Research Advances on Rice Root Breeding

Rice （Oryza sativa L.） roots pIay an important roIe in the deveIopment and yield of rice. Based on the present research situation of rice root breeding, this paper analyzes the significance of rice root breeding for improving yield and changing morphoIogical and physioIogical characteristics of rice. It also discusses research prospects of rice root breeding.

Effects of fitch odor (Mustila eversmanni) on behavior and breeding of root voles (Microtus oeconomus)

From April to December in 1997 at Northwest Plateau Institute of Biology, Chinese Academy of Science, the effect of predation risk on social behavior, feeding, reproduction and sexual hormones of the root voles (Microtus oeconomus) was studied when the root voles (Microtus oeconomus ) were exposed to the odor of fitch (Mustila eversmanni). The results showed that the root voles delayed breeding period and the frequency of the copulation significantly lowered (P【0.01). Comparing with the control group, the accumulated time of amicable behavior in females, and general activity of both sexes increased significantly (P【0.01). The frequencies of general activity (P【0.01), investigating activity (females: P【0.05, males: P【0.01), and self-grooming (P【0.01) of both sexes were less significantly. At the same time, the amount of energy intake (P【0.05) and body weight (P【0.01) of the root voles decreased significantly. The litter weight and ovary index of females decreased (P【0.01). For males the sperm count in epididymides also decreased significantly (P【0.01). The progesterone in the blood serum of root voles females increased significantly under fitch odor (P【0.01).

Elucidating the molecular responses of apple rootstock resistant to ARD pathogens:challenges and opportunities for development of genomics-assisted breeding tools

Apple replant disease(ARD)is a major limitation to the establishment of economically viable orchards on replant sites due to the buildup and long-term survival of pathogen inoculum.Several soilborne necrotrophic fungi and oomycetes are primarily responsible for ARD,and symptoms range from serious inhibition of growth to the death of young trees.Chemical fumigation has been the primary method used for control of ARD,and manipulating soil microbial ecology to reduce pathogen density and aggressiveness is being investigated.To date,innate resistance of apple rootstocks as a means to control this disease has not been carefully explored,partly due to the complex etiology and the difficulty in phenotyping the disease resistance.Molecular defense responses of plant roots to soilborne necrotrophic pathogens are largely elusive,although considerable progress has been achieved using foliar disease systems.Plant defense responses to necrotrophic pathogens consist of several interacting modules and operate as a network.Upon pathogen detection by plants,cellular signals such as the oscillation of Ca^(2+)concentration,reactive oxygen species(ROS)burst and protein kinase activity,lead to plant hormone biosynthesis and signaling.Jasmonic acid(JA)and ethylene(ET)are known to be fundamental to the induction and regulation of defense mechanisms toward invading necrotrophic pathogens.Complicated hormone crosstalk modulates the fine-tuning of transcriptional reprogramming and metabolic redirection,resulting in production of antimicrobial metabolites,enzyme inhibitors and cell wall refortification to restrict further pathogenesis.Transcriptome profiling of apple roots in response to inoculation with Pythium ultimum demonstrated that there is a high degree of conservation regarding the molecular framework of defense responses compared with those observed with foliar tissues.It is conceivable that the timing and intensity of genotype-specific defense responses may lead to different outcomes between rootstocks in response to invasion by necrotrophic pathogens.Elucidation of host defense mechanisms is critical in developing molecular tools for genomics-assisted breeding of resistant apple rootstocks.Due to their perennial nature,use of resistant rootstocks as a component for disease management might offer a durable and cost-effective benefit to tree performance than the standard practice of soil fumigation for control of ARD.

Stress-Tolerant Cassava: The Role of Integrative Ecophysiology-Breeding Research in Crop Improvement

This review highlights an integrative multidisciplinary eco-physiological, breeding and agronomical research on the tropical starchy root crop cassava conducted at CIAT. Laboratory and field studies have elucidated several physio-logical/biochemical mechanisms and plant traits underlying the high productivity in favorable conditions and tolerance to stressful environments, such as prolonged water stress and marginal low-fertility soils. Cassava is endowed with inherent high photosynthetic capacity expressed in near optimal environments that correlates with biological produc- tivity across environments and wide range of germplasm.Field-measured photosynthetic rates were also associated with root yield, particularly under prolonged drought. Extensive rooting systems and stomatal sensitivity to both atmospheric humidity and soil water shortages underlie tolerance to drought. The C4 phosphoenolpyruvate carboxylase (PEPC) was associated with photosynthesis and yield making it a selectable trait, along with leaf duration, particularly for stressful environments. Germplasm from the core collection was screened for tolerance to soils low in P and K, resulting in the identification of several accessions with good levels of tolerance. Cassava has a comparative advantage against major tropical food and energy crops in terms of biological productivity. Results also point to the importance of field research versus greenhouse or growth-chamber studies. In globally warming climate,the crop is predicted to play more role in tropical and subtropical agro-ecosystems. More research is needed under tropical field conditions to understand the interactive responses to elevated carbon dioxide, temperature, soil fertility, and plant water relations.

