Research Advances in Stem Bleeding Disease of Cocos nucifera L.

Stem bleeding disease of coconut(Cocos nucifera L.)is an important disease in main coconut producing areas in China.This article reviews taxonomic status and biological characteristics of Ceratocystis paradoxa,as well as the occurrence regularity,pathogenic factors,propagation path and integrated control methods of stem bleeding disease of coconut.The main problems in the study of stem bleeding disease are summarized,and the future research directions are prospected.

Coconut based multiple cropping systems:An analytical review in Sri Lankan coconut cultivations

Coconut(Cocos nucifera L.)is a gift of nature and is cultivated worldwide because of its multiple uses.Based on the morphological characteristics of the coconut tree,when coconut is grown as a monocrop,land use efficiency is very low.According to previous findings,coconut monocropping planting systems and growth habits effectively used only 22%of the land area,while canopy space utilization was around 30%,and solar radiation was around 45%.Growing coconut along with a variety of other crops is a common practice in most coconut-growing regions to maximize land use efficiency.More than 100 different crops and systems have been identified that can be grown as intercrops with coconut cultivations.When growing intercrops in coconut plantations,the following factors need to be considered;the age of the coconut palms,water availability,shade of understory,soil characteristics,the slope of the land,labor availability,market demand,economic status of the grower,and social characteristics.This article discusses the significance and potential of intercropping and multiple-cropping systems appropriate for various coconut stands.The findings highlight an overview of profitable and sustainable intercrop species for coconut farming,as well as the benefits,constraints,and opportunities associated with various multiple-cropping systems.Finally,the study provides future research directions for the successful adaptation of coconut-based multiple cropping systems.

A sustainable way of increasing productivity of coconut cultivation using cover crops:A review

Coconut,as one of the main components of the daily Sri Lankan diet and one of the predominant crops grown in different agroecological zones except in higher elevations,has become a major export-earning crop.Its productivity is limited by adverse climatic changes in coconut growing areas,biotic and abiotic stresses,and poor agronomic practices.Cover cropping has been identified as a rewarding and time-tested farming solution that increases the productivity of most coconut land while addressing the above issues.It is the practice of growing plants for modifying soil properties,controlling pests and diseases,facilitating crop growth and yield,reducing chemical dependency,enabling the coconut-animal farming system,and generating extra profit.Legumes,fodder and pasture grasses have been identified as the common and trending cover crops for Sri Lanka.Comprehensive knowledge of selecting suitable cover crops,planting materials and proper agronomic practices are important for a successful cover cropping system under coconut.Farmers avoid this practice due to their ignorance on cover cropping,and its benefits,and due to the aggressive characteristics of cover crops such as reappearing behaviour,being an alternative host for pathogens,and competitiveness for natural resources.In this review,the unique attributes of common cover crop species are explained.Furthermore,the variety of on-farm benefits and ecosystem services of cover cropping and some important agronomic considerations are reviewed.Finally,future research potential for recommending new species and their adaptability to a wide range of ecological and ecosystem circumstances under coconut cultivation are investigated.

Genetic diversity, population structure, and genome-wide association analysis of ginkgo cultivars

Ginkgo biloba is an economically valuable tree worldwide.The species has nearly become extinct during the Quaternary,which has likely resulted in reduction of its genetic variability.The genetic variability is now conserved in few natural populations in China and a number of cultivars that are,however,derived from a few ancient trees,helping the species survive in China through medieval times.Despite the recent interest in ginkgo,however,detailed knowledge of its genetic diversity,conserved in cultivated trees and cultivars,has remained poor.This limits efficient conservation of its diversity as well as efficient use of the existing germplasm resources.Here we performed genotyping-by-sequencing(GBS)on 102 cultivated germplasms of ginkgo collected to explore their genetic structure,kinship,and inbreeding prediction.For the first time in ginkgo,a genome-wide association analysis study(GWAS)was used to attempt gene mapping of seed traits.The results showed that most of the germplasms did not show any obvious genetic relationship.The size of the ginkgo germplasm population expanded significantly around 1500 years ago during the Sui and Tang dynasties.Classification of seed cultivars based on a phylogenetic perspective does not support the current classification criteria based on phenotype.Twenty-four candidate genes were localized after performing GWAS on the seed traits.Overall,this study reveals the genetic basis of ginkgo seed traits and provides insights into its cultivation history.These findings will facilitate the conservation and utilization of the domesticated germplasms of this living fossil plant.

