源库调节对厚皮甜瓜植株生长和抗氧化特性及果实产量品质的影响

以厚皮甜瓜品种‘中甜1号’为材料,设V1F2(主蔓顶部留1条顶蔓+单株留2果,下略)、V2F2、V3F2、V1F3、V2F3、V3F3共6个处理,以不留顶蔓、每株只留1果为对照,以研究源库关系中主蔓顶部留蔓数和单株留果数对厚皮甜瓜植株生长、叶片抗氧化特性及果实产量和品质的影响。结果显示:(1)随生育期的延长,增加单株留果数使厚皮甜瓜植株茎粗、节间长、最大功能叶长明显受到抑制,而顶蔓数量对上述3项生长指标无显著影响。(2)留2个果时,叶片O2.-产生速率略低于CK,MDA含量高于CK;留3个果时,叶片中O2.-产生速率和MDA含量最高;在所有处理中,以留果2个的POD活性最低,以留果3个的SOD活性最低。(3)每株留2果时,增加顶蔓数能提高果实品质,而每株留3果同时增加顶蔓数时,果实品质下降,尤以第3果品质最差。研究表明:留果数量对厚皮甜瓜植株生长和叶片抗氧化性影响大于留顶蔓数量,每株留2蔓2果有利于植株生长,可增强叶片抗氧化能力,延缓叶片衰老,从而提高单株产量,改善果实品质。     

甜瓜叶系统发育动态研究

在露地、温室和不同整枝条件下研究了甜瓜子叶面积发育、单个真叶面积、单株叶面积和叶面积指数(LAI)动态,建立了子叶、真叶而积与叶径的相关关系。结果表明：甜瓜子叶的面积在破心期前迅速增长,幼苗期结束时基本完成面积扩展,子叶面积与子叶纵横径乘积之间具有高度线性关系;甜瓜真叶面积随叶龄增大呈对数增长模式,叶片横径可作为田间叶面积估算的可靠指标;甜瓜单株叶面积及群体LAI随生育期的进展呈S型变化,于果实膨大期达到峰值;不同甜瓜品种间叶系统发育模式差异不明显,但幼苗前期的叶面积大小与种子大小有关。整枝方式影响伸蔓期之后的叶系统扩展速度,因此也影响单株叶面积或LAI增长曲线的具体形状。露地甜瓜重孙蔓上发生的叶片属于无效消耗器官,应予严格控制。     

水分和光照对厚皮甜瓜苗期植株生理生态特性的影响

以厚皮甜瓜‘西博洛托’为试材,研究了温室内育苗基质含水量和光照强度对厚皮甜瓜苗期植株生长发育和生理生态特性的影响.结果表明:不同基质含水量和光照强度对厚皮甜瓜苗期植株生长发育影响显著,随基质含水量的降低,苗期植株叶绿素a、叶绿素b和总叶绿素含量升高,叶片相对含水量和比叶面积下降,基质含水量为60%～80%时,幼苗净光合速率最高;随着光照强度的减弱,幼苗的叶绿素a、叶绿素b、总叶绿素含量以及叶片相对含水量、比叶面积和胞间CO2浓度升高,叶绿素a/b和净光合速率下降.在不同处理中,以80%基质含水量 100%温室光照处理的幼苗生长最健壮,壮苗指数、净光合速率等指标最高.     

BTH和SA处理及白粉菌接种对甜瓜叶片光合特性的影响

以抗病品种Tam Dew和感病品种卡拉克赛为材料,研究了BTH和SA处理及白粉菌接种对甜瓜叶片叶面积、叶绿素含量、净光合速率、气孔导度、胞间CO2浓度的影响.结果表明,BTH和SA处理及白粉菌接种对甜瓜苗期叶面积扩展无显著影响;BTH和SA处理植株的叶片(第3叶)和新生叶片(第5叶)的净光合速率、叶绿素含量和气孔导度显著高于对照;白粉菌接种后,2个甜瓜叶片的叶绿素含量、净光合速率和气孔导度显著降低,而BTH和SA处理能缓解由白粉菌接种带来的叶绿素含量、净光合速率和气孔导度的下降趋势.说明BTH和SA处理能延长甜瓜叶片的光合寿命,延缓甜瓜叶片的叶绿素含量、净光合速率和气孔导度的下降趋势.     

