Hanwen Wu - Academia.edu (original) (raw)

Papers by Hanwen Wu

Mitochondrial DNA Part B

Nassella trichotoma is one of the most serious weed species in Australia. It is often confused wi... more Nassella trichotoma is one of the most serious weed species in Australia. It is often confused with other Nassella and stipoid species, especially at the young seedling stage, adding another layer of complexity in effective weed management. We report here the complete chloroplast genome of N. trichotoma (137,568 bp, GenBank accession number {"type":"entrez-nucleotide","attrs":{"text":"KX792500.2","term_id":"1559905670","term_text":"KX792500.2"}}KX792500.2) sequenced using Next Generation Sequencing technology (Illumina). The N. trichotoma was grouped closely with other Nassella species and separated from other Stipeae species in the phylogenetic tree constructed based on the complete chloroplast genome sequences. The sequence information could be used for further identification of novel DNA barcodes for correct weed identification and subsequently improve management of this invasive grass.

The problematic weed silverleaf nightshade (Solanum elaeagnifolium Cav.) was introduced to Austra... more The problematic weed silverleaf nightshade (Solanum elaeagnifolium Cav.) was introduced to Australia during the early 20th century from North America and has since emerged as a Weed of National Significance. This species is almost impossible to eradicate after establishment, with its management in areas of new emergence therefore much aided by prompt identification and early action. Identification of the weed is often confounded because of the weed’s remarkable similarity (especially pre-floral stages) to a variety of native Solanum species. DNA barcoding for improved identification may therefore improve its management. Sequences of the nuclear waxy gene and two chloroplast genes (matK and trnL-trnF) were compared among S. elaeagnifolium (N = 12) and 10 native species (S. brownii, S. centrale, S. coactiliferum, S. esuriale, S. jucundum, S. lasiophyllum, S. lithophyllum, S. petrophilum, S. quadriloculatum and S. sturtianum) with which the weed is commonly confused. A further five spe...

The genus Nassella contains many economically and environmentally important weed species in Austr... more The genus Nassella contains many economically and environmentally important weed species in Australia, such as Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock) and Nassella neesiana (Trin. & Rupr.) Barkworth (Chilean needle grass), which are both Weeds of National Significance (WoNS). Availability of Nassella chloroplast genome sequences can provide a versatile tool for identifying novel gene targets for DNA barcoding of these weeds species. We report here the first chloroplast genome of Nassella (N. trichotoma) obtained through de novo assembly of Illumina paired-end reads produced by total DNA sequencing. The N. trichotoma chloroplast genome is 112,102 bp in size, encodes 140 genes including 99 protein-coding genes, 37 tRNA genes and 4 ribosofmal RNA genes. The total size of intergenic regions within the genome is up to 48,764 bp. The total GC content of the genome is 37.88%, which is relatively lower than that of the reported genomes within the Stipeae tribe. A com...

Chilean needle grass (Nassella neesiana [Trin. & Rupr.] Barkworth) and serrated tussock (Nassella... more Chilean needle grass (Nassella neesiana [Trin. & Rupr.] Barkworth) and serrated tussock (Nassella trichotoma [Nees] Hack. ex Arechav.) are related Weeds of National Significance (WoNS) undergoing rapid range expansion in Australia. They are difficult to distinguish from native tussock grasses and emergences of these weeds often remain undetected until after they have established as difficult to control populations. Genetic diagnostics using loop-mediated isothermal amplification (LAMP) may provide a simple cost-efficient means for rapid identification of these weeds, under laboratory and field conditions. Provision of LAMP diagnostics would assist in minimising the time-lag to initial recognition of tussock weed outbreaks in new areas, and subsequently improve the time to response for eradication of the weeds where they are recently emergent. Here we report laboratory development and tests of seven LAMP assays incorporating novel primer suites matched to species-specific DNA barcode...

Mitochondrial DNA Part B, 2017

Nassella neesiana (Chilean needle grass) is a serious weed in Australia, and has been included in... more Nassella neesiana (Chilean needle grass) is a serious weed in Australia, and has been included in the list of Weeds of National Significance (WoNS). We present here, the complete chloroplast sequence of N. neesiana reconstructed from Illumina whole genome sequencing. The complete chloroplast sequence is 137,700 bp in size, and has similar gene content and structure as other published chloroplast genomes of Stipeae. The N. neesiana chloroplast genome is deposited at GenBank under accession number MF480752.