A high-quality genome assembly of Morinda officinalis,a famous native southern herb in the Lingnan region of southern China

Morinda officinalis is a well-known medicinal and edible plant that is widely cultivated in the Lingnan region of southern China.Its dried roots(called bajitian in traditional Chinese medicine)are broadly used to treat various diseases,such as impotence and rheumatism.Here,we report a high-quality chromosome-scale genome assembly of M.officinalis using Nanopore single-molecule sequencing and Hi-C technology.The assembled genome size was 484.85Mb with a scaffold N50 of 40.97 Mb,and 90.77%of the assembled sequences were anchored on eleven pseudochromosomes.The genome includes 27,698 protein-coding genes,and most of the assemblies are repetitive sequences.Genome evolution analysis revealed that M.officinalis underwent core eudicotγgenome triplication events but no recent whole-genome duplication(WGD).Likewise,comparative genomic analysis showed no large-scale structural variation after species divergence between M.officinalis and Coffea canephora.Moreover,gene family analysis indicated that gene families associated with plant–pathogen interactions and sugar metabolism were significantly expanded in M.officinalis.Furthermore,we identified many candidate genes involved in the biosynthesis of major active components such as anthraquinones,iridoids and polysaccharides.In addition,we also found that the DHQS,GGPPS,TPS-Clin,TPS04,sacA,and UGDH gene families—which include the critical genes for active component biosynthesis—were expanded in M.officinalis.This study provides a valuable resource for understanding M.officinalis genome evolution and active component biosynthesis.This work will facilitate genetic improvement and molecular breeding of this commercially important plant.

Influence of Boric Acid and Sucrose on the Germination and Growth of Areca Pollen

This study investigates the effect of boric acid and sucrose on the germination and growth of Areca catechu L (areca palm). Using areca pollen from Hainan, China, this study determines the influence of culture media with different concentrations of boric acid and sucrose on the germination and growth of areca pollen. Results show that the germination and growth of the pollen tube growth are highest under a boric acid concentration of 0.4 g/L to 0.6 g/L. The germination rate of areca pollen is highest in solid medium with a sucrose concentration of 40 g/L. The optimum culture medium for developing areca pollen comprises 5 g/L agar, 0.4 g/L to 0.6 g/L boric acid, 40 g/L sucrose, and water. Furthermore, areca pollen grows most rapidly approximately 1.5 h after in vitro cultivation at normal temperature, and growth stabilizes at approximately 3 h. The principle that governs the development of areca pollen is also discussed.

Identification and characterization of MeERF genes and their targets in pathogen response by cassava(Manihot esculenta)

Cassava,Manihot esculenta Crantz (Me),is a major dietary source of calories for over 700 million people in tropical regions.The production of cassava is constantly threatened by cassava bacterial blight (CBB),caused by Xanthomonas axonopodis pv.manihotis (Xam).The gene resources for CBB-resistant breeding of cassava are limited.In model plant species,ethylene response factors play important roles in response to pathogen infection.In this study,cassava ethylene response factors (MeERFs) were identified and characterized as the first step in studying their potential for CBB-resistant breeding of cassava.In the cassava genome 155 MeERFs were identified,of which 23 were induced by Xam infection.The promoter regions of204 genes harbored GCC-box that had the potential to interact with MeERFs.Using 37 transcriptomes derived from Xam infection treatment,four gene co-expression modules for the MeERFs and GCC-box containing genes were constructed.Six MeERFs were associated with two GCC-box containing genes:transcription initiation factor TFIIE subunit beta (MeTFIIE),and histone-lysine N-methyltransferase ASHR1 (MeASHR1).Dual-luciferase reporter assays showed that MeERF10 and MeERF58 positively regulated Me TFIIE;MeERF137 negatively regulated Me TFIIE;MeERF10 and MeERF137 positively regulated Me ASHR1;and MeERF35 negatively regulated Me ASHR1.The four MeERFs may mediate pathogen response by regulating the expression of the two GCC-box containing genes.

