The lncRNA20718-miR6022-RLPs module regulates tomato resistance to Phytophthora infestans.

KEY MESSAGE: Sl-lncRNA20718 acts as an eTM of Sl-miR6022 regulating its expression thereby affecting SlRLP6/10 expression. SlRLP6/10 regulate PRs expression, ROS accumulation, and JA/ET content thereby affecting tomato resistance to P. infestans. Tomato (Solanum lycopersicum) is an important horticultural and cash crop whose yield and quality can be severely affected by Phytophthora infestans (P. infestans). Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are widely involved in plant defense responses against pathogens. The involvement of Sl-lncRNA20718 and Sl-miR6022 in tomato resistance to P. infestans as well as the targeting of Sl-miR6022 to receptor-like protein genes (RLPs) were predicted in our previous study. However, uncertainty exists regarding their potential interaction as well as the molecular processes regulating tomato resistance. Here, we found that Sl-lncRNA20718 and Sl-miR6022 are positive and negative regulators of tomato resistance to P. infestans by gain- and loss-of-function experiments, respectively. Overexpression of Sl-lncRNA20718 decreased the expression of Sl-miR6022, induced the expression of PRs, reduced the diameter of lesions (DOLs), thereby enhanced disease resistance. A six-point mutation in the binding region of Sl-lncRNA20718 to Sl-miR6022 disabled the interaction, indicating that Sl-lncRNA20718 acts as an endogenous target mimic (eTM) of Sl-miR6022. We demonstrated that Sl-miR6022 cleaves SlRLP6/10. Overexpression of Sl-miR6022 decreases the expression levels of SlRLP6/10, induces the accumulation of reactive oxygen species (ROS) and reduces the content of JA and ET, thus inhibiting tomato resistance to P. infestans. In conclusion, our study provides detailed information on the lncRNA20718-miR6022-RLPs module regulating tomato resistance to P. infestans by affecting the expression of disease resistance-related genes, the accumulation of ROS and the phytohormone levels, providing a new reference for tomato disease resistance breeding.

Function identification of miR394 in tomato resistance to Phytophthora infestans.

KEY MESSAGE: MiR394 plays a negative role in tomato resistance to late blight. The lncRNA40787 severing as an eTM for miR394 to regulate LCR and exerting functions in tomato resistance. Tomato (Solanum lycopersicum), which was used as model species for studying the mechanism of plant disease defense, is susceptible to multiple pathogens. Non-coding RNA (ncRNA) has a pivotal role in plants response to biological stresses. It has previously been observed that the expression level of miR394 changed significantly after the infection of various pathogens. However, there has been no detailed investigation of the accumulated or suppressed mechanism of miR394. Our previous study predicted three lncRNAs (lncRNA40787, lncRNA27177, and lncRNA42566) that contain miR394 endogenous target mimics (eTM), which may exist as the competitive endogenous RNAs (ceRNAs) of miR394. In our study, the transcription levels of these three lncRNAs were strongly up-regulated in tomato upon infection with P. infestans. In contrast with the three lncRNAs, the accumulation of miR394 was significantly suppressed. Based on the expression pattern, and value of minimum free energy (mfes) that represents the binding ability between lncRNA and miRNA, lncRNA40787 was chosen for further investigation. Results showed that overexpression of lncRNA40787 reduced the expression of miR394 along with decreased lesion area and enhanced disease resistance. Overexpression of miR394, however, decreased the expression of its target gene Leaf Curling Responsiveness (LCR), and suppressed the synthesis components genes of jasmonic acid (JA), depressing the resistance of tomato to P. infestans infection. Taken together, our findings indicated that miR394 can be decoyed by lncRNA40787, and negatively regulated the expression of LCR to enhance tomato susceptibility under P. infestans infection. Our study provided detailed information on the lncRNA40787-miR394-LCR regulatory network and serves as a reference for future research.

Solanum lycopersicum microRNA1916 targets multiple target genes and negatively regulates the immune response in tomato.

