Genome-Wide Exploration of the Grape GLR Gene Family and Differential Responses of VvGLR3.1 and VvGLR3.2 to Low Temperature and Salt Stress

Grapes,one of the oldest tree species globally,are rich in vitamins.However,environmental conditions such as low temperature and soil salinization significantly affect grape yield and quality.The glutamate receptor(GLR)family,comprising highly conserved ligand-gated ion channels,regulates plant growth and development in response to stress.In this study,11 members of the VvGLR gene family in grapes were identified using whole-genome sequence analysis.Bioinformatic methods were employed to analyze the basic physical and chemical properties,phylogenetic trees,conserved domains,motifs,expression patterns,and evolutionary relationships.Phylogenetic and collinear analyses revealed that the VvGLRs were divided into three subgroups,showing the high conservation of the grape GLR family.These members exhibited 2 glutamate receptor binding regions(GABAb and GluR)and 3-4 transmembrane regions(M1,M2,M3,and M4).Real-time quantitative PCR analysis demonstrated the sensitivity of all VvGLRs to low temperature and salt stress.Subsequent localization studies in Nicotiana tabacum verified that VvGLR3.1 and VvGLR3.2 proteins were located on the cell membrane and cell nucleus.Additionally,yeast transformation experiments confirmed the functionality of VvGLR3.1 and VvGLR3.2 in response to low temperature and salt stress.Thesefindings highlight the significant role of the GLR family,a highly conserved group of ion channels,in enhancing grape stress resistance.This study offers new insights into the grape GLR gene family,providing fundamental knowledge for further functional analysis and breeding of stress-resistant grapevines.

Assessment of molecular markers and marker-assisted selection for drought tolerance in barley(Hordeum vulgare L.)

This review updates the present status of the field of molecular markers and marker-assisted selection(MAS),using the example of drought tolerance in barley.The accuracy of selected quantitative trait loci(QTLs),candidate genes and suggested markers was assessed in the barley genome cv.Morex.Six common strategies are described for molecular marker development,candidate gene identification and verification,and their possible applications in MAS to improve the grain yield and yield components in barley under drought stress.These strategies are based on the following five principles:(1)Molecular markers are designated as genomic‘tags’,and their‘prediction’is strongly dependent on their distance from a candidate gene on genetic or physical maps;(2)plants react differently under favourable and stressful conditions or depending on their stage of development;(3)each candidate gene must be verified by confirming its expression in the relevant conditions,e.g.,drought;(4)the molecular marker identified must be validated for MAS for tolerance to drought stress and improved grain yield;and(5)the small number of molecular markers realized for MAS in breeding,from among the many studies targeting candidate genes,can be explained by the complex nature of drought stress,and multiple stress-responsive genes in each barley genotype that are expressed differentially depending on many other factors.

Development of a stable attenuated double-mutant of tobacco mosaic virus for cross-protection

Tobacco(Nicotiana tabacum)and tomato(Solanum lycopersicum)are two major economic crops in China.Tobacco mosaic virus(TMV;genus Tobamovirus)is the most prevalent virus infecting both crops.Currently,some widely cultivated tobacco and tomato cultivars are susceptible to TMV and there is no effective strategy to control this virus.Cross-protection can be a safe and environmentally friendly strategy to prevent viral diseases.However,stable attenuated TMV mutants are scarce.In this study,we found that the substitutions in the replicase p126,arginine at position 196(R^(196))with aspartic acid(D),glutamic acid at position 614(E^(614))with glycine(G),serine at position 643(S^(643))with phenylalanine(F),or D at position 730(D^(730))with S,significantly reduced the virulence and replication of TMV.However,only the mutation of S^(643) to F reduced the RNA silencing suppression activity of TMV p126.A double-mutant TMV-E614G-S643F induced no visible symptom and was genetically stable through six successive passages in tobacco plants.Furthermore,our results showed that TMV-E614G-S643F double-mutant could provide effective protection against the wild-type TMV infection in tobacco and tomato plants.This study reports a promising mild mutant for cross-protection to control TMV in tobacco and tomato plants.

