树木挥发物对植食性昆虫的诱导抗性

树木挥发物质对植食性昆虫取食，产卵所产生的诱导抗性是树木与昆虫的长期协同进化过程中的必然结果，树木与植食性昆虫之间发展了一套互相调节，自身开拓资源，产生生存对策的复杂相互关系，本文着重阐明了树木与植食性昆虫的互相策略，诱导抗性的生物化学基础以及诱导抗性在调节植食性昆虫种群中的重要性。     

Hydroxamic acid content of triticum species

Summary Fifty-five accessions of Triticum species were analyzed for content of hydroxamic acids (Hx), a natural resistance factor against various organisms. Hx were found in all accessions analyzed. Extreme values were found in wild diploid species: highest in T. speltoides (16.0 mmol/kg fr. wt) and lowest in T. tauschii (0.21). Modern polyploid wheats sharing the same genome did not show substantial variations in Hx levels. The data suggest possible sources of high Hx levels for wheat breeding programs.     

Breeding maize lines for complete and partial resistance to maize streak virus (MSV)

Summary S₁ to S₅ inbred lines, derived from a maize population bred for its overall resistance to three tropical viruses, were screened for resistance to maize streak virus (MSV) by artificial plant infection using viruliferous leafhoppers. Symptoms were rated and intra-line frequency distributions studied for all pedigree inbred lines. Mortality due to MSV was very low among these inbreds. Symptoms appeared later, developed slower and were less severe than in the susceptible control hybrid. Results of a study of 500 S₁ and 93 S₂ lines suggested that resistance is under genetic control via a system involving loci with major genes (with dominance for resistance) controlling high to complete resistance, associated with a genetic system involving loci with minor genes controlling partial resistance. Lines expressing complete resistance to MSV were developed from 5 cycles of inbreeding and selection. The relevance of such complete and partial resistance is discussed.Abbreviations MRPS Mean Rating for Plants exhibiting Symptoms     

Genes conferring low seedling reaction to Mexican pathotypes of Puccinia recondita f. sp. tritici,and adult-plant responses of recent wheat cultivars from the former USSR

Fifty-five spring bread wheat (Triticum aestivum L.) cultivars, mostly released between 1975 and 1991 in eight leaf rust-prone spring wheat growing regions of the former USSR, were tested in the seedling growth stage for reaction to 15 Mexican pathotypes of Puccinia recondita f. sp. tritici. In total, seven known and at least two unknown genes were identified, either singly or in combinations: Lr3 (7 cultivars), Lr10 (14), Lr13 (5), Lr14a (1), Lr16 (1), Lr23 (3); the unknown genes were identified in 14 cultivars. The first unknown gene could be either Lr9, Lr19, or Lr25; however, the second unknown gene in 9 cultivars was different from any named gene. Twelve of the 15 pathotypes are virulent for this gene, hence its use in breeding for resistance will be limited. The cultivars were also evaluated at two field locations in Mexico with two pathotypes in separate experiments. The area under the disease progress curve and the final disease rating of the cultivars indicated genetic diversity for genes conferring adult plant resistance. based on the symptoms of the leaf tip necrosis in adult plants, resistance gene Lr34 could be present in at least 20 cultivars. More than half of the cultivars carry high to moderate levels of adult plant resistance and were distributed in each region.     

不同MA袋对鲜食核桃仁保鲜效果的比较

测定不同材质自发气调(modified atmosphere, MA)包装袋对鲜食核桃仁的保鲜效果。以‘香玲’鲜食核桃为试材,分别采用5种不同塑料复合包装袋包装：PA/PE袋-200 μm（处理1）,PA/PE袋-180 μm（处理2）,Al/PET袋-210 μm（处理3）,PET/PE袋-160 μm（表面平滑）（处理4）和PET/PE袋-160 μm（表面网纹）（处理5）,以地膜包装-6 μm（处理6）为对照,低温贮藏,定期测定其呼吸强度、脂肪含量、蛋白质含量、SOD酶活性、POD酶活性、酸价、过氧化值及碘价等指标的变化。结果表明：呼吸强度测试中,除处理3外,处理6和其他处理组在贮藏期前12天内呼吸强度从135 CO₂ mg/(kg·h)下降至60 CO₂ mg/(kg·h)以内,中后期几乎保持稳定状态;处理4和处理5核桃在贮藏15天后呼吸强度在30~40 CO₂ mg/(kg·h)之间;脂肪含量测试中,在贮藏30天内处理3的核桃脂肪含量为34.2 g/100 g;处理1、2、4、5的核桃在贮藏前期脂肪含量持续下降,60天时,处理4、5核桃脂肪含量分别为45.8 g/100 g和46.1g/100 g;在贮存60天时,蛋白质含量处理4、5核桃的蛋白质含量最高,达到17.6 g/100 g和17.1 g/100 g;酸价测试中,在贮藏期间处理6核桃仁的酸价从0.24 mg KOH/g增长到4.3 mg KOH/g,处理4、5核桃的酸价从0.24 mg KOH/g增加到2.7 mg KOH/g以内;SOD酶活性测试中,处理6对照组和处理1、2在贮藏30天时,SOD酶活性达到140.1 U/g和135.2 U/g;处理3、4、5的SOD活性在贮藏45天分别达到139.9、149.7 U/g和150.0 U/g;POD酶活性测试中,处理6对照组和处理3在贮藏30天时,POD活性达到最低值,分别为10.5 U/g和10.7 U/g,其他4组在45天时降至最小值,分别为：10.8、11.0、10.1、10.3 U/g;MDA含量测试中,整个贮藏期,鲜食核桃核仁的MDA含量持续上升,贮藏至60天时,处理4的MDA含量为6.25 mmol/g,处理5为6.08 mmol/g,均低于其他组数据,但差异不显著。上述6种包装材料中,PET/PE-160 μm包装保鲜效果最佳,可以推广使用。     

