Xiyao Wang

De novo characterization of the alligator weed ( Alternanthera philoxeroides ) transcriptome illuminates gene expression under potassium deprivation

As one of the three macronutrients, potassium participates in many physiological processes in plant life cycle. Recently, potassium-dependent transcriptome analysis has been reported in Arabidopsis, rice and soybean. Alligator weed is well known, particularly for its strong ability to accumulate potassium. However, the molecular mechanism that underlies potassium starvation responses has not yet been described. In this study, we used Illumina (Solexa) sequencing technology to analyse the root transcriptome information of alligator weed under low potassium stress. Further analysis suggested that 9253 differentially expressed genes (DEGs) were upregulated, and 2138 DEGs were downregulated after seven days of potassium deficiency. These factors included 121 transcription factors, 108 kinases, 136 transporters and 178 genes that were related to stress. Twelve transcription factors were randomly selected for further analysis. The expression level of each transcription factor was confirmed by quantitative RT-PCR, and the results of this secondary analysis were consistent with the results of Solexa sequencing. Enrichment analysis indicated that 10,993 DEGs were assigned to 54 gene ontology terms and 123 KEGG pathways. Approximately 24% of DEGs belong to the metabolic, ribosome and biosynthesis of secondary metabolite KEGG pathways. Our results provide a comprehensive analysis of the gene regulatory network of alligator weed under low potassium stress, and afford a valuable resource for genetic and genomic research on plant potassium deficiency.

Ectopic Expression of AtCIPK23 Enhances Tolerance Against Low-K+ Stress in Transgenic Potato

Potato (Solanum tuberosum L.) has a relatively high requirement for potassium (K+). In the face of the declining of potato yield and quality as a result of reduction of soil K+ content, it is necessary to determine how to improve the tolerance of potatoes to low-K+ stresses. The protein kinase AtCIPK23 is essential for K+ uptake, and its overexpression significantly enhances K+ uptake and tolerance to low-K+ in Arabidopsis. In this research, AtCIPK23 was transformed into an E3 potato cultivar successfully. In low-K+ conditions, the transgenic potato lines had lower levels of leaf chlorosis, higher K+ uptake rate, increased dry weight and K+ content. The non-transgenic lines displayed reduced stature while the transgenic lines exhibited sustained growth. These results indicate that ectopic expression of AtCIPK23 increases low-K+ tolerance in potato. This study demonstrated the potential use of the transgenic approach to increase potato production in low-K+ fields.ResumenLa papa (Solanum tuberosum L.), tiene un requerimiento relativamente alto de potasio (K+). Encarando la reducción en rendimientos y de la calidad de la papa como resultado de una reducción en el contenido de K+ en el suelo, es necesario determinar cómo mejorar la tolerancia de la papa al agobio por bajo K+. La proteína kinasa AtCIPK23 es esencial para la absorción de K+, y su sobreexpresión aumenta significativamente la absorción de K+ y tolerancia a bajo K+ en Arabidopsis. En esta investigación, se incorporó AtCIPK23 a una variedad E3 con éxito. Bajo condiciones de bajo K+, las líneas trangénicas de papa tuvieron niveles más bajos de clorosis foliar, un nivel más alto de absorción de K+, aumento en peso seco y del contenido de K+. Las líneas no trangénicas expresaron altura reducida mientras que las trangénicas mostraron crecimiento sostenido. Estos resultados indican que la expresión ectópica de AtCIPK23 aumenta la tolerancia al bajo K+ en papa. Este estudio demostró el uso potencial del enfoque trangénico para aumentar la producción de papa en campos de bajo K+.

Identifying the Genes Regulated by AtWRKY6 Using Comparative Transcript and Proteomic Analysis under Phosphorus Deficiency

Phosphorus (P) is an important mineral nutrient for plant growth and development. Overexpressing AtWRKY6 (35S:WRKY6-9) was more sensitive and wrky6 (wrky6-1) was more resistant under low Pi conditions. To better understand the function of AtWRKY6 under low phosphate stress conditions, we applied two-dimensional gel electrophoresis (2-DE) to analyse differentially expressed proteins in the shoots and roots between wild type, 35S:WRKY6-9 and wrky6-1 after phosphorus deficiency treatment for three days. The results showed 88 differentially abundant protein spots, which were identified between the shoots and roots of 35S:WRKY6-9 and wrky6-1 plants. In addition, 59 differentially expressed proteins were identified in the leaves and roots of 35S:WRKY6-9 plants. After analysis, 9 genes with W-box elements in their promoter sequences were identified in the leaves, while 6 genes with W-box elements in their promoter sequences were identified in the roots. A total of 8 genes were identified as potential target genes according to the quantitative PCR (QPCR) and two dimension difference gel electrophoresis, (2D-DIGE) results, including ATP synthase, gln synthetase, nitrilase, 14-3-3 protein, carbonic anhydrases 2, and tryptophan synthase. These results provide important information concerning the AtWRKY6 regulation network and reveal potential vital target genes of AtWRKY6 under low phosphorus stress. two dimension difference gel electrophoresis, 2D-DIGE

