Phenotypic Characterization and QTL/Gene Identification for Internode Number and Length Related Traits in Maize

Internode number and length are the foundation to constitute plant height, ear height and the above-ground spatial structure of maize plant. In this study, segregating populations were constructed between EHel with extremely low ear height and B73. Through the SNP-based genotyping and phenotypic characterization, 13 QTL distributed on the chromosomes (Chrs) of Chr1, Chr2, Chr5-Chr8 were detected for four traits of internode no. above ear (INa), average internode length above ear (ILaa), internode no. below ear (INb), and average internode length below ear (ILab). Phenotypic variation explained (PVE) by a single QTL ranged from 6.82% (qILab2-2) to 12.99% (qILaa5). Zm00001d016823 within the physical region of qILaa5, the major QTL for ILaa with the largest PVE was determined as the candidate through the genomic annotation and sequence alignment between EHel and B73. Product of Zm00001d016823 was annotated as a WEB family protein homogenous to At1g75720. qRT-PCR assay showed that Zm00001d016823 highly expressed within the tissue of internode, exhibiting statistically higher expression levels among internodes of IN4 to IN7 in EHel than those in B73 (P Zm00001d016823 might provide novel insight into molecular mechanism beyond phytohormones controlling internode development in maize.

Timing effect of high temperature exposure on the plasticity of internode and plant architecture in maize

The occurrence of high temperature(HT)in crop production is becoming more frequent and unpredictable with global warming,severely threatening food security.The state of an organ’s growth and development is largely determined by the temperature conditions it is exposed to over time.Maize is the main cereal crop,and its stem growth and plant architecture are closely related to lodging resistance,and especially sensitive to temperature.However,systematic research on the timing effect of HT on the sequentially developing internode and stem is currently lacking.To identify the timing effect of HT on the morphology and plasticity of the stem in maize,two hybrids(Zhengdan 958(ZD958),Xianyu 335(XY335))characterized by distinct morphological traits in the stem were exposed to a 7-day HT treatment from the V6 to V17 stages(Vn presents the vegetative stage with n leaves fully expanded)in 2019-2020.The results demonstrated that exposure to HT during V6-V12 accelerated the rapid elongation of stems.For instance,HT occurring at V7 and V12 specifically promoted the lengths and weights of the 3rd-5th and 9th-11th internodes,respectively.Meanwhile,HT slowed the growth of internodes adjacent to the promoted internodes.Interestingly,compared with control,the plant height was significantly increased soon after HT treatment,but the promotion effect became narrower at the subsequent flowering stage,demonstrating a self-adjusting mechanism in the maize plant in response to HT.Importantly,HT altered the plant architectures,including a rising of the ear position and increase in the ear position coefficient.XY335 exhibited greater sensitivity in stem development than ZD958 under HT treatment.These findings improve our systematic understanding of the plasticity of internode and plant architecture in response to the timing of HT exposure.

A homeodomain-leucine zipper I transcription factor, MeHDZ14,regulates internode elongation and leaf rolling in cassava(Manihot esculenta Crantz)

Drought stress impairs plant growth and other physiological functions. MeHDZ14, a homeodomainleucine zipper I transcription factor, is strongly induced by drought stress in various cassava cultivars.However, the role of MeHDZ14 in cassava growth regulation has remained unclear. Here we report that MeHDZ14 affected plant height, such that a dwarf phenotype and altered internode elongation were observed in transgenic cassava lines. MeHDZ14 was found to negatively regulate the biosynthesis of lignin. Its overexpression resulted in abaxially rolled leaves. The morphogenesis of leaf epidermal cells was inhibited by overexpression of MeHDZ14, with decreased auxin and gibberellin and increased cytokinin contents. MeHDZ14 was found to regulate many drought-responsive genes, including genes involved in cell wall synthesis and expansion. MeHDZ14 bound to the promoter of caffeic acid 3-Omethyltransferase 1(MeCOMT1), acting as a transcriptional repressor of genes involved in cell wall development. MeHDZ14 appears to act as a negative regulator of internode elongation and epidermal cell morphogenesis during cassava leaf development.

