Vital contribution of brassinosteroids to hypoxia-stimulated coleoptile elongation in submerged rice

The rapid elongation of rice(Oryza sativa)coleoptile is pivotal for the plant plumule to evade hypoxia stress induced by submergence,a condition often arising from overirrigation,ponding,rainstorms,or flooding.While brassinosteroids(BRs)are recognized for their diverse roles in plant growth and development,their influence on coleoptile elongation under hypoxic conditions remains largely unexplored.In this study,we demonstrate the significant requirement of BRs for coleoptile elongation in deep water.During coleoptile development,Glycogen Synthase Kinase3-Like Kinase2(GSK2),the central inhibitor of BR signaling in rice,undergoes substantial suppression in deep water but induction in air.In contrast,the dephosphorylated form of BRASSINAZOLE RESISTANT1(OsBZR1),representing the active form of the key BR signaling transcription factor,is induced in water but suppressed in air.Remarkably,the knockout of GSK3-like kinase genes significantly enhances coleoptile elongation in deep water,strongly indicating a vital contribution of BR response to hypoxia-stimulated coleoptile elongation.Transcriptome analysis uncovers both BR-associated and BR-independent hypoxia responses,implicating substance metabolism,redox reactions,abiotic stress responses,and crosstalk with other hormones in the regulation of BR-induced hypoxia responses.In summary,our findings suggest that rice plumules rapidly elongate coleoptiles through the activation of BR response in deep water,enabling them to escape from submergence-induced hypoxia stress.

Modes of Action of Phytochromes in Establishing Different Phototropic Responsiveness of Maize Coleoptiles

Previous studies have examined the effects of red light (R) on phototropism of maize ( Zea mays L. cv. Royaldent Hit 85) coleoptiles. The R effect on time-dependent phototropism (TDP) was further studied by characterizing its fluence-response relationship. The results showed the R effect was a low-fluence-response, unlike those on pulse-induced phototropisms that show a very-low-fluence-response mode. A subsequent pulse of far-red light (FR) could reverse the R effect. TDP responsiveness, however, recovered as the following FR was extended, The FR-dependent increase in TDP responsiveness was obtained even coleoptiles were pretreated only with FR. It suggested that TDP responsiveness could also be established in response to a FR signal. The fluence-response relationship for the effect of FR was then investigated. The effect of FR depended on the time of irradiation and required high photon fluences. Because reciprocity was invalid at the higher fluence range, the effect of FR would be a high-irradiance-response mode. Relation between phytochrome action modes and possible multiple pathways for phototropic signal transduction was analyzed based on the experiment results.

Research on Callus Induction from Coleoptile Explants of Amorphophallus

[Objective] The aim was to explore the ways of callus induction and the effect that different culture condition exerted on the callus induction from coleoptile explants of Amorphophallus. [Method] The test used konjac coleoptile as materials and designed four hormones, including 6-BA, NAA, KT and 2, 4-D, grouping 8 treat- ments to conduct statistics on callus induction in different test conditions. [Result] The result showed that multi-location generation and polymorphism was the impor- tant feature of callus induction from coleoptile explants of Amorphophallus; culture condition had significant influence on callus induction from coleoptile explants （P〈 0.01）. [Conclusion] It reached the best effect of callus induction when the culture condition was MS ＋ 1.0 mg/L 6-BA ＋ 2.0 mg/L NAA or MS ＋ 1.0 mg/LKT ＋ 2.0 mg/L 2, 4-D.

The Effects of Dwarfing Genes (Rht-B1b, Rht-D1b, and Rht8) with Different Sensitivity to GA_3 on the Coleoptile Length and Plant Height of Wheat