乙烯利诱导网纹甜瓜主蔓两性花花芽分化的形态和解剖学研究

以网纹甜瓜(Cucumis melo L.var. reticulatus Naud.)品种’西域1号’为试验材料,于幼苗3叶1心期喷施浓度为150 mg·L^-1的乙烯利溶液进行处理,诱导主蔓形成两性花,以清水为对照,分别对处理和对照植株不同时期的主蔓和侧蔓花芽分化过程进行形态和解剖学观察。结果表明：经乙烯利处理后,幼苗植株主蔓花原基持续向两性花分化,最终发育形成两性花。未经处理植株的主蔓花原基在分化早期与两性花发育过程相同,但在雌蕊出现后,不再继续发育,最终发育形成雄花。处理植株主蔓两性花发育过程与侧蔓两性花发育过程相同。     

辽东栎幼苗生长对种子大小和子叶去除处理的响应

该文在温室内盆播条件下,设置不去除子叶(对照)、去除1/4子叶(轻度子叶去除)、1/2子叶(中度子叶去除)和3/4子叶(重度子叶去除) 4个处理,研究了种子大小和子叶去除处理对辽东栎幼苗生长及其形态学可塑性的影响。结果表明:(1)大种子幼苗株高、基茎、叶片数、单株叶面积、总干质量和根冠比在所有处理均大于小种子幼苗,除株高外,上述其他参数在轻度子叶去除处理的不同大小种子幼苗间均差异显著(P0.05),前者总干质量在中度子叶去除处理与后者差异也显著(P0.05)。大种子幼苗比叶面积和比根长在各处理均大于小种子幼苗,比枝长则相反。(2)随着子叶去除强度增大,大、小种子幼苗株高、基茎、叶片数、单株叶面积和总干质量等均呈减小趋势,株高、基径、叶片数和单株叶面积在重度子叶去除处理均显著小于对照和轻度子叶去除处理;小种子幼苗对子叶损失反应更为敏感,其株高、叶片数、单株叶面积和总干质量在中度子叶去除处理也显著小于对照(P0.05);小种子幼苗根冠比随子叶去除强度增大而增大,在中度和重度子叶去除处理显著大于对照和轻度子叶去除处理(P0.05)。(3)随着子叶去除强度增大,大小种子幼苗的比叶面积和比根长均逐渐增大,但大种子幼苗比枝长持续减小,轻度子叶去除处理的小种子幼苗比枝长最大。     

不同嫁接方式对低温胁迫下甜瓜幼苗光合特性及抗氧化系统的影响

【目的】探讨不同嫁接方式缓解甜瓜幼苗低温伤害的生理机制,为生产实践中选取适宜嫁接方式、提高甜瓜低温抗性提供理论依据。【方法】以厚皮甜瓜品种‘早蜜1号’、‘冰糖雪梨’和薄皮甜瓜品种‘芝麻蜜’为接穗,‘白籽南瓜’为砧木,并以甜瓜自根苗为对照,考察3种方式嫁接苗（双根嫁接、靠接、贴接）在4 ℃低温处理前、中、后期（复温处理）叶片的光合色素含量、光合气体交换参数、细胞膜透性及抗氧化酶活性变化特征。【结果】(1)各甜瓜品种各类嫁接苗叶片的光合色素(叶绿素和类胡萝卜素)含量、光合气体交换参数（净光合速率、气孔导度、蒸腾速率、胞间CO2浓度）在低温处理下均比低温处理前显著降低,其中贴接处理的嫁接苗下降率最小,在复温后所有嫁接苗均比低温处理有所上升,并以贴接苗上升幅度最大;（2）各甜瓜品种各类嫁接苗叶片相对电导率(REC)、丙二醛(MDA)含量、过氧化氢(H2O2)含量及超氧阴离子(O2·-)产生速率在低温处理下均比低温处理前显著升高,并以贴接方式嫁接苗上升幅度最小,在复温处理后均比低温处理有所下降,并以贴接苗下降幅度最大;(3)各甜瓜品种各类嫁接苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性在低温处理下均比低温处理前显著提高,在复温处理后均比低温处理显著升高,期间均以贴接苗上升幅度最为显著。【结论】3种嫁接方式均可显著增强低温胁迫和复温后厚皮和薄皮甜瓜幼苗抗氧化酶活性,有效降低活性氧积累,维持幼苗光合能力,提高幼苗低温耐受性,并均以贴接方式表现最佳。     