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 importantfiber 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 KH_(2)PO_(4)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 P_(0);14.5 vs.1.7 mg P per plant;and 4.7 vs.1.6 g biomass per plant at P_(50)).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.

不同处理方式对蒙古栎压条生长和生根性状的影响

以蒙古栎当年生枝条为穗材,采用不同种类和浓度的外源生长物质、不同基质及不同压条方式作为试验处理,测定并分析穗材生长量、生物量和生根性状,旨在筛选最优外源生长物质的种类和浓度、基质组成及压条方式。结果表明:吲哚丁酸钾和ABT1对蒙古栎压条穗材生根均具有明显的促进作用,但存在一定差异。10000 mg/L ABT1的根、茎、叶和单株等生物量分别是5000 mg/L吲哚丁酸钾的4.07倍、1.57倍、1.29倍和1.48倍,生根率、生根量和最长根长分别是5^(#)处理的1.9倍、3.16倍和1.47倍,偏根率仅为38.79%。因此ABT1更适宜作为蒙古栎压条穗材生根的促进剂,其10000 mg/L浓度处理穗材时,生根率、生根量和最长根长分别达到了23.84%、7.05条和16.71 cm。14^(#)处理的株高、地径、茎生物量、叶生物量、单株生物量、生根率、最长根长和偏根率等指标均优于其他基质处理,为蒙古栎压条较适宜的基质。横缢处理组均生根,而非横缢处理组均不生根,表明横缢对蒙古栎压条穗材生根非常重要。采用直立压条方式的株高、地径、根生物量、茎生物量、叶生物量、单株生物量、生根率、生根量和最长根粗等指标均高于倒伏压条方式,直立压条为蒙古栎适宜压条方式。

基于隶属函数综合评价法筛选蒙古栎压条繁育体系研究

蒙古栎是集用材、园林绿化及橡实利用于一身的优良树种。其无性繁育技术体系不健全是制约其产业发展的瓶颈问题。为完善蒙古栎无性繁育技术体系,满足生产上对苗木的需求,建立蒙古栎压条繁育技术。以2年生蒙古栎的嫩枝为穗材,用不同质量浓度和种类的外源生长物质、不同基质及压条方式处理,以蒙古栎压条苗的生长量、生物量及生根性状为评价指标,采用隶属函数的综合评价法筛选处理组合。不同处理蒙古栎压条苗的生长量、生物量及生根性状等指标存在显著差异(P<0.05),其中,苗高和地径均值分别为69.2 cm和7.0 mm;叶干质量、茎干质量、根干质量和单株生物量均值分别为11.20、15.70、0.21、27.70 g;生根率、偏根率、根长、根粗和根数均值分别为7.4%、80.6%、11.6 cm、1.6 mm和2.9条。蒙古栎压条苗在不同处理间的显著差异为筛选较优组合提供可能,采用隶属函数值法对不同处理进行排序,最终筛选出26~#处理、13~#处理、24~#处理、11~#处理和7~#处理5个处理为蒙古栎压条繁育较优处理,其中,26~#处理的生根率、偏根率、根数、根长和根粗生根性状分别为27.6%、72.1%、3.5条、14.4 cm和1.5 mm,除根粗指标外,其他指标均优于参试处理均值,生根率、根数和根长分别是参试处理均值的3.73、1.21、1.24倍;其苗高和地径等生长量指标分别为90.2 cm和8.7 mm,分别是参试处理均值的1.30、1.24倍;其根干质量、茎干质量、叶干质量和单株生物量分别为0.28、31.8、19.3、51.3 g,分别是参试处理均值的1.33、2.03、1.72、1.85倍。结果表明,基于隶属函数综合评价法筛选试验中最优组合为26~#处理,基质为河沙和园土等体积比混合基质,压条方式为直立压条,同时使用铁丝进行横缢,外源生长物质采用IBA-K(2000 mg/L)。研究结果为完善蒙古栎压条育苗提供支撑,为其他树种压条育苗技术体系的建立提供借鉴。

