生态环境因子对白芨生长发育的影响

研究不同栽培基质、根外追肥、光照条件对白芨(Bletilla striata (Thunb.) Reichb. f.)生长发育的影响,确定适宜的栽培基质配比、根外追肥施用方案以及光照条件,为其科学的栽培方式提供理论依据。选用三年生白芨作为试验材料,通过引种驯化、基质配比、根外追肥、光照条件等处理下白芨各农艺性状和叶绿素含量进行测定及比较分析,开展白芨引种和规范化栽培技术研究。结果表明,白芨在基质配比为农田原土：白沙=2:2的条件下栽植,其生长状况仅次于营养土,但成本低,有利于适应大田栽培;叶面喷施KH2PO4溶液可促进白芨的生长发育,尤以浓度为2‰时效果最显著;适当的遮阴度有利于白芨的生长发育,但当遮阴度达到70%以上时,白芨群体花期、单株开花量明显低于其他处理,抑制了白芨繁殖器官的发育。     

文心兰miR168分子进化特性及其对软腐病侵染的响应模式

【目的】探究文心兰miR168的分子进化特性,揭示文心兰miR168a及其候选靶基因响应软腐病菌侵染的表达模式。【方法】以文心兰miRNA文库、转录组数据库及miRbase数据库获取的植物miR168前体和成熟体序列为研究对象,利用生物信息学方法对其进行系统进化树构建、保守性分析、前体二级结构分析及靶基因预测;通过PCR技术克隆文心兰miR168a前体,采用qRT-PCR技术分析miR168a及其候选靶基因在文心兰不同组织（根、叶、假鳞茎）和感染软腐病（0,12,24,36和48 h）不同时间的表达模式。【结果】植物miR168序列保守性较高,来源于miR168前体的5p臂保守性高于3p臂,miR168前体分歧较大,茎序列的保守性高于环序列;从文心兰中克隆得到93 bp miR168a前体序列,包含21 nt miR168a成熟体序列。进化分析表明,物种亲缘关系对其前体和成熟体序列的形成影响较小;二级结构显示,文心兰miR168a前体能形成典型的发卡结构,其成熟体位于前体的5p臂;随着软腐病侵染时间延长,文心兰miR168a与其候选靶标RNA剪切复合体核心蛋白（AGO1）、RPM1互作蛋白（RIN4）、羧酸酯酶（CXE8）的表达趋势基本呈负相关,而与其候选靶标RNA解旋酶（PRH47A）、泛素羧基末端水解酶（UCH）的表达趋势呈正相关,说明可能存在其他miR168家族成员或miRNAs同时调控。【结论】文心兰miR168与其他植物miR168进化上兼具保守性和特异性,miR168a上调表达可能会增强文心兰的抗病性。     

Breeding against mycorrhizal symbiosis: Modern cotton (Gossypium hirsutum L.) varieties perform more poorly than older varieties except at very high phosphorus supply levels