Genetic Effects and Heterosis in Plant Height and Internode Traits of Japonica-Indica Hybrid Rice

[Objective] This study aimed to investigate the genetic effects and heterosis of plant height and internode traits of japonica-indica hybrid rice. [Methed] Incomplete diallel crosses were made between six japonica CMS lines and nine indica widecompatibility restorer lines; the genetic effects of plant height and internode traits of japonica-indica hybrid rice were analyzed using the additive-dominance genetic model. [Result] The ple, nt height, panicle length and the length of internode 1 of japonica-in- dica hybrid rice were mainly controlled by the additive effects; but the length of in- ternode 3, internode 4 and internode 5 were mainly controlled by dominance effects. Both the narrow sense heritability and broad sense heritability of plant height, panicle length, number of elongated internodes and length of most internodes reached signifi- cance level. The positive phenotypic correlation, genetic correlation, additive correla- tion and dominance correlation between plant height and panicle length, number of e- longated internodes and internode length were significant; and most of the other paired traits were significantly positively correlated. Heterosis analysis showed that the positive heterosis value over mid-parent and positive heterosis value over better- parent of the length of internode 3, internode 4, internode 5 and internode 6 reached significant level, and the heterosis value over mid-parent of plant height reached extreme significance level. [Conclusion] This study will provide reliable theoretical basis for the genetic improvement and heterosis utilization of plant height and internode traits in japonica-indica hybrid rice.

Basal internode elongation of rice as affected by light intensity and leaf area

Short basal internodes are important for lodging resistance of rice(Oryza sativa L.).Several canopy indices affect the elongation of basal internodes,but uncertainty as to the key factors determining elongation of basal internodes persists.The objectives of this study were(1)to identify key factors affecting the elongation of basal internodes and(2)to establish a quantitative relationship between basal internode length and canopy indices.An inbred rice cultivar,Yinjingruanzhan,was grown in two split-plot field experiments with three N rates(0,75,and 150 kg N ha−1 in early season and 0,90,and 180 kg N ha−1 in late season)as main plots,three seedling densities(16.7,75.0,and 187.5 seedlings m−2)as subplots,and three replications in the 2015 early and late seasons in Guangzhou,China.Light intensity at base of canopy(Lb),light quality as determined from red/far-red light ratio(R/FR),light transmission ratio(LTR),leaf area index(LAI),leaf N concentration(NLV)and final length of second internode(counted from soil surface upward)(FIL)were recorded.Higher N rate and seedling density resulted in significantly longer FIL.FIL was negatively correlated with Lb,LTR,and R/FR(P<0.01)and positively correlated with LAI(P<0.01),but not correlated with NLV(P>0.05).Stepwise linear regression analysis showed that FIL was strongly associated with Lb and LAI(R2=0.82).Heavy N application to pot-grown rice at the beginning of first internode elongation did not change FIL.We conclude that FIL is determined mainly by Lb and LAI at jointing stage.NLV has no direct effect on the elongation of basal internodes.N application indirectly affects FIL by changing LAI and light conditions in the rice canopy.Reducing LAI and improving canopy light transmission at jointing stage can shorten the basal internodes and increase the lodging resistance of rice.

Elevated temperature intensity,timing,and duration of exposure affect soybean internode elongation,mainstem node number,and pod number per plant

A study was conducted in four compartments of a polycarbonate greenhouse at Gainesville,FL, USA to investigate how a soybean(Glycine max L. Merr.) cultivar, Maverick(maturity group III, indeterminate), responded to three elevated temperatures, ELT,(day/night of 34/26 °C, 38/30 °C, and 42/34 °C) in comparison to a control growth temperature(30/22 °C).Carbon dioxide(CO_2) concentration was maintained at 700 μmol mol^(-1) in each compartment by a processor controlled air-sampling and CO_2-injection system. Three sequential experiments were conducted at different times of year(summer, autumn, and early spring)to investigate the effect of intensity, timing, and duration of ELT on soybean node number,internode elongation, mainstem length, and number of pods set per plant. At the control temperature, the soybean plants grown in the polycarbonate greenhouse were taller than field-grown plants. When plants were grown under continuous ELT applied soon after sowing or at initial flowering, the number of nodes increased with increasing ELT intensity,whereas the length of individual internodes decreased. When ELT treatment was applied during the beginning of flowering stage(R1–R2) or earlier, more nodes were produced and the length of affected internodes was decreased. When the ELT was imposed later at reproductive stage R5+ just before the beginning of seed filling, effects on node numbers and internode lengths were negligible. Short-term(10-day) duration of ELT applied at four stages from V3 to R5+ did not significantly affect final mean numbers of nodes or mean mainstem lengths. Possible mechanisms of elevated temperature effects on soybean internode elongation and node number(internode number) are discussed. Total pod numbers per plant increased linearly with mainstem node numbers and mainstem length.Furthermore, total pod numbers per plant were greatest at 34/26 °C rather than at the control temperature of 30/22 °C(and remained high at 38/30 °C). Mild increases in temperature might not threaten, but actually increase, yields of soybean in northerly zones where this crop is currently grown at slightly suboptimal temperatures. However, a sustained increase in ambient temperature would likely threaten soybean yields.