Understanding the effects of wheat dwarfing genes on the coleoptile length and plant height is crucial for the proper utilization of dwarfing genes in the improvement of wheat yield. Molecular marker analysis combined with pedigree information were used to classify wheat cultivars widely planted in major wheat growing regions in China into different categories based on the dwarfing genes they carried. The effects of the dwarfing genes with different sensitivity to gibberellins （GA3） on the coleoptile length and plant height were analyzed. Screening of 129 cultivars by molecular marker analysis revealed that 58 genotypes of wheat contained the dwarfing gene Rht-B1b, 24 genotypes of wheat contained Rht-D1b gene and 73 genotypes of wheat possessed Rht8 gene. In addition, among these 129 cultivars, 35 genotypes of wheat cultivars contained both Rht-B1b and Rht8 genes and 16 genotypes of wheat cultivars contained both Rht-D1b and Rht8 genes. Wheat cultivars with the dwarfing genes Rht-B1b or Rht-D1b were insensitive to GA3, while the cultivars with the dwarfing gene Rht8 were sensitive to GA3. Most of the wheat genotypes containing combination of Rht8 gene with either Rht-B1b or Rht-D1b gene were insensitive to GA3. The plant height was reduced by 24.6, 30.4, 28.2, and 32.2%, respectively, for the wheat cultivars containing Rht-B1b, Rht-D1b, Rht-B1b ＋ Rht8, and Rht-D1b ＋ Rht8 genes. The plant height was reduced by 14.3% for the wheat cultivar containing GA3-sensitive gene Rht8. The coleoptile length was shortened by 25.4, 31.3, 28.4 and 31.3%, respectively, in the wheat cultivars containing Rht-B1b, Rht-D1b, Rht-B1b ＋Rht8 and Rht-D1b ＋ Rht8 genes, while the coleoptile length was shortened only by 6.2% for the wheat cultivar containing Rht8 gene. We conclude that GA3-insensitive dwarfing genes （Rht-B1b and Rht-D1b） are not suitable for the wheat improvement in dryland because these two genes have effect on reducing both plant height and coleoptile length. In contrast, GA3- sensitive dwarfing gene （Rht8） is a relatively ideal candidate for the wheat improvement since it significantly reduces the plant height of wheat, but has less effect on the coleoptile length.

Relationship Between Coleoptile Length and Drought Resistance and Their QTL Mapping in Rice

By using a set of recombinant inbred line （RIL） population involving in 195 lines derived from a cross of Zhenshan 97B （lowland variety） and IRAT109 （upland variety）, the correlation analysis between coleoptile length （CL） and drought resistance index （DRI） and their QTL identification were conducted. There existed a significantly positive relationship between CL and DRI with the correlation coefficient of 0.2206＊＊ under water stress conditions. Under normal and water stress conditions, a total of eleven and four QTLs for CL and DRI, respectively, were detected on chromosomes 1,2, 4, 5, 6, 7, 9, 11 and 12 by using a linkage map including 213 SSR markers, which explained 4.84% to 22.65% of phenotypic variance. Chromosomes 1 and 9 possessing the QTLs for DRI harbored simultaneously QTLs for CL, and qCL9 shared the same chromosome location with qDR19 （RM160-RM215）. Comparing the QTLs related to drought resistance in other studies, QTLs for CL and DRI were located in the same or adjacent marker interval as those related to root traits, such as number, dry weight, depth, and length of root. Moreover, sixteen and three pairs of epistatic loci for CL and DRI were found, which accounted for 56.17% and 11.93% of the total variation in CL and DRI, respectively.

Coleoptile Purple Line Regulated by A-P Gene System Is a Valuable Marker Trait for Seed Purity Identification in Hybrid Rice

In plants,a large number of anthocyanin biosynthetic genes encoding enzymes and regulatory genes encoding transcription factors are required for anthocyanin synthesis.Coleoptile purple lines are two purple lines on both sides of coleoptiles after seed germination.However,the molecular mechanism of coleoptile purple line is not clear in rice so far.In this study,two major dominant genes,coleoptile purple line 1(OsCPL1,also known as OsC1)and coleoptile purple line 2(OsCPL2),were isolated via map-based cloning,and both of them were required for anthocyanin biosynthesis of coleoptile purple line in rice.The knockout and complementation experiments confirmed that OsC1 was required for purple color in most organs,such as coleoptile line,sheath,auricle,stigma and apiculus,whereas OsCPL2 was just required for coleoptile purple line.OsC1 was predominantly expressed in coleoptiles,flag leaves,and green panicles,and highly expressed in young leaves,whereas OsCPL2 was predominantly expressed in coleoptiles,and extremely lowly expressed in the other tested organs.Loss-of-function of either OsC1 or OsCPL2 resulted in significant reduction of transcript levels of multiple anthocyanin biosynthesis genes in coleoptiles.Coleoptile purple line was further used as a marker trait in hybrid rice.Purity identification in hybrid rice seeds via coleoptile purple line just needed a little water,soil and a small plate and could be completed within 5 d.Molecular marker and field identification analyses indicated that coleoptile purple line was reliable for the hybrid seed purity identification.Our findings disclosed that coleoptile purple line in rice was regulated by two major dominant genes,OsC1 and OsCPL2,and can be used as a simple,rapid,accurate and economic marker trait for seed purity identification in hybrid rice.

