Aegilops tauschii Coss is one of the most problematic weed species severely invading wheat fields of China. Currently, mesosulfuron-methyl (MSM) is a rare herbicide to selectively control A. tauschii, while being safe to wheat. However, the occurrence, distribution and susceptibility of A. tauschii in Anhui Province still remains unclear. In this study, A. tauschii was identified in 19 out of total 137 sampling sites in 2021 and 28 of total 186 sampling sites in 2024, respectively. Notably, A. tauschii infection mainly concentrated in 6 cities (including Suzhou, Bozhou, Fuyang, Bengbu, Chuzhou and Huaibei), which were located in northern plains of Anhui Province. Dose-response bioassays revealed that the GR50 values of 47 A. tauschii populations to MSM ranged from 4.29 to 13.98 g a.i. ha-1, and the RI values ranged from 1.58- to 3.26-fold, among which 89.4% were sensitive, and 10.6% were low resistant. All MSM-resistant populations occurred in Bozhou, Suzhou, Bengbu or Huaibei, and the occurring frequency and resistance degree increased from 2021 to 2024. Tolerance analysis indicated that applying MSM at 31.5 g a.i. ha-1 (2-fold of the registered dose) had no adverse effect on plant height, tiller number, fresh weight and survival rate of wheat varieties JM22, WKM22 and QM725. The findings provide a key sensitivity data of A. tauschii to MSM, as well as a vital guidance for developing an efficient and safe MSM application strategy in wheat-growing areas.

In our previous study with a wild radish (Raphanus raphanistrum) population resistant to HPPD-inhibiting herbicides we indicated that two additional candidate P450 genes, CYP71A28 and CYP72A13-like, may also contribute to the resistance. This study investigates the role of these two P450 genes in mesotrione resistance in the wild radish population. The full-length R. raphanistrum P450 genes (thereafter named as RrCYP71A28 and RrCYP72A15) were cloned from mesotrione-resistant (R) and -susceptible (S) wild radish plants. RT-qPCR results showed that basal expression levels of the two P450 genes are significantly higher (up to 3-fold) in the R than the S plants. Escherichia coli cells transformed respectively with RrCYP71A28 and RrCYP72A15 were more tolerant to mesotrione. Transgenic Arabidopsis plants expressing RrCYP72A15 showed a modest level of resistance to mesotrione. UPLC-MS/MS analysis demonstrated that tissue mesotrione levels in RrCYP72A15 transgenic Arabidopsis plants were significantly lower (up to 2-fold) than that in the wild type. Structural modelling predicts CYP72A15 can bind to RrCYP72A15 and metabolize mesotrione likely through formation of 4-OH-mesotrione. Although the RrCYP72A15 gene confers a modest level of resistance, overexpression of the multiple herbicide-metabolizing genes could contribute to the low level of mesotrione resistance observed in the R wild radish population.