MicroRNA1916 (miR1916) is one of the nonconserved miRNAs that respond to various stresses in plants, but little has been known at present about its mechanisms in biotic stresses. In this study, the expression of Solanum lycopersicum (sly)-miR1916 in tomato was found to be down-regulated after infection with Phytophthora infestans or Botrytis cinerea. Tomato plants that overexpressed sly-miR1916 displayed significant enhancement in susceptibility to P. infestans and B. cinerea infection, as well as increased tendency to produce reactive oxygen species. Silencing of sly-miR1916 by short tandem target mimic and artificial microRNA strategies caused the tomato plants to become more tolerant to adverse conditions. In addition, lower sly-miR1916 expression could up-regulate the expression of strictosidine synthase (STR-2), UDP-glycosyltransferases (UGTs), late blight resistance protein homolog R1B-16, disease resistance protein RPP13-like, and MYB transcription factor (MYB12), which ultimately resulted in the accumulation of α-tomatine and anthocyanins via STR-2, UGT, and MYB12. Furthermore, ectopic expression of sly-miR1916/STR-2 significantly changed the tolerance of tobacco to B. cinerea. Taken together, the results demonstrated that sly-miR1916 might regulate the expression of STR-2, UGT, and MYB12 in tomato plant, conferring sensitivity to biotic stress via modulating α-tomatine and anthocyanins.

Wortmannilactones I-L, new NADH-fumarate reductase inhibitors, induced by adding suberoylanilide hydroxamic acid to the culture medium of Talaromyces wortmannii.

With the aim of finding more potential inhibitors against NADH-fumarate reductase (specific target for treating helminthiasis and cancer) from natural resources, Talaromyces wortmannii was treated with the epigenome regulatory agent suberoylanilide hydroxamic acid, which resulted in the isolation of four new wortmannilactones derivatives (wortmannilactones I-L, 1-4). The structures of these new compounds were elucidated based on IR, HRESIMS and NMR spectroscopic data analyses. These four new compounds showed potent inhibitory activity against NADH-fumarate reductase with the IC50 values ranging from 0.84 to 1.35µM.

Overexpression of SpWRKY1 promotes resistance to Phytophthora nicotianae and tolerance to salt and drought stress in transgenic tobacco.

WRKY transcription factors are key regulatory components of plant responses to biotic and abiotic stresses. SpWRKY1, a pathogen-induced WRKY gene, was isolated from tomato (Solanum pimpinellifolium L3708) using in silico cloning and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. SpWRKY1 expression was significantly induced following oomycete pathogen infection and treatment with salt, drought, salicylic acid (SA), methyl jasmonate (MeJA) and abscisic acid (ABA). Overexpression of SpWRKY1 in tobacco conferred greater resistance to Phytophthora nicotianae infection, as evidenced by lower malondialdehyde (MDA) content; relative electrolyte leakage (REL); higher chlorophyll content; and higher peroxidase (POD, EC 1.11.1.7), superoxide dismutase (SOD, EC 1.15.1.1) and phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) activities. This resistance was also coupled with enhanced expression of SA- and JA-associated genes (NtPR1, NtPR2, NtPR4, NtPR5 and NtPDF1.2), as well as of various defense-related genes (NtPOD, NtSOD and NtPAL). In addition, transgenic tobacco plants also displayed an enhanced tolerance to salt and drought stresses, mainly demonstrated by the transgenic lines exhibiting lower accumulation of MDA content and higher POD (EC 1.11.1.7), SOD (EC 1.15.1.1) activities, chlorophyll content, photosynthetic rate and stomatal conductance, accompanied by enhanced expression of defense-related genes (NtPOD, NtSOD, NtLEA5, NtP5CS and NtNCED1) under salt and drought stresses. Overall, these findings suggest that SpWRKY1 acts as a positive regulator involved in tobacco defense responses to biotic and abiotic stresses.

The tomato SlWRKY gene plays an important role in the regulation of defense responses in tobacco.

WRKY-type transcription factors are involved in multiple aspects of plant growth, development and stress responses. SlWRKY, a cDNA clone encoding a polypeptide of 552 amino acids and exhibiting the structural features of group I of WRKY protein family, was isolated from tomato (Solanum lycopersicum L. cv Zhongshu No. 4) using the homologous cloning method. Semi-quantitative RT-PCR analysis indicated that SlWRKY was up-regulated by salt and drought treatment in tomato seedlings. To investigate the biological roles of SlWRKY, we generated transgenic tobaccos overexpressing the SlWRKY and analyzed their responses to salt and drought stresses. Transgenic tobacco plants exhibited more vigorous growth than wild-type plants and display high tolerance to salt and drought stresses. In order to minimize oxidative damage, the activities of antioxidant enzymes were increased but EC and the MDA content were decreased in the transgenic tobacco leaves. Furthermore, it was observed that the SlWRKY proteins regulate the downstream genes and increased the expression of defense-related PR1 and PR2 genes. These results demonstrate that, SlWRKY plays an important role in responding to abiotic stress.