Sprouted Sorghum Extract Elicits Coleoptile Emergence, Enhances Shoot and Root Acclimatization, and Maintains Genetic Fidelity in indica Rice

The high growth-stimulating effect of plant extract has urged the plant biotechnologists to use natural supplements in the culture media instead of synthetic phytohormones. We advocated the effect of sprouted sorghum extract(SSE) on emergence, in vitro acclimatization, and genetic fidelity in coleoptile derived callus of indica rice variety ADT36. The use of SSE with Murashige Skoog medium efficiently acclimatized the root and shoot apical systems. A higher mat and seminal roots(3.4 g biomass) with an efficient shoot primordium elongation were observed with an increase in the concentration of SSE. Seeds treated with SSE medium showed higher germination and earlier coleoptile maturation about 48 h compared to untreated seeds, and there was a higher expression of e EF-1α with an increase in coleoptile length. B5 medium was effective on inducing embryogenic and nodular callus from 3-day-old coleoptile with 3.0 mg/L 2,4-dichlorophenoxyacetic acid and further proliferated effectively with 0.8 mg/L kinetin with a fresh weight of 180 mg. Highly significant regeneration was observed with combination of 2.5 mg/L 6-benzylamino purine and 3.0 mg/L α-naphthaleneacetic acid. The metabolic and genetic profiles of in vitro and directly cultivated plants were the same, examined through Fourier-transform infrared spectroscopy, random amplified polymorphic DNA(RAPD), inter-simple sequence repeat(ISSR) and R-ISSR(combination of RAPD and ISSR) markers, respectively, and thus confirming the significant efficacy of the SSE incorporated medium. Disarmed T-DNA was transformed to coleoptile derived callus through Agrobacterium tumefaciens LBA4404 and confirmed by GUS assay. The T-DNA integration was confirmed by DNA blot analysis using DNA from transient GUS-expressed explants. Thus, SSE can be used as a natural and organic supplement for organogenesis and efficient acclimatizations of shoot and root apical meristems in regenerated plants.

Analyses and identifications of quantitative trait loci and candidate genes controlling mesocotyl elongation in rice

Rice direct seeding has the significant potential to save labor and water,conserve environmental resources,and reduce greenhouse gas emissions tremendously.Therefore,rice direct seeding is becoming the major cultivation technology applied to rice production in many countries.Identifying and utilizing genes controlling mesocotyl elongation is an effective approach to accelerate breeding procedures and meet the requirements for direct-seeded rice(DSR) production.This study used a permanent mapping population with 144 recombinant inbred lines(RILs) and 2 828 bin-markers to detect quantitative trait loci(QTLs) associated with mesocotyl length in 2019 and 2020.The mesocotyl lengths of the rice RILs and their parents,Lijiangxintuanheigu(LTH) and Shennong 265(SN265),were measured in a growth chamber at 30°C in a dark environment.A total of 16 QTLs for mesocotyl length were identified on chromosomes 1(2),2(4),3(2),4,5,6,7,9,11(2),and 12.Seven of these QTLs,including qML1a,qML1b,qML2d,qML3a,qML3b,qML5,and qML11b,were reproducibly detected in both years via the interval mapping method.The major QTL,qML3a,was reidentified in two years via the composite interval mapping method.A total of 10 to 413 annotated genes for each QTL were identified in their smallest genetic intervals of 37.69 kb to 2.78 Mb,respectively.Thirteen predicted genes within a relatively small genetic interval(88.18 kb) of the major mesocotyl elongation QTL,qML3a,were more thoroughly analyzed.Finally,the coding DNA sequence variations among SN265,LTH,and Nipponbare indicated that the LOC_Os03g50550 gene was the strongest candidate gene for the qML3a QTL controlling the mesocotyl elongation.This LOC_Os03g50550 gene encodes a mitogen-activated protein kinase.Relative gene expression analysis using qRT-RCR further revealed that the expression levels of the LOC_Os03g50550 gene in the mesocotyl of LTH were significantly lower than in the mesocotyl of SN265.In conclusion,these results further strengthen our knowledge about rice’s genetic mechanisms of mesocotyl elongation.This investigation’s discoveries will help to accelerate breeding programs for new DSR variety development.