Study on the Relationship of the Characteristics of Vascular Bundles in the First Internode and Grain-filling of Heavy Panicle Type Hybrid Rice

The characteristics of vascular bundle in the first internode from top and grain-filling of heavy panicle type hybrid rice(HPTHR) were studied. The results were as follows: The HPTHR had more vascular bundles and a much bigger area of single vascular bundle, all vascular bundle, all phloem and all xylem in the first inter-node than Shanyou63. The vascular bundles had the similar load of spikelet number and sink capacity between the HPTHR and Shanyou63. The HPTHR had not only a larger sink but also normal grain-filling and sink-filling, high seed-setting rate and heavier panicle. Those characteristics of vascular bundle were the biological bases for the larger and heavier panicle of HPTHR. The results also indicated that the breeding model of HPTHR was an effective measure for the super high-yielding rice breeding.

Mathematical expression for the relationship between internode number and internode length for bamboo, Phyllostachys pubescens

We analyzed the relationship between internode number and intemode length for one of the largest bamboo, Phyllostachys pubescens Mazel ex Houz. For 50 sample culms with various sizes felled in a pure stand of P. pubescens, the intemode number was assigned from base to tip and the length for each internode was directly measured. The result indicated that the intemode length should be cumulated from base to tip, and then the cumulated internode length should be relativized by the total culm length. It was inappropriate to relativize the internode length by the maximum intenode length. In addition, the relationship between the relative internode number （the intemode number relativized by the total number of intemodes） and the relative cumulated internode length should be described not by a power function but by a sigmoid function such as the third-order function. The determined function enabled us to estimate the actual internode length, with the root mean squared error being 4 cm. In conclusion, the mathematical expression presented here, i.e., the relativization of the cumulated internode length by the total culm length and the application of the sigmoid function, will be useful in describing the relationship between internode number and internode length for P. pubescens.

Elongation of the Uppermost Internode for Changxuan 3S,a Thermo-Sensitive Genic Male Sterile Rice Line

Changxuan 3S, a thermo-sensitive genic male sterile （TGMS） rice line with eui gene, is derived from the TGMS rice line Pei＇ai 64S by irradiation with 350 Gy of ^60Co γ-ray. To elucidate the uppermost internode elongation of the TGMS line with eui gene, Changxuan 3S and its parent Pei＇ai 64S were used to study the effects of temperature on panicle exsertion. At 24℃, the uppermost internode of Changxuan 3S elongated the fastest from the 4^th day before flowering to 0 day （flowering）, being 2.1-fold as that of Pei＇ai 64S, whereas it elongated slowly during the 12^th day to the 4^th day before flowering and the 1^st to the 3^rd day after flowering. The uppermost internode of Changxuan 3S exserted from the flag leaf sheath at 22℃, 24℃ and 26℃, and the length of elongated uppermost internode increased with the decreasing temperatures. At 28℃, though the panicles of Changxuan 3S were still enclosed in the leaf sheath, the degree of panicle enclosure was significantly lower compared with Pei＇ai 64S. Cytological studies on Changxuan 3S showed that the uppermost internode elongation was attributed to the increase of cell number and cell elongation, and the latter was more significant. Moreover, the numbers of outermost and innermost parenchyma cells and the cell length of the uppermost internode reduced with the increasing temperatures.