Cotton (Gossypium hirsutum L.) is an important fiber cash crop, but its root traits related to phosphorus (P) acquisition, including mycorrhizal root traits, are poorly understood.  Eight cotton varieties bred in northwestern China that were released between 1950 and 2013 were grown in pots with or without one arbuscular mycorrhizal fungal (AMF) species (Funneliformis mosseae) at three P supply levels (0, 50 and 300 mg P as KH₂PO₄ kg^–1).  Eleven root traits were measured and calculated after 7 wk of growth.  The more recent accessions had smaller root diameters, acquired less P and produced less biomass, indicating an (inadvertent) varietal selection for thinner roots that provided less cortical space for AMF, which then increased the need for a high P fertilizer level.  At the two lower P levels, the mycorrhizal plants acquired more P and produced more biomass than non-mycorrhizal plants (3.2 vs. 0.9 mg P per plant; 1.8 vs. 0.9 g biomass per plant at P₀; 14.5 vs. 1.7 mg P per plant; and 4.7 vs. 1.6 g biomass per plant at P₅₀).  At the highest P level, the mycorrhizal plants acquired more P than non-mycorrhizal plants (18.8 vs. 13.4 mg per P plant), but there was no difference in biomass (6.2 vs. 6.3 g per plant).  At the intermediate P level, root diameter was significantly positively correlated with shoot biomass, P concentration and the P content of mycorrhizal plants.  The results of our study support the importance of the outsourcing model of P acquisition in the root economics space framework.  Inadvertent varietal selection in the last decades, resulting in thinner roots and a lower benefit from AMF, has led to a lower productivity of cotton varieties at moderate P supply (i.e., when mycorrhizal, the average biomass of older varieties 5.0 g per plant vs. biomass of newer varieties 4.4 g per plant), indicating the need to rethink cotton breeding efforts in order to achieve high yields without very high P input.  One feasible way to solve the problem of inadvertent varietal selection for cotton is to be aware of the trade-offs between the root do-it-yourself strategy and the outsourcing towards AMF strategy, and to consider both morphological and mycorrhizal root traits when breeding cotton varieties.     

SlTPP4 participates in ABA-mediated salt tolerance by enhancing root architecture in tomato

Salinity tolerance is an important physiological index for crop breeding. Roots are typically the first plant tissue to withstand salt stress. In this study, we found that the tomato (Solanum lycopersicum) trehalose-6-phosphate phosphatase (SlTPP4) gene is induced by abscisic acid (ABA) and salt, and is mainly expressed in roots. Overexpression of SlTPP4 in tomato enhanced tolerance to salt stress, resulting in better growth performance. Under saline conditions, SlTPP4 overexpression plants demonstrated enhanced sucrose metabolism, as well as increased expression of genes related to salt tolerance. At the same time, expression of genes related to ABA biosynthesis and signal transduction was enhanced or altered, respectively. In-depth exploration demonstrated that SlTPP4 enhances Casparian band development in roots to restrict the intake of Na⁺. Our study thus clarifies the mechanism of SlTPP4-mediated salt tolerance, which will be of great importance for the breeding of salt-tolerant tomato crops.     

丁香酸对不同品种烟草苗期根系生长的影响

为探究最新发现的植物源生物硝化抑制剂丁香酸对烟草品种K326和云烟85苗期根系生长的影响,通过基质培养试验,设置0、10、25、50、100、200 μmol/L 6个丁香酸浓度,研究了不同浓度丁香酸在不同时间(3 d和5 d)对K326和云烟85主根伸长量和一级侧根发育的影响。结果表明:与对照(0 μmol/L)相比,25～100 μmol/L丁香酸能促进K326主根伸长,在3 d时促进率为13.33%～30.67%,在5 d时促进率降为8.54%～22.55%,最适浓度为50 μmol/L;10～50 μmol/L丁香酸促进云烟85主根伸长,在3 d时促进率为7.81%～18.75%,在5 d时促进率维持在4.10%～10.66%,最佳促进浓度25 μmol/L;丁香酸对两个烟草品种主根伸长的促进效果均为3 d优于5 d。在侧根发育方面,低浓度丁香酸能显著促进K326和云烟85一级侧根数,两个品种促进侧根发育的最适浓度均为25 μmol/L。相关性分析表明,丁香酸处理下两个烟草品种苗期的主根伸长变化率与侧根数变化率呈显著正相关。可见,适宜浓度的丁香酸对两个典型烟草品种苗期主根增长和...     