BACKGROUND:We have previously demonstrated that an aldo-keto reductase (AKR) from Echinochloa colona (EcAKR4-1) can metabolize glyphosate and confers glyphosate resistance. This study aims to investigate if the EcAKR4-1 orthologs from Lolium rigidum also play a role in glyphosate resistance in non-target-site based, glyphosate-resistant (R) L. rigidum populations from Western Australia.RESULTS:The full-length L. rigidum AKR gene (LrAKR4C10) orthologous to EcAKR4-1, together with a distinct LrAKR1, were cloned from plants of a glyphosate-susceptible (S) (VLR1) and three glyphosate R L. rigidum populations (WALR50, WALR60 and WALR70). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) results showed that basal expression levels of the two LrAKR genes did not differ between the R and S populations, but their expression was significantly induced by glyphosate (up to 4.3-fold) or 2,4-D treatment (up to 3.4-fold) in R populations. Escherichia coli cells transformed respectively with LrAKR4C10 and LrAKR1 were more tolerant to glyphosate. Rice (Oryza sativa) seedlings overexpressing each of the two LrAKR gene survived glyphosate rates that were lethal to the green fluorescence protein (GFP) control plants. Structural modeling predicts a similar way of glyphosate binding and detoxification by LrAKR4C10 and EcAKR4-1, but an alternative way of glyphosate binding by LrAKR1. Relatively lower capacity of the two LrAKRs in conferring glyphosate resistance than the known EcAKR4-1 was discussed in relation to structural interaction.CONCLUSION:Glyphosate-induced higher expression of the two LrAKR genes in L. rigidum populations contributes to a moderate level of glyphosate resistance likely through enhanced glyphosate metabolism. The herbicide 2,4-D can also induce the LrAKR expression, indicating the potential antagonistic effect of 2,4-D to glyphosate. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Asia Minor bluegrass (Polypogon fugax Nees ex Steud.) is one of the major grass weeds in winter crops in China, with populations having developed resistance to herbicides (such as clodinafop-propargyl). In this study, the methods for tissue culture and genetic transformation were established for this weedy species. Callus induction, adventitious bud differentiation and rooting were achieved by using mature seeds of clodinafop-propargyl-susceptible P. fugax, and by manipulating concentration combinations of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzyl aminopurine (6-BA), and naphthaleneacetic acid (NAA). Genetic transformation was conducted by co-culturing generated calli with Agrobacterium tumefaciens EHA105 containing pOx (HA)-GFP plasmids, and regenerated transgenic plants were obtained by hygromycin screening. The green fluorescent protein (GFP) visual analysis showed GFP gene expression in transgenic calli, and RT-qPCR confirmed the stable expression of the exogenous hygromycin gene in P. fugax transgenic plants. Furthermore, Southern hybridization analysis confirmed the transgene integration. This transformation efficiency was 7%. These results indicated successful establishment of a reliable and efficient A. tumefaciens-mediated genetic transformation system, which will provide opportunities to better understand the evolution of herbicide resistance and the resistance genetics.

Eragrostis japonica (Thunb.) Trin, a kind of grass weeds in paddy rice fields, has recently been developing rapidly as the most harmful weed for rice production in addition to Echinochloa crusgalli and Leptochloa chinensis in partial areas of Anhui, Jiangsu, and Zhejiang provinces (Zhou et al.). In September 2019, inflated sori in the ovaries of E. japonica were identified in fields in Chuzhou County, Anhui Province. The disease incidence was approximately 50% at the survey site. Smut sori were in some spikelets of infected inflorescence destroying the inner most floral organs. Sori were ovoid and initially covered with a thin peridium (Figure 1). The sori busted after maturation, and the black powdery spores spread to the plant and soil. The sori were crushed using the sterilized tweezers. The black powdery spores were suspended with sterilized water and spread onto potato dextrose agar (PDA) medium. Spores were covered with spines, and the shape of spores varied from globose to ovoid. Scanning electron microscope was used to observe the morphology of spores. The spores were 7.5-12.3 μm × 5.8-11.8 μm (n=50). The surface of spores was covered with spines, and dense verruca were identified between the spines (Figure 2). For molecular identification, the primers ITS1/ITS4 and GAPDH-F/R were employed to amplify the rDNA region. The resulting sequences from the studied material were submitted to Genbank (MW819938 and MZ508441). BLASTn analysis revealed that ITS sequence shared 99% similarity with EF040584 (719/728) the ITS sequence from type specimen of Ustilago planetella. Based on the above results, the pathogen was identified as Ustilago planetella (Vánky, 2007). To verify the Koch's postulates, a pathogenicity test was performed by infiltrating the inflorescence with microspore suspensions of the strain SMZF-2 (1×106 spores/mL) when the E. japonica flowers for 30 minutes. The plants were inoculated in a moist chamber (with a relative humidity >80%) with a 12-h light cycle at 28℃. Inflated sori were observed after inoculated for 2 weeks, and U. planetella was isolated and identified with the methods described above. No sori were observed in the water-inoculated control plants. U. planetella had been reported to infect Eragrostis japonica in Thailand (Vánky, 2007). To our knowledge, this is the first report of U. planetella causing Smut on E. japonica (Thunb.) Trin in central region of China. The current study may help solve the negative effect of E. japonica in paddy rice production via using U. planetella in the future.