Preparation and Regeneration Conditions of Ceratocystis paradoxa Protoplast

[Objective]The paper was to reveal the preparation and regeneration conditions of Ceratocystis caradoxa protoplast.[Method]Using multi-factors orthogonal test,the effects of hypha age,enzyme system,time of hydrolysis,hydrolysis temperature,osmotic pressure stabilizer and regeneration medium on C.paradoxa protoplast were studied.[Result]The optimum condition for preparing protoplast were conidia cultured in liguid SYM medium for 24 h,enzyme mixture of 1%driselase and 1%lytic enzyme used to digest hypha for 1.5 h,0.7 mol/L MgSO4·7H2O used as osmotic stabilizer,or individual enzyme 1%driselase used to digest hypha for 1.5 h,1.0 mol/L mannitol as osmotic stabilizer.The regeneration rate was over 40%under C.paradoxa protoplast regenerating on CM medium with mannitol and hydrolysis for 2 h.[Conclusion]Higher protoplast yield and higher regeneration rate could be obtained under above conditions,which is beneficial for transformation and further research.

Characterization of wavy root 1,an agravitropism allele,reveals the functions of OsPIN2 in fine regulation of auxin transport and distribution and in ABA biosynthesis and response in rice(Oryza sativa L.)

Root system architecture is influenced by gravity.How the root senses gravity and directs its orientation,so-called gravitropism,is not only a fundamental question in plant biology but also theoretically important for genetic improvement of crop root architecture.However,the mechanism has not been elucidated in most crops.We characterized a rice agravitropism allele,wavy root 1(war1),a loss-of-function allele in OsPIN2,which encodes an auxin efflux transporter.With loss of OsPIN2 function,war1 leads to altered root system architecture including wavy root,larger root distribution angle,and shallower root system due to the loss of gravitropic perception in root tips.In the war1 mutant,polar auxin transport was disrupted in the root tip,leading to abnormal auxin levels and disturbed auxin transport and distribution in columella cells.Amyloplast sedimentation,an important process in gravitropic sensing,was also decreased in root tip columella cells.The results indicated that OsPIN2 controls gravitropism by finely regulating auxin transport,distribution and levels,and amyloplast sedimentation in root tips.We identified a novel role of OsPIN2 in regulating ABA biosynthesis and response pathways.Loss of OsPIN2 function in the war1 resulted in increased sensitivity to ABA in seed germination,increased ABA level,changes in ABA-associated genes in roots,and decreased drought tolerance in the seedlings.These results suggest that the auxin transporter OsPIN2 not only modulates auxin transport to control root gravitropism,but also functions in ABA signaling to affect seed germination and root development,probably by mediating crosstalk between auxin and ABA pathways.

Syntheses,Structures of A Cobalt(Ⅱ) Metal-organic Framework Based on 2,6-di(2',4'-dicarboxylphenyl) pyridine and 4,4'-bis(imidazol-1-ylmethyl) biphenyl-ligands

[Objectives]The paper was to synthesize and describe a new 3D structure of a mew metal organic framework,and to provide new materials for the study of interdisciplinary.[Methods]A mixture of H_(4)L=2,6-di(2,4-dicarboxylphenyl)pyridine,bimb=4,4-bis(imidazole-1-ylmethyl)biphenyl,Co(NO_(3))_(2)·6H_(2)O were added to the solution of DMF∶H_(2)O=4∶2 and heated at 433 K for 4 d.[Results]Purple block crystals of the Co-compound were obtained(yield 83.6%,based on Co).[Conclusions]The crystal data are obtained as follows:C_(51)H_(36)Co_(2)N_(7)O_(9),Triclinic,P-1,a=9.916(8),b=15.926(14),c=15.945(13),α=113.913(13)°,β=93.929(9)°,γ=95.033(3)°,V=2278(3)A^(3),Z=2,R=0.0803(6446),wR_(2)=0.2106(10370),T=296 K.