Genome Wide Characterization of CBL-CIPK Family Genes and Their Responsive Expression in Rosa chinensis

Calcium(Ca^(2+))plays a pivotal role in various signal transduction pathways.Calcineurin B-like proteins(CBLs)are a unique group of Ca^(2+)sensors that decode Ca^(2+)signals by activating the plant specific protein kinase known as the CBL-interacting protein kinase(CIPK).In plants,the CBL-CIPK signaling network regulates multiple signals in response to different extracellular cues including abiotic stress.However,the genome wide annotation and expression patterns of CBLs and CIPKs in woody cutting flower plants are still unclear.In this study,a total number of 7 CBLs(RcCBLs)and 17 CIPKs(RcCIPKs)genes,divided into four and five subfamilies,respectively,were identified from the rose genome.All RcCBLs possess a classic elongation factor-hand(EF-hand)domain,while all RcCIPKs possess both the classic kinase and NAF domains.Most RcCBLs were predicted to be plasma membrane localized,whereas most RcCIPKs were predicted to be cytoplasmic localized.Synteny analysis showed that one RcCBL gene pair and five RcCIPK gene pairs have gone through whole genome duplication events.Promoter cis-element prediction assays indicated that RcCBLs and RcCIPKs could function in different abiotic stress responses in rose plants.Further quantitative real-time PCR analysis demonstrated that RcCBLs and RcCIPKs were expressed in different organs with overlapped but distinct patterns in response to various abiotic stresses.The findings in this work will provide fundamental information and gene resources for further functional research on RcCBLs and RcCIPKs.

High-throughput discovery of plastid genes causing albino phenotypes in ornamental chimeric plants

Chimeric plants composed of green and albino tissues have great ornamental value.To unveil the functional genes responsible for albino phenotypes in chimeric plants,we inspected the complete plastid genomes(plastomes)in green and albino leaf tissues from 23 ornamental chimeric plants belonging to 20 species,including monocots,dicots,and gymnosperms.In nine chimeric plants,plastomes were identical between green and albino tissues.Meanwhile,another 14 chimeric plants were heteroplasmic,showing a mutation between green and albino tissues.We identified 14 different point mutations in eight functional plastid genes related to plastid-encoded RNA polymerase(rpo)or photosystems which caused albinism in the chimeric plants.Among them,12 were deleterious mutations in the target genes,in which early termination appeared due to small deletion-mediated frameshift or single nucleotide substitution.Another was single nucleotide substitution in an intron of the ycf3 and the other was a missense mutation in coding region of the rpoC2 gene.We inspected chlorophyll structure,protein functional model of the rpoC2,and expression levels of the related genes in green and albino tissues of Reynoutria japonica.A single amino acid change,histidine-to-proline substitution,in the rpoC2 protein may destabilize the peripheral helix of plastid-encoded RNA polymerase,impairing the biosynthesis of the photosynthesis system in the albino tissue of R.japonica chimera plant.

Rice ONAC016 promotes leaf senescence through abscisic acid signaling pathway involving OsNAP

Senescence-induced NAC(senNAC)TFs play a crucial role in senescence during the final stage of leaf development.In this study,we identified a rice senNAC,ONAC016,which functions as a positive regulator of leaf senescence.The expression of ONAC016 increased rapidly in rice leaves during the progression of dark-induced and natural senescence.The onac016-1 knockout mutant showed a delayed leaf yellowing phenotype,whereas the overexpression of ONAC016 accelerated leaf senescence.Notably,ONAC016 expression was upregulated by abscisic acid(ABA),and thus detached leaves of the onac016-1 mutant remained green much longer under ABA treatment.Quantitative RT-PCR analysis showed that ONAC016 upregulates the genes associated with chlorophyll degradation,senescence,and ABA signaling.Yeast one-hybrid and dual-luciferase assays revealed that ONAC016 binds directly to the promoter regions of OsNAP,a key gene involved in chlorophyll degradation and ABA-induced senescence.Taken together,these results suggest that ONAC016 plays an important role in promoting leaf senescence through the ABA signaling pathway involving OsNAP.