育种马铃薯单株收获根系稳定性分析与试验

针对育种试验马铃薯机械收获过程中根系团聚体易破碎、株间块茎易混杂,导致后续块茎性状信息提取困难、工作效率低等问题,以中原二作区无性一代马铃薯为研究对象,建立入土角-植株运动模型和根系振动模型,并对马铃薯根系在挖掘过程和输送过程进行受力和运动分析,得出单株根系稳定性随着挖掘铲入土角的增大而减小,随输送时间的增加,块茎在振动方向和输送方向呈往复性运动的规律;进一步应用离散元仿真分析方法建立了块茎-根系-土壤离散元模型,确定了挖掘铲的最佳入土角度范围为20°~28°;设计了以挖掘铲入土角、机具前进速度和输送装置的振动频率为试验因素,以单株完整率为试验指标的正交旋转组合试验,并进行响应曲面分析,结果表明,单株完整率最大时的最佳参数组合为:挖掘铲入土角21.8°,机具前进速度0.96 km/h、振动频率1.44 Hz,单株完整率为100%,该参数组合下田间试验平均单株完整率为95.1%。该研究可为育种试验马铃薯收获机的设计提供工作参数选取依据和理论基础。

Progress of Apple Rootstock Breeding and Its Use

Apple rootstock breeding has achieved great progress worldwide.In this review,we first summarize the rootstock breeding targets and utilization in main apple-producing countries.Furthermore,we discuss the focus and important research areas of apple rootstock breeding through five aspects:parent selection and setting of crosses,target genes and marker-assisted breeding,root configuration-guided breeding,apomictic resource utilization,and the application of genetic engineering.Finally,we propose an apple rootstock division plan for China,which has a large potential to provide guidance for apple rootstock breeding and utilization in different apple-producing areas of China.

Constitutive basis of root system architecture:uncovering a promising trait for breeding nutrient-and drought-resilient crops

Root system architecture(RSA)plays a pivotal role in efficient uptake of essential nutrients,such as phosphorous(P),nitrogen(N),and water In soils with heterogeneous nutrient distribution,root plasticity can optimize acquisition and plant growth.Here,we present evidence that a constitutive RSA can confer benefits for sorghum grown under both sufficient and limiting growth conditions.Our studies,using P efficient SC103 and inefficient BTx635 sorghum cultivars,identified significant differences in root traits,with SC103 developing a larger root system with more and longer lateral roots,and enhanced shoot biomass,under both nutrient sufficient and deficient conditions.In addition to this constitutive attribute,under P deficiency,both cultivars exhibited an initial increase in lateral root development;however,SC103 still maintained the larger root biomass.Although N deficiency and drought stress inhibited both root and shoot growth,for both sorghum cultivars,SC103 again maintained the better performance.These findings reveal that SC103,a P efficient sorghum cultivar,also exhibited enhanced growth performance under N deficiency and drought.Our results provide evidence that this constitutive nature of RSA can provide an avenue for breeding nutrient-and drought-resilient crops.

水稻根系育种的意义与前景

针对目前水稻育种的理论与实践中,主要考虑地上部分的形态、生理性状,而对根系这一重要的营养吸收、物质合成器官的有关性状未能开展明确的育种改良的现状,论述了开展根系育种对改良和提高水稻的品种特性,提高产量和品质的重要性、迫切性以及前景。

大豆根系的研究

根系在作物的生长发育过程中起着重要的作用。有关大豆根系的研究不如地上部深入 ,大豆根系研究信息的缺乏在一定程度上影响了育种工作的成效。文章概括介绍了与大豆育种和生产有关的大豆根系方面的研究 。

水稻根系研究现状与展望

综述了近30年来在水稻根系活力、根系与地上部的关系、根系对环境因子的反应以及根系性状的遗传特性等方面所取得的研究进展,并对研究现状中的不足提出了相应的对策,进而展望了今后的水稻根系研究方向。

非生物因素调控植物根系发育可塑性的研究进展

植物根系的发育具有高度的可塑性,基因型完全相同的植物生长在不同的环境当中根系构型可能会表现出显著的差异,而根系构型的变化会影响到植物根系吸收养分和水分的能力,进而影响到作物的产量,因此对植物根系发育可塑性进行研究具有重要意义。笔者对植物根系发育的可塑性以及非生物因素对根系发育可塑性的调控进行综述,并对根系育种的前景进行探讨。