水稻已克隆中胚轴伸长基因效应解析及优异单倍型鉴定

旱直播是未来水稻生产的重要发展方向,在南亚和东南亚籼稻种植区已有较大面积,然而热带和亚热带地区粳稻种植多采用传统育苗移栽。中胚轴长度(Mesocotyl length,ML)是影响水稻旱直播出苗和幼苗活力的重要因素。基于分子标记辅助选择(Molecular marker assisted selection,MAS)育种,培育长中胚轴种质是促进水稻旱直播推广最为经济、高效的方式。迄今,已有4个水稻中胚轴伸长基因报道,即OsGSK2、GY1、OsPAO5和OsSMAX1。笔者选择3K重测序项目中TROP和TEMP粳稻亚群开展分析,测定中胚轴长度并鉴定OsGSK2、GY1、OsPAO5和OsSMAX1基因的优异单倍型。结果表明,TROP和TEMP亚群中胚轴长度呈典型的连续正态分布。OsGSK2、GY1、OsPAO5和OsSMAX1分别包括3、3、3和6种单倍型;同一基因在TROP和TEMP亚群中单倍型分布频率也存在差异。TROP亚群中OsGSK2-Hap1、GY1-Hap2、OsPAO5-Hap3、OsSMAX1-Hap2和OsSMAX1-Hap3为优异单倍型;TEMP亚群优异单倍型为OsGSK2-Hap1、OsPAO5-Hap2和OsSMAX1-Hap2。另外,TROP和TEMP亚群中多数中胚轴优异单倍型材料所对应的苗高要高于非优异单倍型,在破土出苗时易形成生长优势。鉴定到的优异单倍型在TROP和TEMP亚群中均呈现较显著的加性效应,可用于MAS育种。本研究为不同地区直播粳稻的选育提供参考,促进旱直播技术的快速推广。

OsEIL1 and OsEIL2,two master regulators of rice ethylene signaling,promote the expression of ROS scavenging genes to facilitate coleoptile elongation and seedling emergence from soil

Successful emergence from the soil is a prerequisite for survival of germinating seeds in their natural envi-ronment.In rice,coleoptile elongation facilitates seedling emergence and establishment,and ethylene plays an important role in this process.However,the underlying regulatory mechanism remains largely unclear.Here,we report that ethylene promotes cell elongation and inhibits cell expansion in rice coleoptiles,result-ing in longer and thinner coleoptiles that facilitate seedlings emergence from the soil.Transcriptome analysis showed that genes related to reactive oxygen species(ROS)generation are upregulated and genes involved in ROS scavenging are downregulated in the coleoptiles of ethylene-signaling mutants.Further investiga-tions showed that soil coverage promotes accumulation of ETHYLENE INSENSITIVE 3-LIKE 1(OsEIL1)and OsEIL2 in the upper region of the coleoptile,and both OsEIL1 and OsEIL2 can bind directly to the promoters of the GDP-mannose pyrophosphorylase(VTC1)gene OsVTC1-3 and the peroxidase(PRX)genes OsPRX37,OsPRX81,OsPRX82,and OsPRX88 to activate their expression.This leads to increased ascorbic acid content,greater peroxidase activity,and decreased ROS accumulation in the upper region of the coleoptile.Disruption of ROS accumulation promotes coleoptile growth and seedling emergence from soil.Thesendings deepen our understanding of the roles of ethylene and ROS in controlling coleoptile growth,and this information can be used by breeders to produce rice varieties suitable for direct seeding.

