黑籽南瓜砧木对黄瓜生长结实、抗病性及营养元素含量的影响

为了探索黑籽南瓜(Cucurbita ficifolia Bouché)对黄瓜(Cucumis sativus Linn.)生长的影响,以前者为砧木,‘津绿21-1'和‘津研4号'2个黄瓜品种为接穗,以自根植株为对照,对嫁接植株的形态指标、抗病性、单株产量及叶片营养元素含量进行研究.结果表明,嫁接植株在不同时期的形态指标均高于自根植株;嫁接黄瓜的单株产量显著高于自根黄瓜;枯萎病、病毒病、霜霉病和灰霉病4种病害在嫁接植株上的病情指数和发病率均低于自根植株;2个品种嫁接植株叶片的N、P、K、Ca和Mg含量均显著或极显著高于自根植株.结果表明,黑籽南瓜作为优良砧木可显著促进黄瓜的生长结实,提高其抗病性及对营养元素的吸收能力.     

复合茶树接穗与接穗母本的代谢物差异分析

以两个通过群体选育获得的云南普洱茶优良品种‘云瑰’和‘福云6号’为接穗,均以茶树品种‘短节白毫’为砧木所形成的嫁接复合茶树为研究对象,通过代谢组学技术,对两个品种的接穗与接穗母本的代谢物进行分析,考察嫁接前后茶树品种‘云瑰’和‘福云6号’的差异代谢物和共同代谢物的种类、数量变化特征。结果发现：(1)两品种茶树嫁接后比嫁接前的农艺性状均有所改善,嫁接优势明显。(2)相对于‘云瑰’,‘福云6号’的接穗与接穗母本茶叶中差异代谢物的数量与种类都比较少,说明‘福云6号’嫁接在‘短节白毫’上时,接穗能最大程度地保留母本的特点。(3)‘云瑰’的接穗和接穗母本茶叶中检测和定量了115个差异代谢物,且含量表现上调的代谢物数量低于下调的数量;‘福云6号’的接穗和接穗母本茶叶中共检测和定量了47个差异代谢物,且含量表现上调的代谢物数量高于下调的数量。(4)‘云瑰’的接穗和接穗母本茶叶中差异代谢物在38条KEGG通路中富集,大多数已经鉴定的差异代谢物存在于苯丙氨酸代谢等相关途径中;‘福云6号’的接穗和接穗母本茶叶中差异代谢物在21条KEGG通路中富集,大多数已经鉴定的差异代谢物存在于与嘌呤代谢等相关途径中。该研究结果对充分发挥茶树嫁接技术在茶叶生产中的作用提供了理论依据。     

接穗与砧木对月季嫁接苗性状影响的探究

选择花色、花大小等性状不同的2种月季植株互为接穗和砧木进行嫁接,在活动中了解嫁接的概念,理解嫁接成活原理,掌握植物嫁接的方法和技能,培养学生科学素养。嫁接成活后,通过嫁接苗和原植株的性状对比,得出接穗与砧木对月季嫁接苗性状的影响是不同的。     

不同类型茄对镉的富集及嫁接对镉富集特性的影响

以普通茄(Solanum melongena,绿健)和野生茄(S.torvum,托鲁巴姆)为实验材料,通过对嫁接处理前后7叶龄植株开展7d含Cd水培实验(Cd浓度为0.1 mg· L-1),研究Cd在不同类型茄体内的富集特征以及嫁接对茄体内Cd运输途径和富集特性的影响.结果表明:绿健对Cd的富集能力强于托鲁巴姆.不同部位器官中Cd的分布特征为根＞叶＞茎,其中植株吸收的Cd 80.0％左右富集于根部;不同部位叶片,Cd优先富集于植株顶端幼叶中.嫁接使得Cd在茄地上部的富集量明显减少,接穗Cd的富集量均显著低于砧木:以绿健为对照,正向嫁接减少了48.4％,反向嫁接减少了34.2％,托鲁巴姆自嫁接减少了88.5％;以托鲁巴姆为对照,仅自嫁接地上部Cd富集量减少了58.0％.嫁接减少Cd在茄体内富集的原因可能是嫁接使接穗与砧木植物韧皮部结构产生了差异,由此推断Cd在茄体内的长距离运输过程中韧皮部起到了关键作用.     

