低甲烷排放转基因水稻是实现水稻低碳生产的理想材料.土壤微生物驱动了稻田甲烷的产生,低甲烷排放转基因水稻土壤微生物群落组成的变化不仅影响稻田甲烷排放,也关系到土壤微生态系统的稳定性.通过对细菌16S rRNA基因、真菌ITS基因的高通量测序及mcrA、nifH、amoA和nirS等功能基因的荧光定量PCR,分析了低甲烷排放转基因水稻(86R27-3)与野生型水稻(MH86)土壤微生物群落间的差异.结果显示:稻田土壤细菌群落的α-多样性指数在86R27-3与MH86间无明显差异,且仅在水稻分蘖期86R27-3的土壤真菌群落多样性指数Shannon、Simpson及均匀度指数Pielou_e显著高于MH86(P＜0.05);β-多样性分析表明土壤细菌或真菌群落组成在86R27-3与MH86间均没有显著差异;但在水稻齐穗期:86R27-3 土壤的放线菌门(Actinobacteria)、罗泽真菌门(Rozellomycota)的相对丰度显著高于MH86(P＜0.05),而酸杆菌门(Acidibacteria)、子囊菌门(Ascomycota)的相对丰度显著低于MH86(P＜0.05);土壤微生物群落功能预测显示,86R27-3 土壤氮、硫和锰代谢细菌功能群丰度显著低于MH86(P＜0.05),如分蘖期的土壤硝酸盐还原、硝酸盐呼吸、硫代硫酸盐呼吸及硫呼吸,齐穗期和成熟期的好氧亚硝酸盐氧化及成熟期的锰氧化等;与MH86相比,86R27-3的土壤真菌功能群丰度有减有增,如在水稻不同生育期内的其未定义腐生物银耳目、嗜热囊菌科、镰刀菌属及韦斯特氏菌功能群丰度显著降低(P＜0.05),而其分蘖期的动物内共生体腐生生物毕赤酵母属和未定义腐生物马勃科功能群丰度显著提高(P＜0.05).定量PCR分析表明86R27-3 土壤中的产甲烷细菌mcrA基因丰度显著低于MH86(P＜0.05),同时,土壤固氮菌nifH基因、氨氧化细菌amoA基因及反硝化细菌nirS基因的丰度在86R27-3土壤中也显著降低(P＜0.05).综上所述,低甲烷排放转基因水稻(86R27-3)对土壤细菌或真菌的群落组成没有影响,但可引起主要细菌或真菌种类的相对丰度及某些细菌或真菌功能群丰度发生变化,并显著降低了稻田土壤微生物功能基因丰度.

本文对内蒙古锡林郭勒草原不同灌丛化阶段(轻度、中度、重度)下小叶锦鸡儿的种群特征及其土壤影响因子进行研究.结果表明:在草原轻度-中度-重度灌丛化的发展过程中,小叶锦鸡儿的密度和高度逐渐增加,两阶段密度和高度分别增长196.0％、34.5％和25.4％、17.6％.小叶锦鸡儿的冠幅、基径、每丛分蘖数和地上生产力均呈先减少后增加的趋势,地上生物量向叶片的分配比例减少.小叶锦鸡儿在中度灌丛化阶段与草本植物之间的竞争最为强烈,其通过减少横向生长如冠幅、基径和每丛分蘖数,增加密度和高度以获取竞争优势.在不同灌丛化阶段小叶锦鸡儿所受到的土壤限制因子明显不同.在轻度灌丛化阶段,土壤因子对小叶锦鸡儿生长的限制作用较小;在中度灌丛化阶段,深层(20～50 cm)土壤水分和土壤pH是限制小叶锦鸡儿密度的关键因素;在重度灌丛化阶段,深层土壤水分和pH限制小叶锦鸡儿纵向生长的主要因素,浅层(0～20 cm)土壤水分和养分是限制灌从横向扩张的主要因素.

种群是草原生态系统结构、功能形成和发展的基础.然而,长期放牧伴随着全球气候变化深刻影响着种群的生长和繁殖.长芒草(Stipa bungeana)是黄土高原典型草原的优势种,具有较高的生态和经济价值.该研究依托黄土高原典型草原长期滩羊轮牧实验平台,采用完全随机的裂区实验设计,以放牧率(0、2.7、5.3、8.7 sheep.hm-2)作为主因子,氮添加水平(0、5、10、20g·m-2)作为副因子,探究放牧、氮添加及其交互作用对长芒草的形态性状、地上生物量及其占群落生物量比例的作用.结果表明:随放牧率的增加,长芒草的株高、冠幅直径、分蘖密度、实生苗密度、地上生物量和生物量占比呈"单峰"曲线变化趋势,种群密度降低.而氮添加增加长芒草的株高、冠幅直径、生殖枝密度、分蘖密度、地上生物量和生物量占比;实生苗密度随氮添加的增加呈先增后减的趋势.相比氮添加,放牧对长芒草地上生物量和生物量占比的总效应小,放牧对地上生物量有直接的负效应,并通过调控分蘖密度、种群密度及地上生物量影响其生物量占比;氮添加不仅对地上生物量有直接的积极效应,还通过株高、生殖枝密度对地上生物量有间接的正效应,同时通过调控种群密度、冠幅直径、分蘖密度和生殖枝密度影响生物量占比.总体上,氮添加增加长芒草的冠幅直径和生殖枝密度(相比株高和分蘖密度),放牧增加实生苗密度(相比种群密度),而放牧和氮添加的交互作用显著影响生殖枝密度.放牧率为4.10和5.29 sheep·hm-2时长芒草具有最大地上生物量及其群落占比.上述结果表明放牧和氮添加通过影响长芒草种群的形态特征来调控其地上生物量和群落地位.