In 2014 and 2015, replicated field trials were performed at commercial paddocks in moderate to lo... more In 2014 and 2015, replicated field trials were performed at commercial paddocks in moderate to low rainfall zones at Wagga Wagga and Condobolin NSW, respectively. In 2014, a total of 11 winter wheat cultivars (Triticum aestivum L.) representing four major breeding family lines grown in Australia were evaluated with 13 cultivars assessed in 2015. At each site, crop and/or weed growth were monitored at various stages of growth: early season (tillering), vegetative, grain filling, harvest and post-harvest. Significant differences between wheat cultivar and location were observed for crop biomass, early vigour, leaf area index (LAI), weed number, weed biomass, canopy architecture and yield in both 2014 and 2015. Differences in weed suppression were largely impacted by crop architecture and phenology early in the growing season. Cultivar competitive traits were also influenced by both genotype and environmental factors, as shown by clear differences in cultivar performance, yield and wee...

Frontiers in Agronomy, 2021

Witchgrass (PanicumcapillareL.) is a summer growing grass weed species and is increasing its prev... more Witchgrass (PanicumcapillareL.) is a summer growing grass weed species and is increasing its prevalence in southern Australia. A better understanding of the seed biology is needed to effectively manage this weed. A series of field and laboratory studies were conducted to determine seed germination factors, field emergence patterns, and soil seedbank longevity. Witchgrass germination was stimulated by light and it germinated better at temperature over 20°C, with 93–100% germination at the two constant temperatures of 20 and 30°C, and the two alternating day/night temperatures of 30/25 and 35/25°C. It is highly tolerant to moisture stress at germination, with 2–7% germination even at −0.48 Mpa. Witchgrass seed lost 47–68% viability after 12 months of burial in the soil, however the seed persisted for more than 4 years if buried at 10 cm in the soil. Witchgrass emergence in southern New South Wales (NSW) commenced in mid spring (early October), with peak emergence of 63–83% in November...

Phytoparasitica, 2021

Herbicide resistance in weeds necessitates the continued monitoring of herbicide resistance evolu... more Herbicide resistance in weeds necessitates the continued monitoring of herbicide resistance evolution in weed species. This study investigated the level of paraquat resistance in two species of Conyza including Conyza sumatrensis (Retz.) E. Walker (tall fleabane) and Conyza bonariensis (L.) Cronquist (flaxleaf fleabane). Twenty-two biotypes of C. bonariensis and three biotypes of C. sumatrensis were screened for paraquat resistance evaluation. All tested biotypes of C. bonariensis were susceptible to paraquat at the recommended rate of 500 g a.i./ha. Whole plant dose–response assays showed that the two biotypes (TF-COLEA and TF-NANDI) of C. sumatrensis are resistant to the herbicide paraquat, with a ED 50 more than fourfold that of the susceptible biotype (TF-TALWD). The two resistant biotypes also showed a hormetic growth increase at two lower doses (62.5 and 125 g a.i./ha) of paraquat, resulting in 31% and 17% higher biomass production at 62.5 g a.i./ha of paraquat, and 19% and 11% at 125 g a.i./ha of paraquat for the resistant biotypes TF-NANDI and TF-COLEA, respectively, than those of the untreated control. The two resistant biotypes at the two lower doses of paraquat generated 33% to 65% higher numbers of seed buds/plant in TF-COLEA and 40% to 68% in TF-NANDI compared to the untreated control. Such stimulatory responses to lower rates of paraquat can enhance the competitiveness of these resistant plants against neighboring weed and crop plants, potentially increasing the seedbank size of resistant biotypes.