乙烯对网纹甜瓜花器官及花粉结构和活力的影响

以网纹甜瓜‘西域1号'为材料,于幼苗三叶一心期喷施浓度为150 mg/L的乙烯利诱导主蔓形成两性花,以清水为对照,比较乙烯处理后形成的主蔓、侧蔓和对照侧蔓两性花,以及处理与对照雄花外观形态、解剖结构及花粉表面超微结构间的异同,并对其花粉活力进行了测定,以明确乙烯对甜瓜花器官形态及花粉结构和活力的影响.结果表明:乙烯诱导形成的主蔓两性花外观形态和解剖结构与对照侧蔓两性花没有差异,花粉超微结构相似,但存在部分畸形花粉,花粉活力仅为70%左右,显著低于其他花粉的活力,但其雌蕊发育正常,授粉后可正常结实.研究证实,乙烯处理对主蔓雄花及侧蔓两性花器官形态及花粉结构和活力无显著影响.     

甜瓜幼苗生长及光合特性与育苗基质pH相关性研究

以新疆厚皮甜瓜皇后为试材,在泥炭珍珠岩复合基质中,按一定比例加入CaCO3,构成pH梯度值分别为5.0、5.5、6.0、6.5、7.0、7.5和8.0的7种基质类型,研究了基质pH对甜瓜幼苗生长及其光合特性的影响。结果表明,基质酸碱性对甜瓜幼苗的光合特性、根系活力、单株叶面积、根系和地上部干物重都产生显著影响,酸性和微酸性基质(pH<6.0)时,幼苗叶片叶绿体超微结构发生降解,叶绿素堆积,叶片净光合速率下降,单株叶面积减小,根和地上部干重降低;pH为6.0～7.0的各处理在叶面积以及根和地上部干重指标上,F检验不显著;pH>7.0的微碱性和碱性基质虽然对幼苗产生不利影响,但与pH<6.0的处理比较,其影响要小些。鉴于此,甜瓜幼苗生长的基质pH范围为6.0～7.0,偏碱不会对幼苗产生严重的生理障碍。采用CaCO3调节基质pH时,最佳调节范围为pH6.0～6.5。     

甜瓜花粉母细胞减数分裂及雄配子体的细胞学研究

以薄皮和厚皮类型甜瓜为试材,采用改良的染色体制片方法,系统观察了甜瓜花粉母细胞的减数分裂及雄配子体发育的过程,结果表明:(1)甜瓜细胞核减数分裂的同步性较高,细胞质是同时型分裂,在细胞核分裂的过程中,核仁在前期Ⅰ到中期Ⅰ逐渐消失,在前期Ⅱ再次出现,随后消失,染色体在前期Ⅰ到中期Ⅰ逐渐收缩,变得清晰,至末期Ⅰ变得模糊,在前期Ⅱ再次清晰;(2)2种类型甜瓜终变期的染色体构型都以环状二价体为主;(3)在后期Ⅱ,观察到染色体的垂直和平行2种分离方式;(4)在前期Ⅰ和前期Ⅱ,伽师瓜"形成了多个较小的核仁,呈现一定的特殊性;(5)雄配子体发育经历了单核期和双核期,最后形成了成熟的花粉粒.研究表明,薄皮和厚皮类型甜瓜减数分裂的染色体行为基本一致,没有明显差异;伽师瓜"的核仁数量表现特殊可能与其长期的生态适应性有关.     

应用基因芯片检测酸味抗病甜瓜果实基因表达

利用Melon cDNA array ver1.0检测新疆厚皮甜瓜(Cucumis melo var.ameri)果实基因表达的可行性,并检测了经60Coγ射线辐射诱变后的新疆厚皮甜瓜酸味抗病变异株成熟果实基因的表达.结果显示:该芯片平均能够检测新疆厚皮甜瓜基因2 008个,检测出的基因占该芯片基因探针总数的65.4%;检测酸味抗病变异株上调表达的基因251个,占检出基因总数的12.5%;下调表达的基因224个,占检出基因总数的11.16%.利用RT-PCR验证芯片结果的可靠性,结果表明,用Melon cDNA array ver 1.0检测新疆厚皮甜瓜成熟果实基因表达水平是可行的.     