Callogenesis of Cork Oak(Quercus suber L.)through In Vitro Culture of Nodes and Internodes

The present study is about in vitro culture of cork oak, through callogenesis from nodes and internodes, withdrawn from seedlings of three months. These latter were obtained after acorns germination on peat. Nodes showed a high capacity for callogenesis and the best rate was obtained on a medium containing Woody Plant Medium (WPM) macronutrients, Murashige and Skoog (MS) micronutrients and vitamins, 4.5 μM of 6-Benzylaminopurine (BAP), 7 μM of 2-naphthalineacetic acid (NAA) and 30 g/L of Sucrose. Calluses are transplanted onto the same mineral solution, with or without growth regulators, and in the 3rd transplanting;small white embryos appear on the surface of calluses.

The Genetic Analysis of Internode Length in Bitter Gourd

Performing the genetic mechanism research of internode length in bitter gourd has important guiding significance for making breeding strategy. A cross was made between CN19-1 and Thai4-6, and an F2 segregation population was constructed. The genetic characteristic of the internode length was analyzed through employing the major gene plus polygene mixed genetic model. The results showed that the internode length was continuous distribution in the F2 population. The optimum model for internode length genetic analysis was B-1. The additive effect values of two pairs of major genes controlling the internode length were 3.206 3 and 2.638 3, respectively, which showed a positive effect. The dominant effect values were-3.434 6 and-1.459 6, respectively, which showed a negative effect. The dominant degree of major genes is-1.07 and-0.55, respectively, indicating that the first pair of major genes was over dominant and the second pair of major genes was incompletely dominant. The heritability of the major gene was 82.25%, indicating the genetic stability was high. This study could provide a theoretical reference for the breeding of bitter gourd.

Development of Elongated Uppermost Internode CMS Lines for Hybrid Rice Breeding in India

Development of cytoplasmic male sterile (CMS) lines with elongated uppermost internode (EUI) trait provides a genetic option to eliminate the use of GA 3 in hybrid rice. During the past two decades, extensive work

64份小麦种质的赤霉素响应评价及矮秆基因分子鉴定

为深入了解小麦矮秆种质资源的性状表现和遗传组成,研究了64份小麦品种(系)的株高和节间长度对外施赤霉素的响应,并利用分子标记对矮秆基因组成等进行了鉴定。结果表明,不同材料的株高、节间数量和节间长度对赤霉素响应存在差异。节间长对赤霉素的响应集中在倒二节、倒三节和倒四节。供试材料可以通过增加穗长和穗颈长弥补节间数量减少对株高的影响。赤霉素浓度对供试材料株高构成指数影响较小。通过对不同材料株高构成指数分析发现,SH-04和川麦86两份材料具有良好的株高构成比例。分子标记鉴定表明,供试材料中Rht-B1b、Rht-D1b和Rht8的分布频率为31.25%、10.94%和65.63%。矮秆基因的降秆效应表现为Rht-B1b>Rht8、Rht9和Rht13。本研究得出Rht9+Rht13的株高构成指数为0.613,最接近于0.618,含有该基因组合的材料可以在株型育种中加以利用。

玉米多叶矮化突变体lyd1的鉴定与基因克隆

玉米株高降低通常是由节间数目减少、节间长度变短或二者共同作用所致。而本研究在基因编辑后代中发现的玉米多叶矮化突变体lyd1却表现为节间数目显著增加,株高显著降低。lyd1株高仅为93.10 cm,与野生型KN5585的株高159.95 cm相比,降低了41.79%,差异达到极显著水平。然而lyd1叶片数平均达到27.8片,相较野生型平均17.8片叶,增加56.18%,差异达到极显著水平。遗传分析表明,lyd1的突变表型由1对隐性核基因控制,通过图位克隆将控制多叶矮化性状的基因定位于玉米3号染色体标记Indel10和Indel11之间,物理距离0.74 Mb。对定位区间内13个基因(不包含假基因)的序列进行测序,发现仅ZmTE1在第4外显子出现1个A碱基的替换,其他基因无差异。ZmTE1编码一个RNA结合蛋白,氨基酸的替换发生在第3个RNA结合结构域内(RRM3),导致天冬氨酸转变为缬氨酸。突变体lyd1的突变位点与已报道的te1-mum1、te1-mum^(2)、te1-mum^(3)、zm66不同,lyd1的发现为进一步解析玉米叶片和节间发育平衡的遗传机制提供了宝贵的材料。

