Ethyl methanesulfonate (EMS) mutagenesis is a common technique for developing genetic diversity in microorganisms. The present study investigates the genetic and biological effects of EMS mutagenesis in Fusarium proliferatum (F. proliferatum), the causative agent of Pokkah Boeng Disease (PBD) of sugarcane in China. F. proliferatum wild-type strain (PB6–3) was treated with different EMS concentrations of 0.0%, 1.0%, 2.5%, 5.0%, and 7.5%, and exposure times were kept at 30, 60, 90, and 120 min (mins) for the development of EMS mutagenesis. The EMS-mutagenized strains were screened for changes in virulence using detached sugarcane leaf assays. The strain with the most notable mutations relative to PB6–3, denoted MPB6–3, showed reduced virulence, an altered phenotype, and reduced growth and sporulation. Molecular markers were used to validate the successful induction of EMS mutagenesis in MPB6–3, and subsequent research showed that varying nitrogen (N) sources affected growth and sporulation rate, as well as the synthesis rate of secondary metabolites (SMs), e.g., phytohormones and mycotoxins. The study showed that N sources significantly affected metabolic rates in both PB6–3 and MPB6–3. Notably, the MPB6–3 showed varied rates of N assimilation. The results highlighted the applicability of EMS mutagenesis for developing biological mutants with altered virulence and metabolite profiles, and also provided valuable insights into F. proliferatum, enabling the development of a novel disease control strategy for sugarcane.

The mechanization in sugarcane cultivation is required to improve the performance of sugarcane production capacity in China. The mechanization process is very substantial because it can enhance the production of agricultural land. There is an urgent need to breed advance sugarcane cultivars for mechanization process. In this article, cross-breeding was carried out using YT01-23 (female parent) and ROC22 (male parent) cultivars, and "five nursery system" was applied. The new sugarcane cultivar Guitang 10-2018 (GT10-2018) was comprehensively assessed through regional demonstrations in the Guangxi province, China. Morphological and production responses of Guitang 66 (GT66) cultivar were observed. It concluded that GT66 is a medium to medium-large stem cultivar with early maturity, better ratoon, stress tolerance, and mechanization-friendly approaches. The average yield of ratoons planted in the first and second (2018 and 2019) year was found about 86,537 kg/ha. The production capacity enhanced at 11.37% compared to ROC22 cultivar. The average sucrose content was found 14.35% in November-December, and 15.10% in the month of March. The average sucrose content was found optimum in GT66 than ROC22. The yield of newly planted sugarcane was 86,717 kg/ha lower than ROC22 (0.64%) in the first year. The average sugar content was found 11,619 kg/ha lower than ROC22. The average ratoon yield was 87,196 and 86,447 kg/ha, enhanced 11.58 and 26.62% compared to ROC22 in 2018 and 2019 cropping season. The average sugar content was 11,574 and 14,588 kg/ha (increase 5.42 and 26.98%). The average sugarcane fibre content was 12.18%, which is 0.08% lower than ROC22. The growth, development and production performance of GT66 was more significant during the regional field demonstrations, and it has strong production capacity. The current sugarcane production and cultivation strategies are suitable for sugarcane plantation sustainable development in Guangxi province, China.

Defoliation is a primary agronomic traits, its variation depends on different plant species or cultivars. The present article assess the leaf morphological responses, oxidative metabolites and enzymatic activities at sheath base of sugarcane cultivars during defoliation stage of plant leaves. The mature leaf sheath of GT47 strongly wrapped to the stem, and no stem was exposed. The upper and lower edges of the immature fusing abscission zone were parallel, and slightly lower browning area (+ 3 to + 7 leaf position). The ROC22 cultivar was monitored highest leaf sheath-based cellulose and lignin content, followed by GT60 and GT47. Peroxidase activity was higher in leaf sheath base edge (ROC22) as compare to other cultivars. The malondialdehyde content was found highest in GT60, followed by ROC22, and GT47. The exo-beta-1,4-glucanase/ cellobiohydrolase activity was found highest in the margin of GT47 than lateral and medial axis of ROC22 and GT60. The axis activity increased exponentially, and ROC22 gradually decreased from the periphery of the mid-axis and lower than GT47 and GT60 in the lateral and mid-axis of leaf. In conclusion, the mature leaves are easy to defoliate mainly loose leaf sheaths, large leaf sheath inclination angles, more deformation during the growth period of the abscission zone, early with large cracks, and slow browning process. Leaf sheaths with high fibre and lignin content showed significant hardness and thickness. The sugarcane cultivars showed positive correlation between peroxidase and malondialdehyde content with the browning process at the base of mature leaf sheaths.