寄主大豆对根结瘤的控制

我国９个大豆（ＧｌｙｃｉｎｅｍａｘＬ．Ｍｅｒｒ．）品种感染根瘤菌ＵＳＤＡ１１０后,产生不同的结瘤数,低者在２０个以下．高者在６０个以上。赤豆、绿赤豆也可被感染结瘤,而豇豆、扁豆则不能。超结瘤大豆ｎｔｓ３８２作为接穗时能诱导我国大豆原结瘤数有４５个的开育１０号、原结瘤数有１２个的大黄分别发生高结瘤。ｎｔｓ３８２作为砧木时,则不能表现超结瘤．表明超结瘤因子能传给我国大豆,反之存在于我国大豆中的限制超结瘤的因子也能传给ｎｔｓ３８２。ｎｔｓ３８２于ＮＯ３－环境中仍表现超结瘤的特点也能导入开育１０号、大黄及赤豆根部,并使之在ＮＯ３－环境中结瘤。在ＮＯ３－环境中不能结瘤的开育１０号作为接穗,ｎｔｓ３８２作为砧木的嫁接植株,于子叶生长阶段接受ＮＯ３－时,仍能结瘤,于真对生长时接受ＮＯ３－时．则不能结瘤,表明限制结瘤因子于真叶细胞中被诱导形成。     

美味猕猴桃优良株系“实美”的砧木选择研究

美味猕猴桃优良株系“实美”的接穗嫁接于 1 0个不同种类的砧木上 ,观测其嫁接体的亲和力、生长特性、开花结果习性、抗逆性、产量、果实品质等。结果表明 :“实美”以中华猕猴桃桂海 4号为砧木 ,具有良好的亲和力 ,嫁接成活率达 1 0 0 % ,接合部位断裂率仅 5 % ;5年生植株保存率 1 0 0 % ,生长指数高达 0 .9,病死株率为 0 ;物候期相对稳定 ,萌芽率和结果枝率高 ;连续 3年的平均产量极显著地高于其它 9种砧木的产量 ;果实内含物丰富 ,品质优良。根据观测结果 ,可以认为中华猕猴桃桂海 4号是“实美”的优良砧木。     

电波传递在嫁接基本理论研究中的应用

研究发现电波从接穗跃过嫁接面向砧木传递与嫁接的组织学变化相关。砧木和接穗愈伤组织细胞突破隔离层互相嵌合之前,接穗中产生的电波不能传到砧木。砧木和接穗细胞间产生次生胞间连丝后,电波即可沿接穗传至砧木,但此时传递速度慢。当砧木和接穗间产生维管束桥时,电波下传的速度加快。由此可见,通过检测电波跃过嫁接面与否及下传的速度,就可推断嫁接接合部组织学变化状况。电波传递法是一种快速鉴定嫁接植株发育过程的新方法。     

黄瓜贴接苗砧木子叶淀粉代谢的动态变化特征

该研究以黄瓜品种‘中农18号’、南瓜砧木品种‘京欣砧5号’为试验材料,以南瓜自根苗(P)和去除1片子叶及生长点的南瓜苗( /P)为对照,采用单子叶贴接法进行黄瓜/南瓜异体嫁接(C/P)和南瓜/南瓜自体嫁接(P/P),测定嫁接后砧木子叶形态指标和淀粉代谢的动态变化,分析嫁接后去除砧木子叶对嫁接苗生长发育的影响,以揭示砧木子叶淀粉代谢在黄瓜嫁接苗生长中的作用,为黄瓜嫁接苗的壮苗培育提供理论依据。结果显示：(1)贴接后,C/P、P/P和 /P砧木子叶鲜质量和面积显著增大,且增加量依次递减,表现为 /P > C/P > P/P > P。(2)贴接后,C/P和P/P砧木子叶中淀粉含量在嫁接后0~3 d时降低,之后迅速升高,至嫁接后13 d再次逐渐降低,且C/P砧木子叶淀粉含量及其淀粉分支酶(SBE)和水解酶(β AL)活性均显著高于P/P。(3)在嫁接后0~10 d 去除砧木子叶可显著抑制C/P嫁接苗接穗和根系生长,减弱根系活力,同时降低根系可溶性糖含量及其CWIN、HXK基因表达水平,并以嫁接后0 d 去除砧木子叶的抑制效果最显著。研究表明,黄瓜C/P单子叶贴接苗中,砧木子叶作为贮存器官,在幼苗生长早期以淀粉形式储存光合产物,之后淀粉水解成单糖为嫁接苗接穗和根系快速生长提供物质和能量。     