小麦胚芽鞘长度QTL定位和GWAS分析

在干旱条件下,小麦(Triticum aestivum L.)适当深播可提高出苗率,胚芽鞘长度决定了小麦播种的最大深度,因此培育长胚芽鞘小麦品种至关重要。为了挖掘控制小麦胚芽鞘长度相关的数量性状位点(quantitative trait loci,QTL),本研究以275份豆麦/石4185重组自交系(recombinant inbred lines,RIL)群体和186份自然群体为材料,根据90K SNP芯片的分型结果,利用3个环境下小麦胚芽鞘长度表型数据进行QTL鉴定。采用完备区间作图法(inclusive composite interval mapping,ICIM)在RIL群体中鉴定到2个稳定的QTL位点,分别位于4BS(30.17~40.59 Mb)和6BL(700.08~703.53 Mb)染色体上,解释表型变异率(PVE)分别为26.29%~28.46%和4.16%~4.36%;全基因组关联分析(GWAS)采用混合线性模型(Mixed linear model,MLM)方法,共鉴定到36个稳定的QTL位点,分别位于1A(3)、1B(3)、1D(2)、2A(1)、3A(2)、3B(2)、4B(11)、5A(1)、5B(3)、6B(4)、7A(2)、7B(2)染色体上,在3个环境中重复检测到的显著关联位点有7个,其中3个位点与已报道的位点重叠或邻近,其他4个位点推测为新位点,分别位于1A(499.03 Mb)、3A(73.06 Mb)、4B(648.74~648.87 Mb)、7A(36.31 Mb)染色体上,预测了5个候选基因(TraesCS1A03G0748300、Rht1、TraesCS4B03G0110000、TraesCS4B03G0112200和TraesCS7A03G0146600)。在两个群体中均鉴定到位于4BS(30.17~40.59 Mb)染色体上的主效QTL位点,该位点的候选基因Rht1已被证实能降低小麦胚芽鞘长度。该研究结果为挖掘控制小麦胚芽鞘长度的基因以及胚芽鞘长度相关性状分子标记辅助选择育种奠定了基础。

不同植物胚芽鞘在“达尔文向光性实验”中应用的再探讨

本文以小麦和燕麦胚芽鞘为实验材料,对“达尔文向光性实验”进行定量分析,从单子叶植物的选择、胚芽鞘切除长度、观察时间等方面对该实验进行了优化,取得了较好的实验效果。

探究重力和单侧光对胚芽鞘弯曲程度的影响

阐述了以小麦与玉米胚芽鞘为实验材料,探究重力和单侧光对胚芽鞘弯曲程度的影响。分析实验结果发现,重力对胚芽鞘弯曲的影响要大于单侧光的影响。

Screening for Rice Germplasms with Specially-Elongated Mesocotyl

The lengths of mesocotyl in the seedlings of 84 lowland rice varieties and 12 upland rice varieties were measured following the treatments of daylight and darkness during germination. The elongation of mesocotyl in the varieties tested was inhibited under daylight condition, and the mesocotyl of all the varieties elongated variably under darkness condition. The elongated lengths of the mesocotyl in upland rice, ranging from 0.36 cm to 1,61 cm with an average of 0.81 cm, was obviously longer than those in lowland rice, ranging from 0.12 cm to 1.56 cm with an average of 0.42 cm. Among 14 rice varieties with over 1 cm of mesocotyl length, five belonged to upland rice, and nine to lowland rice. The possible utilization of the elongated-mesocotyl rice germplasm in varietal imorovement, direct-seeded plantina and seed ouritv testina were discussed.

Integrated transcriptome, small RNA, and degradome analysis to elucidate the regulation of rice seedling mesocotyl development during the passage from darkness to light

The mesocotyl,a structure located between the basal part of the seminal root and the coleoptile node of seedlings,contributes to pushing the shoot tip through the soil surface,a function that is essential for the uniform emergence of direct-seeded rice.Its elongation is inhibited by light and induced in darkness.This investigation of an indica rice(P25)with vigorous mesocotyl elongation was aimed at identifying the"omics"basis of its lightinduced growth inhibition.A transcriptomic comparison between mesocotyl tissues that had developed in the dark and then been exposed to light identified many differentially expressed genes(DEGs)and differentially abundant micro RNAs(mi RNAs).Degradome sequencing analysis revealed 27 negative mi RNA-target pairs.A co-expression regulatory network was constructed based on the mi RNAs,their corresponding targets,and DEGs with a common Gene Ontology term.It suggested that auxin and light,probably antagonistically,affect mesocotyl elongation by regulating polyamine oxidase activity.

