by enhancing the antioxidant capacity. Overall, this study lays a foundation for revealing the molecular regulatory mechanism underlying the response of rice to prolonged HS