不同种衣剂处理对小麦茎基腐病的田间防治效果评价

小麦茎基腐病是由镰刀菌侵染引起的一种重要的真菌性土传病害,在小麦产区呈流行态势,严重威胁中国小麦的安全生产。本研究评价了不同的种衣剂处理、以及返青期喷药对小麦茎基腐病的综合防控效果。从拌种剂对苗期的影响来看：多粘类芽孢杆菌（≥5亿cfu/g）FC+三氟吡啶胺(200 g/L)FS组合能显著增加麦苗的4项评价指标,且能显著降低苗期的病株率。拔节期调查发现：各处理都能较好的控制小麦茎基腐病的扩散流行,以多粘类芽孢杆菌（≥5亿cfu/g）600mL FC+三氟吡啶胺(200 g/L)300mL FS组合效果最好,病株率为15.55%。灌浆期调查结果表明：多粘类芽孢杆菌（≥5亿cfu/g）FC+三氟吡啶胺(200 g/L)FS组合能较好控制小麦茎基腐病,病茎率为17.78%~23.33%,防效为77.27%~83.74%。最终的测产结果表明：多粘类芽孢杆菌（≥5亿cfu/g）FC+三氟吡啶胺(200 g/L)FS组合最优,小麦增产率为16.03%~17.55%,生产上可以采用此药剂组合进行种子包衣预防小麦茎基腐病。     

多功能根际生防促生放线菌的分离鉴定及其对辣椒的益生效果

从健康辣椒根际土壤筛选具防病促生功能的菌种并应用于生物障碍土壤,可为辣椒提质增产和根腐病的防治提供优质的菌剂资源。本研究以辣椒根腐病的病原菌——腐皮镰孢菌（Fusarium solani）为靶标菌,采用平板对峙法筛选优良生防菌株,对其固氮、溶磷、解钾、分泌3-吲哚乙酸（3-indole acetic acid,IAA）、产铁载体、产纤维素酶和蛋白酶、利用酚酸类连作障碍物质等能力进行定性和定量测定。采用形态学、生理生化及16S rRNA基因序列对分离菌株进行鉴定,并采用田间原位栽培试验检测其生防和促生效果。结果表明,从设施连作抗病辣椒根际土中获得6株具有抑菌作用的放线菌,通过定性、定量测试发现菌株G-1拮抗效果最强,其对设施蔬菜5种常见病原菌均具有较好的抑制效果,抗菌谱广,且具有分泌IAA、产铁载体、产纤维素酶和蛋白酶、溶解有机磷、利用酚酸类化感物质等特性。结合形态学、生理生化及16S rRNA进化树分析结果,将其鉴定为弗氏链霉菌（Streptomyces fradiae）。田间原位栽培试验显示,G-1菌剂对辣椒根腐病具有较好的防病作用,可显著降低根腐病的病情指数,促进辣椒根系生长,且可使辣椒增产31.04%。研究表明,弗氏链霉菌G-1具有优良的防病促生功能,其固体菌剂的田间应用对辣椒根腐病具有较好的防治效果,且对辣椒具有明显的促生增产作用,可作为辣椒益生菌剂的候选菌株资源。     

Resistance Evaluation of Some Commonly Used Maize Germplasm Resources to Fusarium Diseases in China