水稻中胚轴伸长相关候选基因的关联分析

旱直播技术可有效提升水稻生产效率。中胚轴长度(ML,mesocotyl length)是影响旱直播水稻出苗和幼苗活力的重要性状。选育长中胚轴品种是促进旱直播技术推广最为经济、有效的方式。旱直播在南亚和东南亚地区的籼稻种植区已有一定推广面积,在粳稻种植区推广面积较少。前人已发现一批中胚轴伸长相关候选基因,但其可靠性及适用性尚待验证。基于已报道的97个中胚轴伸长相关候选基因,在不同来源的TROP和TEMP两个粳稻自然群体开展候选基因关联分析,鉴定到4个显著候选基因,解释4.7%~6.3%和5.4%~6.7%的遗传变异。其中,LOC_Os01g44130、LOC_Os03g50560和LOC_Os05g27790在TROP和TEMP群体中均显著关联,而LOC_Os11g10990和LOC_Os10g20860分别在TROP和TEMP群体中显著关联。候选基因所编码蛋白主要参与植物激素合成与代谢、信号转导和植物生长进程。进一步在TROP群体(LOC_Os05g27790-Hap3和LOC_Os05g27790-Hap6、LOC_Os03g50560-Hap1、LOC_Os01g44130-Hap1和LOC_Os11g10990-Hap1和LOC_Os11g10990-Hap3)和TEMP群体(LOC_Os05g27790-Hap6、LOC_Os01g44130-Hap1和LOC_Os10g20860-Hap5)中分别鉴定到6个和3个可用于分子标记辅助育种的优异单倍型。本研究鉴定到的显著关联候选基因及其优异单倍型可应用于水稻长中胚轴分子育种实践中。

利用高密度遗传图谱定位水稻耐低氧萌发QTL

【目的】耐低氧萌发能力是水稻直播适应性的核心性状之一。采用直播型温带粳稻品种Francis和多穗型优质恢复系R998衍生的重组自交系群体开展水稻耐低氧萌发QTL定位研究,旨在为直播稻品种培育提供新的有价值的基因资源,促进直播稻新品种培育和直播稻生产方式的推广。【方法】以28℃淹水10 cm暗培养7 d的水稻胚芽鞘长、芽长和最大根长作为耐低氧萌发能力指标,通过低倍基因组重测序构建含有3106个bin标记的高密度遗传图谱,采用WinQTL Cart 2.5进行QTL扫描。【结果】低氧萌发条件下,Francis的胚芽鞘长度和根长显著高于R998,但是两者芽长差异不显著。构建的遗传图谱总图距为3646.2 cM,其中12号染色体标记数最少,1号染色体标记数最多,分别为174个和389个。遗传图谱的标记平均图距为1.21 cM,各染色体的平均图距范围为0.68~1.84 cM,5 cM以上的Gap比例为0.36%。采用复合区间作图法(CIM),共检测到分布于5条染色体上的6个耐低氧萌发相关QTL。其中,控制胚芽鞘长度、芽长和根长的QTL个数分别为3、1、2个。表型贡献率超过10%的2个QTL是胚芽鞘长度位点qCL9和芽长位点qSL5,二者分别解释群体表型变异的13.39%和10.78%。qCL9与根长QTL qRL2-1的增效等位基因均来自亲本Francis,其余4个QTL的增效等位基因来自亲本R998。6个QTL中有3个暂未见报道,可能是新的QTL。【结论】Francis和R998低氧萌发特性存在显著差异,双亲中均含有耐低氧萌发的增效等位基因。qCL9和qSL5是分别影响胚芽鞘长和芽长的主效QTL,在直播稻分子育种中具有潜在应用价值。

