卫星搭载对甘草种子萌发中生理特性的影响

为探讨卫星搭载处理对甘草种子萌发中生理特性的影响,本文运用卫星搭载技术对甘草种子进行太空诱变处理,考察了卫星搭载后甘草种子（卫星1号,GF）在干旱胁迫条件下,萌发过程中的发芽率、胚根长势、可溶性蛋白变化以及过氧化物酶和过氧化氢酶的活力,并与地面对照组种子（地面组,GN）进行了比较。结果表明,在干旱胁迫条件下（水势－1．0MPa）,飞行组种子的发芽率、胚根长势要高于地面对照组,其萌发过程中的过氧化物酶、过氧化氢酶活力也高于地面对照组。卫星搭载处理后,甘草种子的抗旱性能增强。     

小麦与高冰草属间体细胞杂交获可育杂种植株

普通小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．２ｎ＝４２）“济南１７７”与紫外线照射的高冰草（长穗偃麦草Ａｇｒｏｐｙｒｏｎｅｌｏｎｇａｔｕｍ,２ｎ＝７０）原生质体在ＰＥＧ诱导下融合,获杂种再生植株。取杂种子房诱导产生愈伤组织并再生植株,经染色体和同工酶鉴定,它们仍保留杂种性质。其中两株移栽成活并结实,杂种性质也经表型、染色体、同工酶和ＲＡＰＤ分析得到证明。在Ｆ０和Ｆ１代植株根尖细胞中,均发现高频率地存在着染色体断片;从Ｆ２代花粉母细胞减数分裂的染色体数目及行为发现,杂种细胞染色体数目主要分布在１８Ⅱ～２２Ⅱ,染色体断片发生配对及分离,表明它们是小染色体（ｍｉｎｉｃｈｒｏｍｏｓｏｍｅｓ）。Ｆ１及Ｆ２代植株比亲本小麦（“济南１７７”）秆茎粗硬、生长健壮,穗大粒大,已经产生具有优良性状的Ｆ２代穗系     

Z6／陕7859胚培养再生植株的细胞遗传学研究与易位系选育

二体附加系Ｚ６携带抗大麦黄矮病毒病基因,为了将其抗性导入小麦,将Ｚ６与普通小麦陕７８５９杂交,杂种Ｆ１经幼胚培养诱导形成再生植株,对再生植株及后代进行抗性鉴定,农艺性状考察及对ＳＣ２部分抗病植株花粉母细胞减数分裂期染色体行为进行了观察。结果表明,（１）ＳＣ２不同单株间存在染色体数目,结构的变异。（２）同一再生植株后代的不同单株,染色体数目可能相同,但染色体组成及减数分裂期行为可心不同,致使后代抗性     

航天诱变凤仙花小孢子母细胞减数分裂的研究

对卫星搭载凤仙花与对照组的小孢子母细胞减数分裂以及四分孢子期内的小孢子数目、形状进行了对比研究,发现经过航天搭载的凤仙花种子在第一代(SP1)植物的小孢子母细胞减数分裂中出现了染色体桥、落后染色体和分散染色体;四分孢子时期易出现多分孢子及四分孢子不分离等现象。而对照组则很难发现染色体畸变和小孢子的异常现象。     

空间条件对草地早熟禾植株过氧化物同工酶和酯酶同工酶的影响

将草地早熟禾(Poa pratensis L.)巴润(baron)干种子分别进行蒸馏水和硼酸处理后利用返回式卫星搭载,以未搭载干种子作为对照.对不同处理植株过氧化物同工酶(POD)和酯酶同工酶(EST)酶谱进行分析.结果表明,空间条件处理引起部分草地早熟禾植株POD和EST的差异,在酶带位置、数量、强弱等方面与对照相比出现了一定的变化,说明空间条件作用后草地早熟禾种子后代植株产生了一定变异.     