Manipulating Aeroponically Grown Potatoes with Gibberellins and Calcium Nitrate

Maximizing tuber number and yield in an aeroponics production system is imperative to make it cost effective and to make the best use of all facilities and inputs. Manipulating the plants hormonal makeup is a strategy. GA3(GA), Calcium Nitrate(CaN) and their combination were foliarly applied several times to potato plants of cvs. Favorita and Mira during both the autumn and spring growing seasons in a semi tropical setting in Sichuan. A contrasting treatment of an anti-gibberellin(Anti) was also studied in both seasons. Significant differences in plants height, stem diameter, chlorophyll content, leaf area index, the number of stolons, the number of stolon branches and tuber production were observed among different treatments and cultivars. For the cv. Favorita, CaN + GA and GA increased tuber weight per plant by 63 and 49% in autumn and 53 and 73% in spring respectively as compared to the control(CK); tuber number per plant under CaN + GA and GA treatments increased by 90 and 85% in autumn and 35 and 52% in spring respectively. For cv. Mira, the trend was similar but not as dramatic. Tuber numbers over 1400 per square meter were harvested with cv. Mira during the spring season with the GA and CaN + GA treatments.ResumenLa maximización del número de tubérculos y el rendimiento en un sistema de producción aeropónico es imperativo para hacerlo redituable y para hacer el mejor uso de todas las facilidades e insumos. La manipulación de la constitución hormonal es una estrategia. GA3 (GA), nitrato de calcio (CaN) y su combinación, se aplicaron foliarmente varias veces a plantas de papa de las vars. Favorita y Mira durante los ciclos de cultivo del otoño y la primavera en una instalación semi-tropical en Sichuan. También se estudió un tratamiento contrastante de una antigiberelina (Anti) en ambos ciclos. Se observaron diferencias significativas entre los tratamientos y variedades en altura de las plantas, diámetro de tallos, contenido de clorofila, índice de área foliar, número de estolones, número de ramificaciones de los estolones y producción de tubérculo. Para la variedad Favorita, CaN + GA y GA incrementaron el peso de tubérculo por planta en un 63 y 49% en el otoño, y 53 y 73% en la primavera, respectivamente, en comparación con el testigo (CK); el número de tubérculos por planta bajo los tratamientos con CaN + GA y GA aumentaron 90 y 85% en el otoño y 35 y 52% en la primavera, respectivamente. Para la variedad Mira, la tendencia fue similar, pero no tan dramática. Se cosecharon tubérculos en números superiores a 1400 por metro cuadrado de la variedad Mira durante el ciclo de cultivo de la primavera con los tratamientos GA y CaN + GA.

Comparative Morphology, Transcription, and Proteomics Study Revealing the Key Molecular Mechanism of Camphor on the Potato Tuber Sprouting Effect

Sprouting regulation in potato tubers is important for improving commercial value and producing new plants. Camphor shows flexible inhibition of tuber sprouting and prolongs the storage period of potato, but its underlying mechanism remains unknown. The results of the present study suggest that camphor inhibition caused bud growth deformities and necrosis, but after moving to more ventilated conditions, new sprouts grew from the bud eye of the tuber. Subsequently, the sucrose and fructose contents as well as polyphenol oxidase (PPO) activity were assessed after camphor inhibition. Transcription and proteomics data from dormancy (D), sprouting (S), camphor inhibition (C), and recovery sprouting (R) samples showed changes in the expression levels of approximately 4000 transcripts, and 700 proteins showed different abundances. KEGG (Kyoto encyclopaedia of genes and genomes) pathway analysis of the transcription levels indicated that phytohormone synthesis and signal transduction play important roles in tuber sprouting. Camphor inhibited these processes, particularly for gibberellic acid, brassinosteroids, and ethylene, leading to dysregulation of physiological processes such as cutin, suberine and wax biosynthesis, fatty acid elongation, phenylpropanoid biosynthesis, and starch and sucrose metabolism, resulting in bud necrosis and prolonged storage periods. The KEGG pathway correlation between transcripts and proteins revealed that terpenoid backbone biosynthesis and plant–pathogen interaction pathways showed significant differences in D vs. S samples, but 13 pathways were remarkably different in the D vs. C groups, as camphor inhibition significantly increased both the transcription levels and protein abundance of pathogenesis-related protein PR-10a (or STH-2), the pathogenesis-related P2-like precursor protein, and the kirola-like protein as compared to sprouting. In recovery sprouting, these genes and proteins were decreased at both the transcriptional level and in protein abundance. It was important to find that the inhibitory effect of camphor on potato tuber sprout was reversible, revealing the action mechanism was similar to resistance to pathogen infection. The present study provides a theoretical basis for the application of camphor in prolonging seed potato storage.

Genomic in situ hybridization analysis between Rubus coreanus and its relatives in Rubus (Sect. Idaeobatus)

Abstract To further investigate the phylogenetic relationship between Rubus coreanus and its relatives in the section Idaeobatus, we used genomic in situ hybridization (GISH) to ascertain the degree of their genomic homology. Genomic DNA from R. parvifolius and R. inopertus hybridized throughout the centromeric and sub-terminal regions on 14 and 12 chromosomes of R. coreanus, respectively. The probes from R. niveus and R. ellipticus var. obcordatus gave robust signals at the same region of eight chromosomes. R. ellipticus and R. pinfaensis generated strong signals at the centromeric and sub-terminal parts of six chromosomes. The hybridization signals from the R. tsangii and R. corchorifolius probes existed only at the telomeric parts of four chromosomes. The two signals at the sub-terminal region on chromosome 6 of R. coreanus might be 45S rDNA repeats. These results indicated that R. coreanus and R. parvifolius shared many repeat sequences. It could be deduced that the genome of R. parvifolius was most closely related to that of R. coreanus among the species tested, R. inopertus came next, while R. tsangii and R. corchorifolius showed the farthest relationship. The phylogenetic relationships between R. parvifolius and R. coreanus, as well as among the five subsections were mainly discussed.