Detection and Location of Seed-Borne Inoculum of Didymella bryoniae and its Transmission in Seedlings of Cucumber and Pumpkin

Of the 91 tested cucurbit seed samples from thirteen countries nine from four countries were found to be infected with Didymella bryoniae. The pathogen is located on and in the seed coat including the perisperm and in the tissue of the cotyledons. Primary seedling infection occurred on the radicle, hypoctyl and cotyledons. Infection of the radicle generally caused pre-emergence tot while infection on the hypocotyl and cotyledons developed furthere inoculum for infection of the first true leaves and the stem. Experimentally, all the isolates of D. bryoniae could infect cucumber (Cucumis sativus), oriental melon (Cucumis melo var. makuwa), pumpkin (Cucurbita pepo) and watermelon (Citrullus vulgaris) at different growth stages; the susceptibility of cucumber and pumpkin was markedly influenced by previailing humid conditions.The blotter method was found more suitable for detection of seed-borne infection than the agar plate method.     

Novel, Starch-Like Polysaccharides Are Synthesized by an Unbound Form of Granule-Bound Starch Synthase in Glycogen-Accumulating Mutants of Chlamydomonas reinhardtii

We isolated two muskmelon (Cucumis melo) cDNA homologs of the Arabidopsis ethylene receptor genes ETR1 and ERS1 and designated them Cm-ETR1 (C. melo ETR1; accession no. AF054806) and Cm-ERS1 (C. melo ERS1; accession no. AF037368), respectively. Northern analysis revealed that the level of Cm-ERS1 mRNA in the pericarp increased in parallel with the increase in fruit size and then markedly decreased at the end of enlargement. In fully enlarged fruit the level of Cm-ERS1 mRNA was low in all tissues, whereas that of Cm-ETR1 mRNA was very high in the seeds and placenta. During ripening Cm-ERS1 mRNA increased slightly in the pericarp of fruit before the marked increase of Cm-ETR1 mRNA paralleled climacteric ethylene production. These results indicate that both Cm-ETR1 and Cm-ERS1 play specific roles not only in ripening but also in the early development of melon fruit and that they have distinct roles in particular fruit tissues at particular developmental stages.     

采用SSR和RAPD标记研究黄瓜属（葫芦科）的系统发育关系

野黄瓜Cucumis hystrix（2n=24）是在亚洲发现的第一个染色体基数为12的黄瓜属物种。这一发现对现行的以染色体基数和地理分布为基础的黄瓜属分类系统提出了质疑。采用SSR和RAPD两种分子标记对黄瓜属22份不同类型材料的亲缘关系进行了研究。结果表明,野黄瓜C.hystrix与黄瓜C.sativus var.sativus（2n=14）间的遗传距离（SSR:0.59,RAPD:0.57）小于其与甜瓜C.melo var.melo（2n=24）间的距离（SSR:0.87,RAPD:0.70）。SS     

西双版纳黄瓜Cs-Psy1基因的序列特征与表达分析

西双版纳黄瓜是我国特有的果肉橙黄色的黄瓜变种资源,不同种质间的β-胡萝卜素含量差异明显。PSY是胡萝卜素生物合成途径中的第1个限速酶。本文以西双版纳黄瓜为试材,分别克隆西双版纳黄瓜八氢番茄红素合成酶(Cs-PSY1)的DNA和c DNA序列,结果显示,DNA长2797 bp,包含5个内含子和6个外显子,c DNA序列长1385 bp,编码421个氨基酸。Psy1推测的氨基酸序列包含该家族的2个特征序列,保守性很高。该蛋白为不稳定蛋白,无明显疏水区,未预测到跨膜结构;系统进化分析结果显示,西双版纳黄瓜的Cs-PSY1蛋白与甜瓜的同源性较高;与栽培黄瓜深度测序材料"9930"和"GY14"的序列进行比较分析,结合115份黄瓜重测序结果,共发现5个SNP,其中2个位于起始密码子上游27 bp处和971 bp处,3个位于内含子区域。其中SNP4在重测序的19份西双版纳黄瓜中的突变率为100%,在96份栽培黄瓜中的特异性为5.3%。转录因子结合位点预测结果显示,在普通栽培黄瓜该位点处存在一个CTAG motif,在西双版纳黄瓜中该位点突变后则不存在该motif。利用实时荧光定量PCR技术分析Cs-Psy1的表达量变化趋势,结果表明,在黄瓜不同果实发育时期,该基因的表达量均呈现先上升后下降的趋势,在西双版纳黄瓜中表达量变化的差异明显,在授粉后50 d达到最大值,是果实发育初期表达量的8倍多,是同时期普通黄瓜的4倍多,而普通黄瓜表达量的总体变化相对平缓。西双版纳黄瓜果实内果皮的表达水平明显高于中果皮,最高相差约5倍,普通黄瓜差异不明显。从上述研究结果推测Psy1基因可能影响西双版纳黄瓜的β-胡萝卜素积累。     