OsWRKY65 enhances immunity against fungal and bacterial pathogens in rice

Diverse bacterial and fungal pathogens attack plants,causing biotic stress and severe yield losses globally.These losses are expected to become more serious as climate change improves conditions for many pathogens.Therefore,identifying genes conferring broad-spectrum disease resistance and elucidating their underlying mechanisms provides important resources for plant breeding.WRKY transcription factors affect plant growth and stress responses.However,the functions of many WRKY proteins remain to be elucidated.Here,we demonstrated the role of rice(Oryza sativa)WRKY groupⅢtranscription factor OsWRKY65 in immunity.OsWRKY65 localized to the nucleus and acted as transcriptional repressor.Genetic and molecular functional analyses showed that OsWRKY65 increases resistance to the fungal pathogen Fusarium fujikuroi through downregulation of GA signaling and upregulation of JA signaling.Moreover,OsWRKY65 modulated the expression of the key genes that confer susceptibility or resistance to Xanthomonas oryzae pv.oryzae to enhance immunity against the pathogen.In particular,OsWRKY65directly bound to the promoter region of OsSWEET13 and repressed its expression.Taken together,our findings demonstrate that the OsWRKY65 enhances resistance to fungal and bacterial pathogens in rice.

Methane Emission from Rice Fields:Necessity for Molecular Approach for Mitigation

Anthropogenic methane emissions are a leading cause of the increase in global averagetemperatures,often referred to as global warming.Flooded soils play a significant role in methaneproduction,where the anaerobic conditions promote the production of methane by methanogenicmicroorganisms.Rice fields contribute a considerable portion of agricultural methane emissions,as riceplants provide both factors that enhance and limit methane production.Rice plants harbor both methaneproducingand methane-oxidizing microorganisms.Exudates from rice roots provide source for methaneproduction,while oxygen delivered from the root aerenchyma enhances methane oxidation.Studies haveshown that the diversity of these microorganisms depends on rice cultivars with some genes characterizedas harboring specific groups of microorganisms related to methane emissions.However,there is still aneed for research to determine the balance between methane production and oxidation,as rice plantspossess the ability to regulate net methane production.Various agronomical practices,such as fertilizerand water management,have been employed to mitigate methane emissions.Nevertheless,studiescorrelating agronomic and chemical management of methane with productivity are limited.Moreover,evidences for breeding low-methane-emitting rice varieties are scattered largely due to the absence ofcoordinated breeding programs.Research has indicated that phenotypic characteristics,such as rootbiomass,shoot architecture,and aerenchyma,are highly correlated with methane emissions.This reviewdiscusses available studies that involve the correlation between plant characteristics and methaneemissions.It emphasizes the necessity and importance of breeding low-methane-emitting rice varieties inaddition to existing agronomic,biological,and chemical practices.The review also delves into the idealphenotypic and physiological characteristics of low-methane-emitting rice and potential breeding techniques,drawing from studies conducted with diverse varieties,mutants,and transgenic plants.

The role of wild goose(Anser) populations of Russia and theTibet Plateau in the spread of the avian influenza virus

Wild birds of the orders Anseriformes and Charadriiformes represent a natural reservoir of low pathogenic avian influenza(LPAI) viruses(family Orthomyxoviridae).Wild geese(order Anseriformes)relating to waterfowls undertake extensive migration flights reaching thousands of kilometers.Isolation of the avian influenza virus(AIV) from wild geese is quite low or absent.The aims of this study are to monitor the AIV in different wild goose species,nesting on Russian territory and the Tibet Plateau and to analyze the derived data for the purpose of determining the role of these wild bird species in spreading pathogens.In our study 3245 samples from nine wild goose species in nine regions of Russia and on the territory of the Tibet Plateau(the Xizang Autonomous Region) were tested and no AIV were detected.Our study shows the non-essential role of wild geese in the spread of the AIV over long distances and reaches theconclusion that geese are probably not natural reservoirs for the primary viruses.However,further inquiry of AIV in wild goose populations is required.Studies of wild geese and AIV ecology will allow us to obtainmore information about pathogen-host relationships and to make arrangements for the maintenance ofwild goose populations.

