茄子种质资源抗青枯病的鉴定与评价

对304份茄子种质资源进行抗青枯病苗期人工接种鉴定,筛选出免疫材料10份,高抗材料51份,抗病材料35份,中抗材料32份,感病或高感材料176份,分别占鉴定材料的3.3%、16.8%、11.5%、10.5%和57.9%.茄子野生近缘种Solanum sisymbriifolium和S.torvum对青枯病有较强的抗病性,可作为茄子青枯病的抗源材料.获得4份抗青枯病的种间体细胞杂种.茄子对青枯病的抗性遗传较为复杂,主要由多基因控制.     

番茄抗青枯病种苗选育初步研究

通过大量收集野生茄科植物作为栽培番茄的嫁接砧木 ,进行嫁接试验并观察嫁接成活率。栽植各砧木苗、番茄实生苗及嫁接成活率较高的嫁接苗 ,观察比较它们在自然条件下青枯病的发病率 (如果自然条件下青枯病发病率低的地块 ,可考虑人工接种病原 )、植株生长情况、产量和品质等 ,筛选出 2种嫁接成活率高 ,抗青枯病能力强 ,并能保持或提高接穗果产量和品质的番茄嫁接砧木。为深入进行番茄抗青枯病种苗选育研究和生产实践奠定了基础。     

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。     

砧用瓠瓜抗枯萎病相关性及杂种优势分析

枯萎病是一种严重危害瓜类蔬菜生产的土传病害,嫁接栽培是防治瓜类枯萎病的有效方法。该文研究了砧用瓠瓜种质幼苗生长指标与抗病性的相关性,并对抗病杂种优势进行了分析。结果表明:(1)砧用瓠瓜种质H041对西瓜枯萎病表现高抗(HR),对瓠瓜枯萎病表现抗病(R),种质H01、H05和杂交组合H01×H041、H041×H05、H05×H041对两种枯萎病均表现抗病(R)。(2)砧用瓠瓜幼苗接种西瓜枯萎病菌后,病情指数与下胚轴粗度呈显著负相关;接种瓠瓜枯萎病菌后,总根长、根系表面积与病情指数呈极显著负相关,表明砧用瓠瓜对枯萎病的抗病性与根系生长具有相关性,可以根据根系生长情况快速评价砧用瓠瓜对瓠瓜枯萎病的抗性表现。(3)分析砧用瓠瓜杂交组合的抗病性杂种优势显示,供试杂交组合H05×H041对西瓜枯萎病具备超中亲优势;杂交组合H01×H041和H02×H041对瓠瓜枯萎病抗性具有负向杂种优势。综合研究结果发现,种质H01、H041、H05兼抗西瓜枯萎病和瓠瓜枯萎病,且配制出的杂交组合表现抗性杂种优势,可作为选育抗两种枯萎病的砧木或栽培品种的抗源亲本,其中H041可作为优势骨干亲本。     

砧用南瓜品种资源耐热性鉴定及形态指标选择

高温是制约黄瓜生产的重要非生物胁迫因子之一。黄瓜(Cucumis sativus L.)嫁接苗能够有效缓解高温胁迫危害,但目前黄瓜嫁接砧木品种并不多。为此,本研究收集了国内外48份砧用南瓜种质,对萌发期和幼苗期进行高温处理(38℃和42℃),通过UPGMA聚类分析,鉴定其耐热性,并筛选适宜的形态指标。共测定了10个性状(发芽率、发芽势、发芽指数、活力指数、株高、茎粗、全株鲜重、全株干重、壮苗指数、热害指数)指标。结果表明,48份砧用南瓜种质耐热性在萌发期及幼苗期都可以分为4类。在2个时期皆表现出较耐高温的种质为日本绿霸和日本强力士;对高温敏感的种质有11份。种子相对发芽势、相对发芽指数、相对活力指数以及幼苗相对干重可作为砧用南瓜种质资源耐热性鉴定的可靠指标。     

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。     

砧/穗间交流的物质及其嫁接愈合效应

植物嫁接愈合受砧/穗自身和外部环境等多种因素的调节和控制。在嫁接伤口愈合期间,砧木与接穗的相互作用不仅体现在明显的组织学特征的变化,还涉及了复杂的生理生化和分子调控机制。砧木和接穗愈合经历隔离层的形成、愈伤组织的发生、分化以及维管组织的再分化四个步骤,在此过程中砧/穗细胞、组织或器官之间相互影响,频繁发生物质交流,如植物激素、蔗糖、核酸和蛋白质等物质通过胞间连丝发生短距离运输或是经韧皮部进行长距离运输,从而开始形成砧/穗之间的识别、接纳、包容效应,最终完成愈合过程,并对嫁接苗后续生长过程起到重要影响。该文就当前植物嫁接过程中砧/穗愈合的组织学特征、砧/穗间交流物质的属性及其对砧/穗愈合进程的影响进行综述,为植物嫁接繁殖的生产实践提供基础理论指导。     