Badila (Saccharum officinarum) is one of the important chewing cane in south China. During the year 2019-2020, as much as 60.2%-87.5% of sugarcane plants stem showed red rot developments were observed in the fields of Yongning District, Nanning city, Guangxi province. Symptomatic plants showed red rot at basal stem nodes and sheath, when the disease serious, the epidermis and aerial roots decomposed and exfoliated, then formed sclerotiums, the upper stem also occurred the symptom. Infected plant tissues were dissected into small pieces with 0.1 × 0.1cm in size and surface sterilized in 0.1% HCl2 for 2 min, followed by 75% ethanol for 30 s, rinsed three times with sterile distilled water. Then the tissues were placed onto potato dextrose agar (PDA) plates and incubated at 25 °C for 3 days. Numerous white globoid sclerotia were formed on PDA after 5 days of growth. The sclerotia (2 to 3 mm in diameter) were white at first and then gradually turned dark brown. Aerial mycelia usually formed many narrow hyphal strands 4 to 9 μm wide. Five uniform isolates were obtained from diseased sugarcane plants. Pathogenicity of representative strain W1 was confirmed by inoculating 120-day-old Badila plants grown in field. Five plants were inoculated with colonized agar discs (6mm in diameter) by applying toothpick tips to the lower part of the stem. Five non-inoculated plants served as control. The inoculated and non-inoculated plants were sprayed sterile water then incubated with plastic film for maintained high moisture. All the plants were placed inside of a growth chamber at 26 ± 2°C with a 14-h photoperiod and 80% relative humidity. All inoculated plants showed red rot at stem and sheath after 2 weeks, whereas the control plants were symptomless. By the third week, mycelium and sclerotia developed on the crown on the inoculated plants. The fungus was re-isolated from the artificially inoculated plants. To confirm the species-level identification, partial of the ribosomal DNA internal transcribed spacer (ITS), mitocondrial small subunit (SSU), and nuclear ribosomal large subunit (LSU) regions of representative strain W1 were amplified and sequenced using the primers pairs ITS1/ITS4 (White et al. 1990), ITS-Fu-F /ITS-Fu-R and SRLSU1//SRLSU2 (Kumar et al., 2016), respectively. The resulting ITS, SSU and LSU sequences were deposited in GenBank (GenBank accession no. MW620994, MW617878, and MW617872) and shared 99.42%, 100% and 100% sequence identity with Athelia rolfsii isolate (JN017199, OM319631, and MT225781). Phylogenetic analysis conducted with neighbor-joining (NJ) method using MEGA6.0 revealed that the isolate share a common clade with reference sequence of A. rolfsii in GenBank Data Library. Based on morphological and molecular characteristics, the fungus was identified as A. rolfsii (anamorph: Sclerotium rolfsii) (Paul et al. 2017; Paparu et al. 2020). Although S. rolfsii has been reported causing sugarcane sett rot in Australia (Bhuiyan et al., 2019) and seedlings of sugarcane in Indian (Gopi et al., 2023), as we know, this is the first report of sugarcane basal stem rot disease caused by this fungus in China. This study will be helpful for the prevention and control sugarcane basal stem rot in the future.

Fusarium pathogens and their mycotoxins are considered as the main threats to cereal production and food safety worldwide. However, due to the constant discovery of new Fusarium species especially along with mycotoxin production profile differentiation in certain species, efforts on their species composition, geographical distribution, and chemotype proportion are urgently required. In the Fusarium goolgardi species, two distinct trichothecene (TB) genotype populations have recently been identified. Previous studies have shown that the structural variance of TBs biosynthesized by the two genotypes is attributed to the Tri1 gene. Polymorphisms of Tri1 gene from type A TB-producers were investigated in different Fusarium species in the current study. According to these DNA sequence variations identified in Tri1 gene sequences, a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based diagnostic approach for the differentiation of T-2 and 4,15-diacetoxyscirpenol (DAS) genotypes in F. goolgardi was successfully developed. The PCR-RFLP assay will facilitate the studies on geographic distribution, frequency and other aspects of the two genotypes within F. goolgardi species.