Sequential disruption of ALV host receptor genes reveals no sharing of receptors between ALV subgroups A, B, and J

Background: Previously, we showed that targeted disruption of viral receptor genes in avian leukosis virus(ALV)subgroups using clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9))-based genome editing confers resistance to ALV subgroups B and J. Here, we used the same strategy to target the receptor expressed by ALV subgroup A(TVA) and generate chicken cells resistant to infection by this virus.Results: CRISPR/Cas9-based disruption of exon 2 within the tva gene of DF-1 fibroblasts conferred resistance to infection by ALV subgroup A regardless of whether frameshift mutations were introduced during editing. Conversely,overexpression of the wild-type TVA receptor(wtTVA) by tva-modified DF-1 clones restored susceptibility to ALV subgroup A. The results confirm that exon 2, which contains the low-density lipoprotein receptor class A domain of TVA, is critical for virus entry. Furthermore, we sequentially modified DF-1 cells by editing the tva, tvb, and Na^+/H^+ exchange 1(chNHE1) genes, which are the specific receptors for ALV subgroups A, B, and J, respectively.Conclusions: Simultaneous editing of multiple receptors to block infection by different subgroups of ALV confirmed that ALV subgroups A, B, and J do not share host receptors. This strategy could be used to generate cells resistant to multiple viral pathogens that use distinct receptors for cell entry.

Acquisition of pluripotency in the chick embryo occurs during intrauterine embryonic development via a unique transcriptional network

Background: Acquisition of pluripotency by transcriptional regulatory factors is an initial developmental event that is required for regulation of cell fate and lineage specification during early embryonic development. The evolutionarily conserved core transcriptional factors regulating the pluripotency network in fishes, amphibians, and mammals have been elucidated. There are also species-specific maternally inherited transcriptional factors and their intricate transcriptional networks important in the acquisition of pluripotency. In avian species, however, the core transcriptional network that governs the acquisition of pluripotency during early embryonic development is not well understood.Results: We found that chicken NANOG(c NANOG) was expressed in the stages between the pre-ovulatory follicle and oocyte and was continuously detected in Eyal-Giladi and Kochav stage I(EGK.I) to X. However, c POUV was not expressed during fol iculogenesis, but began to be detectable between EGK.V and VI. Unexpectedly, c SOX2 could not be detected during fol iculogenesis and intrauterine embryonic development. Instead of c SOX2, c SOX3 was maternally inherited and continuously expressed during chicken intrauterine development. In addition, we found that the pluripotency-related genes such as c ENS-1, c KIT, c LIN28 A, c MYC, c PRDM14, and c SALL4 began to be dramatical y upregulated between EGK.VI and VII.Conclusion: These results suggest that chickens have a unique pluripotent circuitry since maternally inherited c NANOG and c SOX3 may play an important role in the initial acquisition of pluripotency. Moreover, the acquisition of pluripotency in chicken embryos occurs at around EGK.VI to VI I.

Analysis of Indica-Japonica Differentiation in Rice Parents and Derived Lines Using ILP Markers