木薯新品种华南8号的选育

木薯新品种华南8号(Manihot esculenta Crantz.cv.M.SC8)是由中国热带农业科学院热带作物品种资源研究所通过CIAT从泰国引进的CMR38-120的自然杂交种F1无性系后代中选育而成的。该品种具有良好的丰产性和广泛的适应性,并有很强的抗风能力和出苗率。其鲜薯产量约36.79t/hm2,比现大面积种植的当家品种华南20(5SC205)增产40.90%,其块根干物率和淀粉含量分别为质量分数40.86%和32.69%,分别比SC205高2.70个百分点和2.16个百分点。因此,华南8号是一个高产、优质的饲用和工业应用型木薯新品种。为了保护新品种及便于产权鉴定,对新品种华南8号建立分子指纹。

木薯新品种华南12号的选育

木薯新品种华南12号(Manihot esculenta Crantz cv.SC No.12)是利用OMR36-34-1(♀)与ZM99247(♂)杂交的杂种后代,经实生苗试验、初级系比、中级系比、高级系比、区域性和生产性试验等选育而成,该品种具有良好的丰产性和广泛的适应性。鲜薯产量约39.37 t/hm2,比现大面积种植的当家品种华南205增产28.65%;其干物率和淀粉含量分别为42.19%和31.11%,分别比华南205高2.51和1.86个百分点;氢氰酸含量低,为42.20 mg/kg。说明华南12号是一个高产、优质、食用型和工业应用型兼备的木薯新品种。此外,还对华南12号建立了分子指纹图谱,为新品种保护与产权鉴定提供理论依据。

大豆疫霉根腐病抗病资源筛选及抗性遗传研究

在人工接种条件下 ,用大豆疫霉根腐病菌 1号生理小种对 5 80份大豆材料 (生产上主栽品种、即将推广的新品系、以及大豆资源材料 )进行鉴定 ,筛选出一批抗大豆疫霉根腐病的品种和资源材料。为大豆疫霉根腐病重发生区提供了种植品种 ,也为抗疫霉根腐病育种提供了杂交亲本。并对其抗性遗传进行初步研究和探讨。

多花黄精根茎芽高效组培增殖和生根体系研究

为了建立多花黄精高效组培增殖和生根体系,给其工厂化、规模化育苗提供可行的关键技术方案,以其根茎芽培养的无菌苗为研究对象,就外植体的不同采集时间和切分处理方式、增殖培养周期、继代培养次数和培养基中活性炭的浓度对其根茎芽增殖和生根的影响情况进行了离体组织培养试验。结果表明：3~4月采集的外植体其生长势和腋芽萌发的表现均最好,平均萌发腋芽6.6个;外植体的最佳切分方式为处理Ⅰ,即将根茎芽切成1份的无菌块茎;最佳增殖培养周期为45 d,平均萌发芽数为6.5个;最适继代培养次数为7次,继代培养7次后平均每个根茎能诱导6.2个不定芽,能诱导的平均根数达20.8条;增殖培养基中活性炭的最佳浓度为0.05 g·L-1,生根培养基中活性炭的最佳浓度为0.20 g·L-1。

烟草根结线虫病研究进展

对烟草根结线虫病原种类、鉴定技术、发生流行规律、抗病育种以及防治方面的研究进展做了详细评介 ,对研究中存在的问题做了初步探讨 。

番茄抗根结线虫接种鉴定技术及其应用

用3个番茄抗线虫品种和两个感线虫品种作为试验材料,对北京地区危害番茄的南方根结线虫进行 苗期人工接种鉴定,研究结果表明,采用灌根接种法,适宜的接种体浓度为2000卵／株,适宜的接种苗龄为10 ～20 d,供试3种栽培基质培育的幼苗对接种效果没有明显影响,接种后30 d进行调查即可明显区分出不同 番茄品种对根结线虫的抗、感差异。运用该方法对28份番茄育种材料进行抗线虫评价,筛选出对线虫免疫的 材料8份,高抗线虫的材料12份,抗线虫材料3份,感病材料5份,其中抗线虫材料占82．1％,说明番茄蕴藏着 丰富的对改良线虫抗性有利用价值的基因资源。