The Fusarium graminearum species complex is the main causal agent of wheat head blight worldwide. Trichothecenes produced by the pathogen in infected grains have important food safety implications. Previously reported studies on trichothecene production have all focused on the conditions conducive to mycotoxin production, while the molecular mechanisms of trichothecene biosynthesis in Fusarium strains under normal or non-inducing conditions are still unclear. Here, a global analysis of the fungal gene expression of three strains using the Affymetrix Fusarium GeneChip under non-inducing conditions is reported. Differentially expressed genes were identified among strains with different trichothecene-production ability, and some novel genes associated with trichothecene biosynthesis were found by bioinformatics analysis. To verify the transcriptome results, proteomic analyses of the three strains were conducted under the same culture conditions. In total, 69 unique fungal proteins were identified in 77 protein spots. Combined with transcriptome and proteome analysis, 27 novel genes were predicted to be associated with trichothecene mycotoxin production. A protein, encoded by FGSG_01403, was found to be associated with trichothecene production via proteome analysis. Gene knock-out mutations of FGSG_01403 resulted in mutants with increased production of trichothecenes. Future functional analysis of the candidate genes identified in this study may reveal new insights into the negative regulation of trichothecene production in the Fusarium graminearum species complex.

The moth stalk borer Chilo sacchariphagus is the most destructive insect pests limiting the production of sugarcane in Guangxi province, China. Current control strategies are mainly focused to the application of chemical insecticides. During 2016-18, the occurrence of the overwintering generation of C. sacchariphagus and its egg parasitoid wasps Trichogramma chilonis and Telenomus dignus were investigated. Findings showed that the overwintering generation of C. sacchariphagus began to emerge in early March and the peak of adult emergence was from the mid-March to early April. At the beginning of peak period, fewer egg masses were laid by C. sacchariphagus and percentage of egg parasitism by parasitoid wasps was low. At the peak period of C. sacchariphagus, more egg masses were laid and parasitism level increased. Both Telenomus dignus and Trichogramma chilonis are dominant natural enemies in Guangxi, which play an important role to mitigate population level of stalk borers. The seasonal dynamic of egg parasitoids' parasitism was typically adapted to the natural enemy following-up pattern. The percentage of parasitism was lower at the early stage of sugarcane growth from March to April and higher (up to 90%) at the late growth stage in September which played an important role in controlling Chilo sacchariphagus.

为研究甘蔗梢腐病不同病原菌的致病力差异,利用4份野生菌株(2份Fusarium sacchari、1份F.proliferatum和1份F.andiyazi)与2份诱变菌株(F.sacchari和F.andiyazi的EMS诱变菌株),采用室内离体接种方法对9份甘蔗种质材料进行梢腐病病原菌致病力测定及甘蔗抗性鉴定,根据病斑大小划分抗性等级评价甘蔗的抗性.结果表明,试验的9份材料中,不同甘蔗材料对不同梢腐病病原菌抗性不同,诱变菌株致病力整体上明显变弱,但在个别甘蔗材料上结果相反,说明不同甘蔗品种对病原的不同致病基因响应效果不同.F.andiyazi能够较快识别并侵入甘蔗叶引起发病,CP85-1308对5个不同菌株抗病性最好,F134和CP72-1210材料对3种病原菌均表现为高感.甘蔗分蘖期对梢腐病菌的免疫力较伸长期差、易感染,甘蔗梢腐病的抗性评价较佳时期为分蘖期.