Phosphorus is an essential macronutrient for plant development and metabolism,and plants have evolved ingenious mechanisms to overcome phosphate(Pi)starvation.However,the molecular mechanisms underlying the regulation of shoot and root architecture by low phosphorus conditions and the coordinated utilization of Pi and nitrogen remain largely unclear.Here,we show that Nodulation Signaling Pathway 1(NSP1)and NSP2 regulate rice tiller number by promoting the biosynthesis of strigolactones(SLs),a class of phytohormones with fundamental effects on plant architecture and environmental responses.We found that NSP1 and NSP2 are induced by Oryza sativa PHOSPHATE STARVATION RESPONSE2(OsPHR2)in response to low-Pi stress and form a complex to directly bind the promoters of SL biosynthesis genes,thus markedly increasing SL biosynthesis in rice.Inter-estingly,the NSP1/2-SL signaling module represses the expression of CROWN ROOTLESS 1(CRL1),a newly identified early SL-responsive gene in roots,to restrain lateral root density under Pi deficiency.We also demonstrated that GR244DO treatment under normal conditions inhibits the expression of OsNRTs and OsAMTs to suppress nitrogen absorption but enhances the expression of OsPTs to promote Pi absorption,thus facilitating the balance between nitrogen and phosphorus uptake in rice.Importantly,we found that NSP1p:NSP1 and NSP2p:NSP2 transgenic plants show improved agronomic traits and grain yield under low-and medium-phosphorus conditions.Taken together,these results re-vealed a novel regulatory mechanism of SL biosynthesis and signaling in response to Pi starvation,providing genetic resources for improving plant architecture and nutrient-use efficiency in low-Pi environments.

Rice is one of the earliest domesticated crops,and the plant and panicle architecture are critical domesticated traits that greatly affect yield(Xu and Sun,2021).Previous studies revealed that PROSTRATE GROWTH 1(PROG1)regulates tiller angle,tiller number,and panicle architecture during rice domestication(Jin et al.,2008;Tan et al.,2008).

The lack of genome editing platforms has hampered efforts to study and improve forage crops that can be grown on lands not suited to other crops.Here,we established efficient Agrobacterium-mediated clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated nuclease 9(Cas9)genome editing in a perennial,stress-tolerant forage grass,sheepgrass(Leymus chinensis).By screening for active single-guide RNAs(sgRNAs),accessions that regenerate well,suitable Agrobacterium strains,and optimal culture media,and co-expressing the morphogenic factor TaWOX5,we achieved 11%transformation and 5.83%editing efficiency in sheepgrass.Knocking out Teosinte Branched1(TB1)significantly increased tiller number and bio-mass.This study opens avenues for studying gene function and breeding in sheepgrass.

Crop yield plays a critical role in global food security.For optimal plant growth and maximal crop yields,nutrients must be balanced.However,the potential significance of balanced nitrogen-iron(N-Fe)for improving crop yield and nitrogen use efficiency(NUE)has not previously been addressed.Here,we show that balanced N-Fe sufficiency significantly increases tiller number and boosts yield and NUE in rice and wheat.NIN-like protein 4(OsNLP4)plays a pivotal role in maintaining the N-Fe balance by coordi-nately regulating the expression of multiple genes involved in N and Fe metabolism and signaling.OsNLP4 also suppresses OsD3 expression and strigolactone(SL)signaling,thereby promoting tillering.Balanced N-Fe sufficiency promotes the nuclear localization of OsNLP4 by reducing H2O2 levels,reinforcing the func-tions of OsNLP4.Interestingly,we found that OsNLP4 upregulates the expression of a set of H2O2-scav-enging genes to promote its own accumulation in the nucleus.Furthermore,we demonstrated that foliar spraying of balanced N-Fe fertilizer at the tillering stage can effectively increase tiller number,yield,and NUE of both rice and wheat in the field.Collectively,these findings reveal the previously unrecognized ef-fects of N-Fe balance on grain yield and NUE as well as the molecular mechanism by which the OsNLP4-OsD3 module integrates N-Fe nutrient signals to downregulate SL signaling and thereby promote rice tillering.Our study sheds light on how N-Fe nutrient signals modulate rice tillering and provide potential innovative approaches that improve crop yield with reduced N fertilizer input for benefitting sustainable agriculture worldwide.

