Peroxidase Isozyme Pattern in Pearl Millet Lines Resistant and Susceptible to Downy Mildew

Peroxidase isozyme patterns of five downy mildew (DM) resistant inbred lines (PIB-57-1, PIB-1248, PIB-1356, PIB-1364 and PIB-1440), five susceptible lines (PIB-1335-1-1, PIB-1314-2-2, PIB-2231-1, 7042 and PIB-1530-1-1) and DM free plants from the susceptible lines of pearl millet were studied. The results suggested a possible involvement of an isoperoxidase (C9) in imparting the resistance. The involvement of two other isozymes (C5 and C6) was also indicated in the1 resistance mechanism. The specific differentiation m particular isozyme pattern can be a useful criterion for characterization of resistance to downy mildew.     

Recurrent Selection for Increased Grain Yield and Resistance to Downy Mildew in Pearl Millet*

Six pearl millet (Pennisetum glaucum [L.] R. Br.) composites were subjected to three or more cycles of selection in multilocational yield trials and downy mildew disease nurseries in India. The base and selected populations were tested (a) over four years at three locations in India (11° to 29°N), (b) under terminal-drought and optimal moisture conditions for two years, and (c) under induced downy mildew infections to determine the impacts of selection on grain yield, agronomic traits, and resistance to downy mildew (Sclerospora graminicola Sacc. Schroet.). Mean grain yield increases for four composites undergoing three to six cycles of selection ranged between 23 to 94 kg ha^-1 cycle^-1 (0.9 to 4.9 % cycle^-1) which, averaged over composites, amounted to 3.3 % cycle^-1. Yield gains were generally expressed at all test locations and under both terminal-drought and optimal moisture environments. The gains in grain yield were associated with increases of both biomass and harvest index without extending the growth duration except in the earliest composite. Susceptibility to downy mildew remained below 10 % in all selected populations. Thus, the effectiveness of recurrent selection for increasing yield and yield stability of pearl millet is clearly demonstrated.     

Recurrent selection for downy-mildew resistance in pearl millet

One population of pearl millet (Pennisetum glaucum (L.) R. Br.) highly susceptible to downy mildew (Sclerospora graminicola (Sacc.) Schroet.) was subjected to two cycles of recurrent selection for downy mildew resistance using a modified greenhouse screening method. The response to selection was evaluated under greenhouse and field conditions using 50 random S₁ progenies and 50 random full-sib progenies from each cycle bulk. Significant progress over cycles of selection was observed in all evaluation trials. These results demonstrated that, in a susceptible population, recurrent selection effectively increased the level of resistance to downy mildew. The modified greenhouse method for assessing resistance to downy mildew effectively differentiated genotypes and had the advantages of greater rapidity and suitability for use throughout the year, independent of season. A rapid decline of genotypic variance was observed in advanced cycles of selection, indicating that a small number of genes controls downy-mildew resistance in this population. The comparison of genotypic and error variance components from S₁ progenies and full-sib progenies suggested that full-sib progenies can be used successfully in recurrent selection for increased downy-mildew resistance.     

葡萄霜霉病研究进展

文章介绍了葡萄霜霉病病害症状及侵染循环过程,归纳了其对卵孢子的形成发育及该病菌侵染后相关分泌蛋白的产生与变化,总结了葡萄霜霉病的致病机理。同时针对目前葡萄霜霉病的防治手段,分别从选育抗性品种、农业物理防治、生物防治、化学防治及综合防治等方面进行梳理与综述,以期为后续的葡萄霜霉病的研究与病害治理提供参考。     

几种化学诱导物对黄瓜幼苗霜霉病抗性的诱导作用

别用苯并噻二唑（BTH）、水杨酸（SA）、β-氨基丁酸（BABA）、草酸、KCl溶液处理二叶期的黄瓜幼苗并在2d后接种,结果表明：除KCl以外其余的四种诱导剂都可诱导黄瓜幼苗对霜霉病产生抗性,其中BTH和草酸诱导效果最好,诱导的最适浓度分别为0.5mmol/L和10mmol/L,它们能诱导黄瓜幼苗对霜霉病产生局部抗性和系统的抗性,且抗性的持久期至少在15d以上。复合诱导剂和相应的单一诱导剂的诱导效果相比,霜霉病的病情指数并没有显著差异。     