小麦新种质“普冰3228”穗下节长度QTL定位与候选基因分析

【目的】挖掘小麦新种质“普冰3228”穗下节的有效位点/基因,探讨其穗下节分子遗传机制。【方法】以“普冰3228”ד京4839”杂交产生的210个小麦重组自交系群体为材料,利用55K SNP芯片构建该群体高密度分子遗传连锁图谱,采用完备区间作图法(ICIM⁃ADD)对穗下节长度进行QTL定位分析,并基于QTL定位结果对穗下节长度候选基因进行预测分析。【结果】研究发现210个小麦重组自交系遗传群体穗下节长度存在丰富的遗传差异,分布于16.00~117.50 cm。共检测到6个与小麦穗下节相关的QTL,该QTL主要分布于2B、4B、4D、5B和6D染色体上,其LOD值介于2.55~7.88,解释变异率分布于3.43%~15.84%,且绝大多数QTL均来自母本“普冰3228”。定位于4B染色体上AX⁃109373490~AX⁃111540511区间的QUIL⁃4B.e1和定位于4D染色体上AX⁃110984743~AX⁃109230716区间的QUIL⁃4D.e1为穗下节长度主效QTL,可在2种环境下均被检测到的QUIL⁃4D为穗下节长度稳定QTL。进一步分析发现15个与穗下节长度相关的候选基因。该候选基因主要编码一些相关蛋白及功能酶,通过调节或影响植物代谢活动进而对小麦穗下节长度产生影响。例如TraesCS4D01G039200可能编码一种原纤维家族蛋白,直接影响小麦穗下节长度,TraesCS4D01G040300可能编码代谢产物转运蛋白,通过调节代谢产物在穗下节区域的分配影响穗下节的长度。【结论】研究共检测到与小麦穗下节长度相关QTL 6个,预测到与穗下节相关候选基因15个,研究结果有助于小麦穗下节遗传机制解析,并为穗下节遗传改良提供新种质。

基于近红外光谱技术的水稻节间主要碳氮代谢组分分析

近年来,近红外光谱技术在作物样品组分检测和育种材料快速筛选等方面得到广泛应用,而关于水稻源库器官,尤其是水稻节间主要碳氮代谢组分高通量检测的研究鲜见报道。本研究以试验获得的576份代表性节间样本为材料,在获得样本化学实测值的基础上,采集样本的近红外光谱信息,并利用偏最小二乘(partial least square,PLS)法构建水稻节间主要碳氮代谢组分蔗糖、淀粉、总氮模型。模型验证结果显示:水稻节间蔗糖、淀粉、总氮含量PLS模型验证集决定系数分别为0.988、0.977和0.957,相对分析误差均大于3,模型的性能指数分别为85.20、85.80和86.50,表明所建模型预测结果准确可靠。此外,水稻叶片和叶鞘的淀粉、总氮含量和碳氮比的PLS模型也具有较高的精度。本研究构建了水稻节间主要碳氮代谢组分的近红外光谱模型,为水稻栽培生理和高产栽培理论研究提供了技术支撑。

