In-situ recommendation of alternative soil samples during field sampling based on environmental similarity

Field sampling is an essential step for digital soil mapping and various sampling strategies have been designed for achieving desirable mapping results. Some unpredictable complex circumstances in the field, however, often prevent some samples from being collected based on the pre-designed sampling strategies. Such circumstances include inaccessibility of some locations, change of land surface types, and heavily-disturbed soil at some locations, among others. This may result in the missing of some essential samples, which could impact the quality of digital soil mapping. Previous studies have attempted to design alternative samples for the selected ones beforehand to address this issue. It cannot solve the problem completely as those pre-designed alternative samples could also be inaccessible. In this paper, we propose a dynamic method to recommend alternative samples for those unavailable samples in the field. The identification of alternative samples is based on the environmental similarity between an unavailable soil sample and its alternative candidates, as well as the spatial accessibility of these candidates. For the convenience of fieldwork, the proposed method was implemented to be a mobile application on the Android platform. A simulated soil sampling study in Xuancheng county, Anhui province of China was used to evaluate its performance. From a sample set for the study are, 30 samples were assumed to be inaccessible. For each of them, an alternative soil sample from the set was recommended using the proposed method. A deviation analysis of silt and sand content at the depth of 20 ~ 40 cm between the soil samples and their alternatives shows that the deviation on silt content is less than 20% for half of the soil samples. A larger deviation on sand content might be attribute to the limited alternative candidates in this virtual experiment. In a second experiment, we randomly selected a number of existing soil samples and replaced them with their corresponding alternative soil samples. This created 1000 hybrid sample sets. Each hybrid sample set was then used for digital soil mapping with iPSM. An evaluation using 59 independent soil samples indicated that the RMSE and MAE with the hybrid sample sets were close to that with the original sample set. The proposed method proved to be able to recommend effective alternative samples for those unavailable samples in the field

Characterization of Peanut Germin-Like Proteins, <i>AhGLPs</i> in Plant Development and Defense

<div><p>Background</p><p>Germin-like superfamily members are ubiquitously expressed in various plant species and play important roles in plant development and defense. Although several <i>GLPs</i> have been identified in peanut (<i>Arachis hypogaea</i> L.), their roles in development and defense remain unknown. In this research, we study the spatiotemporal expression of <i>AhGLPs</i> in peanut and their functions in plant defense.</p><p>Results</p><p>We have identified three new <i>AhGLP</i> members (<i>AhGLP3b</i>, <i>AhGLP5b</i> and <i>AhGLP7b</i>) that have distinct but very closely related DNA sequences. The spatial and temporal expression profiles revealed that each peanut <i>GLP</i> gene has its distinct expression pattern in various tissues and developmental stages. This suggests that these genes all have their distinct roles in peanut development. Subcellular location analysis demonstrated that AhGLP2 and 5 undergo a protein transport process after synthesis. The expression of all <i>AhGLPs</i> increased in responding to <i>Aspergillus flavus</i> infection, suggesting <i>AhGLPs'</i> ubiquitous roles in defense to <i>A. flavus.</i> Each <i>AhGLP</i> gene had its unique response to various abiotic stresses (including salt, H₂O₂ stress and wound), biotic stresses (including leaf spot, mosaic and rust) and plant hormone stimulations (including SA and ABA treatments). These results indicate that <i>AhGLPs</i> have their distinct roles in plant defense. Moreover, <i>in vivo</i> study of <i>AhGLP</i> transgenic <i>Arabidopsis</i> showed that both <i>AhGLP2</i> and <i>3</i> had salt tolerance, which made transgenic <i>Arabidopsis</i> grow well under 100 mM NaCl stress.</p><p>Conclusions</p><p>For the first time, our study analyzes the <i>AhGLP</i> gene expression profiles in peanut and reveals their roles under various stresses. These results provide an insight into the developmental and defensive roles of <i>GLP</i> gene family in peanut.</p></div

Expression of <i>AhGLPs</i> in response to <i>A. flavus</i> infection in pre - and post- harvested peanut seeds.

<p>A: Con: control; Dt: drought stress; Ad: <i>A. flavus</i> infection under drought stress condition; B: Changes of the expression of <i>AhGLP</i> family genes in damp-dry peanut seed with 20% RH (relative humidity) under <i>A. flavus</i> infection. Con: control; A. f: <i>A. flavus</i> infection.</p

Overexpression of <i>AhGLP</i>s and salt tolerance analysis in transgenic <i>Arabidopsis thaliana</i>.

<p>WT: wild type; control: The modified pCAMBIA1301 inserted with 35S only was used as negative control. (A): Diagrams of the constructs (the pCAMBIA1301-35S- <i>AhGLP1</i>, <i>2</i>, <i>3</i>, <i>4</i>, <i>5</i> and <i>7</i>) used for <i>Agrobacterium tumefaciens</i>-mediated transformation of <i>Arabidopsis</i>. (B): Effects of different NaCl content (0, 50 and 100 mM) on the germination of transgenic <i>Arabidopsis</i> seeds for 5 days after germination; (C): Comparison of germination rates and percentages of seedlings with green cotyledons between transgenic lines and wild-type plants under 100 mM NaCl stress. (D): The seeding cultivated on 1/2 MS agar plate containing 50 mM NaCl for 15 days. (E): Transcript analysis of <i>AhGLPs</i>-activated defense related genes (DFR, CHS, 3GT, and AtPR3, 4 and 5) in transgenic <i>Arabidopsis</i> plants.</p

Subcellular localization of AhGLPs-GFP proteins in onion epidermal cells.

<p>Localization of AhGLPs-GFP fusion protein. Control: fluorescence of onion epidermal cells under empty vector. 35S-smGFP: onion epidermal cells expressing the <i>GFP</i> gene only driven by he 35S promoter. GFP fluorescence and differential interference contrast images and Visible/GFP merged images are shown from left to right.</p

Difference of closely related multiple <i>AhGLPs</i>.

a<p><i>AhGLP3a</i> (GU457419.1), <i>AhGLP5a</i> (GU457421.1) and <i>AhGLP7a</i> (GU457423.1) were the known genes as reported by Chen et al (2011) in NCBI genebank, three newfound genes were designated AhGLP3b, AhGLP5b and AhGLP7b distinguished from AhGLP3a, AhGLP5a and AhGLP7a respectively.</p>b<p>un-know bases in the nucleotide sequence of AhGLP5a and AhGLP7a with indefinable amino acids (*).</p

Venn diagram representing the expression profiles of <i>AhGLP</i> genes commonly or specifically regulated by various environmental stimuli, including plant hormones, abiotic stress and/or biotic stress in peanut leaves.

<p>1, 2, 3, 4, 5, 6, 7, 8 were AhGLP1, AhGLP1, AhGLP2, AhGLP3, AhGLP4, AhGLP5, AhGLP6, AhGLP7 and AhGLP8, respectively. The underline numbers indicated down-regulated genes, and the numbers without underlines were up-regulated genes.</p