Identification of tomato circular RNAs responsive to Phytophthora infestans.

Circular RNAs (circRNAs), a novel branch of noncoding RNAs, are widespread in eukaryotic cells. Particularly, due to their abilities to bind microRNA (miRNA) and serve as "sponges", circRNAs can regulate gene expression and participate in multiple biological processes. To detect the function of the circRNAs in tomato resistance, in our study, high-throughput sequencing were used to detect the circRNAs in tomatoes before and after Phytophthora infestans (P. infestans) infection. A total of 68 circRNAs were identified, of them, 18 (26%) were termed as exonic circRNAs, 33 (49%) were termed as intergenic circRNAs, 17 (25%) were termed as intronic circRNAs. Thirty-six out of 68 circRNAs differentially expressed in tomatoes after infection, including 9 up- and 27 down-regulated. Among the up-regulated circRNAs, two exoinc circRNAs, circRNA45 and circRNA47 were annotated as whitefly-induced gp91-phox and ethylene-forming enzyme, respectively. Both of them could act as miR477-3p sponge. Transgenic plants transiently overexpressed circRNA45 and circRNA47 both displayed smaller lesion area than the control plants upon infection, accompanied by lower expression levels of miR477-3p. Furthermore, transiently overexpression of miR477-3p in tomatoes leading to a decline in their targeted disease related genes expression. Our results firstly identified circRNAs in tomato upon P. infestans infection and demonstrated that circRNA45 and circRNA47 may act as positive regulators in tomato resistance by regulating miRNA-mRNAs expression levels.

Predicting miRNA-lncRNA interactions and recognizing their regulatory roles in stress response of plants.

It has been found that each non-coding RNA (ncRNA) can act not only through its target gene, but also interact with each other to act on biological traits, and this interaction is more common. Many studies focus mainly on the analysis of microRNA(miRNA) and message RNA (mRNA) interactions. In this study, we investigated miRNA and long non-coding RNA (lncRNA) interactions using support vector regression (SVR) for prediction of new target genes in Arabidopsis thaliana and identify some regulatory roles in stress response. The networks of miRNA-mRNA, miRNA-lncRNA and miRNA-mRNA-lncRNA were constructed. They were further analyzed and interpreted in R. We showed that miRNA with low sequence number, targeted lncRNA with high sequence number and miRNA with high sequence number targeted lncRNA with low sequence number. The experimental results showed that there is a regulatory relationship between miRNA-lncRNA. New RNA targets were predicted using SVR with new gene expression mechanism and the stress related functions were annotated.

Overexpression of MiR482c in Tomato Induces Enhanced Susceptibility to Late Blight.

Tomato is the highest-value fruit/vegetable crop worldwide. However, the quality and yield of tomatoes are severely affected by late blight. MicroRNA482s (miR482s) are involved in the plant's immune system. In this study, miR482c was transiently and stably overexpressed in tomatoes in transgenic plants to explore its mechanism in tomato resistance against late blight. Transgenic tomato plants with transiently overexpressed miR482c displayed a larger lesion area than the control plants upon infection. Furthermore, compared with wild-type (WT) tomato plants, the transgenic tomato plants stably overexpressing miR482c displayed a decreased expression of target genes accompanied by lower peroxidase (POD), superoxide dismutase (SOD), and phenylalanine ammonia-lyase (PAL) activity activities and higher malondialdehyde (MDA) content, thereby leading to a decline in reactive oxygen species (ROS) scavenging ability and aggravating the damage of lipid peroxidation product accumulation on the cell membrane, eventually enhancing plant susceptibility. This finding indicates that miR482c may act as a negative regulator in tomato resistance by regulating nucleotide binding sites and leucine-rich repeat (NBS-LRR) expression levels and ROS levels.

Characterization and Function of MicroRNA∗s in Plants.

MicroRNAs, a group of non-coding RNA molecules, play essential roles in a wide range of cellular processes in different molecules, cells, and organisms. In plants, microRNAs are a class of 20- to 24-nucleotides endogenous small RNAs that repress gene expression. The microRNA guide strand (miRNA) and its complementary strand (miRNA∗) both originate from the miRNA/miRNA∗ duplex. Generally, the guide strands act as post-transcriptional regulators that suppress gene expression by cleaving their target mRNA transcripts, whereas the complementary strands were thought to be degraded as 'passenger strands.' However, the complementary strand has been confirmed to possess significant biological functionality in recent reports. In this review, we summarized the binding characteristics of the miRNA∗ strands with ARGONAUTE proteins, their tissue-specific accumulations and their biological functions, illustrating the essential roles of miRNA∗s in biological processes and therefore providing directions for further exploration.