[目的]评价桂果蔗1号不同级数健康种苗的生长特征和变异特性,为提高果蔗健康种苗生产用种质量及高产栽培提供科学依据.[方法]对桂果蔗1号组培苗、第一级种茎和第二级种茎苗期生长表型性状进行连续观测,分析3个不同级数果蔗幼苗的苗数、株高、地径、叶片数及+1叶的叶长、叶宽和叶面积等7个表型性状的生长特征和变异稳定性.[结果]不同级数果蔗种苗生长特征差异明显.第一级种茎和第二级种茎各方面生长特征相近,且均显著优于组培苗(P＜0.05),但第二级种茎各方面表现仍明显优于第一级种茎.桂果蔗1号健康种苗各性状平均变异系数为5.48%,变异幅度为3.01%～11.88%,变异幅度最大的是苗数,最小的是地径.除了第二级种茎+1叶叶宽变异幅度有所上升外,其余6项表型性状变异均伴随着级数的增加而趋向稳定.3个不同级数种源所有性状的平均变异系数为3.32%～8.25%,以组培苗的平均变异系数最大(8.25%),第一级种茎苗次之(4.88%),第二级种茎苗最小(3.32%).说明组培苗性状分离最大,高级苗(第二级种茎)性状较稳定.[结论]桂果蔗1号健康种苗第二级种茎的生长特性综合表现显著优于第一级种茎和组培苗,遗传变异也较稳定,为生产栽培最佳用种.

细菌污染是甘蔗组培苗生产上的一个主要问题.为明确甘蔗组培中常出现的污染细菌的种类,本研究通过梯度稀释的方法分离污染细菌,结合生化特性、16S rRNA和phaC基因序列比对及系统发育分析鉴定其分类地位.结果表明,共分离获得2种不同类型污染细菌,除了甘露醇,其余9个生化指标完全一致.基因序列比对发现,2种类型分离物的种内2个基因序列完全一致,而种间16S rRNA序列只有2个碱基差异,种间phaC序列有23个碱基差异.2个基因序列构建的系统发育树显示,2种细菌遗传距离较近,并均能形成独立的2个分支.结合生化特征、序列比对及系统发育树,将2种污染细菌分别鉴定为巨大芽孢杆菌(Bacillus megaterium)和阿氏芽孢杆菌(B.aryabhattai),且首次报道阿氏芽孢杆菌为甘蔗组织培养中的污染细菌.本研究揭示了巨大芽孢杆菌可能来源于甘蔗的内生菌,而阿氏芽孢杆菌来源于环境.

本研究通过调查2008—2017年广西甘蔗新品种区域试验中'新台糖22号'('ROC22')的农艺性状,结合分析同期该品种在广西蔗区的生产性状表现,以及种植面积、经济效益变化等情况,结果表明,'ROC22'的分蘖能力和宿根发株能力随年份增加而逐渐减弱,株高和茎径则在一定范围内波动.2012年之后,平均甘蔗单产持续下降,蔗糖分也出现一定程度下降,以11月蔗糖分下降较为显著;黑穗病发病率迅速上升,从2.94％上升至9.02％,已成为广西甘蔗生产的最主要病害;螟虫危害程度逐年加重,枯心苗率从2.29％上升至4.27％.该品种种植面积于2011年达到顶峰,之后迅速下降,从756.4×103 hm2下降至255.9×103 hm2,占比从69.5％下降至31.6％.广西蔗农种植该品种所获取的原料蔗经济收入从2011/2012榨季的340.4亿元下降至2017/2018榨季的115.2亿元.可见,'ROC22'在广西作为主栽品种多年,为广西蔗糖产业发展作出了巨大贡献,但随着种植年限的增加,其种性已明显退化,病虫对该品种为害加重,甘蔗产量和蔗糖分显著下降,被其他优良新品种替代已不可避免.

为了筛选抗甘蔗梢腐病的优异种质材料,采用室内离体接种方法对70份甘蔗种质材料进行梢腐病抗性鉴定.根据发病程度划分的抗性等级和聚类分析的方法综合评价种质材料的抗性.结果表明,甘蔗分蘖期对梢腐病菌的免疫力较伸长期差.参试的70个种质材料中,高抗材料6个,占8.57％;抗病材料15个,占21.43％;中抗材料13个,占18.57％;中感材料12个,占17.14％;感病材料13个,占18.57％;高感材料11个,占15.71％.在2次不同生育期接种过程中'HoCP02-263'均未发病,很可能是对Fusarium sacchari免疫的材料.系统聚类分析的结果与材料的抗性表现基本一致.甘蔗梢腐病的抗性评价较佳时期为分蘖期.