Revealing the indica-japonica differentiation in parents of hybridization between indica and japonica rice and their derived lines can provide theoretical and practical bases for the breeding of practical inter-subspecific hybrid rice. Using subspeciesspecific molecular markers ILP （intron length polymorphism） and Cheng＇s index, the indica-japonica differentiation was analyzed with special materials including 18 indica-japonica hybrid parents and 39 derived lines, which accumulated different wide compatibility and restoring genes by convergent cross method in 21 years spanning four breeding phases. The indica-japonica differentiation was detected on all tested loci in 57 materials. Among the 18 parental lines, 4 were japonica type, 5 japonicaclinous type, 8 indicaclinous type and one indica type. The japonica proportion indexes in indica restorer lines Minghui 63 and 9308 were 12.50 and 33.33 %, respectively, while that in japonica restorer line C418 was only 31.25%. Among the 39 derived lines from indica-japonica hybridization, one was japonica type, 11 japonicaclinous type, 20 indicaclinous type and 7 indica type. The japonica proportion index in Minghui 502 was only 10.42%. The results of indica and japonica classification by ILP molecular markers and Cheng＇s index were relatively consistent. The correlation coefficient between the japonica proportion index and morphology index was 0.794＊＊, while that between the indica proportion index and morphology index was -0.7662＊＊. ILP markers could be used to accurately detect the proportion of indica/japonica content in the genome of a rice variety. The results of indica-japonica differentiation analysis could make reasonable explanation for that the hybrids obtained from indica-japonica type restorer lines had obvious heterosis. This conclusion would provide important guidance in efficient use of beneficial genes of inter-subspecific hybrid rice.

Site-directed mutagenesis identified the key active site residues of alcohol acyltransferase PpAAT1 responsible for aroma biosynthesis in peach fruits

The aroma of peach fruit is predominantly determined by the accumulation of γ-decalactone and ester compounds.A previous study showed that the biosynthesis of these aroma compounds in peach fruit is catalyzed by PpAAT1,an alcohol acyltransferase.In this work,we investigated the key active site residues responsible for γ-decalactone and ester biosynthesis.A total of 14 candidate amino acid residues possibly involved in internal esterification and 9 candidate amino acid residues possibly involved in esterification of PpAAT1 were assessed via site-directed mutagenesis.Analyses of the in vitro enzyme activities of PpAAT1 and its site-directed mutant proteins(PpAAT1-SMs)with different amino acid residue mutations as well as the contents of γ-decalactone in transgenic tobacco leaves and peach fruits transiently expressing PpAAT1 and PpAAT1-SMs revealed that site-directed mutation of H165 in the conserved HxxxD motif led to lost enzymatic activity of PpAAT1 in both internal esterification and its reactions,whereas mutation of the key amino acid residue D376 led to the total loss ofγ-decalactone biosynthesis activity of PpAAT1.Mutations of 9 and 7 other amino acid residues also dramatically affected the enzymatic activity of PpAAT1 in the internal esterification and esterification reactions,respectively.Our findings provide a biochemical foundation for the mechanical biosynthesis ofγ-decalactone and ester compounds catalyzed by PpAAT1 in peach fruits,which could be used to guide the molecular breeding of new peach species with more favorable aromas for consumers.

Application of Cellulose Nanofibril as a Wet-end Additive in Papermaking:A Brief Review

Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceutical applications,as well as in industrial applications such as paints,drill muds,packaging,and papermaking.The application of CNF in papermaking is expected to be implemented in the near future to broaden the commercial market of cellulose.Numerous studies and patents have reported on the manufacturing,properties,and applications of nanocellulose.This present paper focuses on the recent progresses in the application of CNF as a wet-end additive in papermaking.

Whole-genome,transcriptome,and methylome analyses provide insights into the evolution of platycoside biosynthesis in Platycodon grandiflorus,a medicinal plant

Triterpenoid saponins(TSs)are common plant defense phytochemicals with potential pharmaceutical properties.Platycodon grandiflorus(Campanulaceae)has been traditionally used to treat bronchitis and asthma in East Asia.The oleanane-type TSs,platycosides,are a major component of the P.grandiflorus root extract.Recent studies show that platycosides exhibit anti-inflammatory,antiobesity,anticancer,antiviral,and antiallergy properties.However,the evolutionary history of platycoside biosynthesis genes remains unknown.In this study,we sequenced the genome of P.grandiflorus and investigated the genes involved in platycoside biosynthesis.The draft genome of P.grandiflorus is 680.1 Mb long and contains 40,017 protein-coding genes.Genomic analysis revealed that the CYP716 family genes play a major role in platycoside oxidation.The CYP716 gene family of P.grandiflorus was much larger than that of other Asterid species.Orthologous gene annotation also revealed the expansion ofβ-amyrin synthases(bASs)in P.grandiflorus,which was confirmed by tissue-specific gene expression.In these expanded gene families,we identified key genes showing preferential expression in roots and association with platycoside biosynthesis.In addition,wholegenome bisulfite sequencing showed that CYP716 and bAS genes are hypomethylated in P.grandiflorus,suggesting that epigenetic modification of these two gene families affects platycoside biosynthesis.Thus whole-genome,transcriptome,and methylome data of P.grandiflorus provide novel insights into the regulation of platycoside biosynthesis by CYP716 and bAS gene families.