空间飞行对小麦种子的生长和细胞学特性的影响(英文)

中国科学探测和技术实验卫星于1987年8月5日到10日在空间飞行5天期间,一批小麦干种子由卫星带入空间。返回地面后进行了有关生理学和细胞学研究。空间飞行的小麦种子的萌发率和地面对照组无差异,株高比对照组高。飞行前后用116.4 Gy的X—射线照射种子,其幼苗均比相同剂量照射的地面对照组生长快。空间飞行的小麦根尖的畸变细胞数高于地面对照组。飞行前用5 mmol/L半胱氨酸处理小麦种子,能促进小麦的生长,减少畸变细胞数。     

小麦等离子束处理的生物学效应研究

本文以早熟品种冀麦31号和晚熟品系88—4284萌动种子为材料,报道了等离子束处理对小麦种子萌发的影响和细胞学效应。观察表明,等离子束长时间处理抑制种子发芽。在根尖细胞有丝分裂中期观察到染色体断裂和断片,冀麦31号染色体断裂的频率为0.49—1.34％,88—4284为0.21—2.14％。随着处理时间延长,染色体断裂频率逐渐提高。有丝分裂后期和末期出现大量的落后染色单体和染色体桥。在花粉母细胞减数分裂中期Ⅰ,经过等离子束处理的材料出现环状单价体。后期Ⅰ观察到染色体倒位造成的染色体桥和断片。在四分体期还有微核出现。     

空间诱变高粱突变体的研究

1996年经返回式卫星搭载处理的纯系高粱品种晋粮5号（CK）的种子经次年播种后,获得少量矮秆早熟突变体（SP3）。此后连续二年播种,该突变体矮秆早熟性状稳定。该突变体与未经搭载的对照相比,有如下不同之处：（1）成熟期缩短15 d左右,株高降低40 cm。（2）穗长增加3.9 cm ,每穗籽粒数比对照多400粒。（3）SP3平均千粒重为34 g,对照为27 g。（4）SP3叶片变窄,变短,增厚,叶面积减少了43%～22%。（5）SP3穗轴长度比对照增加30%,各节间长度比对照缩短了67%～15%。（6）SP3种子中亮氨酸含量比对照增加15%,可溶性糖含量比对照增加25%,单宁含量降低了30%。     

外空飞行后小麦根尖细胞的染色体畸变

小麦种子在科学探测和技术实验卫星上进行空间飞行,返回地面后浸种萌发,经不同时间培养后取根尖固定并观察根尖细胞染色体畸变情况。空间飞行可引起根尖细胞的染色体畸变率的增加,其损伤随取样时间的延后呈下降趋势,说明空间飞行所诱导的染色体损伤可被部分修复;种子经辐射保护剂芥子碱和半胱氨酸顶处理能显著降低空间飞行诱发的根尖细胞染色体畸变率,而经辐射敏化剂咖啡因预处理的情况则相反。     

小麦ph 1 b、ph2a,ph2b突变体与粘果山羊草杂种及其衍生后代的细胞遗传学研究

利用小麦品种“中国春”及其phlb, ph2a、ph2b基因突变体与粘果山羊草杂交, 分析了可交配性方 面的差异,观察了F,花粉母细胞减数分裂中期I染色体配对,就phlb, Ph2a, ph26 3个基因的作用进 行了比较。首次获得了F：回交种子和自交种子,调查了自交、回交一代植株染色体数目,分析了ph基 因对配子育性的影响以及回交结实与染色体配对的关系。本文还分析了F：自交结实的可能原因。     

Radiobiological effects of a low-energy ion beam on wheat

The radiobiological effects of a low-energy nitrogen ion (N⁺) beam on wheat were studied, particularly with regard to the induction of chromosome aberrations. The results demonstrated that the three test varieties showed different sensitivities to ion implantation, and a higher dose of ion implantation had a marked effect on the germination and survival rate of the seeds exposed. The germination rate and survival rate curve basically followed a similar trend in the same variety. Cytological analysis indicated that ion beams were effective in producing chromosome aberrations. The frequencies of mitotic or meiotic cells with chromosome aberrations increased linearly with increasing doses. The aberration types included, for example, acentric fragments, chromosome deletions, lagging chromosomes, chromosome bridges and micronuclei. In the root tip cells, aberrations chiefly consisted of acentric fragments and deletions. Chromosome bridges and lagging chromosomes were the main aberration phenomena observed in the pollen mother cells. The highest frequencies of root tip cells and pollen mother cells with chromosome aberrations were 15.2% and 39.8%, respectively. Changes in morphology and mutant were also observed in the plants derived from exposed seeds. Received: 10 April 2000 / Accepted: 10 October 2000     