通过比较黑穗病菌1号生理小种与混合孢子粉的致病性,并评价103份甘蔗材料对黑穗病菌1号生理小种的抗性,为甘蔗黑穗病菌生理小种的深入研究及甘蔗优良抗病品种的选育提供科学依据.结果表明,在致病力测试的10份材料中,黑穗病菌1号生理小种对4份材料的致病力较混合孢子粉降低,抗性等级提高1～2级,对2份材料的致病力提高,抗性等级均下降2级,两种接种体对其余4份材料的致病性均表现完全一致.抗性评价的103份甘蔗材料中,43份不发病,60份材料的发病率为1.32％～30.06％,其中感病4份,中感10份,中抗5份,抗27份,高抗14份.发病率最高的是桂糖11-80,平均发病率为30.06％,重复最高发病率为44.74％.引起桂糖42号和LC05-136黑穗病的病原可能是2号小种.部分材料对黑穗病的抗性产生不同程度分化.黑穗病潜伏期为57～146d,发病率较高(10％以上)的甘蔗材料黑穗病潜伏期主要集中在57～93d.对黑穗病发病率与潜伏期的相关性进行分析表明,潜伏期越长,甘蔗材料对黑穗病菌的抗性越好.统聚类分析的结果与参试甘蔗品种的抗性表现一致.

通过测定'柳城05-136'、'桂糖29'和'桂糖42'三个甘蔗品种在不同时长水分胁迫下蔗茎重量、糖分、锤度和简纯度等指标的变化情况,探究甘蔗砍收后浸水胁迫对其重量及蔗糖分等的影响程度,旨在为榨季制糖企业评估及解决多雨天气条件下甘蔗砍运过程中遇到的问题提供参考依据.结果表明,泡水6 h、24 h和48 h与不泡水相对应处理时长相比,其重量增幅为1.27％～1.70％(平均1.50％)、1.13％～1.45％(平均1.32％)和1.20％～1.88％(平均1.62％),砍收后48 h内的蔗茎受水分胁迫表现出吸水-释放-再吸水的过程,而蔗糖分、锤度和简纯度均随着泡水时间的延长而逐渐下降,泡水6 h的蔗糖分下降0.19～0.20个百分点(平均0.20个百分点),24 h降幅为0.08～0.71个百分点(平均0.34个百分点),48 h降幅0.31～0.84个百分点(平均0.51个百分点);泡水6 h、24 h和48 h简纯度平均分别下降1.98、2.01、2.58个百分点.未泡水而自然堆放48 h的蔗茎各项指标变化趋势基本上与之相反,蔗茎重量逐渐下降,蔗糖分和锤度先小幅下降,然后大幅增加;简纯度先增加,然后下降,再上升.与避雨免晒自然存放的甘蔗相比,砍收后受浸水胁迫的甘蔗重量更重,蔗糖分更低,品质更差.

广西是我国的主要甘蔗产区,总面积和产量均占全国的60％以上,但蔗区土壤肥力低,氮肥施用量大,甘蔗生产成本居高不下,缺乏国际竞争力.通过甘蔗的固氮特性,结合有性杂交育种的途径,选育具有较强固氮能力的甘蔗新品系,最终育成具有固氮特性的高产高糖甘蔗新品种,来大幅度降低氮肥施用量,减少生产成本,提高蔗糖产业和能源产业的竞争力,对我国甘蔗种植业的健康发展有积极意义.