Neofusicoccum parvum Causing Leaf Spot of Camellia drupifera in China

[Objectives]The study was to identify the causal agent of leaf spots of Camellia drupifera in Hainan Province,China.[Methods]Phylogenetic analyses,spore morphology and pathogenicity tests were adopted to identify the pathogen.[Results]The fungus was identified as Neofusicoccum parvum.The colonies were initially pale to white on PDA,with diffuse yellow pigment around the colonies in the agar after 5 d.After 10 d,the aerial mycelium became gray,and the substrate mycelium became black.Thirty days later,a large number of conidia were generated on OMA.Conidia were hyaline,nonseptate,and fusiform.The mean size of 100 conidia was(13.6-25.4)×(6.2-10.3)μm;the mean length/width ratio was(2.5±0.3)μm.[Conclusions]N.parvum was the causal agent of leaf spots of C.drupifera observed in Hainan Province,China.

Preparation and Characterization of Nano-ZnO Precursor for the Antibacterial Activity against Thielaviopsis paradoxa

[Objectives]The paper was to explore a new method for preparing nano ZnO particles.[Methods]A mixture of 2,6-di(2′,4′-dicarboxylphenyl)pyridine(0.05 mM),Zn(NO_(3))2·6H_(2)O(0.1 mM)were added to the solution of DMA(3 mL)and H_(2)O(3 mL),and heated at 90℃for 12 h.The PXRD,TGA and fluorescence properties were characterized.[Results]Transparent block crystals of the[Zn_(2)(2,6-ddpp)(DMA)_(3)(H_(2)O)·H_(2)O]n were obtained(yield 85.4%,based on Zn).The Zn-MOF framework would collapse to form ZnO particles when the temperature exceeded 350℃.[Conclusions]A new Zn(II)-MOF is successfully constructed,and the compound exhibits monoclinic P21/c space group.The results will provide a theoretical basis for the preparation of nano ZnO.

Crystal Structure of Poly[(2,6-di(2’,4’-dicarboxylphenyl)pyridine-κ4 O:O′:O″:O′′′)-(μ2-1,4-bis(1-imidazolyl)benzene-κ2N:N’)cobalt(II)],C_(39)H_(24)Co_(2)N_(7)O_(8)

[Objective]The paper was to synthesize a new structure of metal organic framework,and to provide new materials for plant pathogens testing.[Method]A mixture of 2,6-di(2’,4’-di-carboxylphenyl)pyridine,1,4-bis(1-imidazolyl)benzene,Co(NO_(3))2·6H_(2)O were added to the solution of DMF:H2O=3:3 and heated at 433K for 4 d.[Result]Red crystals of the title compound were obtained(yield 76.3%,based on Co).[Conclusion]The crystal data were obtained as follows:C_(39)H_(24)Co_(2)N_(7)O_(8),monoclinic,P21/c,a=16.222(7)A,b=12.653(5)A,c=17.456(7)A,β=102.386(6)°,V=3500(2)A_(3),Z=4,Rgt(F)=0.0550,wRref(F2)=0.1509,T=293(2)K.

Detection and Identification of Phytoplasma of Cleome rutidosperma in Areca Palm Yellow Leaf Disease Field

[Objectives]The paper was to detect and identify the phytoplasma of Cleome rutidosperma in areca palm yellow leaf disease(YLD)field in Wenchang City,Hainan Province,China.[Methods]The nested PCR technique was employed to amplify the phytoplasma 16S rDNA of C.rutidosperma samples,followed by sequence analysis.Concurrently,this study examined C.rutidosperma in YLD field,collecting symptomatic leaves for phytoplasma detection.[Results]The 16S rDNA sequence of the C.rutidosperma witches'-broom phytoplasma was found to be identical to that of the HNWC5 strain associated with areca palm yellows phytoplasma,leading to the identification of this phytoplasma as belonging to the 16SrII-A subgroup.Field investigations revealed a higher incidence of C.rutidosperma in areca palm fields,with symptoms of leaf yellows observed in six of these fields.Quantitative PCR(qPCR)analysis confirmed the presence of phytoplasma infection in these instances.[Conclusions]Through the analysis of geographical distribution,sequence alignment,and field occurrence data,a significant correlation has been identified between witches'broom disease and YLD.It is proposed that the former may act as an intermediate host for the areca palm yellows phytoplasma.