播量对超晚播冬小麦基部节间性状、机械强度及倒伏率的影响

为探究北疆超晚播栽培方式下小麦基部节间结构特点及播期和播量的最佳组合,以新冬18号为试验材料,设D1(10月25日)、D2(11月4日)、D3(11月14日)3个超晚播期及M1(7.50×10^(6)粒·hm^(-2))、M2(1.00×10^(7)粒·hm^(-2))、M3(1.25×10^(7)粒·hm^(-2))、M4(1.50×10^(7)粒·hm^(-2))4个播量,选择当地适宜播期和播量(9月25日、6.00×10^(6)粒·hm^(-2))为对照(CK),分析了播期和播量对开花期、乳熟期及蜡熟期超晚播小麦基部节间形态结构、3种力学特征及倒伏率的影响。结果表明,小麦开花后抗倒伏性能逐渐降低。与CK相比,超晚播小麦基部节间长度、直径、壁厚、干物质量、茎粗系数、充实度、压碎力、穿刺力及抗折力均减少,表观倒伏率、倒伏级别增加,抗倒伏能力降低。在超晚播条件下,播量相同时,基部节间长度表现为D1>D2>D3,基部节间直径和干物质量表现为D1>D3>D2,田间表观倒伏率和节间壁厚、茎粗系数、充实度以及3种力学指标均表现为D3>D1>D2;播期相同时,增加播量后,基部节间长度、直径、壁厚、干物质量、茎粗系数、充实度、压碎力、穿刺力及抗折力均减少,表观倒伏率、倒伏级别增加;播期与播量对各项指标均不存在互作效应。加大播量后,收获穗数增加,有利于超晚播小麦产量形成。本试验条件下,经综合抗倒伏相关指标和产量考虑,11月4日播种1.00×10^(7)粒·hm^(-2)是北疆超晚播小麦适宜的播期与播量组合。

天然不含节竹管在轴向压缩冲击载荷下冲击响应与吸能特性的数值分析

天然不含节竹管在工程中应用较广,研究此类天然薄壁管结构的抗冲击能力具有重要的意义。利用分离式霍普金森压杆(split Hopkinson pressure bar, SHPB),研究天然竹管的抗冲击性能并进行有限元分析。在ABAQUS中应用三维Hashin和Puck单向纤维复合材料失效准则,结合应变率效应对强度的修正建立竹管本构模型,对冲击载荷下的天然不含节竹管进行模拟,得到的动态应力-应变曲线和破坏模式与SHPB实验接近,验证有限元模型的准确性。结果表明:实验与模拟的极限抗压强度误差最小为2.19%、最大为8.68%;在不同的冲击压缩载荷下,竹管出现端面压溃、沿轴向劈裂等破坏形式;竹管外壁节点处的位移、速度和加速度响应均随冲击载荷的增加而增加;随冲击载荷升高,入射能、反射能、吸收能和比吸能随时间均呈上升趋势,透射能随时间变化不大;不含节竹管的峰值载荷远低于薄壁圆管GFRP (glass fiber reinforcement plastic),但比吸能较为接近,说明不含节竹管并不适用于需承受大冲击能量的高速冲击防护领域。初步结果可为竹管用于工程结构防护给予理论参考。

不同化控产品对镇江地区小麦抗倒性及产量的影响

为验证不同化控产品对小麦倒伏的预防效果,在小麦不同时期喷施“矮壮丰”“灵滟”“植播龙”“百睿”“穗伴侣”5种化控产品,调查处理后小麦茎秆的抗折力、鲜质量、干质量及产量。结果表明,不同化控产品通过降低小麦第1节间、第2节间或穗茎节间长度从而降低小麦高度,降低小麦倒伏的可能性。拔节期喷施“矮壮丰”、返青期和拔节期喷施“灵滟”、拔节前施用“植播龙”能明显降低小麦第1节间的长度,返青期和拔节期喷施“灵滟”还能降低第2节间的长度,破口期喷施“穗伴侣”可降低穗茎节间的长度。5种化控产品处理小麦产量均显著高于对照处理,增产幅度为7.73%~20.62%,以“穗伴侣”处理小麦籽粒产量最高(7593.75 kg/hm^(2)),比对照增加20.62%,增产原因主要为增加单位面积穗粒数和穗数。从抗倒伏角度看,返青-拔节期田间喷施“灵滟”(900 mL/hm^(2))加胺鲜酯(150 mL/hm^(2))可有效降低小麦株高,增加小麦抗倒伏能力;从抗倒伏和增产的角度看,在破口期喷施“穗伴侣”(1500 mL/hm^(2)),对水450 L喷雾,可增加小麦穗长和穗粒数,在提高小麦产量的同时,能有效防止小麦成熟期倒伏。

Axonal Conduction Velocity: A Computer Study

This paper derives rigorous statements concerning the propagation velocity of action potentials in axons. The authors use the Green’s function approach to approximate the action potential and find a relation between conduction velocity and the impulse profile. Computer simulations are used to bolster the analysis.