两种砧木对樱桃番茄青枯病抗性及根际微生物数量的影响

青枯病是危害我国华南地区番茄生产最严重的土传性病害之一。为探讨在人工接种青枯菌条件下,两种不同砧木嫁接对番茄青枯病的抗性及根际微生物数量的影响。该研究分别用砧木“番砧1号”和“茄砧21号”与樱桃番茄“粉贝贝”进行嫁接,采用稀释平板法对各嫁接组合的根际微生物进行分离。结果表明:(1)采用抗病砧木嫁接显著提高了番茄的抗病性,降低了发病率和病情指数,延缓了发病时间。(2)青枯菌在侵染植株过程中呈现动态变化,其数量从根系到地上茎部逐渐减少;砧穗嫁接植株、砧木自根嫁接植株根际基质和根系中的青枯菌数量降低,且地上茎部中的病原菌数量显著低于接穗自根嫁接植株;接种青枯菌后,各嫁接组合根际基质中的细菌、真菌和放线菌的数量随发病期的变化呈先增加后降低的趋势。(3)采用抗病砧木嫁接总体上提高了植株根际微生物总量、细菌及放线菌的数量,降低了真菌的数量,改善了嫁接植株根际微环境,对降低番茄青枯病发病率具有重要作用。     

高温干热时节黄瓜嫁接技术试验研究

黄瓜通过嫁接有效地利用抗病砧木的根系取代黄瓜的根系,增强抗逆性,防止土传病虫害和连作障碍,明显增加产量。本文采用黑籽南瓜、12号、17号、29号为嫁接砧木,博耐二号黄瓜为接穗,探索在高温季节下黄瓜嫁接的最佳管理技术。通过试验表明,高温干热时节嫁接黄瓜时,日温度控制在25-30℃和湿度通过人工喷雾使叶片湿度控制在98%以上时能有效提高黄瓜嫁接成活率。     

Effects of mutual grafting on the cadmium accumulation characteristics of two ecotypes of Solanum photeinocarpum

Abstract

The effects of mutual grafting on the cadmium (Cd) accumulation characteristics of two ecotypes (farmland and mining) of the potential Cd-hyperaccumulator Solanum photeinocarpum were studied through a pot experiment for one month. Four treatments were used in the experiment: ungrafted farmland ecotype (F-CK), ungrafted mining ecotype (M-CK), the farmland ecotype as the scion grafted onto rootstocks of the mining ecotype (F-Scion), and the mining ecotype as the scion grafted onto rootstocks of the farmland ecotype (M-Scion). Mutual grafting increased the rootstock biomass of both S. photeinocarpum ecotypes. However, mutual grafting decreased the scion biomass of F-Scion compared with F-CK and M-CK, and the scion biomass of M-Scion was higher than that of M-CK and lower than that of F-CK. The Cd content in the rootstock of M-Scion increased compared with F-CK, and the Cd content in the rootstock of F-Scion increased compared with M-CK, but mutual grafting decreased the Cd content in scions of both S. photeinocarpum ecotypes. Mutual grafting increased Cd extraction by rootstocks of both S. photeinocarpum ecotypes, but decreased extraction by scions. Therefore, mutual grafting can increase Cd accumulation in S. photeinocarpum rootstocks but not increase Cd accumulation in S. photeinocarpum scions in a short period.     

Rootstock effects on xylem conduit dimensions and vulnerability to cavitation of <Emphasis Type="Italic">Olea europaea</Emphasis> L.

Two clones of Olea europaea L. were studied for their potential impact on hydraulic architecture and vulnerability to xylem cavitation, when used as rootstocks. The clones used were “Leccino Minerva” (LM), showing vigorous growth and “Leccino Dwarf” (LD) with strongly reduced growth. Self-rooted LM and LD plants as well as their grafting combinations were compared, namely, LM/LD (Leccino Minerva grafted onto Leccino Dwarf rootstock) and LD/LM (Leccino Dwarf grafted onto Leccino Minerva rootstocks). Plants with LD roots (LD and LM/LD) showed significantly reduced leaf surface area compared with plants with LM roots. Xylem conduits of LD shoots were 25% more numerous than in LM shoots. When grafted onto LM rootstocks, however, LD shoots produced consistently wider and longer vessels than measured in LD self-rooted plants. This caused LD/LM plants to increase stem vulnerability to cavitation with threshold pressures for cavitation (P _c) of less than 0.5 MPa compared with LD self-rooted plants that had P _c of over 2.0 MPa. By contrast, although LD rootstocks caused some reduction of vessel diameter and length of LM scions, their influence on LM hydraulic architecture was too small to reduce vulnerability to cavitation of LM scions with respect to that measured for LM self-rooted plants. Our conclusion is that although dwarfing rootstocks effectively reduce grafted plant size, they do not necessarily confer higher resistance to xylem cavitation to scions which would improve plant resistance to drought.     