Differential transcriptional regulation of the NANOG gene in chicken primordial germ cells and embryonic stem cells

Background:NANOG is a core transcription factor(TF)in embryonic stem cells(ESCs)and primordial germ cells(PGCs).Regulation of the NANOG gene by TFs,epigenetic factors,and autoregulatory factors is well characterized in ESCs,and transcriptional regulation of NANOG is well established in these cells.Although NANOG plays a key role in germ cells,the molecular mechanism underlying its transcriptional regulation in PGCs has not been studied.Therefore,we investigated the mechanism that regulates transcription of the chicken NANOG(cNANOG)gene in PGCs and ESCs.Results:We first identified the transcription start site of cNANOG by 5′-rapid amplification of cDNA ends PCR analysis.Then,we measured the promoter activity of various 5′flanking regions of cNANOG in chicken PGCs and ESCs using the luciferase reporter assay.cNANOG expression required transcriptional regulatory elements,which were positively regulated by POU5F3(OCT4)and SOX2 and negatively regulated by TP53 in PGCs.The proximal region of the cNANOG promoter contains a positive transcriptional regulatory element(CCAAT/enhancer-binding protein(CEBP)-binding site)in ESCs.Furthermore,small interfering RNA-mediated knockdown demonstrated that POU5F3,SOX2,and CEBP played a role in cell type-specific transcription of cNANOG.Conclusions:We show for the first time that different trans-regulatory elements control transcription of cNANOG in a cell type-specific manner.This finding might help to elucidate the mechanism that regulates cNANOG expression in PGCs and ESCs.

Combination of cell signaling molecules can facilitate MYOD1-mediated myogenic transdifferentiation of pig fibroblasts

Background:Myogenic transdifferentiation can be accomplished through ectopic MYOD1 expression,which is facilitated by various signaling pathways associated with myogenesis.In this study,we attempted to transdifferentiate pig embryonic fibroblasts(PEFs)myogenically into skeletal muscle through overexpression of the pig MYOD1 gene and modulation of the FGF,TGF-β,WNT,and cAMP signaling pathways.Results:The MYOD1 overexpression vector was constructed based on comparative sequence analysis,demonstrating that pig MYOD1 has evolutionarily conserved domains across various species.Although forced MYOD1 expression through these vectors triggered the expression of endogenous muscle markers,transdifferentiated muscle cells from fibroblasts were not observed.Therefore,various signaling molecules,including FGF2,SB431542,CHIR99021,and forskolin,along with MYOD1 overexpression were applied to enhance the myogenic reprogramming.The modified conditions led to the derivation of myotubes and activation of muscle markers in PEFs,as determined by qPCR and immunostaining.Notably,a sarcomere-like structure was observed,indicating that terminally differentiated skeletal muscle could be obtained from transdifferentiated cells.Conclusions:In summary,we established a protocol for reprogramming MYOD1-overexpressing PEFs into the mature skeletal muscle using signaling molecules.Our myogenic reprogramming can be used as a cell source for muscle disease models in regenerative medicine and the production of cultured meat in cellular agriculture.