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。     

荔枝新品种‘贵妃红’和‘草莓荔’嫁接亲和性试验

以荔枝新品种‘贵妃红’和‘草莓荔’与10种砧木为试材,对各砧穗组合的嫁接成活率及嫁接苗田间生长指标进行测定及比较。结果表明,不同砧穗组合间嫁接成活率以及嫁接苗田间生长势存在明显差别,‘贵妃红’以钦州红荔、黑叶、禾荔为砧木的嫁接成活率分别达80.0%、78.0%和74.0%,‘草莓荔’以禾荔为砧木的嫁接成活率最高,达82.0%。综合其成活率及嫁接苗生长状况等指标,‘贵妃红’宜以黑叶、禾荔、钦州红荔、白腊为砧木进行嫁接,而‘草莓荔’宜以黑叶、禾荔、钦州红荔、镇奉为砧木进行嫁接。     

柑桔接穗对砧木生长及若干生理生化特性的影响

以体细胞杂种红桔+枳、红桔+粗柠檬和有性杂种Troyer枳橙、Swingle枳柚以及枳作砧木的"国庆4号"温州蜜柑、脐橙(无枳砧)和不嫁接的砧木幼树为试材,通过两年盆栽试验研究接穗对砧木生长、根系活力和根系抗氧化酶活性的影响。结果表明,Swingle枳柚和红桔+粗柠檬的砧粗易受接穗影响,接穗显著地影响砧木根系体积。在一般情况下,同一种砧木嫁接后砧木根系活力、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性低于未嫁接砧木,或与其差异不显著;同时存在接穗促进根系过氧化氢酶(CAT)活性升高的现象。     

肉桂酸和香草醛对嫁接茄子根系生长及生理特性的影响

以“托鲁巴姆”茄子为砧木,“西安绿”茄子为接穗,采用盆栽试验研究了自毒物质肉桂酸和香草醛对嫁接、自根和砧木茄子根系生长及抗氧化酶活性、渗透调节物质含量的影响.结果表明：肉桂酸、香草醛对茄子根系生长及生理代谢的化感作用基本表现为“低促高抑”,两物质对自根茄子根系表现促进、抑制效应的临界浓度点分别为0.1和0.5 mmol·kg^-1;对嫁接、砧木茄子表现促进、抑制效应的临界浓度点分别为0.5和1 mmo·kg^-1.茄子根系对自毒物质耐性大小依次为：砧木茄>嫁接茄>自根茄;在较高浓度肉桂酸(0.5～4 mmol·kg^-1)和香草醛(1～4mmol·kg^-1)作用下,与自根茄子相比,嫁接茄子根系SOD活性提高了8.50%～24.50%,脯氨酸含量增加了9.39%～27.64%,可溶性糖含量增加了12.77%～81.81%,可溶性蛋白含量、根系鲜、干物质量和根系活力显著高于自根茄.表明嫁接换根使茄子根系具有了砧木抗自毒物质的特性,缓解了自毒物质给茄子根系生长带来的不良影响.     

陆地棉品种和骨干品系黄萎病抗性鉴定

选育和推广抗病品种是防治陆地棉黄萎病的主要措施,为了早日实现多类型、多区域大面积抗病品种的应用,本研究选取107份遗传背景差异较大的种质,利用河北省农林科学院棉花研究所小安舍试验站黄萎病病圃进行了3年黄萎病抗性重复鉴定。鉴定得到抗病品系8个,占7.5%;耐病品种(系)20个,占18.7%。本研究表明,当前被作为育种亲本的抗病品系还太少,需要深入开展抗病遗传机制,以及与其他经济性状协同改良的关系,为陆地棉抗病育种提供理论指导;达到抗病或接近抗病水平的大部分品种(系)来自于海陆野远缘后代,具有外源基因血统,证明了远缘杂交是陆地棉黄萎病抗性改良的有效手段。     

Effects of transgenic rootstocks on growth and development of non-transgenic scion cultivars in apple