Eragrostis japonica (Thunb.) Trin, a kind of grass weeds in paddy rice fields, has recently been developing rapidly as the most harmful weed for rice production in addition to Echinochloa crusgalli and Leptochloa chinensis in partial areas of Anhui, Jiangsu, and Zhejiang provinces (Zhou et al.). In September 2019, inflated sori in the ovaries of E. japonica were identified in fields in Chuzhou County, Anhui Province. The disease incidence was approximately 50% at the survey site. Smut sori were in some spikelets of infected inflorescence destroying the inner most floral organs. Sori were ovoid and initially covered with a thin peridium (Figure 1). The sori busted after maturation, and the black powdery spores spread to the plant and soil. The sori were crushed using the sterilized tweezers. The black powdery spores were suspended with sterilized water and spread onto potato dextrose agar (PDA) medium. Spores were covered with spines, and the shape of spores varied from globose to ovoid. Scanning electron microscope was used to observe the morphology of spores. The spores were 7.5-12.3 μm × 5.8-11.8 μm (n=50). The surface of spores was covered with spines, and dense verruca were identified between the spines (Figure 2). For molecular identification, the primers ITS1/ITS4 and GAPDH-F/R were employed to amplify the rDNA region. The resulting sequences from the studied material were submitted to Genbank (MW819938 and MZ508441). BLASTn analysis revealed that ITS sequence shared 99% similarity with EF040584 (719/728) the ITS sequence from type specimen of Ustilago planetella. Based on the above results, the pathogen was identified as Ustilago planetella (Vánky, 2007). To verify the Koch's postulates, a pathogenicity test was performed by infiltrating the inflorescence with microspore suspensions of the strain SMZF-2 (1×106 spores/mL) when the E. japonica flowers for 30 minutes. The plants were inoculated in a moist chamber (with a relative humidity >80%) with a 12-h light cycle at 28℃. Inflated sori were observed after inoculated for 2 weeks, and U. planetella was isolated and identified with the methods described above. No sori were observed in the water-inoculated control plants. U. planetella had been reported to infect Eragrostis japonica in Thailand (Vánky, 2007). To our knowledge, this is the first report of U. planetella causing Smut on E. japonica (Thunb.) Trin in central region of China. The current study may help solve the negative effect of E. japonica in paddy rice production via using U. planetella in the future.

Asia Minor bluegrass (Polypogon fugax Nees ex Steud.) is a problematic grass weed of winter crops in China, where some populations have become resistant to herbicides. Previously, we identified a P. fugax population QS exhibiting target-site-based resistance (TSR) and non-target-site-based resistance (NTSR) to clodinafop-propargyl. This study aims to understand the metabolic resistance to clodinafop-propargyl between susceptible (XC) and resistant (QS) populations of P. fugax in the seedling and tillering stage, separately. Several differentially expressed candidate genes in the seedling and tillering stages were identified by RNA-Seq, including three P450 family genes, one glutathione S-transferase (GST) gene, and two ATP-binding cassette transporters. Additionally, we discovered a GST gene that was significantly differentially expressed in the resistant population during the seedling stage, as well as three peroxidase genes that were presumed to be related to NTSR metabolism. Three other peroxidase genes and one esterase were presumed to be related to NTSR metabolism during the tillering stage of the resistant population. Overexpression of the three randomly selected candidate genes can enhance herbicide-resistance in Arabidopsis transgenic plants. This study provided a novel insight into herbicide metabolism regulation genes during the different growth stages of resistant P. fugax population.