番茄ACC合酶反义基因对河套蜜瓜的转化

河套蜜瓜（CucumismeloLcvHetau）的子叶经预培养。芽诱导和生根培养,获得再生小植株,诱导率达58％。取带有番茄ACC合酶反义基因的双元载体pMQ6／JM109与农杆菌（Agrobacteriumtumefaciens）LBA4404经三亲融合后,与在MS0上萌发5d、并在MS＋1mg／LNAA培养基上预培养3d的子叶共培养48h,然后转入含50mg／L卡那霉素的MS＋6mg／LZT的芽诱导培养基中,1l个月后诱导生芽,待芽长1．5－2cm时转入生根培养基中,1－2周后可诱导产生大量的根,形成完整的转基因小植株。经PCR和分子杂交检测证明,目的基因已整合入河套蜜瓜的基因组中。     

Transformation of Cucumis melo cv. Hetau with Tomato Antisense ACC Synthase Gene

An efficient in vitro plant regeneration system of Cucumis melo L. cv. Hetau was established. Regenerated plantlets were obtained from cotyledons after preculture, shoot inducing culture and root inducing culture. A high regeneration rate was achieved up to 58%. Cucumis melo was transformed with the antisense tomato ACC synthase gene in binary vector pMQ6 via Agrobacterium tumefaciens mediated gene transfer. Kanamycin resistant plantlets were obtained on MS medium with 6 mg/L zeatin, 50 mg/L kanamycin and 650 mg/L cefotaximine. PCR and molecular hybridization analysis showed that tomato ACC synthase antisense cDNA was integreted into the genome of C. melo.     

Sugar accumulation in roots of two grape varieties with contrasting response to water stress

Root sugar accumulation was studied in two grapevine varieties contrasting in tolerance to water stress. During a 10‐day water withholding treatment, the drought‐tolerant variety, Grenache, sustained less negative predawn and midday leaf water potentials as well as root water potential compared with the sensitive variety, Semillon. Grenache vines also maintained lower stomatal conductance and transpiration than Semillon vines throughout the drying period. In both varieties there was accumulation of sucrose in the roots and concentrations were inversely correlated to leaf and root water status. In both Grenache and Semillon, elevated root osmolality was associated with decreased soil moisture indicating that sugar accumulation may play a role in osmotic protection. Petiole xylem sap abscisic acid (ABA) concentrations increased with water deficit in both varieties and were highest for vines with the most negative root and predawn leaf water potentials. Furthermore, root sucrose concentrations were positively correlated with leaf xylem sap ABA concentrations, indicative of integration between carbohydrate metabolism and the ABA signalling system. Similar root sugar accumulation patterns between the two varieties, however, demonstrate that other factors are likely influencing the ability of the drought‐tolerant variety to remain hydrated.     

Possible phytotoxic metabolites in culture filtrates of Diaporthe phaseolorum var. sojae

Filter-sterile culture filtrates of an isolate of Diaporthe phaseolorum var. sojae (Phomopsis sojae), causal agent of pod and stem blight and seed decay of soybeans (Glycine max), grown on Czapeks-dox broth significantly (P = 0.05) inhibited germination of cabbage (Brassica oleracea), cantaloupe (Cucumis melo), onion (Allium cepa), soybean, and wheat (Triticum vulgare) seeds and wilted soybean seedling cuttings within 24 hr. Inhibition of seed germination and severity of soybean seedling wilt increased with increased concentrations of culture filtrates and increased incubation time of the cultures.