【Objective】 Maize ear rot, stalk rot and sheath rot are the three common Fusarium diseases in maize producing areas in China, and there is a trend of serious mixing occurrence in recent years. The main pathogens of the three major diseases are F. verticillioides, F. graminearum and F. proliferatum. Planting resistant varieties is the most economical and effective method to control this kind of diseases. The objective of this study is to screen out the maize resistant germplasms to ear rot, stalk rot and sheath rot, and to provide references for scientific breeding and rational layout of maize varieties.【Method】 Sixteen common inbred lines of maize including B73, B37, Zheng 58, Chang 7-2, Qi 319 and so on were selected to inoculate F. verticillioides, F. graminearum, and F. proliferatum on maize ears, stalks and sheaths, respectively. The suspension spores of F. verticillioides were injected into healthy maize ears along the filament channel with a continuous syringe at silk stage. The stem of the first aboveground segment of healthy maize was pinned and then injected with the suspension spores of F. graminearum. The suspension spores of F. proliferatum were injected into the sheath of the aboveground 2-5 internodes along the base of healthy maize sheath. Sterile water was used as control. In 2016 and 2018, experiments were conducted in fields to evaluate the disease index of ear rot, sheath rot and the lesion areas of stalk rot, so as to evaluate the resistance level to the ear rot, stalk rot and sheath rot.【Result】 The tested inbred lines Ji 853, OH43 and X178 were moderate resistance to ear rot, 13 of the tested inbred lines such as B73, B37, PH6WC, Ye 478, Zheng 58, 9058, Chang 7-2, Xun 928, Mo17, A619, PH4CV, Qi 319 and 13-1077 were sensitivity or high sensitivity to ear rot; 8 of the tested inbred lines including Qi 319, PH4CV, Mo17, 9058, B37, B73, Chang 7-2 and 13-1077 were moderate resistance and high resistance to stalk rot, 7 of the tested inbred lines such as Zheng 58, Ye 478, PH6WC, Xun 928, Ji 853, A619 and OH43 were sensitivity or high sensitivity to stalk rot; 15 of the tested inbred lines such as B73, B37, Zheng 58, Ye 478, PH6WC, 9058, Chang 7-2, Ji 853, Xun 928, Mo17, A619, PH4CV, OH43, Qi 319 and 13-1077 were moderate resistance or resistance to sheath rot. According to the population of 16 inbred lines, Reid group was susceptible to ear rot. Lancaster group and Tangsipingtou group were resistant to sheath rot. The resistant levels of other groups to Fusarium diseases dispersed to a large extent, and there was no obvious regularity.【Conclusion】 The tested inbred lines Ji 853 and OH43 showed moderate resistance or resistance to sheath rot and ear rot, 8 of the tested inbred lines including Qi 319, PH4CV, Mo17, 9058, B37, B73, Chang 7-2 and 13-1077 showed moderate resistance, resistance or high resistance to sheath rot and stalk rot, but the materials with good resistance to all three diseases had not yet been screened, and other germplasm resources needed to be further screened.     

发根农杆菌介导的白花草木樨毛状根转化体系的建立

白花草木樨（Melilotus albus Medic.ex Desr.）是草木樨最常见的栽培用种之一，具有较强的抗逆性和固氮能力。为了开发一套高效的草木樨转化体系，本研究以白花草木樨为材料，以结瘤基因MaROP6为目的基因，建立了发根农杆菌（Agrobacterium rhizogenes）介导的高效白花草木樨毛状根转化体系。结果表明：利用该方法可以在两周左右获得毛状根，其发生率可达78%，MaROP6基因的毛状根转化率可达70.8%。qRT-PCR鉴定结果表明，MaROP6转基因毛状根的平均相对表达量为对照的36.87倍。毛状根转化体系的建立为白花草木樨基因功能的验证奠定了基础。     

不同乳酸菌组合对苜蓿青贮细菌群落结构的影响

为探讨不同乳酸菌互作对苜蓿（Medicago sativa）青贮细菌群落结构的影响，以2种植物乳杆菌、乳酸片球菌、戊糖片球菌及凝结芽孢杆菌形成的6种乳酸菌组合按1.5 mL·kg^-1的添加量制作苜蓿青贮，以等量蒸馏水替代添加剂作为对照，45 d后运用高通量测序分析细菌群落结构。结果表明，各苜蓿青贮的优势乳酸菌群均为厚壁菌门（Firmicates）的乳杆菌属（Lactobacillus）和片球菌属（Pediococcus），二者相对丰度之和为65.4%~79.0%，其中含植物乳杆菌处理高于对照和含凝结芽孢杆菌处理；与对照相比，乳酸菌组合处理提高了菌群Chao1和ACE指数但降低了Simpson和Shannon指数；6个乳酸菌组合处理中，含凝结芽孢杆菌处理组与对照相似性较高，对苜蓿青贮细菌群落影响较小；相关分析表明，苜蓿青贮菌群结构和多样性可较好地解释其营养品质的变化。综上，乳酸菌组合在一定程度上改善了苜蓿青贮的细菌群落结构，其中含植物乳杆菌的组合效果较好。