λDNA导入引起小麦染色体变异的研究

小麦种子从萌动至２叶期,用λＤＮＡ进行浸滴处理,Ｄ１代出现花粉母细胞染色体变异的植株占观察株的７３．３％,染色体变异的细胞占观察细胞数的２８．３％。主要有染色体落后、单价体、染色体桥、多价体、染色体多极分离,染色体螺旋化不同步,异常二分体和卤分体及微核等类型,随世代增进,染色体行为趋于稳定,但不同个体间存在的较大差异。这种复杂的染色体变异可能是外源ＤＮＡ在受体整合过程中的细胞学反应。     

Dynamics of storage reserve deposition during Brassica rapa L. pollen and seed development in microgravity

Pollen and seeds share a developmental sequence characterized by intense metabolic activity during reserve deposition before drying to a cryptobiotic form. Neither pollen nor seed development has been well studied in the absence of gravity, despite the importance of these structures in supporting future long-duration manned habitation away from Earth. Using immature seeds (3-15 d postpollination) of Brassica rapa L. cv. Astroplants produced on the STS-87 flight of the space shuttle Columbia, we compared the progress of storage reserve deposition in cotyledon cells during early stages of seed development. Brassica pollen development was studied in flowers produced on plants grown entirely in microgravity on the Mir space station and fixed while on orbit. Cytochemical localization of storage reserves showed differences in starch accumulation between spaceflight and ground control plants in interior layers of the developing seed coat as early as 9 d after pollination. At this age, the embryo is in the cotyledon elongation stage, and there are numerous starch grains in the cotyledon cells in both flight and ground control seeds. In the spaceflight seeds, starch was retained after this stage, while starch grains decreased in size in the ground control seeds. Large and well-developed protein bodies were observed in cotyledon cells of ground control seeds at 15 d postpollination, but their development was delayed in the seeds produced during spaceflight. Like the developing cotyledonary tissues, cells of the anther wall and filaments from the spaceflight plants contained numerous large starch grains, while these were rarely seen in the ground controls. The tapetum remained swollen and persisted to a later developmental stage in the spaceflight plants than in the ground controls, even though most pollen grains appeared normal. These developmental markers indicate that Brassica seeds and pollen produced in microgravity were physiologically younger than those produced in 1 g. We hypothesize that microgravity limits mixing of the gaseous microenvironments inside the closed tissues and that the resulting gas composition surrounding the seeds and pollen retards their development.     

温度对斯托克通氏烟草雄配子体形成和发育的影响

为探究低温对斯托克通氏烟草(Nicotiana stocktonii)花粉母细胞(PMC)减数分裂及其雄配子体发育过程的影响,采用卡宝品红染色法,研究不同温度条件下该材料雄配子体形成和发育的过程。结果表明:种植于昼温(31±0.5)℃、夜温(11±0.5)℃人工气候箱中的Nicotiana stocktonii花粉母细胞减数分裂过程异常现象较少,出现微核的比率较低,用新鲜成熟的花粉做萌发实验花粉萌发率较高,为(71±3)%; 而种植于昼温(25±0.5)℃、夜温(3±0.5)℃条件下的Nicotiana stocktonii开花后花药大多干瘪,用新鲜成熟花粉做萌发实验花粉萌发率低,为(13.67±3)%,花粉母细胞减数分裂过程出现染色体桥、染色体不同步、染色体断片、落后染色体等现象,存在微核的细胞比率较高。因此,Nicotiana stocktonii花粉母细胞减数分裂与小孢子发育过程易受温度影响,从而影响花粉的可育性。     

Biosynthesis and excretion of hydrolases in germinating cereal seeds

The initial formation site of hydrolases in germinating cerealseeds and their subsequent release were examined using the substrate-filmtechnique. Early in the germination of cereal seeds, e.g., barley,wheat, rye, oat and maize, -amylase invariably appeared in theregion of the epithelial cells of the scutellum, whereas itlater gradually diffused into the entire region of the endospermtissues. The initial formation site of proteinase and RNA-asein germinating barley seeds was also confirmed to be in theepithelium. We conclude that the epithelium has a more importantrole in the enzymic breakdown of reserve substances stored inthe endosperm tissues than the aleurone layer. (Received October 19, 1979; )     