转甜菜碱醛脱氢酶基因马铃薯的抗旱耐盐性

通过根癌农杆菌介导法将甜菜碱醛脱氢酶(BADH)基因导入马铃薯栽培品种甘农薯2号, 经PCR、Southern杂交和Northern杂交证明BADH基因已整合到马铃薯基因组中并在转基因植株中转录和表达。测定表明对照植株没有BADH酶活性, 各转化株系在胁迫前后BADH酶活性近似, 在2~11 U之间。BADH酶活性与叶片的相对电导率呈一定的负相关(y= –3.7738x+57.083, r=0.989^**)。在NaCl和PEG胁迫下, 转基因植株生长正常, 株高比对照提高0.41~1.00 cm, 单株重量比对照增加10%~35%, 说明外源BADH基因的导入提高了马铃薯植株对干旱和盐碱的抗性。     

Genetical relationships between reactions to bacterial leaf spot,yellow mosaic and Cercospora leaf spot diseases in mungbean (Vigna radiata)

Summary Studies on the inheritance pattern of bacterial leaf spot (BLS), yellow mosaic (YM) and Cercospora leaf spot (CLS) reactions in crosses of BLS and YM resistant/tolerant but CLS susceptible × CLS resistant but BLS and YM susceptible parents indicated that resistances to BLS and CLS were governed by single dominant genes, whereas YM tolerance was a monogenic recessive character. The studies also indicated that these three genes were inherited independently. The simple inheritance pattern and independent assortment of the genes governing resistance/tolerance to these diseases suggest that the usual breeding methods will be adequate to develop multi-disease resistant mungbean cultivars.Paper XII in the series Studies on resistance in crops to bacterial diseases in India.     

Gummy stem blight resistance of cucumbers (Cucumis sativus L.)

Summary A start was made with breeding for resistance to gummy stem blight in cucumber. A method has been development for screening plants in a young stage. Using this method a distinct level of resistance was found in plants of Leningradsky, Wjarnikovsky,a P.I. entry from Birma, Rheinische Vorgebirge and a P.I.entry from Turkey. Lines developed from this material show a higher level of resistance than Dutch slicing and pickling cucumber varieties.     

Evaluation of a simple technique for characterizing rice root systems in relation to drought resistance

Summary Drought is a constraint to rice yields in much of Asia's rainfed rice crop. Although genotypic variation for root system characteristics is well documented in this semiaquatic species, little improvement of rice for drought resistance has been attempted. No simple method to evaluate root systems exists. In this paper we report the development and testing of a simple device to measure the pulling force required to uproot rice seedlings. The force required to pull rice seedlings from the paddy soil was correlated with root weight, root branching and thick root number. The capability to separate rice cultivars by this technique and relationship of the root pulling force to other drought screening methods are illustrated.     

河北省不同小麦品种抗旱性研究

通过水培和20%聚乙二醇（PEG-6000）胁迫条件下,比较五个不同小麦品种的发芽率、胚芽鞘长度、胚根数目、主胚根长。结果表明,5个品种间抗旱性存在显著差异,‘麦1’的抗旱性最强,‘麦99’、‘石4185’、‘北农大3383’次之,‘师栾02-1’抗旱性最弱。同时,胚芽鞘长度和种子的相对发芽率可作为小麦萌发期抗旱性鉴定的主要指标,主胚根长和胚根数可作为参考指标来判断品种的抗旱性。