Although cultivation of genetic modified (GM) annual crops has been steadily increasing in the recent 10 years, the commercial cultivation of GM fruit tree is still very limited and reports of field trials on GM fruit trees are rare. This is probably because development and evaluation of GM fruit trees require a long period of time due to long life cycles of trees. In this study, we report results from a field trial on three rolB transgenic dwarfing apple rootstocks of M26 and M9 together with non-transgenic controls grafted with five non-transgenic scion cultivars. We intended to investigate the effects of transgenic rootstock on non-transgenic scion cultivars under natural conditions as well as to evaluate the potential value of using the rolB gene to modify difficult-to-root rootstocks of fruit trees. The results showed that all rolB transgenic rootstocks significantly reduced vegetative growth including tree height regardless of scion cultivar, compared with the non-transgenic rootstocks. Flowering and fruiting were also decreased for cultivars grown on the transgenic rootstocks in most cases, but the fruit quality was not clearly affected by the transgenic rootstocks. Cutting experiment and RT-PCR analysis showed that the rolB gene was stably expressed under field conditions. PCR and RT-PCR analyses displayed that the rolB gene or its mRNA were not detectable in the scion cultivars, indicating no translocation of the transgene or its mRNA from rootstock to scion. Our results suggest that rolB modified rootstocks should be used in combination with vigorous scion cultivars in order to obtain sufficient vegetative growth and good yield. Alternatively, the rolB gene could be used to dwarf vigorous rootstocks of fruit trees or produce bonzai plants as it can significantly reduce the vegetative growth of plants.     

嫁接茄子根系分泌物变化及其对黄萎菌的影响

采用番茄为砧木嫁接茄子,经过GC-MS检测,研究了黄萎菌胁迫前后嫁接对茄子植株根系次生代谢的影响。通过比较黄萎菌胁迫前后茄子根系次生代谢物质的变化,探讨了嫁接在胁迫前后对植株根系次生代谢的调节作用,并对嫁接茄根系分泌物中丁二酸二甲酯对茄子黄萎菌及茄子种子萌发、幼苗生长的化感效应进行了研究。结果表明,黄萎菌胁迫前,嫁接影响了根系的次生代谢物质的分泌,表现为物质种类和数量的增加,各类物质相对含量改变。嫁接茄子根系分泌物中检测出9大类、66种物质,比自根茄处理多出4大类、33种物质。黄萎菌胁迫时,嫁接茄子田间表现出明显的抗病性;进一步对根系分泌物进行检测发现,嫁接茄根系分泌物中物质种类和相对含量与自根茄处理相比均有显著差别;嫁接茄根系分泌物中烃和酚醇类物质相对含量分别增加了3.25%和0.07%,苯类、茚类和脂肪酸酯类物质相对含量降低,降幅分别为2.62%、0.26%和0.07%。新出现了胺类物质,芴类物质。黄萎菌胁迫前后茄子根系次生代谢物质成分同样发生了变化。与接菌前嫁接茄子植株根系分泌物相比,接菌后嫁接处理的苯类、茚类、酚醇类和胺类物质相对含量增加,增幅分别为22.07%、1.72%、1.21%和0.34%;烃类和脂肪酸酯类物质相对含量降低了1.28%和21.75%;酮类、咔唑类和芴类物质消失。新增物质中以丁二酸二甲酯的相对含量最高,达14.38%。随后的生物检测结果显示,丁二酸二甲酯能够提高茄子田间抗病性,对黄萎菌菌丝生长起化感抑制作用,并促进了茄子种子的萌发和幼苗的生长,随着处理浓度升高作用效果增强,并在1 mmol/L处理时达到最佳作用效果。     

Effects of high grafting on tomato plants infected by Meloidogyne incognita and Ralstonia solanacearum

The root‐knot nematode Meloidogyne incognita is known to increase the severity of bacterial wilt in many solanaceous crops. In Japan, several bacterial wilt‐resistant rootstocks that have the M. incognita resistance (Mi) gene in their genome have been developed for tomatoes. In this study, we aimed to examine whether the presence of Mi gene‐breaking M. incognita population affects the development of bacterial wilt in bacterial‐wilt‐resistant tomato rootstocks with Mi in their genetic background. We also aimed to examine the possibility of using high‐grafted tomatoes to control bacterial wilt in plants infected by M. incognita. Our results indicate that the resistance to bacterial wilt was easy to break in usual‐grafted tomato plants infected with M. incognita and that M. incognita enhanced the vertical movement of Ralstonia solanacearum in the bacterial‐wilt‐resistant tomato rootstocks. In addition, our results suggest that high grafting led to significantly less wilting in the plants infected by M. incognita than did usual grafting.     

Influence of rootstocks on growth,yield, fruit quality and leaf mineral element contents of pear cv. ‘Santa Maria’ in semi-arid conditions

Background

Rootstocks play an essential role to determining orchard performance of fruit trees. Pyrus communis and Cydonia oblonga are widely used rootstocks for European pear cultivars. The lack of rootstocks adapted to different soil conditions and different grafted cultivars is widely acknowledged in pear culture. Cydonia rootstocks (clonal) and Pyrus rootstocks (seedling or clonal) have their advantages and disadvantages. In each case, site-specific environmental characteristics, specific cultivar response and production objectives must be considered before choosing the best rootstock. In this study, the influence of three Quince (BA 29, Quince A = MA, Quince C = MC) and a local European pear seedling rootstocks on the scion yield, some fruit quality characteristics and leaf macro (N, P, K, Ca and Mg) and micro element (Fe, Zn, Cu, Mn and B) content of ‘Santa Maria’ pear (Pyrus communis L.) were investigated.

