Analysis of Yield and Disease Resistance Traits of New Winter Rapeseed Varieties over the Past Twenty Years in China

Based on the results of the national regional trail for winter rapeseed in four groups,including the upper reaches,middle reaches and lower reaches of Yangtze River and Huang-Huai region in the past twenty years,new varieties of winter rapeseed showed upward trend in average yield,the yield level in Huang-huai group was higher than other groups.The changes of average effective pods per plant were not significant in any group,but the number of grain per pod and 1 000-grain weight showed increase trend.However,the increment of grains per pod in three Yangtze River groups was higher than that in Huang-Huai River group,while the increment of 1 000-grain weight was just opposite.The incidence rate of Sclerotinia sclerotiorum and viral disease in new varieties of winter rapeseed obviously decreased,and the incidence rate of S.sclerotiorum decreased lower than 5%.Genetic improvement for winter rapeseed should be focus on the number of grain per pod and 1 000-grain weight in the future,and yield level of new varieties in all four groups is expected to increase.

Resistance of barley varieties to Heterodera avenae in the Qinghai–Tibet Plateau,China

The cereal cyst nematode,Heterodera avenae,is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China.The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare(QH2R,QH6R and TB2R)to H.avenae under field and pot conditions.Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation.Analyses of 186selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant(NFP)method were significantly higher than those identified with the Pf/Pi ratio(PPR)method,which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley.The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations,and eight HR varieties(Sunong 7617,Sunong 7635,Dongyuan 87-14,Rudong 14-46,Rudong 87-57,Rudong 87-8-45,Rudong 88-14-2,and Rudong 88-67-1)were identified in QH2R,with the NFP numbers below 4.2.Further microscopic observation of nematode development suggested that H.avenae often penetrated less into highly resistant varieties(Sunong 7635 and Dongyuan 87-14)and more frequently failed to develop into females than the susceptible barleys.The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H.avenae populations effectively at low costs.

Resistance Evaluation of Part of Leading Rice Varieties to Rice Blast in Guangxi Province

In order to determine the resistance of leading rice varieties to rice blast in Guangxi, three natural induction rice blast nurseries were established in Cenxi, Sanjiang and Yongfu. The resistance of the 45 leading rice varieties in Guangxi to rice blast was determined under conditions of spray inoculation and natural induction at seedling stage. The results showed that resistance frequencies of the 45 leading rice varieties ranged from 8.33% to 94.44%. Among the 45 tested varieties, there were 8 varieties of which the resistance frequencies were all higher than 80%, accounting for 17.78%; there were 11 varieties of which the resistance frequencies ranged from 50% to 80%, accounting for 24.44%; the resistance frequencies of the remaining varieties were all lower than 50%, accounting for 57.78% of the total tested varieties. The twoconsecutive-year determination results showed none of the 45 leading rice varieties showed resistance to rice blast. In 2010, there were 26, 12 and 7 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 57.78%, 26.67% and 15.56% of the total tested varieties. In 2011, there were 16, 23 and 12 varieties that were moderately sensitive, sensitive and greatly sensitive to rice blast respectively, accounting for 35.56%, 51.11% and 13.33%. The overall resistance of the 45 leading rice varieties trended to be decreased year by year. So in rice production, they should be selected properly.

Identification of candidate genes for aphid resistance in upland cotton by QTL mapping and expression analysis

Lignin is one of the main components of cell walls and is essential for resistance to insect pests in plants.Cotton plants are damaged by aphid(Aphis gossypii) worldwide but resistant breeding is undeveloped due to scarce knowledge on resistance genes and the mechanism. This study reported a lignin biosynthesisrelated gene identified in the F_(2) population derived from the cross between cotton cultivars Xinluzao 61(resistant to aphid) and Xinluzao 50(susceptible to aphid). A quantitative trait locus was mapped on chromosome D04 with a logarithm of odds(LOD) score of 5.99 and phenotypic effect of 27%. RNA-seq analysis of candidate intervals showed that the expression level of GH_D04G1418 was higher in the resistant cultivar than in the susceptible cultivar. This locus is close to AtLAC4 in the phylogenetic tree and contains a conserved laccase domain. Hence, it was designated GhLAC4-3. Silencing of GhLAC4-3 in Xinluzao 61 via virus-induced gene silencing(VIGS) resulted in decreased lignin content and increased susceptibility to aphids. These results suggest that GhLAC4-3 might enhance aphid resistance by regulating lignin biosynthesis in cotton.

Evaluation of Chinese rice varieties resistant to the root-knot nematode Meloidogyne graminicola

The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa （aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica）. Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly （r=0.87, P≤0.05） with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11 （aus）, Shenliangyou 1 （hybrid aus） and Cliangyou 4418 （hybrid indica） were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.

Identification of Soybean Resources of Resistance to Aphids

Four soybean [Glycine max （L.） Merr.] cultivars with soybean aphid resistance （Aphis glycines Matsmura）, p189, P203, P574, and P746, were identified in field test, choice test, and non-choice test, The grade of resistance to aphids and the damage index of P189, P203, and P746 were significantly different from the susceptible cultivars （P=0.05）. P574 and P746 showed antibiosis resistance, preventing aphids from reproducing on the plants. P203 showed antixenosis resistance, preventing aphids from reproducing in field test and choice test, but susceptible in non-choice test. Population development on plants was significantly different in field test, choice test, and non-choice test, which was caused by different selective pressures.