Parallel gene selection and dynamic ensemble pruning based on Affinity Propagation.

Gene selection and sample classification based on gene expression data are important research areas in bioinformatics. Selecting important genes closely related to classification is a challenging task due to high dimensionality and small sample size of microarray data. Extended rough set based on neighborhood has been successfully applied to gene selection, as it can select attributes without redundancy and deal with numerical attributes directly. However, the computation of approximations in rough set is extremely time consuming. In this paper, in order to accelerate the process of gene selection, a parallel computation method is proposed to calculate approximations of intersection neighborhood rough set. Furthermore, a novel dynamic ensemble pruning approach based on Affinity Propagation clustering and dynamic pruning framework is proposed to reduce memory usage and computational cost. Experimental results on three Arabidopsis thaliana biotic and abiotic stress response datasets demonstrate that the proposed method can obtain better classification performance than ensemble method with gene pre-selection.

Protein function prediction based on data fusion and functional interrelationship.

One of the challenging tasks of bioinformatics is to predict more accurate and confident protein functions from genomics and proteomics datasets. Computational approaches use a variety of high throughput experimental data, such as protein-protein interaction (PPI), protein sequences and phylogenetic profiles, to predict protein functions. This paper presents a method that uses transductive multi-label learning algorithm by integrating multiple data sources for classification. Multiple proteomics datasets are integrated to make inferences about functions of unknown proteins and use a directed bi-relational graph to assign labels to unannotated proteins. Our method, bi-relational graph based transductive multi-label function annotation (Bi-TMF) uses functional correlation and topological PPI network properties on both the training and testing datasets to predict protein functions through data fusion of the individual kernel result. The main purpose of our proposed method is to enhance the performance of classifier integration for protein function prediction algorithms. Experimental results demonstrate the effectiveness and efficiency of Bi-TMF on multi-sources datasets in yeast, human and mouse benchmarks. Bi-TMF outperforms other recently proposed methods.

Horizontal Transfer of Small RNAs to and from Plants.

Genetic information is traditionally thought to be transferred from parents to offspring. However, there is evidence indicating that gene transfer can also occur from microbes to higher species, such as plants, invertebrates, and vertebrates. This horizontal transfer can be carried out by small RNAs (sRNAs). sRNAs have been recently reported to move across kingdoms as mobile signals, spreading silencing information toward targeted genes. sRNAs, especially microRNAs (miRNAs) and small interfering RNAs (siRNAs), are non-coding molecules that control gene expression at the transcriptional or post-transcriptional level. Some sRNAs act in a cross-kingdom manner between animals and their parasites, but little is known about such sRNAs associated with plants. In this report, we provide a brief introduction to miRNAs that are transferred from plants to mammals/viruses and siRNAs that are transferred from microbes to plants. Both miRNAs and siRNAs can exert corresponding functions in the target organisms. Additionally, we provide information concerning a host-induced gene silencing system as a potential application that utilizes the transgenic trafficking of RNA molecules to silence the genes of interacting organisms. Moreover, we lay out the controversial views regarding cross-kingdom miRNAs and call for better methodology and experimental design to confirm this unique function of miRNAs.

SpMYB overexpression in tobacco plants leads to altered abiotic and biotic stress responses.

The MYB transcription factors are involved in various plant biochemistry and physiology processes and play a central role in plant defense response. In the present study, a full-length cDNA sequence of a MYB gene, designated as SpMYB, was isolated from tomato. SpMYB encodes the R2R3-type protein consisting of 328 amino acids. The expression level of SpMYB was strongly induced by fungal pathogens. Transgenic tobacco plants overexpressing SpMYB had an enhanced salt and drought stress tolerance compared with wild-type plants, and showed significantly improved resistance to Alternaria alternate. Further analysis revealed that transgenic tobaccos exhibited less accumulation of malondialdehyde (MDA) and more accumulation of superoxide dismutase (SOD), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) after inoculation with A. alternate. Meanwhile, changes in some photosynthetic parameters, such as photosynthetic rate (Pn), transpiration rate (Tr) and intercellular CO2 concentration (Ci) were also found in the transgenic tobaccos. Furthermore, transgenic tobaccos constitutively accumulated higher levels of pathogenesis-related (PR) gene transcripts, such as PR1 and PR2. The results suggested that the tomato SpMYB transcription factor plays an important role in responses to abiotic and biotic stress.