Herbicide-driven selective pressures on weeds promote genetic changes in various physiological traits, including flowering time and fructification, allowing weeds to evade control techniques. Previously, we showed that early flowering was associated with resistance to acetyl coenzyme A carboxylase (ACCase) inhibitor herbicides in a population of Polypogon fugax. Here, we isolated the type I–like MADS-box gene PfAGL28 from ACCase inhibitor-resistant P. fugax, and showed that this gene was strongly upregulated in the resistant compared to susceptible populations at the flowering stage. Overexpression of PfAGL28 in Arabidopsis thaliana resulted in the early-flowering phenotype and early seed formation likely due to the upregulation of FLOWERING LOCUS T (FT), and AGMOUS-LIKE 23 (AGL23), AGMOUS-LIKE 61 (AGL61), and AGMOUS-LIKE 80 (AGL80). These results indicate that PfAGL28 gene is likely involved in the regulation of early flowering and pod formation in P. fugax. Our study thus provides a reference for future explorations of the flowering mechanisms of herbicide-resistant weeds.

Background: Herbicides are the major tool for controlling large populations of yield depleting weeds. However, overreliance on herbicides has resulted in weed adaptation and herbicide resistance. In recent years, early flowering weed species related to herbicide resistance is emerging, which may cause seed loss before crop harvest, creating a new problem for non-chemical weed management. However, mechanisms regulating early flowering in weedy species is rarely investigated. Results: The MADS-box gene family plays an important role in flowering time regulation and floral organogenesis. In this study, a homolog gene of AGAMOUS sub-family (referred to as PfAG5) of the MADS-box family was cloned from plants of an early flowering Polypogon fugax population resistant to the ACCase inhibitor herbicide (clodinafop-propargyl). The PfAG5 gene was functionally characterized in Arabidopsis thaliana. Over-expression of the PfAG5 gene in Arabidopsis resulted in early flowering with abnormal flowers (e.g. small petals, short plants and reduced seed set) compared to the wild type. The expression of the PfAG5 gene was high in leaves and flowers, but low in pods in transgenic Arabidopsis. The PfAG5 gene was earlier and higher expressed in the resistant (R) than the susceptible (S) P. fugax plants. Furthermore, one protein (FRIGIDA-like protein) interacting with PfAG5 in R P. fugax was identified by the yeast two-hybrid system with relevance to flowering time regulation. Conclusions: These results suggest that the PfAG5 gene is involved in modulating early flowering in P. fugax. This study provides the first evidence for the regulation mechanism of early flowering in an herbicide resistant weed species.

稗草是安徽省稻田主要的恶性杂草之一,近年来安徽省多地区稗草对市面上常用除稗剂均产生了一定的抗药性.为初步探明安徽省稻田稗草的抗性分布及机制,采集安徽省主要稻区稗草种群样本51份,通过室内生测法,施用二氯喹啉酸、双草醚、唑酰草胺和五氟磺草胺4种常用除稗剂,对稗草种群抗药性进行初筛.结果表明,安徽省主要稻区稗草对二氯喹啉酸的抗性频率最高,已达34.8％,对双草醚、五氟磺草胺、唑酰草胺的抗性频率则分别为21.7％、13.7％、9.8％.其中,有2个种群(2016B2和B24)对4种除稗剂都表现出明显抗药性,4个种群(B6、B7、B9、2015B1)对3种除稗剂均表现出抗药性,5个种群(B4、B11、B26、B27、2016B3)对2种除稗剂表现抗药性,有8个种群仅对1种除稗剂表现出抗药性(其中有6个种群仅对二氯喹啉酸表现出抗药性),其余32个种群没有检测到抗药性.