嫁接与施氮对甜瓜产量和氮素吸收、利用的影响

通过裂区设计田间试验,主区为2种栽培方式(嫁接栽培和自根栽培),副区为4个施氮水平(0、120、240、360 kg N·hm^-2),研究了栽培方式和施氮量对甜瓜产量和品质、氮素运移和分配,以及氮素利用率的影响.结果表明: 嫁接栽培的甜瓜商品瓜产量较自根甜瓜提高了7.3%,可溶性固形物含量降低了0.16%～3.28%;生长前期嫁接栽培甜瓜氮素累积量较自根栽培低,结果后嫁接栽培氮素累积量显著升高,收获时植株氮素累积量较自根栽培增加了5.2%,果实中的氮素累积量提高了10.3%;嫁接栽培植株氮素向果实的转移量较自根栽培提高了20.9%,嫁接栽培果实中的氮素分配率在80%以上,自根栽培的分配率在80%以下;在同一施氮水平下,嫁接栽培的甜瓜氮素吸收利用率较自根栽培提高了1.3%～4.2%,氮素农学效率提高了2.73～5.56 kg·kg^-1,氮素生理利用率提高了7.39～16.18 kg·kg^-1;从商品瓜产量、氮素吸收量和氮素利用率综合考虑,施氮量240 kg·hm^-2为本区域嫁接甜瓜较适宜的氮素用量.     

Conferring high‐temperature tolerance to nontransgenic tomato scions using graft transmission of RNA silencing of the fatty acid desaturase gene

We investigated graft transmission of high‐temperature tolerance in tomato scions to nontransgenic scions from transgenic rootstocks, where the fatty acid desaturase gene (LeFAD7) was RNA‐silenced. Tomato was transformed with a plasmid carrying an inverted repeat of LeFAD7 by Agrobacterium. Several transgenic lines showed the lower amounts of LeFAD7 RNA and unsaturated fatty acids, while nontransgenic control did not, and siRNA was detected in the transgenic lines, but not in control. These lines grew under conditions of high temperature, while nontransgenic control did not. Further, the nontransgenic plants were grafted onto the silenced transgenic plants. The scions showed less of the target gene RNA, and siRNA was detected. Under high‐temperature conditions, these grafted plants grew, while control grafted plants did not. Thus, it was shown that high‐temperature tolerance was conferred in the nontransgenic scions after grafting onto the silenced rootstocks.     

Transmission of RNA silencing signal through grafting confers virus resistance from transgenically silenced tobacco rootstocks to non-transgenic tomato and tobacco scions

We examined the transmission of RNA silencing signal in non-transgenic tomato and tobacco scions grafted onto the tobacco Sd1 rootstocks, which is silenced in both NtTOM1 and NtTOM3 required for tobamovirus multiplication. When the non-transgenic tomato scions were grafted onto the Sd1 rootstocks, RT-PCR analysis of the scions showed the reduced level of mRNA compared with that before grafting in both LeTH3 and LeTH1, tomato homologs of NtTOM1 and NtTOM3, respectively. siRNAs from both genes were detected in the scions after grafting but not before grafting. Further tomato scions were inoculated with Tomato mosaic virus (ToMV) and used for virus infection. They showed very low level of virus accumulation. Necrotic responding tobacco to tobamovirus was grafted onto the rootstock of Sdl. RT-PCR analysis showed low level expression of both NtTOM1 and NtTOM3 in the scions but siRNA was detected after grafting. When the leaves of scions were inoculated with ToMV or Tobacco mosaic virus, they produced very few local necrotic lesions (LNLs) while the control scions did many LNLs. These results suggest that RNA silencing was transmitted to non-transgenic tomato and tobacco scions after grafting onto the Sd1 rootstocks and that virus resistance was induced in the scions.     

Grafting on a Non-Transgenic Tolerant Tomato Variety Confers Resistance to the Infection of a Sw5-Breaking Strain of Tomato spotted wilt virus via RNA Silencing

RNA silencing controls endogenous gene expression and drives defensive reactions against invasive nucleic acids like viruses. In plants, it has been demonstrated that RNA silencing can be transmitted through grafting between scions and silenced rootstocks to attenuate virus and viroid accumulation in the scions. This has been obtained mostly using transgenic plants, which may be a drawback in current agriculture. In the present study, we examined the dynamics of infection of a resistance-breaking strain of Tomato spotted wilt virus (RB-TSWV) through the graft between an old Apulian (southern Italy) tomato variety, denoted Sl-Ma, used as a rootstock and commercial tomato varieties used as scions. In tests with non-grafted plants, Sl-Ma showed resistance to the RB-TSWV infection as viral RNA accumulated at low levels and plants recovered from disease symptoms by 21 days post inoculation. The resistance trait was transmitted to the otherwise highly susceptible tomato genotypes grafted onto Sl-Ma. The results from the analysis of small RNAs hallmark genes involved in RNA silencing and virus-induced gene silencing suggest that RNA silencing is involved in the resistance showed by Sl-Ma against RB-TSWV and in scions grafted on this rootstock. The results from self-grafted susceptible tomato varieties suggest also that RNA silencing is enhanced by the graft itself. We can foresee interesting practical implications of the approach described in this paper.     