2种生物诱抗剂对葡萄霜霉病的诱导抗病作用

通过探讨不同诱抗剂对葡萄霜霉病抗性诱导的影响及其抗性生理机制,为利用诱抗剂防控葡萄霜霉病提供参考依据。本研究采用叶片喷雾施药方式研究2种诱抗剂对葡萄霜霉病抗性的诱导作用。结果表明,2种诱抗剂处理均对葡萄霜霉病有较好的诱抗效果,其中以β-1,3-葡寡糖10倍的防治效果最佳,病指防效达65.44%;与CK相比,β-1,3-葡寡糖10倍诱抗剂处理后的叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)活性、几丁质酶(CHI)活性和苯丙氨酸解氨酶(PAL)活性增强(P<0.05)。本研究说明葡萄经β-1,3-葡寡糖10倍液诱导后,提高了体内防御酶和抗病相关蛋白活性,进而诱导植株产生系统抗病性,β-1,3-葡寡糖可作为防治葡萄霜霉病的抗性诱导剂。     

Diallel Analysis of the Inheritance of Partial Resistance to Downy Mildew in Peas

The aim of the investigation was to see if the partial resistance of three sister-lines is determined by identical genes. The sister-lines were selected from a cross between a susceptible line and a partially resistant line. These lines and the susceptible parent line were crossed in all directions. The downy-mildew resistance of the different combinations was investigated in the F₁, F₃ and F₄ generations. The resistance of the sister-lines is not determined by the same genes. The moderate resistance of line X309 is recessive and might be determined by a single gene. The more resistant line X282 carry at least one resistance gene that shows dominance in crosses with X309. Line X311 carries, in addition to the resistance in X309, some resistance gene or genes with an intermediate effect.     

Inheritance of Resistance to Downy Mildew (Peronospora destructor [Berk.] Casp.) from Allium roylei Stearn in the Backcross Allium cepa L. × (A. roylei ×A. cepa)

Allium roylei Stearn and both reciprocals of the interspecific hybrid between Allium cepa L. and A. roylei displayed no symptoms of Peronospora destructor (Berk.) Casp. after artificial or natural inoculations, whereas A. cepa was susceptible. In the offspring from the backcross A. cepa× (A. roylei ×A. cepa) resistant and susceptible plants segregated after artificial inoculations, fitting a 1: 1-ratio. This suggests that resistance is controlled by a single, dominantly-inherited locus (designated Pd₁) from the nuclear genome of A. roylei. During a severe epidemic in the field, plants from the same backcross segregated resistant and susceptible individuals in a 3: 1-ratio. Escapes may explain the deviation from the 1: 1-segregation, but the presence of a second resistance locus segregating independently from Pd₁ cannot be excluded, implicating possible differences in virulence between populations of P. destructor. The occurrence in the backcross offspring of plants having a morphology similar to A. cepa without showing symptoms of downy mildew opens perspectives for breeding P. destructor-resistant onion varieties.     

小麦材料CH7034中成株期抗白粉病QTL定位

小麦生长过程中常因白粉病侵扰而造成产量和品质损失,发掘新抗源、鉴定新位点是小麦品种抗性改良的基础。CH7034是本实验室选育的一份抗白粉病材料。本研究利用芯片技术对CH7034与感病品种SY95-71的重组自交系(recombinant inbred lines, RIL)群体进行扫描,结合3年成株抗白粉病鉴定数据,鉴定出5个QTL-Pm,之后开发SSR标记对主效位点QPm.sac-2B.1 (表型变异解释率为30.6%~33.6%)进行图谱加密,进一步将其定位在小麦2B染色体长臂683 034 934~703 889 622基因组区段内,侧翼标记为X2BL-NRM12和X2BL-NRM17。本研究结果为小麦抗病育种提供了新抗源和可用于PCR检测的常规分子标记。     

Breeding Strategies for Adaptation of Pearl Millet and Sorghum to Climate Variability and Change in West Africa

Semi‐arid and subhumid West Africa is characterized by high inter‐annual rainfall variability, with variable onset of the rainy season, somewhat more predictable endings, and drought or excess water occurrence at any time during the growing season. Climate change is predicted to increase this variability. This article summarizes options for plant breeders to enhance the adaptation of pearl millet (Pennisetum glaucum [L.] R. Br.) and sorghum (Sorghum bicolor [L.] Moench) to climate variability in West Africa. Developing variety types with high degrees of heterozygosity and genetic heterogeneity for adaptation traits helps achieving better individual and population buffering capacity. Traits that potentially enhance adaptive phenotypic plasticity or yield stability in variable climates include photoperiod‐sensitive flowering, plastic tillering, flooding tolerance, seedling heat tolerance and phosphorus efficiency. Farmer‐participatory dynamic gene pool management using broad‐based populations and diverse selection environments is useful to develop new diverse germplasm adapted to specific production constraints including climate variability. For sustainable productivity increase, improved cultivars should respond to farmer‐adoptable soil fertility management and water harvesting techniques. Larger‐scale, on‐farm participatory testing will enable assessments of varietal performance under evolving climatic variability, provide perspective on needs and opportunities and enhance adoption. Strengthening seed systems will be required to achieve sustainable impacts.