Inactivation of recombinant human brain-type creatine kinase during denaturation by guanidine hydrochloride in a macromolecular crowding system.

In this study, we quantitatively examined the effects of the macromolecular crowding agents, polyethylene glycol 2000 (PEG 2000) and dextran 70, on guanidine hydrochloride (GdnHCl)-induced denaturation of recombinant human brain-type creatine kinase (rHBCK). Our results showed that both PEG 2000 and dextran 70 had a protective effect on the inactivation of rHBCK induced by 0.5 M GdnHCl at 25 °C. The presence of 200 g/L PEG 2000 resulted in the retention of 35.33 % of rHBCK activity after 4 h of inactivation, while no rHBCK activity was observed after denaturation in the absence of macromolecular crowding agents. The presence of PEG 2000 and dextran 70 at a concentration of 100 g/L could decelerate the k (2) value of the slow track to 21 and 33 %, respectively, in comparison to values obtained in the absence of crowding agents. Interestingly, inactivation of rHBCK in the presence of 200 g/L PEG 2000 followed first-order monophasic kinetics, with an apparent rate constant of 8 × 10(-5) s(-1). The intrinsic fluorescence results showed that PEG 2000 was better than dextran 70 at stabilizing rHBCK conformation. In addition, the results of the phase diagram indicate that more intermediates may be captured when rHBCK is denatured in a macromolecular crowding system. Mixed crowding agents did not produce better results than single crowding agents, but the protective effects of PEG 2000 on the inactivation and unfolding of rHBCK tended to increase as the ratio of PEG 2000 increased in the mixed crowding agent solution. Though it is not clear which crowding agents more accurately simulated the intracellular environment, this study could lead to a better understanding of protein unfolding in the intracellular environment.

Optimized transformation of Streptomyces sp. ATCC 39366 producing leptomycin by electroporation.

Streptomyces sp. ATCC 39366 produces leptomycin derivatives. Leptomycin B, a potent and specific inhibitor against the export of nuclear proteins, is the main product; however, the introduction of DNA into this strain is almost impossible, which has impeded its further use. We developed a Streptomyces sp. ATCC 39366 transformation protocol to introduce foreign DNA via electroporation. Various conditions were examined, including treatments of the cell wall with weakening agents, electroporation parameters, and DNA content. We found that only plasmid DNA isolated from a dam (-) ET12567 strain resulted in successful transformation. The mycelium growing in a yeast-peptone-dextrose medium supplemented with 1% glycine at 28°C on a rotary shaker (220 rpm) was more dispersed than those without supplementation and prone to electroporation. The maximum transformation efficiency of 8×10(2) CFU/µg plasmid DNA was obtained at a field strength of 13 kV/cm with a time constant of 13 ms (25-µF capacitor; parallel resistance, 600 Ω) using 1-mm electrocuvettes. The results of the transformations of two other Streptomyces species indicated that the optimized conditions established in this study might only be applicable to Streptomyces sp. ATCC 39366. However, this is the first report of successful transformation of Streptomyces sp. ATCC 39366, and will facilitate the construction of a gene knockout mutant in Streptomyces sp. ATCC 39366 to produce series of new leptomycin derivatives.

Effects of macromolecular crowding on refolding of recombinant human brain-type creatine kinase.

In this study, we quantitatively measured the effects of the macromolecular crowding agents, polyethylene glycol 2000 (PEG 2000), dextran 70, and calf thymus DNA (CT DNA), on the refolding and aggregation of recombinant human brain-type creatine kinase (rHBCK) denatured by guanidine hydrochloride (GdnHCl). The results showed that there is more aggregation in the presence of either a single crowding agent or in a mixture of crowding agents than in the absence of crowding agents, especially in the presence of a mixture containing CT DNA and PEG 2000 (or dextran 70). In the presence of high concentrations of PEG 2000 (100 g/L), dextran 70 (100 g/L), and CT DNA (15 g/L), the refolding yield remarkably decreased from 70% to 20%, 52% and 57%, respectively. A remarkable decrease in the refolding yield and rate with mixed crowding agent containing CT DNA and PEG 2000 (or dextran 70) was also observed. In comparison to refolding in the presence of 100 g/L PEG 2000, the refolding yields and rates improved in the presence of a mixture of PEG 2000 and dextran 70. We speculate that the crowding agents can favor both correct folding and misfolding/aggregation of denatured-rHBCK. Though it is not known what combination of crowding agents most accurately reflects the physiological environment within a cell, we believe our study could contribute to the understanding of protein folding and the factors that contribute to proper conformation and function in the intracellular environment.