Anatomic changes due to interspecific grafting in cassava (Manihot esculenta)

Cassava rootstocks of varieties UnB 201 and UnB 122 grafted with scions of Manihot fortalezensis were prepared for anatomic study. The roots were cut, stained with safranin and alcian blue, and examined microscopically, comparing them with sections taken from ungrafted roots. There was a significant decrease in number of pericyclic fibers, vascular vessels and tyloses in rootstocks. They exhibited significant larger vessels. These changes in anatomic structure are a consequence of genetic effects caused by transference of genetic material from scion to rootstock. The same ungrafted species was compared. This is the first report on anatomic changes due to grafting in cassava.     

Expression of Pokeweed Antiviral Protein in Transgenic Plants Induces Virus Resistance in Grafted Wild-Type Plants Independently of Salicylic Acid Accumulation and Pathogenesis-Related Protein Synthesis

Pokeweed antiviral protein (PAP), a 29-kD protein isolated from Phytolacca americana, inhibits translation by catalytically removing a specific adenine residue from the large rRNA of the 60S subunit of eukaryotic ribosomes. Transgenic tobacco (Nicotiana tabacum) plants expressing PAP or a variant (PAP-v) were shown to be resistant to a broad spectrum of plant viruses. Expression of PAP-v in transgenic plants induces synthesis of pathogenesis-related proteins and a very weak (<2-fold) increase in salicylic acid levels. Using reciprocal grafting experiments, we demonstrate here that transgenic tobacco rootstocks expressing PAP-v induce resistance to tobacco mosaic virus infection in both N. tabacum NN and nn scions. Increased resistance to potato virus X was also observed in N. tabacum nn scions grafted on transgenic rootstocks. PAP expression was not detected in the wild-type scions or rootstocks that showed virus resistance, nor was there any increase in salicylic acid levels or pathogenesis-related protein synthesis. Grafting experiments with transgenic plants expressing an inactive PAP mutant demonstrated that an intact active site of PAP is necessary for induction of virus resistance in wild-type scions. These results indicate that enzymatic activity of PAP is responsible for generating a signal that renders wild-type scions resistant to virus infection in the absence of increased salicylic acid levels and pathogenesis-related protein synthesis.     

Regulatory network of microRNA399 and PHO2 by systemic signaling

Recently, we showed that microRNA399s (miR399s) control inorganic phosphate (Pi) homeostasis by regulating the expression of PHO2 encoding a ubiquitin-conjugating E2 enzyme 24. Arabidopsis (Arabidopsis thaliana) plants overexpressing miR399 or the pho2 mutant overaccumulate Pi in shoots. The association of Pi translocation and coexpression of miR399s and PHO2 in vascular tissues suggests their involvement in long-distance signaling. In this study, we used reciprocal grafting between wild-type and miR399-overexpressing transgenic plants to dissect the systemic roles of miR399 and PHO2. Arabidopsis rootstocks overexpressing miR399 showed high accumulation of Pi in the wild-type scions because of reduced PHO2 expression in the rootstocks. Although miR399 precursors or expression was not detected, we found a small but substantial amount of mature miR399 in the wild-type rootstocks grafted with transgenic scions, which indicates the movement of miR399 from shoots to roots. Suppression of PHO2 with miR399b or c was less efficient than that with miR399f. Of note, findings in grafted Arabidopsis were also discovered in grafted tobacco (Nicotiana benthamiana) plants. The analysis of the pho1 mutant provides additional support for systemic suppression of PHO2 by the movement of miR399 from Pi-depleted shoots to Pi-sufficient roots. We propose that the long-distance movement of miR399s from shoots to roots is crucial to enhance Pi uptake and translocation during the onset of Pi deficiency. Moreover, PHO2 small interfering RNAs mediated by the cleavage of miR399s may function to refine the suppression of PHO2. The regulation of miR399 and PHO2 via long-distance communication in response to Pi deficiency is discussed.