水稻萌发耐淹性鉴定评价方法研究及种质资源筛选

低氧胁迫下出苗率下降是限制直播稻安全生产的关键问题之一。建立准确、高效的水稻萌发耐淹性鉴定方法,并筛选强萌发耐淹性的水稻种质对直播稻新品种选育具有重要意义。本研究以20份水稻品种为供试材料,设置不同淹水深度(3 cm、6 cm、9 cm、12 cm、15 cm和18 cm)、不同处理温度(20℃、25℃和30℃)和不同淹水天数(3 d、5 d、7 d、9 d、11 d、13 d和15 d)进行萌发耐淹性鉴定,以胚芽鞘长度为指标进行萌发耐淹性评价,旨在明确水稻萌发耐淹性的评价方法。结果表明,水稻种质在淹水临界深度上存在籼粳间差异,粳稻的淹水临界深度为6 cm,而籼稻的淹水临界深度为9 cm;在温度梯度处理中,30℃时种质间的胚芽鞘长四分位差最大,因此认为30℃是水稻种质萌发耐淹性鉴定的最适温度;调查时期梯度试验表明,淹水11 d时参试种质的胚芽鞘长四分位差最大,因此认为淹水11 d是水稻萌发耐淹性调查的最适时期。本研究建立了一种以纯水隔绝空气,在温度30℃、淹水深度9 cm以上、第11 d调查胚芽鞘长度进行水稻萌发耐淹性鉴定的简便方法,为水稻种质资源的大规模鉴定提供了方法基础。依据上述确立的鉴定方法,对140份来自不同地区的水稻种质进行萌发耐淹性评价,筛选获得6份强萌发耐淹性种质(胚芽鞘长≥55 mm),为水稻萌发耐淹性遗传机制解析和育种利用提供材料基础。

糯高粱顶土能力与幼苗器官形态关系的研究

[目的]高粱是传统的特色杂粮作物,具有食用、酿酒、饲用、能源、青贮用等多种用途。然而,高粱种子出苗率低直接影响其大面积推广种植。通过研究高粱顶土能力与幼苗器官形态的关系,旨在为提高高粱种质出苗率以及高粱新品种选育成效提供理论依据。[方法]本研究选用3个糯高粱品种晋糯3号(10480A_(2)×L17)、晋糯4号(11476A_(2)×L2R)、红糯16号(11494A_(2)×L17)及对应的父母本共8份材料,采用培养皿无阻力发芽、黑暗水培发芽、3个不同播深沙培发芽及大田出苗率调查试验4种发芽试验,分析中胚轴和胚芽鞘伸长特性与出苗率之间的关系。[结果]无阻力条件下,高粱种子发芽试验结果表明不同种质发芽率和发芽势具有明显差异,杂交种的发芽率和发芽势大于其对应的父母本。黑暗水培处理下,杂交种与母本中胚轴伸长达到显著或极显著差异。进一步模拟大田环境沙培发芽试验发现,不同种质顶土能力对播种深度的敏感程度不同,11476A_(2)、10480A_(2)对播种深度有一定的耐受力,顶土能力较强,而11494A_(2)、L17则对播种深度较敏感,顶土能力较弱;杂交种的顶土能力基本与其对应的母本相一致。不同播种深度处理下,种质胚芽鞘长度变化不明显,而中胚轴显著伸长,说明高粱顶土能力与中胚轴伸长直接相关。大田试验出苗率与各性状指标相关分析结果表明,出苗率与中胚轴呈显著正相关,说明中胚轴的伸长能力是高粱种质出苗率变化的重要因素,可作为今后评价高粱种质出苗率的指标。本研究发现,不同播种深度条件下种质11476A_(2)、10480A_(2)中胚轴长度差变化较大,顶土能力较强,是杂交测配的优良亲本。[结论]为保证高粱出苗率,在遗传育种过程中,要注重选育中胚轴伸长能力大、顶土能力强的亲本种质,尤其是母本的选育。

小麦赤霉病复合天然抑菌剂的制备及其在小麦胚芽鞘上的验证

比较了肉桂醛、柠檬醛、香芹酚、芳樟醇、百里香酚、薄荷醇、紫苏醇对小麦赤霉病菌的体外抑菌效果,并进一步将香芹酚和百里香酚组合成复合天然抑菌剂。结果显示,当香芹酚和百里香酚质量比为1∶2时,抑菌剂对小麦赤霉病菌的体外抑制效果最佳,二者间具有协同作用。制备的抑菌剂能够改变病原菌细胞膜的通透性,并显著抑制被侵染小麦胚芽鞘上病斑的生长。