Effects of osmolytes on human brain-type creatine kinase folding in dilute solutions and crowding systems.

The effects of osmolytes on the unfolding and refolding process of recombinant human brain-type creatine kinase (rHBCK) were comparatively, quantitatively studied in dilute solutions and macromolecular crowding systems (simulated by 100 g/L polyethylene glycol 2000), respectively. The results showed that the osmolytes, including glycerol, sucrose, dimethylsulfoxide, mannitol, inositol, and xylitol, could both protect the rHBCK from denaturation induced by 0.8 M GdnHCl and aid in the refolding of denatured-rHBCK in macromolecular crowding systems. When we examined the effects of sucrose and xylitol on the parameters of residual activity, reaction kinetics and intrinsic fluorescence of rHBCK during unfolding, it was found that the protecting effects of osmolytes in a macromolecular crowding system were more significant compared with those in a dilute solution, which resulted in more residual activities, protected the conformational changes and greatly decreased the rates of both the fast and slow tracks. Regarding the effects of glycerol, sucrose and mannitol on the denatured-rHBCK refolding parameters of refolding yield, reaction kinetics and aggregation, the results indicated that the osmolytes could alleviate the aggregation of rHBCK during refolding in both dilute solutions and macromolecular crowding systems, and the refolding yields and reaction rates under macromolecular crowding environment could be increased by the addition of osmolytes, though higher yields were obtained in the dilute solution. For further insight, osmolyte docking simulations and rHBCK denaturation were conducted successfully and confirmed our experimental results. The predictions based on the docking simulations suggested that the deactivation of guanidine may be blocked by osmolytes because they share common binding sites on rHBCK, and the higher number of interactions with rHBCK by osmolytes than guanidine may be one of the causes of rHBCK refolding. In brief, the additive effects of the exclusive volume effect from the macromolecular crowding system and the osmophobic effects from the osmolytes resulted in better performance of the osmolytes in a macromolecular crowding system, which also led to a better understanding of protein folding in the intracellular environment.

Molecular characterization of sweet potato leaf curl virus isolate from China (SPLCV-CN) and its phylogenetic relationship with other members of the Geminiviridae.

A Sweet potato-infecting sweet potato leaf curl virus (SPLCV) isolated in China was detected by Polymerase Chain Reaction (PCR). PCR products amplified from DNA-A were cloned and sequenced. The isolates of SPLCV from China(SPLCV-CN)has a genome organization similar to that of monopartite begomoviruses. The DNA-A had two ORFs (AV1 and AV2) in the virion sense and four ORFs (AC1, AC2, AC3, and AC4) in the complementary sense, separated by an intergenic region (IR) containing a conserved stem-loop motif. Three incomplete direct repeat iterons were also found within the IR. The presence of AV2 ORF supports the relationship of SPLCV-CN to the Old World gemimiviruses. Sequence comparisons showed that the DNA-A sequence of SPLCV-CN were closely related to those of sweet potato leaf curl Georgia virus-[16] (SPLCGV-[16]), Ipomoea yellow vein virus (IYVV-SI), and sweet potato leaf curl virus (SPLCV) with nucleotide sequence identity ranging from 88% to 91%. Comparison of individual encoded proteins between SPLCV-CN and that of three other SPLCV isolates showed the coat protein (AV1) shared the highest amino acid sequence identity (93%-96%), suggesting the coat protein of these viruses may have identical ancestor. The relationships between SPLCV-CN and other whitefly-transmitted geminiviruses were investigated by using phylogeny of derived AV1, AC1, and AV2 amino acid sequences. In all phylogenetic trees, SPLCV-CN clustered with three other isolates of SPLCV. The analyses revealed that the four isolates of SPLCV have coat proteins which are unique from its counterparts from both the Old World and New World. The present of AV2 and phylogenic analysis of AC1 suggest that SPLCV is more close to begomoviruses from the Old World but isolates of this virus seems to form a separate subset.