Plant architecture and panicle architecture are two critical agronomic traits that greatly affect the yield of rice(Oryza sativa).PROSTRATE GROWTH 1(PROG1)encodes a key C2H2-type zinc-finger transcription factor and has pleiotropic effects on the regulation of both plant and panicle architecture,thereby influ-encing the grain yield.However,the molecular mechanisms through which PROG1 controls plant and panicle architecture remain unclear.In this study,we showed that PROG1 directly binds the LAZY 1(LA1)promoter and acts as a repressor to inhibit LA1 expression.Conversely,LA1 acts as a repressor of PROG1 by directly binding to the PROG1 promoter.These two genes play antagonistic roles in shaping plant architecture by regulating both tiller angle and tiller number.Interestingly,our data showed that PROG1 controls panicle architecture through direct binding to the intragenic regulatory regions of OsGIGANTEA(OsGI)and subsequent activation of its expression.Collectively,we have identified two crucial targets of PROG1,LA1 and OsGI,shedding light on the molecular mechanisms underlying plant and panicle architecture control by PROG1.Our study provides valuable insights into the regulation of key domestication-related traits in rice and identifies potential targets for future high-yield rice breeding.

研究根茎型禾草的克隆生长特性在揭示草地植物的适应对策中具有重要意义.本研究在观测24种根茎型禾草地上、地下克隆生长格局的基础上,选择3种代表性禾草,采用"单位土体挖掘取样法",对其芽库及克隆构件季节性变化进行监测.结果表明:(1)根茎型禾草的克隆生长格局包含三类:(Ⅰ)以无芒雀麦为代表的"短根茎平面扩展型"、(Ⅱ)以赖草为代表的"长根茎平面扩展型"和(Ⅲ)以白草为代表的"空间层片扩展型".(2)白草的分蘖(540～680个·m-2)、节间(3200～4600个·m-2)和芽库(350～1000个· m-2)密度成倍数高于其他2种禾草,其空间克隆生长能力最强(P≤0.05);赖草的节间密度(1300～1700个·m-2)和长度(3.5～4.0 cm)显著高于无芒雀麦的节间密度(70～320个·m-2)与长度(1.0～1.5 cm),根茎延伸能力较后者强(P≤0.05).(3)无芒雀麦的分蘖密度与分蘖芽呈正相关,但与向上芽呈负相关,呈"密集型"生长(P≤0.05);赖草的分蘖密度和节间密度与根茎芽、分蘖芽、水平芽和向上芽的芽密度均呈正相关,呈"密集-游击型"过渡生长;白草分蘖密度和节间密度均与根茎芽呈正相关,呈"游击型"生长.结合研究区干旱、夏季高温、冬季寒冷、土壤贫瘠等特点,"密集-游击型"生长的赖草既可以集中利用资源,也可以索取分散资源,更易于在该区形成优势种群.通过分析芽库、克隆构件的分布与数量关系,了解根茎型禾草克隆生长特性,有助于揭示植物在群落中的分布,为退化草地的恢复提供有益参考.

该研究通过测定不同光周期(8、12、14和16 h·d-1)和光照强度(1500、2500和3500 lux)处理下醉马草内生真菌共生体幼苗的形态指标以及叶绿素、可溶性糖、麦角酰胺和麦角新碱的含量,以明确醉马草内生真菌共生体幼苗生长和生物碱积累的最适光照条件,为醉马草内生真菌共生体的应用提供理论依据.结果发现:(1)醉马草内生真菌共生体幼苗株高、叶绿素和可溶性糖含量随着光照时间的延长而增加,并在光周期为16 h·d-1时显著(P<0.05)高于其他处理;根长、单株分蘖数和单株生物量均先升高后降低,且均在14 h·d-1处理下达到最大值.(2)随着光照强度的增加,醉马草内生真菌共生体幼苗4个形态指标以及叶绿素和可溶性糖含量均呈增加的趋势,并在光照强度为3500 lux时均达到最大值.(3)随着处理时间的延长,醉马草内生真菌共生体幼苗麦角酰胺和麦角新碱的含量在不同光周期处理下均呈上升的趋势,并在光周期为12 h·d-1和光照强度为2500 lux处理下麦角酰胺和麦角新碱的含量均显著高于其他处理(P<0.05),且在处理第15天时达到最大值.研究表明,适宜的光照环境能显著促进醉马草内生真菌共生体幼苗生长和生物碱的积累,并以12 h·d-1光周期和2500 lux光照处理下最有利于麦角酰胺和的麦角新碱积累.