Overexpression of IbSINA5 Increases Cold Tolerance through a CBF SINA-COR Mediated Module in Sweet Potato

Seven in absentia(SINA)family proteins play a central role in plant growth,development and resistance to abiotic stress.However,their biological function in plant response to cold stress is still largely unknown.In this work,a seven in absentia gene IbSINA5 was isolated from sweet potato.Quantitative real-time polymerase chain reaction(qRT-PCR)analyses demonstrated that IbSINA5 was ubiquitously expressed in various tissues and organs of sweet potato,with a predominant expression in fibrous roots,and was remarkably induced by cold,drought and salt stresses.Subcellular localization assays revealed that IbSINA5-GFP fusion protein was mainly localized in cytoplasm and nucleus.Overexpression of IbSINA5 in sweet potato led to dramatically improved resistance to cold stress in transgenic plants,which was associated with the up-regulated expression of IbCOR(cold-regulated)genes,increased proline production,and decreased malondialdehyde(MDA)and H2O2 accumulation in the leaves of transgenic plants.Furthermore,transient expression of IbCBF3,a C-repeat binding factor(CBF)gene,in the leaf protoplasts of wild type sweet potato plants up-regulated the expression of both IbSINA5 and IbCOR genes.Our results suggest that IbSINA5 could function as a positive regulator in the cold signaling pathway through a CBF-SINA-COR mediated module in sweet potato,and have a great potential to be used as a candidate gene for the future breeding of new plant species with improved cold resistance.

The influence of environmental factors on species composition and distribution in a community forest in Northern Thailand

Understanding the environmental factors that influence tree species composition is essential for successful management of biodiversity and sustainable use of community forest resources.This study aims to assess tree species composition and distribution in the deciduous Ban Mae Chiang Rai Lum Community Forest in Northern Thailand and to analyze the influence of environmental factors on tree biodiversity in the forest.We conducted a stratified systematic sampling of the forest’s total area of 3925 ha,and twenty-five 0.16 ha survey plots were established in three different stands of the deciduous forests to estimate and characterize the difference in biological diversity among the stands.Canonical correspondence analysis(CCA)was used to investigate the environment factors affecting such differences in biodiversity of the stands.The results showed a high diversity of trees in the forest as 197 species,144 genera,and 62 plant families were recorded.The CCA ordination identified the environmental factors—the most important of which were elevation,distance to streams,soil moisture,organic matter,and distance to communities—that signifi-cantly influenced the diversity and distribution of tree species(p<0.05)in the community forest.Our findings indicate that the implementation of drought reduction measures such as building check dams,fire protection,and monitoring community forest-product usage would be recommended to further biodiversity conservation and the sustainable use of community forest resources.

DNA polymorphisms and genetic relationship among populations of Acacia leucophloea using RAPD markers

RAPD （randomly amplified polymorphic DNA） markers were employed to characterize polymorphisms among 5 provenances of Acacia leucophloea and to detect genetic relatedness of the species with 6 other acacias （A. holosericea, A. auriculiformis, A. mangium, A. dealbata, A. ferruginea, and A. nilotica） widely grown in India. Of 194 markers scored for the provenances, 29.38% exhibited polymorphism. Also, 326 markers were generated among 7 species of Acacia, accounting for 55.82% of the polymorphisms. The fifteen 10-mer primers employed were capable of producing 1-8 polymorphic bands for the provenances, and 6-17 for all seven species of Acacia. The genetic similarity coefficient based on Jaccard＇ s coefficient revealed that provenances Thirumangalam and Dharmapuri were closely related. The dendrogram based on a sequential agglomerative hierarchical non-overlapping （SAHN） clustering analysis grouped 4 provenances of A. leucophloea （Dharapuram, Thirumangalam, Pudukottai and Dharmapuri） into one cluster and the other provenance, Sendurai, into a separate cluster. The genetic similarity matrix for 7 Acacia species showed that A. nilotica and A. dealbata were distantly related, while A. holosericea and A. ferruginea were very closely related. Cluster analysis grouped the species of Acacias into 3 major groups of which A. dealbata alone formed a separate group. The RAPD markers generated 36 provenance-specific markers and 162 species-specific markers that could have strong applications for species identification and tree breeding programs for A. leucophloea and for other Acacia species included in this study.