The effect of biochar on mycorrhizal fungi mediated nutrient uptake by coconut(Cocos nucifera L.)seedlings grown on a Sandy Regosol

Biochar amendment of soil may ameliorate inherently infertile soils,such as in the typical coconut(Cocos nucifera L.)growth areas along tropical coasts,where,moreover,temporary moisture stress commonly occurs.We conducted a pot experiment to evaluate the effects of biochar soil amendment(1%w/w)produced from Gliricidia sepium stems(BC-Gly)and rice husks(BC-RiH)on the growth of coconut seedlings and on N and P uptake mediated by mycorrhizae under wet or dry conditions in a Sandy Regosol.The pots were divided into root and hyphal zones by a nylon mesh,where 15N labelled N and P nutrients were only provided in the hyphal zone.Under wet conditions,biochar applica-tion did not affect plant growth,while under dry conditions,the BC-Gly increased root and plant growth similar to that under wet conditions.BC-Gly increased the acidic pH of the soil to a neutral level,and the microbial community shifted towards a higher fungal abundance.The P accumulated(Pacc)in roots was higher with BC-Gly and BC-RiH under dry and wet conditions,respectively.Pacc weakly correlated with the abundance of arbuscular mycorrhizal fungi(AMF)in the hyphal zone.With BC-Gly roots showed lower N derived from fertilizer.We conclude that biochar application has no impact on crop growth under wet conditions,while under dry conditions,BC-Gly stimulates crop growth and P uptake,probably through liming induced P availability but also possibly by some enhancement of AMF growth.The shift in the fungal-oriented microbial community and reduced plant fertilizer N uptake suggested that BC-Gly acted as an additional N source.

Comparison of blood glucose responses by cane sugar(Saccharum offi cinarum)versus coconut jaggery(Cocos nucifera)in type 2 diabetes patients

Type 2 diabetic mellitus is a predominant metabolic disorder that has a direct impact on human health.Although scientific data are deficit,coconut jaggery has been suggested as a better alternative for cane sugar by some individuals.This study was conducted to assess the credibility of this claim.Coconut jaggery was prepared at Coconut Research Institute,Sri Lanka and nutritional composition of coconut jaggery was compared with cane sugar using standard methods.Significantly higher(P<0.05)moisture(8.92±0.22)%,ash(2.09±0.33)%,protein(1.91±0.28)%,fat(0.14±0.02)%and fiber(0.05±0.03)%contents were observed in coconut jaggery compared to cane sugar.The total starch and total sugar content of the coconut jaggery was significantly(P<0.05)lower than that of the cane sugar.Forty-three patients(Male:16,Female:27)with type 2 diabetes from the Endocrinology unit,National Hospital Colombo,Sri Lanka were voluntarily engaged in the study,subjected to an initial health screening.Then,determination of postprandial blood glucose responses after intake of the standard(glucose),cane sugar and coconut jaggery.Average age of the selected group was(48.19±7.95)years and they were all overweight(BMI>23.0).The mean fasting blood glucose level and HbA1c of the subjects were(149.05±54.88)mg/dL and(9.170±2.022)%,respectively.There was no significant difference(P>0.05)in peak blood glucose concentrations or incremental area under the curve in blood glucose response of two test food.Therefore,coconut jaggery cannot be considered as a healthy substitute for cane sugar in type 2 diabetic patients.

Activity-density and spatial distribution of termites on a fine-scale in a tropical rainforest in Xishuangbanna,southwest China

The community composition and activity-density of termites can influence nutrient cycling and other ecological functions.However,the spatial distribution and the activity-density of termites on a fine-scale in tropical forests are still unknown.We checked the spatial distribution patterns of the feeding groups and species of termites and their co-occurrence pattern in a 1-ha(100 m×100 m)plot,and their correlatiion with the environmental factors.We used a standard protocol to collect termite assemblages and classified them into five feeding groups based on their preferrred diet:fungus growers,litter feeders,soil feeders,soil-wood feeders,and wood feeders.We measured the environmental factors:soil pH,litter mass,aboveground plant biomass,and topographic position index(TPI).Soil-wood feeders showed the highest activity-density,followed by wood feeders,fungus growers,soil feeders,and litter feeders.Soil-wood feeders and fungus growers demonstated a strong correlation while litter feeders showed weak correlations with other feeding groups.Termite feeding groups and most of the termite species displayed a positive association with the high TPI and the low soil pH patches.Our results indicated that the examined environmental factors influenced the termite community assemblages and distribution patterns on a fine-scale in tropical rainforests.