Localization of repetitive DNA in cereals byin situ hybridization: Cross hybridization among wheat,rye, barley,and oat

³H-RNA, complementary to repetitive DNA of wheat, rye, barley, and oat, was hybridizedin situ to root tip or pollen mother cells of the species mentioned. The cRNAs hybridized best with the DNA in cell nuclei of the species from which they were prepared. Cross hybridization with cells of the other related species resulted in a significant but diminished labelling. Wheat, rye, and barley hybridized better to each other than to oat, andvice versa, in agreement with the usual taxonomical classification. Over the interphase nuclei the label was distributed unevenly; not all regions of dense chromatin were labelled, and little label was found over the nucleoli. On chromosomes, the repetitive DNA was located somewhere along the chromosome arms or near the centromers in wheat, barley, and oat. Only in rye, most of the label was located near the telomers, probably over the large heterochromatin areas.     

A new insight into application for barley chromosome addition lines of common wheat: achievement of stigmasterol accumulation

Barley (Hordeum vulgare) has a much higher content of bioactive substances than wheat (Triticum aestivum). In order to investigate additive and/or synergistic effect(s) on the phytosterol content of barley chromosomes, we used a series of barley chromosome addition lines of common wheat that were produced by normal crossing. In determining the plant sterol levels in 2-week-old seedlings and dry seeds, we found that the level of stigmasterol in the barley chromosome 3 addition (3H) line in the seedlings was 1.5-fold higher than that in the original wheat line and in the other barley chromosome addition lines, but not in the seeds. Simultaneously, we determined the overall expression pattern of genes related to plant sterol biosynthesis in the seedlings of wheat and each addition line to assess the relative expression of each gene in the sterol pathway. Since we elucidated the CYP710A8 (cytochrome P450 subfamily)-encoding sterol C-22 desaturase as a key characteristic for the higher level of stigmasterol, full-length cDNAs of wheat and barley CYP710A8 genes were isolated. These CYP710A8 genes were mapped on chromosome 3 in barley (3H) and wheat (3A, 3B, and 3D), and the expression of CYP710A8 genes increased in the 3H addition line, indicating that it is responsible for stigmasterol accumulation. Overexpression of the CYP710A8 genes in Arabidopsis increased the stigmasterol content but did not alter the total sterol level. Our results provide new insight into the accumulation of bioactive compounds in common wheat and a new approach for assessing plant metabolism profiles.     

Effects of space flight on the growth and some cytological characteristics of wheat seedlings.

Researchers report on the terrestrial growth of wheat seeds after exposure to microgravity and cosmic radiation in space. Some groups of experimental and control seeds were treated with cysteine before flight. The germination of space-flown seeds was not different from ground controls. Cysteine promoted growth in both experimental and control groups of seeds. Roots tips of seedlings grown from experimental seeds exhibited aberrant cells; preflight treatment with cysteine decreased the number of aberrant cells.     

EFFECTS OF POLLINATION INTENSITY IN CAMPSIS RADICANS

I examined effects of pollination intensity on fruit, seed and seedling characteristics in Campsis radicans, and joint effects of pollen donor and pollination intensity on fruit production. Large pollen loads were more likely to initiate fruit production than small pollen loads, and the former fruits contained more seeds and a greater total seed mass. No further increases in seed number or mass occurred for pollen loads above 4,000 grains. The weight of individual seeds was unaffected by pollen load. Effects of pollen donor were generally larger than effects of pollen load, and fruit production from small loads of pollen from one donor were sometimes equal to fruit production from larger pollen loads from another donor. The ratio of pollen grains deposited to resultant seeds increased with pollen load, and several explanations are proposed. Seeds from heavy pollinations emerged better than seeds from light pollinations, but did not differ in speed of germination or in the performance of seedlings up to 126 days. The emergence differences are probably due to differing intensities of pollen tube competition.