Weed Science, 2018

Prairie groundcherry [Physalis hederifolia (A. Gray) var. fendleri (A. Gray) Cronquist] is an inv... more Prairie groundcherry [Physalis hederifolia (A. Gray) var. fendleri (A. Gray) Cronquist] is an invasive perennial weed with the potential to become a significant summer weed across 409 million hectares in Australia. Current management practices do not provide effective control of established populations. A better understanding of the seed biology is needed to effectively manage this weed. A series of field and laboratory studies were conducted to determine plant fecundity, soil seedbank longevity, and the factors that affect seed germination. Physalis hederifolia has the capacity to produce 66 to 86 berries plant−1, 51 to 74 seeds berry−1, and approximately 4,500 seeds plant−1, with the seeds potentially able to persist in the soil seedbank for 20 yr if buried in an intact dry berry pod. The bare-seed component of the soil seedbank can be virtually exhausted within 3 yr if cultivation is minimized to avoid burial of seed. Optimal temperature for germination is diurnal fluctuations of...

Crop and Pasture Science, 2016

Canola (Brassica napus L.) is an important rotational crop in the temperate cropping zone of sout... more Canola (Brassica napus L.) is an important rotational crop in the temperate cropping zone of southern Australia. Herbicide-resistant weeds are rapidly spreading and reducing canola grain yield and quality. Crop competition is a useful tool for reducing weed costs and dependence on herbicides, and retarding the spread of herbicide resistance. The potential interaction of canola seeding rate and cultivar for weed management has not been quantified in Australia. A field experiment was conducted in three environments to examine the impact of two contrasting canola cultivars (a low vigour type and a high vigour hybrid) at four seeding rates (10–100 plants/m2) on volunteer wheat (~50 plants/m2). Significant but variable effects of crop seeding rate, cultivar and weed were detected on canola density and grain yield, and on the suppression of volunteer wheat. The canola hybrids suppressed volunteer wheat more than the less vigorous cultivars in all the experiments. There was no benefit of i...

Silverleaf nightshade is considered amongst the worst weeds of crop and pasture systems in Austra... more Silverleaf nightshade is considered amongst the worst weeds of crop and pasture systems in Australia due to its extensive root system. Cultivation may exacerbate the problem due to the regenerative capacity of the root system. Glasshouse experiments were conducted to determine the importance of cultivation in the spread of silverleaf nightshade by investigating the regenerative abilities of various root fragment lengths (1, 2.5, 5 and 10 cm) buried at three soil depths of 2.5, 5 and 10 cm. Regeneration occurred from root fragments as short as 1 cm, with shoot production increasing with root fragment length. Optimum burial depth was 5 cm for 1 and 2.5 cm root fragments, while 5 and 10 cm root fragments were equally prolifi c at stem production from the 2.5 cm burial depth. High levels of fragment mortality occurred in 1 cm fragments, with mortality levels signifi cantly declining as fragment length increased. This research suggests that minimum tillage techniques should be encouraged on areas with silverleaf nightshade infestations. Implements should be thoroughly cleaned before leaving the infested area, as even short root fragments adhered to machinery are capable of starting a new infestation in a clean fi eld.

Weed Research, 2013

ABSTRACT Solanum elaeagnifolium (silverleaf nightshade) is an invasive perennial weed in Australi... more ABSTRACT Solanum elaeagnifolium (silverleaf nightshade) is an invasive perennial weed in Australia, with aerial growth commencing in spring from either the perennial root system or the soil seedbank, with senescence occurring in autumn. A total of 642 S. elaeagnifolium individuals were collected at flowering from 92 locations in south-eastern Australia to study morphological variation and its implications for management. Large morphological variation was found between individuals from different locations. Leaf length, width and area ranged from 1.44 to 10.6 cm, 0.39 to 4.09 cm and 0.41 to 25.8 cm2 respectively. Plants from higher rainfall regions were significantly taller and had larger leaves, suggesting a possible correlation between rainfall and morphology. Scanning electron microscopy comparison of leaf surfaces showed lower trichome and stomatal densities on the adaxial surface (67.0 ± 3.3 trichomes mm−2 and 603.4 ± 29.2 stomata mm−2 respectively) than on the abaxial surface (131.9 ± 7.2 trichomes mm−2 and 813.7 ± 30.5 stomata mm−2 respectively). The morphological plasticity of S. elaeagnifolium highlighted in this study could probably contribute to its adaptability and partly explain its establishment and continuing expansion in Australia.

