燕麦属颖果微形态特征及其分类学意义

为探讨燕麦属颖果微形态特征的分类学意义,采用体视显微镜和扫描电子显微镜观察燕麦属27种颖果的微形态特征,结合分子系统发育证据分析其分类学意义。燕麦属颖果有纺锤形、倒披针形、椭圆形3种形状,条纹、棱纹、网纹3种纹饰。燕麦属颖果形状、纹饰和花柱基宿存模式具有有限的属下分类学意义,颖果大小和表面大毛密度具有种间鉴定价值,而颖果腹面形态、压扁方式、胚比不具有种间鉴定价值。大穗燕麦(Avena macrostachya Balansa ex Coss.Durieu)颖果纺锤形,条纹纹饰,隶属于燕麦属颖果微形态特征的变异范围。大粒裸燕麦(A.nuda L.)与普通栽培燕麦(A.sativa L.)颖果大小、形状及纹饰特征的差异支持将大粒裸燕麦作为独立种处理。燕麦属颖果大小、表面大毛密度、胚比变异幅度大,推测与分布区广幅的气候变异相适应,凹腹面颖果体积相对缩减,有利于颖果快速发育、成熟,推测与燕麦属植物在温带、寒带分布区适生期较短相适应。     

高蛋白谷物—莜麦

燕麦是一种古老的作物,在我国至少有几千年的栽培历史。类似于小麦中的一粒小麦、二粒小麦和普通小麦,燕麦也有二倍体(2n=2x=14)、四倍体(2n=4x=28)、和六倍体(2n=6x=42)三个种群。按其外稃性状可分成带稃型和裸粒型两大类,中国以种植大粒裸燕麦为主,俗称莜麦。虽说现今我国莜麦单产水平还没法与小麦相比,可是农业科技工作者对它却寄予厚望。有人甚至把它做为第二次绿色革命的主攻方向之一。     

四倍体大燕麦与六倍体裸燕麦的受精作用和胚胎发育

用石蜡切片法,对四倍体大燕麦（Avena magna L.）和六倍体裸燕麦（Avena nuda L.）杂交的受精作用和胚胎发育进行了观察。结果表明,六倍体裸燕麦花偻在四倍体大燕麦柱头上萌发良好,花粉管可顺利长入花柱和胚囊,观察的168个四倍体大燕麦子房中,2.38%发生了双受精,产生了胚和胚乳;1.79%发生了单卵受精,只产生胚乳而无胚;总受精率为5.36%;成胚率为4.17%。由于胚乳的缺管或发育异常及败育,最终难以获得有生活力的种子,为四倍体大燕麦和六倍体裸燕麦杂交提供了细胞胚胎学证据。     

四倍体大燕麦×六倍体裸燕麦的杂种F1的产生及鉴定

本研究以四倍体大燕麦（Avena magna L.）做母本,六倍体裸燕麦（Avena nuda L.）做父本进行杂交,利用幼胚拯救技术获得了杂种F1,并对其后代形态特征进行了观察;对杂种F1同工酶图谱和DNA指纹图谱进行了分析。杂种F1形态特征偏亲本或介于双亲之间;同工酶研究表明多数F1具有双亲互补酶带;RAPD分析不同引物扩增产物F1呈共显性或偏父、偏母。这些结果表明F1为真杂种。     

四倍体大燕麦与六倍体裸燕麦的受精作用和胚胎发育

用石蜡切片法,对四倍体大燕麦(Avena magna L.)和六倍体裸燕麦(Avena nuda L.)杂交的受精作用和胚胎发育进行了观察。结果表明,六倍体裸燕麦花粉在四倍体大燕麦柱头上萌发良好,花粉管可顺利长入花柱和胚囊。观察的168个四倍体大燕麦子房中,238%发生了双受精,产生了胚和胚乳;179%发生了单卵受精,只产生胚乳而无胚;总受精率为536%;成胚率为417%。由于胚乳的缺乏或发育异常及败育,最终难以获得有生活力的种子。为四倍体大燕麦和六倍体裸燕麦杂交提供了细胞胚胎学证据。     

保健谷物──燕麦

禾本科燕麦属（Ａｖｅｎａ）中有许多种已被人类培育为禾谷类作物，广布于世界的温带和热带地区，其中普通燕麦（Ａ．ｓａｔｉｖａ）（又称玉麦、莜麦）和裸燕麦（Ａ．ｕｎｄａ）在我国西南和西北有栽培。 燕麦籽粒富含淀粉、蛋白质、谷蛋白、清蛋白、无机盐、胶油和生育酚（维生素Ｅ），营养十分丰富。可加工为燕麦粉或燕麦片供食用（但不适于制面包）。还可从其中提取燕麦油。康复期病人食用燕麦，可滋补身体，加速康复。燕麦也是马的良好饲料（但不宜喂猪）。 燕麦籽粒还可入药。根据传统医疗经验，燕麦籽粒有健神经、镇痉和兴奋之效。其…     

内蒙古冰草属（禾本科）一新变种——毛稃沙芦草

报道了内蒙古冰草属一新变种——毛稃沙芦草(Agropyron mongolicum Keng var. helinicum L.Q.Zhao et J. Yang)。该变种外稃密被长柔毛,颖光滑无毛不同于沙芦草（A. mongolicum Keng）和毛沙芦草（A. mongolicum Keng var. villosum H.L.Ying）。     

燕麦属细胞遗传学研究进展

整理燕麦属(Avena L.)细胞遗传学研究文献,总结相关研究进展。燕麦属有7组29种植物,分属5个基因组类型(A、C、AB、AC、ACD)。基于荧光原位杂交技术和种间杂交实验表明,A、C基因组染色体结构差异较大,A基因组二倍体物种具有等臂染色体,C基因组二倍体物种具有不等臂染色体。燕麦属植物D基因组和A基因组间分化程度较小,B基因组有可能是A基因组的变型——A′基因组。普遍观点认为A基因组二倍体物种可能是燕麦属六倍体物种母系亲本,砂燕麦(A.strigosa)为该属多倍体物种A基因组祖先的假说备受争议,有学者认为加那利燕麦(A.canariensis)可能是多倍体物种A或D基因组的供体。燕麦属多倍体物种基因组互换及染色体重排事件,增加燕麦属种间亲缘关系、多倍体物种基因组起源研究的困难。结合基因组学、分子细胞遗传学技术,有望为上述问题提供新证据。     

裸燕麦Ty1-copia类反转录转座子反转录酶序列的分离、鉴定与分析

本研究根据Ty1-copia类反转录转座子反转录酶的保守区设计简并引物,通过PCR扩增,从裸燕麦(Avena nuda L.)品种‘品燕1号’基因组中分离获得23条Ty1-copia类反转录转座子序列,并对序列特征、系统发育关系及其转录活性进行分析。结果显示,23条Ty1-copia类反转录转座子存在较高的异质性,序列间的一致性为45%～98%,存在插入、移码和终止密码突变,但频率不高;系统发育分析结果表明,燕麦Ty1-copia类反转录转座子在进化过程中主要为垂直传递。本研究通过检索燕麦基因表达数据库,发现了5个有转录活性的Ty1-copia类反转录转座子。     

罗布麻资源利用与罗布麻植物分类问题

叙述了有关罗布麻分类的简要历史,讨论了我国罗布麻的植物分类问题,从植物分类学的依据和生产实践的需要考虑,应将我国罗布麻植物划分为1属2种,即罗布麻属（Apocynum L．）和罗布红麻（A．venetum L．）及罗布白麻（A．hendersonii Hook．f．）2种。     

Dynamics and distribution patterns of acarine populations in stored-oat ecosystems

Population dynamics and aggregation patterns of nine kinds of stored-grain mites were studied in two 7.5 tonne lots of hulled (cv. Random) and hulless (cv. Terra) oat cultivars with 12–14% moisture content stored in two wooden bins in Manitoba, Canada during 1978–84. Random oats harbored more mites than Terra oats. Lepidoglyphus destructor Schrank was the most common granivorous mite and Cheyletus eruditus Shrank the most common predatory mite. Ecological data on a tydeid mite, Paratriophtydeus coineaui André, are presented for the first time. Because they were more abundant in Terra oats with higher fat acidity values (FAV) than Random oats with lower FAVs, L. destructor and Tarsonemus granarius Lindquist could be used as bioindicators of spoilage of stored oats. All species analyzed showed some significant difference in their abundance at different depths in the grain bulk; some species showed depthxtime interaction. Aggregation patterns indicated most mite species had overdispersed (clumped) distribution. T. granarius, and Blattisocius keegani Fox-Androlaelaps casalis Berlese had a distinct aggregation pattern in each oat cultivar.     

A SURVEY OF WILD OATS (AVENA FATUA AND A. LUDOVICIANA) IN ENGLAND AND WALES IN 1951

In 621 samples of wild oats, collected in England and Wales by N.A.A.S. and N.I.A.B. Officers, only two species ( Avena fatua and A. ludoviciana ) were found but both were very variable. A. fatua occurred in all wheat- and barley-growing areas, in both winter and spring corn and on all soil types. A. ludoviciana occurred (with two exceptions) only within approximately 80 miles radius of Oxford, mainly on heavy soila and chiefly in winter corn.
The amount of wild oats present appeared to depend on the frequency in the rotation of corn or other crops in which wild oats would shed seed. Deep ploughing often increased the infestation. The data did not show whether a field could be freed of wild oats by grassing down for a number of years, nor what is the maximum period of survival of buried wild oat seeds.     

Germination stimulation in wild oats (Avena fatua L.) by synthetic strigol analogs and gibberellic acid

At concentrations of 0.01–1 mM, five synthetic multiring analogs of strigol were effective germination stimulants of intact and dehulled wild oat (Avena fatua L.) seeds. The effect was concentration-dependent and equaled or exceeded that produced by equimolar gibberellic acid (GA₃). The most effective strigol analog treatments induced 55–80% germination within 7 days in intact wild oat seeds and resulted in 63–86% germination and normal seedling growth over 14 days. Intact wild oat controls germinated 14% after 14 days. The stimulation of wild oat germination by these synthetic strigol analogs demonstrates that these compounds, initially developed as germination stimulants for the seeds of the parasitic weed, witchweed (Striga asiatica L. Kuntz.), have bioregulatory activity in dormant seeds of monocots, as well as dicots. None of the compounds tested significantly affected the germination of nondormant cultivated oat seeds (Avena sativa L.). The commonly used dispersal agent, Tween 20 (0.1%), was found to inhibit germination of cultivated oats, alone and in the presence of 2% acetone.     

Germination stimulation in wild oats (Avena fatua L.) by synthetic strigol analogs and gibberellic acid

At concentrations of 0.01–1 mM, five synthetic multiring analogs of strigol were effective germination stimulants of intact and dehulled wild oat (Avena fatua L.) seeds. The effect was concentration-dependent and equaled or exceeded that produced by equimolar gibberellic acid (GA₃). The most effective strigol analog treatments induced 55–80% germination within 7 days in intact wild oat seeds and resulted in 63–86% germination and normal seedling growth over 14 days. Intact wild oat controls germinated 14% after 14 days. The stimulation of wild oat germination by these synthetic strigol analogs demonstrates that these compounds, initially developed as germination stimulants for the seeds of the parasitic weed, witchweed (Striga asiatica L. Kuntz.), have bioregulatory activity in dormant seeds of monocots, as well as dicots. None of the compounds tested significantly affected the germination of nondormant cultivated oat seeds (Avena sativa L.). The commonly used dispersal agent, Tween 20 (0.1%), was found to inhibit germination of cultivated oats, alone and in the presence of 2% acetone.Names of companies or commercial products are given solely for the purpose of providing specific information; their mention does not imply recommendation or endorsement by the U.S. Department of Agriculture over others not mentioned.     

Control of sawtoothed grain beetles (Coleoptera: Silvanidae) in stored oats by using an entomopathogenic fungus in conjunction with seed resistance

We tested the hypothesis that the entomopathogenic fungus Beauveria bassiana would be more efficacious on oat cultivars that prolonged the immature developmental period of sawtoothed grain beetle, Oryzaephilus surinamensis (L.), a storage pest. However, percentage of reduction in progeny production was similar on whole 'Don' and 'Paul' oats treated with fungus, even though immature developmental time was longer on whole 'Don' than on 'Paul' oats. In our initial test at 10 mg of conidia per kilogram of oats, the number of beetle progeny produced was reduced by 38-67% in whole oats, and there was no effect of the fungus on insects developing on cracked oats. Therefore, we conducted two dose-response studies that showed that adding 150 mg of conidia per kilogram to cracked or whole 'Paul' oats resulted in a 70 and 98% reduction, respectively, in number of progeny produced. No further reduction was obtained by adding 200 mg of conidia per kilogram of cracked or whole 'Paul' oats. Presence of the fungus did not affect developmental time in any of our tests. A previous study showed that cleaned oats should limit insect population growth to allow long-term storage of oats without insect damage. However, the current study shows that if the oats are not cleaned, and not cleaning oats is the normal storage practice, then B. bassiana could be used to help control sawtoothed grain beetles.     

Role of mycorrhizal infection in the growth and reproduction of wild vs. cultivated plants

Summary We tested the hypothesis that mycorrhizal infection benefits wild plants to a lesser extent than cultivated plants. This hypothesis stems from two observations: (1) mycorrhizal infection improves plant growth primarily by increasing nutrient uptake, and (2) wild plants often possess special adaptations to soil infertility which are less pronounced in modern cultivated plants. In the first experiment, wild (Avena fatua L.) and cultivated (A. sativa L.) oats were grown hydroponically at four different phosphorus levels. Wild oat was less responsive (in shoot dry weight) to increasing phosphorus availability than cultivated oat. In addition, the root: shoot ratio was much more plastic in wild oat (varying from 0.90 in the low phosphorus solution to 0.25 in the high phosphorus solution) than in cultivated oat (varying from 0.44 to 0.17). In the second experiment, mycorrhizal and non-mycorrhizal wild and cultivated oats were grown in a phosphorus-deficient soil. Mycorrhizal infection generally improved the vegetative growth of both wild and cultivated oats. However, infection significantly increased plant lifespan, number of panicles per plant, shoot phosphorus concentration, shoot phosphorus content, duration of flowering, and the mean weight of individual seeds in cultivated oat, while it had a significantly reduced effect, no effect, or a negative effect on these characters for wild oat. Poor positive responsiveness of wild oat in these characters was thus associated with what might be considered to be inherent adaptations to nutrient deficiency: high root: shoot ratio and inherently low growth rate. Infection also increased seed phosphorus content and reproductive allocation.     

Inhibition of germination and α-amylase induction by 6-methoxy-2-benzoxazolinone in twelve plant species

6-Methoxy-2-benzoxazolinone (MBOA) inhibited germination of rice (Oryza sativa L.), wheat (Triticum aethiopicum Jakubz), rye (Secale cereale L.), onion (Allium cepa L.), wild oat (Avena fatua L.), barnyard grass [Echinochloa crus-galli (L.) Beauv.], ryegrass (Lolium rigidum Gaudin), cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), tomato (Lycopersicum esculentum Mill.), carrot (Daucus carota L.) and amaranth (Amaranthus retroflexus L) and the inhibition increased with increasing MBOA concentrations. MBOA also inhibited the induction of α-amylase in these plant seeds and the inhibition increased with increasing MBOA concentrations. There were variations in sensitivity of these plant species to MBOA, and species of family Poaceae (barnyard grass, wild oat, rice, rye, ryegrass, and wheat) were less sensitive to MBOA than the other plant species.     

Naked Oat×Maize Hybridization

There is a certain frequency of fertilization and embryo productivity in naked oat (Avena nuda L. ) × maize (Zea mays L. ) crosses. The maize pollen readily germinated on the naked oat stigma and more than one pollen tubes grew into the style in about 68% of florets. In a sample of 163 florets fixed after pollination, 5 (3.07%) had only an embryo, 3 (1.84%) had only an endosperm and 10 (6.13%) had both. Overall, 9 haploid and 3 diploid naked oat plants were obtained from 12 seeds which formed following application of maize pollen to about 2200 emasculated naked oat florets. Preliminary studies indicated that elimination of the maize chromosomes occurred early in the embryo and endosperm development. This method gives a new approach for obtaining haplo!d naked oat.     

燕麦种质资源主要农艺性状的遗传多样性分析

燕麦种质资源是燕麦育种的重要基础,对燕麦遗传多样性的研究不仅有助于种质资源的搜集、管理和利用,也有利于进行核心种质的研究。为了解不同地区燕麦种质资源在农艺性状上的遗传多样性,对74份皮、裸燕麦种质资源13个性状的遗传多样性进行了聚类分析与主成分分析。结果表明:各性状的遗传多样性指数较大,多样性指数最高的是主穗粒重,其次是千粒重和穗长;性状变异系数最大的是单株分蘖数,其后依次为单株粒重和主穗粒重,最小的为株高;根据品种间各性状的遗传差异,通过聚类分析将74份资源材料划分为5类,其中36份皮燕麦资源被分为2类,26份裸燕麦资源被分为2类,7份皮燕麦和5份裸燕麦被分为一类,其中,类群Ⅰ可作为高产育种目标的亲本,类群Ⅲ可作为粒型育种目标的亲本,类群Ⅳ、Ⅴ可作为株高和小穗等育种目标的亲本;8个数量性状主成分分析的结果表明,前4个主成分对变异的累计贡献率达86.27%,第一主成分反应产量,第二主成分反应粒型,第三、第四主成分分别反应分蘖数和株高。