[目的]调查不同种植模式下甘蔗梢腐病和香蕉枯萎病的病情指数及致病菌种类,探讨两种病害的发病特征,为病害防控提供参考依据.[方法]2015—2017年在广西隆安和百色分别设置甘蔗连作、香蕉—甘蔗轮作、香蕉连作和甘蔗—香蕉轮作4种种植模式,于每年7—10月调查各点甘蔗梢腐病和香蕉枯萎病的病情指数;对采集到的具有典型甘蔗梢腐病和香蕉枯萎病病株叶片采用组织分离法分离病原菌,并对病原菌进行鉴定.[结果]香蕉—甘蔗轮作模式下,百色点2016年甘蔗梢腐病病情指数明显高于2015和2017年,隆安点2016年的甘蔗梢腐病病情指数略高于2015年同期,2017年的病情指数低于2015和2016年;甘蔗连作模式下,百色点的甘蔗梢腐病病情指数变化不明显,隆安点2016年的病情指数明显高于2015和2017年.香蕉连作模式下,百色点香蕉枯萎病病情指数随种植年限延长呈不断增长趋势,而隆安点明显高于同期百色点;甘蔗—香蕉轮作模式下,百色点香蕉枯萎病病情指数虽然随种植年限延长呈不断增长趋势,但同期病情指数低于连作模式.病原菌分离检测结果表明,甘蔗梢腐病和香蕉枯萎病存在多种致病菌,其中以尖孢镰刀菌分离频率最高.[结论]香蕉和甘蔗上均存在丰富的镰刀菌类群,可能存在交叉感染现象.轮作模式有利于丰富真菌种类,同时有效降低甘蔗梢腐病和香蕉枯萎病的发病率.

2018年对广西农业科学院花卉研究所种质资源圃收集的15种金花茶叶片炭疽病发病情况进行了系统调查,根据发病率采用聚类分析对金花茶炭疽病自然条件下的抗性进行评价.结果 表明,不同种金花茶对炭疽病抗性差异较大,其发病率在4.07％～81.48％之间.根据发病率进行聚类分析,15个种的抗性水平分为5个类群:第1类群抗性最高,发病率为4.07％ ～5.93％,包括毛籽金花茶(Camellia ptilosperm)、弄岗金花茶(C.grandis)和顶生金花茶(C.pingguoensis);第5类群抗性最差,发病率为75.56％～81.48％,包括罗斯曼金花茶(C.rosmannii)和大叶凹脉金花茶(C.impressinervis).根据植株形态学特征以及炭疽病的抗性水平分化分析,凹脉金花茶和显脉金花茶可能分别存在种级水平分类地位以下的分化.

Apart from causing serious yield losses, various kinds of mycotoxins may be accumulated in plant tissues infected by Fusarium strains. Fusarium mycotoxin contamination is one of the most important concerns in the food safety field nowadays. However, limited information on the causal agents, etiology, and mycotoxin production of this disease is available on pepper in China. This research was conducted to identify the Fusarium species causing pepper fruit rot and analyze their toxigenic potential in China. Forty-two Fusarium strains obtained from diseased pepper from six provinces were identified as F. equiseti (27 strains), F. solani (10 strains), F. fujikuroi (five strains). This is the first report of F. equiseti, F. solani and F. fujikuroi associated with pepper fruit rot in China, which revealed that the population structure of Fusarium species in this study was quite different from those surveyed in other countries, such as Canada and Belgium. The mycotoxin production capabilities were assessed using a well-established liquid chromatography mass spectrometry method. Out of the thirty-six target mycotoxins, fumonisins B1 and B2, fusaric acid, beauvericin, moniliformin, and nivalenol were detected in pepper tissues. Furthermore, some mycotoxins were found in non-colonized parts of sweet pepper fruit, implying migration from colonized to non-colonized parts of pepper tissues, which implied the risk of mycotoxin contamination in non-infected parts of food products.

本文旨在解析甘蔗响应梢腐病菌侵染过程中的生理生化机制,为甘蔗抗梢腐病育种及病害防治提供理论指导和科学参考.以我国甘蔗梢腐病主要致病菌Fusarium verticillioides孢子悬浮液为病原,以高抗梢腐病品种YT94/128和高感梢腐病品种GT37为宿主材料,在温室条件下进行针刺法接种,提取病情指数最严重时期,即接种后第14天的甘蔗叶片蛋白质进行iTRAQ定量表达分析.结果显示,从GT37中成功鉴定3707个蛋白,获得542个差异表达蛋白,其中上调表达187个,下调表达355个;从YT94/128中成功鉴定到3068个蛋白,获得差异蛋白449个,其中上调表达191个,下调表达258个.这说明遗传背景不同的甘蔗品种在蛋白质组成上有很大差异,推测这是不同甘蔗品种间抗梢腐病性差异的重要分子基础.