Molecular Diagnosis and Evolutionary Relationship Analysis Of Plant Parasitic Tea Garden Nematodes From Different Tea Estates In Sylhet Region of Bangladesh

Nematodes from plant-parasitic sources are ever-present and incidental to plant growth as well as crop production. The damage of tea gardens caused by nematode is often non-specific and easily confused with symptoms. The present study determined the parasitic and non-parasitic nematodes population in different tea gardens of the Sylhet region by their morphological and partial molecular characterization. Out of 13 tea gardens, it was observed that BTRI, Karimpur, Mathiura, and Tarapur tea garden has the highest number of parasitic and non-parasitic nematodes. After PCR amplification, DNA bands with desired amplicon size were detected by gel electrophoresis. Among thirteen soil samples, nematodes from Malnichara, Karimpur, BTRI, Mathiura , and Finlay had partially confirmed the presence of rootknot nematode (Meloidogyne spp.), root-lesion nematode (Pratylenchus brachyurus), burrowing nematode (Radopholus similis), reniform nematode (Rotylenchulus reniformis) and lance nematode (Hoplolaimus columbus) consequently based on approximately base pair of 1.7, 1.1 and 0.52 kb (different Meloidogyne spp.) 0.52, 0.52, 0.25 and 2.3 kb of specific genes. From evolutionary analysis, it might be said that Meloidogyne species are strongly related with each other making clusters except Meloidogyne natalie where this one is closely related with Hoplolaimus columbus in their evolutionary relationship as remaining others (Rotylenchulus reniformis, Radopholus similis, Pratylenchus brachyurus) are in different clusters in the same clade and this result could be confirmed after sequencing. J. Bio-Sci. 29(1): 101-109, 2021 (June)

First genomic resource of the Columbia lance nematode Hoplolaimus columbus

The Columbia lance nematode Hoplolaimus columbus has been reported frequently from North America due to its negative impact on agricultural production. In this study, for the first time, we sequenced the whole genome of a female specimen by using whole-genome-amplification and Illumina MiSeq. Data were <I>de novo </I> assembled to form scaffolds of 205.75 Mbp consisting of 118,374 contigs. The largest scaffold was 636,881 bp. BUSCO completeness was 66.6% (eukaryotic dataset), and over 8,000 unique genes were predicted by GeneMark-ES. A total of 61,855 protein sequences were predicted by AUGUSTUS, and 10,085 of them were annotated by PANNZER2 with at least one function. These data will provide valuable resources for studies focusing on pathogenicity and phylogenomics of plant-parasitic nematodes.

Hoplolaimus columbus: a prime candidate for site-specific management in cotton and soybean production.

This paper focuses on the economic importance, host range, geographical distribution, damage symptoms and biology and life cycle of Hoplolaimus columbusinfesting cotton and soyabean in South Carolina, USA. Information on this pest to other nematodes and pathogens, the efficacy and optimization of some recommended integrated nematode management strategies and future outlook and research requirements in nematode control are also presented.

Distribution of Hoplolaimus Species in Soybean Fields in South Carolina and North Carolina

Hoplolaimus columbus is an important nematode pest of soybean in South Carolina and North Carolina. Tolerant cultivars are available for the management of this plant-parasitic nematode; however, variation in the response of soybean cultivars to H. columbus populations has been observed. This variation may be due to the presence of different species or high genetic diversity of H. columbus populations. The objective of this study was to identify the Hoplolaimus spp. present in fields representing the main soybean-growing regions in South Carolina and North Carolina and to examine the genetic variability of these populations. In South Carolina, the only species found associated with soybean was H. columbus but, in North Carolina, H. stephanus was the dominant species. The two species were never found together. Genetic variability analyses of a mitochondrial and a nuclear marker showed that only one haplotype was shared by the H. columbus populations. H. stephanus showed higher genetic variability, with private haplotypes per sampling location. Knowledge of the distribution and genetic variability of these two Hoplolaimus spp. is valuable to growers to determine potentially damaging infestations of these plant-parasitic nematodes in soybean fields.

Hoplolaimus columbus. [Distribution map].

A new distribution map is provided for Hoplolaimus columbus Sher Nematoda: Hoplolaimidae Hosts: Cotton (Gossypium hirsutum), soyabean (Glycine max), and sugarcane (Saccharum officinarum). Information is given on the geographical distribution in ASIA, India, Orissa, Pakistan, AFRICA, Egypt, NORTH AMERICA, USA, Alabama, Florida, Georgia, Louisiana, North Carolina, South Carolina, Texas, CENTRAL AMERICA & CARIBBEAN, Trinidad and Tobago.

Cotton Tolerance to Hoplolaimus columbus and Impact on Population Densities

Glyphosate-tolerant transgenic-cotton cultivars were evaluated for tolerance to Hoplolaimus columbus in field experiments conducted from 2001 to 2003. The studies were arranged in a split-plot design that included treatment with 1,3-dichloropropene at 42 liter/ha to establish fumigated versus nonfumigated subplots with cultivars as whole plots. Cotton cultivars were divided by relative maturity into two separate but adjacent experiments in order to facilitate cotton defoliation, with 10 early-maturity and 5 late-maturity cultivars. Fumigation was effective in suppressing H. columbus population densities and increased cotton lint yield. The cultivar-fumigation interaction was significant for early-season cotton cultivars but not for late-season cultivars. A tolerance index ([yield of nontreated/yield of treated] × 100) was used to compare cultivar differences. Both groups of cultivars expressed significant levels of tolerance to H. columbus, but late-season cultivars tended to yield more than early-season cultivars in infested fields.

Effects of Rate and Time of Application of Poultry Litter on Hoplolaimus columbus on Cotton

Field experiments were conducted to evaluate the effect of soil-incorporated poultry litter on the population dynamics of Hoplolaimus columbus and cotton lint yield. Rates of poultry litter applied varied from 0.0 to 27.0 t/ha and were applied in December, February, or March. Time of application did not influence population densities of this nematode or cotton yield. The rate of poultry litter applied was negatively related to the population density of H. columbus at midseason, but not at other sampling dates. The lower midseason levels of this nematode corresponded with increases in cotton lint yield in all experiments. Cotton yield increases generally were linear with respect to the rate of litter applied, although the highest rates of litter applied did not always result in the greatest cotton yield. Poultry litter can be used effectively to supply nutrients to the crop and suppress damaging levels of H. columbus. Optimal rates of litter application were from 6.0 to 13.4 t/ha. Application of poultry litter at these rates, however, may exceed nutrient levels required for best management practices.