Archives of Agronomy and Soil Science, 2019

Weeds are a major constraint to canola (Brassica napus L.) production, reducing grain yield and q... more Weeds are a major constraint to canola (Brassica napus L.) production, reducing grain yield and quality. The repeated use of pre-and post-emergent herbicides to control several grasses and broadleaf weeds has escalated the problem of herbicide resistance in weeds. The development of herbicide-tolerant canola cultivars has increased the flexibility of weed management but has also increased the risks of outcrossing with wild relatives and weed shifts to resistance. Herbicideresistant weed species, and the related biological repercussions, pose a major threat to sustainable weed management. These developing risks have led researchers to examine integrated weed management (IWM) techniques for sustainable weed control. Weed control strategies using non-A c c e p t e d M a n u s c r i p t chemical tactics have valid roles for managing weeds. However, in broad-acre commercial fields, the effectiveness of several non-chemical selections are less proven than commercial chemical herbicides. Canola competition and allelopathy for weed suppression are potential components for integrated weed management in canola. This review examines current chemical and nonchemical options available for developing IWM strategies for profitable canola production, as well as future research directions.

International Journal of Molecular Sciences, 2021

The perennial grass Cenchrus spinifex (common sandbur) is an invasive species that grows in arid ... more The perennial grass Cenchrus spinifex (common sandbur) is an invasive species that grows in arid and semi-arid regions due to its remarkable phenotypic plasticity, which confers the ability to withstand drought and other forms of abiotic stress. Exploring the molecular mechanisms of drought tolerance in common sandbur could lead to the development of new strategies for the protection of natural and agricultural environments from this weed. To determine the molecular basis of drought tolerance in C. spinifex, we used isobaric tags for relative and absolute quantitation (iTRAQ) to identify proteins differing in abundance between roots growing in normal soil and roots subjected to moderate or severe drought stress. The analysis of these proteins revealed that drought tolerance in C. spinifex primarily reflects the modulation of core physiological activities such as protein synthesis, transport and energy utilization as well as the accumulation of flavonoid intermediates and the scaveng...

Weed Research, 2015

Summary Screening crop accessions for allelopathic activity is of paramount importance for crop a... more Summary Screening crop accessions for allelopathic activity is of paramount importance for crop allelopathy research. Previous bioassays often did not use a mixed culture of donor and target plants, did not use soil and were not conducted under natural conditions. In this study, we designed an inhibitory-circle method in which a rice accession (donor plant) and Echinochloa crus-galli (target plant) were cultured together in paddy soil under natural conditions. First, we determined that the highest allelopathic activity of allelopathic rice accession PI312777 was at the 5-leaf stage, and the suitable distance of rice seedlings and E. crus-galli was 12 cm apart. This method was then validated by a field test. A further 40 rice accessions were evaluated for allelopathic activity to E. crus-galli using this method. Two rice accessions, PI312777 and Taichung Native 1, had highly allelopathic activity to E. crus-galli (inhibitory rate > 50%), while another accession, Lemont, had non-allelopathic activity. These experimental results were in accordance with previous studies using direct field experiments. The inhibitory-circle method integrated three necessary conditions, that is donor and target plants grown together, with soil as the medium and under natural conditions for reliable results. The ‘inhibitory-circle method’, which combined donor and target plants, soil medium and field conditions, can give reliable results in one step, compared with laboratory screening methods. Also, the ‘inhibitory-circle method’ gave results in 30-35 days, thereby substantially reducing the requirements for time, labour and cost.

caws.org.au

Field studies were conducted in southern Queensland to determine the impact of sorghum cultivars ... more Field studies were conducted in southern Queensland to determine the impact of sorghum cultivars and crop densities on weed suppression and sorghum yield loss due to weeds. Japanese millet (Echinochloa esculenta (A.Braun) H.Scholtz) was used to mimic barnyard grass (Echinochloa spp.). Results showed that differences in competitive ability of the cultivars were consistent over the two years, with MR Goldrush and Bonus MR being the most competitive cultivars, and 86G87 the least competitive. Sorghum density also had a significant effect on the crop's ability to compete with millet, with the strongest millet suppression at the highest density of 7.5 plants m −2. Millet caused significant yield loss, up to 34% in comparison with weed-free plots. These results indicate that sorghum competition against Japanese millet can be improved by choosing competitive cultivars and the use of higher crop densities. Improved sorghum competition provides a non-chemical option for integrated weed management.

The information contained in this publication is intended for general use to assist public knowle... more The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication.