增施氮肥对节节麦与小麦苗期竞争的影响

土壤氮含量是影响植物生长发育的主要限制因素,氮素的增加会提高外来植物的入侵性。采用de Wit取代试验和增施氮肥的方法,在盆栽条件下,依据植株形态结构、生物量积累及分配等变化,研究了不同水平氮[0(CK)、6、12、18、24 g/m~2]添加对入侵植物节节麦与小麦种间竞争关系的影响。结果表明:增施氮肥对节节麦与小麦的生长发育及种间竞争关系均造成了一定的影响。单种时,节节麦与小麦均表现了对氮营养的响应,随着施氮量的增加,根冠比、叶面积比呈下降变化,依据总生物量及总叶面积增幅大小可知节节麦氮响应能力大于小麦;混栽时,随着施氮量的增加,节节麦与小麦根冠比同样呈下降变化,当施氮量大于12 g/m2时,节节麦根冠比与CK差异达到显著水平(P0.05),而小麦则不明显,由此说明竞争条件下节节麦对氮素的敏感程度大于小麦。此外,除茎生物量及叶面积比外,节节麦其余5个指标的表型可塑性指数均大于小麦,节节麦对氮肥的高响应能力可能与其高效率的氮肥利用率有关。依据根生物量、地上生物量和总生物量计算得出的相对竞争强度及竞争攻击力系数结果显示,增施氮肥明显提高了节节麦的竞争效应及其地下部分竞争资源的优势。基于本文研究结果,节节麦在氮响应能力、表型可塑性及竞争能力方面均大于小麦,这可能是导致其在麦田中得以快速扩张蔓延的重要原因,而当前大气氮沉降逐渐增加的现状必定会促进节节麦的入侵,增加本地群落的可入侵性。     

Isozyme variation in species of the section Comopyrum of Aegilops

Genetic variation at 21 enzyme loci was studied in Aegilops comosa and Ae. uniaristata, the two species belonging to section Comopyrum of Aegilops. In Ae. comosa, the mean number of alleles per locus was 2.00 and the proportion of polymorphic loci was 0.667; in Ae. uniaristata they were 1.19 and 0.143, respectively. The two species were genetically distant from each other (I=0.561) supporting the previously assigned different genome symbols, M and N.     

First-division restitution in hybrids of Langdon durum disomic substitution lines with rye and Aegilops squarrosa

Durum wheat ‘Langdon’(LDN) caused a high frequency of first‐division restitution (FDR) and partial fertility in hybrids with rye, Secale cereale L., and Aegilops squarrosa L. In order to determine the genetic control of FDR, a complete set of 14 Langdon durum D‐genome disomic substitution lines (LDNDS) was crossed with ‘Gazelle’ rye and one accession (RL5286) of A. squarrosa. The microsporogenesis and fertility of the hybrids were studied. The results showed that most of the hybrids expressed a high frequency of FDR and partial fertility. However, the hybrids of 2D(2A), 4D(4A), 5D(5B) and 6D(6B) crossed with both rye and A. squarrosa, as well as 1D(1A) with A. squarrosa, had either little or no FDR and were completely sterile. These hybrids had different types of first meiotic divisions compared with LDN control hybrids. The hybrids with 2D(2A), 4D(4A) and 6D(6B) had a high frequency of random segregation of chromosomes at the first division. The hybrids with 5D(5B), as expected, showed high homoeologous pairing. The hybrid of 1D(1A) with A. squarrosa had a high frequency of equational division at first division. These results suggest that the reduced or absent FDR in such hybrids might be related to the substitution of chromosomes with an FDR gene and poor compensation ability of the D‐genome chromosomes for their homoeologous A‐ or B‐ genome chromosomes. Cytological analysis suggested that chromosome 4A in LDN most likely carries a gene for high frequency of FDR in hybrids. In addition, some monads were observed at the end of meiosis in the hybrids of 3D(3A) and 6D(6A) crossed with rye. They were formed from FDR cells that failed to divide at second division, suggesting that the LDN 3A and 6A chromosomes might carry genes for normal second division of FDR cells in the rye crosses.     

小麦K-CMS恢复系1BL/1RS和非1BL/1RS核型的鉴定及育性恢复基因的效应分析

为给K型小麦细胞质雄性不育系(K-CMS,本文简称K型不育系)的易恢性及恢复系的恢复度研究提供参考,以三个K型不育系及69份恢复系为材料,综合采用特异性分子标记及醇溶蛋白的A-PAGE检测方法对恢复系进行1BL/1RS核型鉴定,并初步推断恢复系恢复基因的遗传组成及其效应。结果表明,69份恢复系材料中,有65份属于非1BL/1RS类型(占94.2%),4份属于1BL/1RS类型(占5.8%);三个K型不育系的易恢性强弱依次为KTM3315A、KTP3315A、K3315A,且三个不育系间无显著差异。各恢复系间的恢复力表现出较大差异,其中恢复系KR8-1-2的恢复能力较强且稳定。初步推测K型不育系的育性恢复主效基因多位于1BS染色体上,恢复基因Rfv1效应约为60%,恢复基因Rfv2的效应约为10%。     

五种山羊草细胞质对普通小麦几个主要性状的遗传效应

将五种山羊草细胞质导入普通小麦 ,研究其对普通小麦主要农艺性状的遗传效应。结果表明 ,沙伦山羊草、粗厚山羊草和瓦维洛夫山羊草细胞质使普通小麦育性降低 ,离果山羊草、沙伦山羊草细胞质对普通小麦的农艺性状存在不良效应 ,五个性状中 ,除穗下节间长和单株有效分蘖数差异不显著外 ,旗叶面积、株高、结实率均存在细胞质效应。这说明只有导入合适的异源细胞质 ,才可能创造出可为生产利用的核质杂种小麦     

17个粗山羊草品种(系)抗叶锈基因的鉴定

为鉴定17个粗山羊草品种(系)中可能含有的抗叶锈病基因,用10株具有不同毒力的小麦叶锈菌混合菌对17个粗山羊草品种进行成株期抗叶锈性鉴定,筛选出7个在田间对叶锈菌有抗性的材料。用抗叶锈基因Lr1、Lr9、Lr19、Lr21、Lr24、Lr28、Lr29和Lr34的STS、SCAR或CAPS标记对这些品种进行分子辅助鉴定。初步明确粗山羊草CN40033和CN30823中可能含有Lr1基因;CN42471中可能含有Lr9基因;CN30942中可能含有Lr21;供试的17个粗山羊草品种中都不含有Lr19、Lr24、Lr28、Lr29和Lr34。     

单芒山羊草染色体组优异基因发掘

单芒山羊草是小麦遗传改良的优异基因源,为发掘其基因组优异基因,以中国春小麦为对照,对一套中国春-单芒山羊草附加系进行农艺性状调查、抗病性鉴定以及品质性状测定。结果发现,单芒山羊草5N染色体上含有矮秆基因,1N和7N染色体上含有密穗基因;1N染色体上具有抗小麦条锈病基因;4N染色体导入小麦能够显著提高小麦品质。这些优异基因可用于小麦染色体工程育种中。     

普通小麦-欧山羊草异附加系对干旱胁迫的生理生化响应

为探究异源染色体对小麦抗旱能力的影响,选取3个普通小麦-欧山羊草异附加系和3个普通小麦为试验材料,以聚乙二醇(PEG6000)模拟干旱胁迫,在苗期测定干旱胁迫下叶片丙二醛(MDA)积累量、可溶性蛋白含量和酶促防御系统(SOD、POD和CAT)活性变化。结果表明,随着干旱胁迫程度的加重和时间的延长,供试基因型所测定的五个生理指标的变化趋势较为一致。MDA含量都不断升高,三个普通小麦-欧山羊草异附加系(Ae9013、Ae9041和Ae9061)的MDA积累幅度较抗旱性最好的小麦对照晋麦47小,积累量也较少。三个异附加系的可溶性蛋白含量受干旱胁迫影响较小,虽有小幅度的下降,但保持着较高的含量。干旱胁迫下,各基因型的SOD、POD和CAT活力增加,在一定时间内,随着干旱胁迫的持续,晋麦47表现出先上升后下降的趋势,而Ae9013、Ae9041和Ae9061的SOD和POD活力随着胁迫程度的加重和时间的延长呈现不断上升趋势;Ae9013、Ae9041的CAT活力在15%PEG6000胁迫下不断增加,在25%PEG6000胁迫下先增加后下降,而Ae9061的CAT活力在高浓度PEG6000胁迫下仍持续增加。由此可见,普通小麦-欧山羊草异附加系具备更有效的酶促防御系统和渗透调节能力,说明U组染色体附加提高了小麦的抗旱能力。     

Variation in zinc efficiency among and within Aegilops species

Fifteen accessions of Aegilops tauschii (DD), 10 of Ae. speltoides (SS) and 8 of the tetraploid Aegilops species sharing the U genome were used to study the influence of varied zinc (Zn) supply on development of Zn-deficiency symptoms, and on shoot dry weight and Zn concentration. Plants were grown in a Zn-deficient calcareous soil under greenhouse conditions with (+Zn = 5 mg kg^—1 soil) and without (—Zn) Zn supply. Four accessions of wild tetraploid wheat, Triticum turgidum var. dicoccoides (BBAA), a group known for its high sensitivity to Zn-deficiency, were used in the experiments for comparison. As expected, the accessions of wild T. turgidum var. dicoccoides showed the highest sensitivity to Zn deficiency, and had more severe leaf symptoms of Zn deficiency (whitish-brown necrotic patches). Among the Aegilops species, leaf symptoms of Zn deficiency were, in general, more distinct in Ae. tauschii (DD) and least in Ae. speltoides (SS). Zinc efficiency, expressed as the percentage of shoot dry weight produced under conditions of Zn deficiency compared to Zn supply, averaged, 15% for T. turgidum, 32% for Ae. tauschii, 52% for Ae. speltoides and 61% for the tetraploid Aegilops species carrying the U genome. Differences in Zn efficiency among and within Aegilops species and T. turgidum were significantly correlated with the Zn amount per shoot, but not with the Zn amount per unit dry weight of shoots. The results show that Aegilops species can be exploited as an important genetic source for Zn efficiency genes, particularly Ae. speltoides var. ligustica (SS) and Ae. triuncialis (UUCC). Transfer of these genes to cultivated modern wheat may bring about a greater variation in Zn efficiency in wheat, and facilitate production of Zn-efficient modern wheat cultivars for Zn-deficient soil conditions.     

Polymorphism of high molecular weight glutenin subunits in three species of Aegilops

A collection of 136 accessions of Aegilops umbellulata (39), Ae. comosa (75) and Ae. markgrafii (22) was analysed for high-molecular-weight (HMW) glutenin subunits composition. The homogeneity of the accessions was studied and 55.1% of the collection was homogeneous for HMW glutenin subunits (29 Ae. umbellulata, 33 Ae. comosa and 14 Ae. markgrafii). The HMW glutenin subunits of Ae. umbellulata are encoded by the Glu-U1 locus; in Ae. comosa results showed that this proteins are encoded at the 1M chromosome, and the locus was named Glu-M1. In Ae. markgrafii it was assumed that HMW glutenin subunits were encoded by an homoeologous locus and it was named Glu-C1. All the accessions of Ae. umbellulata and Ae. markgrafii expressed both, x-type and y-type subunits. Among the Ae. comosa accessions, only one expressed an x-type subunit alone. All the accessions of Ae. umbellulata and some of Ae. comosa had x-type glutenins of higher molecular weights than those commonly present in bread wheat. A total of 8 alleles were detected at the Glu-U1 locus, 11 at the Glu-M1 and 4 at the Glu-C1. The new HMW glutenin variation found in this work suggests their possible utilisation in breeding for wheat quality.