The evolution of herbicide resistance in weedy plants leads to various adaptation traits including flowering time and seed germination. In our previous studies, we found an association of the early flowering phenotype with the ACCase inhibitor herbicide resistance genotype in a population of Polypogon fugax. MADS-box transcription factors are known to play pivotal roles in regulating plant flowering time. In this study, a SHORT VEGETATIVE PHASE (SVP)-like gene, belonging to the StMADS11 subfamily in the MADS-box family, was cloned from the early flowering P. fugax population (referred to as PfMADS16) and resistant to the herbicide clodinafop- propargyl. Overexpression of the SVP-like gene PfMADS16 in Arabidopsis thaliana resulted in early flowering and seed abortion. This is consistent with the phenotypic characters of resistant P. fugax plants, but contrary to the conventional role of SVP-like genes that usually suppress flowering. In addition, down regulation of the seed formation gene AtKTN1 in flowers of PfMADS16 transgenic Arabidopsis plants indicates that PfMADS16 may be indirectly associated with seed viability. Furthermore, one protein (PfMADS2) from the APETALA1 (AP1) subfamily interacting with PfMADS16 in P. fugax was identified with relevance to flowering time regulation. These results suggest that the PfMADS16 gene is an early flowering regulation gene associated with seed formation and viability in resistant P. fugax population. Our study provides potential application of PfMADS16 for integrated weed management (such as genetic-based weed control strategies) aiming to reduce the soil weed seedbank.

为明确近年来安徽省麦田杂草种类组成及群落结构变化情况,本研究采用倒置“W”取样法对安徽省麦田杂草进行了连续两年的跟踪调查,结果发现麦田杂草有19科72种,其中禾本科、菊科、蓼科种类最多.优势杂草有节节麦Aegilops tauschii、野燕麦Avena atua、日本看麦娘Alopecurus ja ponicus、看麦娘A.aequalis、菵草Beckmannia syzigachne、猪殃殃Galium spurium等6种,区域性优势杂草有5种,常见杂草有8种,一般杂草有53种.此外,不同地区优势杂草存在差异,淮北草害区是以猪殃殃+节节麦+野燕麦为主的杂草群落;江淮丘陵草害区为日本看麦娘+看麦娘+猪殃殃+菵草;江南草害区为日本看麦娘+看麦娘+菵草.从杂草的分布来看,江淮丘陵草害区的杂草群落物种丰富度、多样性最高,杂草有56种,香农指数最高,为2.34;江南草害区杂草群落物种丰富度最低,有17种杂草,辛普森指数最高,为0.037,均匀度指数也较低,为0.29,优势杂草突出;从相似性指数来看,安徽省三大草害区之间的相似性指数都小于等于0.5,差异性较大.同时,安徽省麦田杂草入侵问题严重,节节麦甚至已经成为某些地区的优势杂草之一,而大穗看麦娘A.myosuroides在安徽省局部地区也多有发生.

[目的]评价19种大田农药对家蚕的急性毒性作用,并根据田间推荐使用浓度进行初级风险性评价.[方法]参照《农化学农药环境安全评价试验准则》,开展急性毒性试验.[结果]26％烟嘧·莠去津可分散油悬浮剂对家蚕表现为低毒,但属于高风险性;其余18种药剂对家蚕表现为低毒和中低风险性.[结论]26％烟嘧·莠去津可分散油悬浮剂、40％麦畏·草甘膦水剂和960 g/L精异丙甲草胺乳油使用时多注意风向和喷药高度等因素,避免对附近桑园造成影响.

[目的]评价13种大田农药对松毛虫赤眼蜂的急性毒性作用,并参考各农药的田间推荐使用浓度进行安全性评价.[方法]参照《农化学农药环境安全评价试验准则》,开展急性毒性试验.[结果]50％氟环唑悬浮剂对赤眼蜂表现为高风险性,其余12种农药对赤眼蜂表现为中低风险性.[结论]50％氟环唑悬浮剂使用中应严格控制其用量和用药次数,避免对赤眼蜂造成区域性毁灭.