Results

Trees on seedling rootstock had the highest annual yield, highest cumulative yield (kg tree⁻¹), largest trunk cross-sectional area (TCSA), lowest yield efficiency and lowest cumulative yield (ton ha⁻¹) in the 10^th year after planting. The rootstocks had no significant effect on average fruit weight and fruit volume. Significantly higher fruit firmness was obtained on BA 29 and Quince A. The effect of rootstocks on the mineral element accumulation (N, K, Ca, Mg, Fe, Zn, Cu, Mn and B) was significant. Leaf analysis showed that rootstocks used had different mineral uptake efficiencies throughout the early season.

Conclusion

The results showed that the rootstocks strongly affected fruit yield, fruit quality and leaf mineral element uptake of ‘Santa Maria’ pear cultivar. Pear seedling and BA 29 rootstock found to be more prominent in terms of several characteristics for ‘Santa Maria’ pear cultivar that is grown in highly calcareous soil in semi-arid climate conditions. We determined the highest N, P (although insignificant), K, Ca, Mg, Fe and Cu mineral element concentrations on the pear seedling and BA 29 rootstocks. According to the results, we recommend the seedling rootstock for normal density plantings (400 trees ha⁻¹) and BA 29 rootstock for high-density plantings (800 trees ha⁻¹) for ‘Santa Maria’ pear cultivar in semi-arid conditions.     

Role of hydrogen peroxide and ascorbate-glutathione pathway in host resistance to bacterial wilt of eggplant

Ralstonia solanacearum, a soil-borne bacterium causes bacterial wilt, is a lethal disease of eggplant (Solanum melongena L.). However, the first line of defense mechanism of R. solanacearum infection remains unclear. The present study focused on the role of induced H₂O₂, defense-related enzymes of ascorbate-glutathione pathway variations in resistant and susceptible cultivars of eggplant under biotic stress. Fifteen cultivars of eggplant were screened for bacterial wilt resistance, and the concentration of antioxidant enzymes were estimated upon infection with R. solanacearum. A quantitative real-time PCR was also carried out to study the expression of defense genes. The concentration of H₂O₂ in the pathogen inoculated seedlings was two folds higher at 12 h after pathogen inoculation compared to control. Antioxidant enzymes of ascorbate-glutathione pathway were rapidly increased in resistant cultivars followed by susceptible and highly susceptible cultivars upon pathogen inoculation. The enzyme activity of ascorbate-glutathione pathway correlates by amplification of their defense genes along with pathogenesis-related protein-1a (PR-1a). The expressions of defense genes increased 2.5?3.5 folds in resistant eggplant cultivars after pathogen inoculation. The biochemical and molecular markers provided an insight to understand the first line of defense responses in eggplant cultivars upon inoculation with the pathogen.     

Rootstock‐to‐scion transfer of transgene‐derived small interfering RNAs and their effect on virus resistance in nontransgenic sweet cherry

Small interfering RNAs (siRNAs) are silencing signals in plants. Virus‐resistant transgenic rootstocks developed through siRNA‐mediated gene silencing may enhance virus resistance of nontransgenic scions via siRNAs transported from the transgenic rootstocks. However, convincing evidence of rootstock‐to‐scion movement of siRNAs of exogenous genes in woody plants is still lacking. To determine whether exogenous siRNAs can be transferred, nontransgenic sweet cherry (scions) was grafted on transgenic cherry rootstocks (TRs), which was transformed with an RNA interference (RNAi) vector expressing short hairpin RNAs of the genomic RNA3 of Prunus necrotic ringspot virus (PNRSV‐hpRNA). Small RNA sequencing was conducted using bud tissues of TRs and those of grafted (rootstock/scion) trees, locating at about 1.2 m above the graft unions. Comparison of the siRNA profiles revealed that the PNRSV‐hpRNA was efficient in producing siRNAs and eliminating PNRSV in the TRs. Furthermore, our study confirmed, for the first time, the long‐distance (1.2 m) transfer of PNRSV‐hpRNA‐derived siRNAs from the transgenic rootstock to the nontransgenic scion in woody plants. Inoculation of nontransgenic scions with PNRSV revealed that the transferred siRNAs enhanced PNRSV resistance of the scions grafted on the TRs. Collectively, these findings provide the foundation for ‘using transgenic rootstocks to produce products of nontransgenic scions in fruit trees'.