Study on the Relationship Betweenthe Toxin of Phytophthora infestans(Mont.) de Bary and Resistance of Potato

Plant pathogenic fungi produce mycotoxins which may lead host plants to produce disease symptoms and may have a significant positive role in the course of disease development.The putative Phytophthora infestans toxins were prepared by culturing in liquid medium（60 g rye and 10% tomato juice L-1） for 1 mon at 17℃,filtering through four layers of cheesecloth and being precipitated by ammonium sulfate.The resulted putative toxin solutions were used to study the effects on 3 potato varieties（both leaf and tuber tissues）.The results show that potato leaves and tubers exhibit symptoms similar to the late blight resulted from P.infestans infection.Potato varieties reacting differentially to both the toxin dilutions and toxins produced by different P.infestans isolates suggested the presence of toxin-mediated specificities between potato and P.infestans.Potato leaf and tuber tissues have different and contrary reactions to the toxin.Toxin-mediated specificities are likely present between potato and P.infestans.

Including predator presence in a refined model for assessing resistance of alfalfa cultivar to aphids

The aphid quantity ratio（AQR） is defined as the number of aphids on each cultivar divided by the number of aphids on all cultivars. AQR is based on the correlation between aphid populations and their host plants and is an important tool that has been utilized in evaluating Medicago sativa（alfalfa） cultivar resistance to aphids. However, assessment of alfalfa resistance to aphids can be confused by the presence of aphid predators, causing the assessment of plant resistance to aphids to be based on incorrect aphid population data. To refine the AQR and account for the effect of predators on aphid population assessments, we introduced a parameter ‘α＇, corresponding to the predator quantity ratio, and used αAQR as the ratio to quantify aphid populations. Populations of both aphids（4 species） and their predators（12 species） occurring in 28 M. sativa cultivars were sampled over two years at a research station near Cangzhou, Hebei Province, China. Results showed that the most suitable evaluation period was from May to June, as the aphid population was stable during this period. Compared with the AQR method, the predator population numbers based on the αAQR had a significant inverse relationship with aphid population numbers and the 28 cultivars were clustered into three classes： the resistant class, tolerant class, and susceptible class. In addition, 17 cultivars were reassigned when evaluated using αAQR. All numerical values calculated by αAQR were displayed as a Gaussian distribution, which showed that the 28 cultivars could be clustered into nine groups using a median value（±SE） of 1±0.1. Hence, ongoing alfalfa breeding trials will be assessed using the αAQR to establish a robust system that includes agronomic performance parameters in order to generalize the new method for further studies.

The Research on Identification of Resistance to Sorghum Aphid [Melanaphis Sacchari(Zehntner)] Employing Indoor Artificial Infestation Technique

[ Objective] The paper was to establish a quick and effective indoor identification method of sorghum resistance to aphid uninfluenced by seasons. [ Method] Based on the indoor reproduction technique of aphids, the sorghum varieties with different resistant performances against aphids in fields were conducted inoculation test in the laboratory according to different seedling culture media, different survey periods of aphid quantity, different leaf ages for inoculation, different inoculation quantity of aphids and different aphid sizes. Three hundred sorghum materials were identified in both laboratory and field. [ Result ] The number of aphids per seedling on the fifth day after inoculation gave the best score of plant resistance to sorghum aphid by using the loam as the seedling culture media, and inoculating three different sizes of aphids in seedlings at two-leaf stage. Thus, the indoor identification technique of resistance to sorghum aphids was as follows ： （ 1 ） sorghum seeds were sown in loam at room temperature of 22 - 26 ℃ and air humidity of 55% - 75% ; （2） three aphids with different sizes were inoculated in scedIings at two-leaf stage; （3） the number of aphids per seeding were surveyed on the fifth day after inoculation; （4） plant resistance to sorghum aphid was evalu- ated according to number of aphids per seedling on the fifth day after inoculation. The resistant grade of sorghum variety was evaluated according to distribution of aphid quantity per seedling in a 100-seedlings population. The resistance materials identified by indoor method at seedling stage had consistent performance with fidd identification. [ Conclusion] The method could be used for resistance identification of sorghum varieties and hybrids, and accurate identification and selectlon of individual resistance of hybrid offspring, which could improve selection efficiency of individual resistant plant against aphids in hybrid offspring and identification accuracy of individual resistant plant among molecular marker population.

Detection of Resistances of Different Corn Varieties to Corn Borer

In order to practice integrated management of corn insect pests effectively, a field experiment was made to study the resistances of 33 corn varieties to corn borer （ Ostrinia furnacalis） in the corn area to the north of the Huaihe River in Anhui Province. The results showed that there were evident differences in resistances of different corn varieties to corn borer and the resistant levels of the same corn variety to corn borer were also different in the whorl stage and the ear stage. In the whorl stage of corn, eight corn varieties, ＇ ‘Zhongnougda 311＇, ‘Zhongke 11＇, ‘ Denghai 3＇, ＇ Dongdan 80＇ , ‘ Liyu 16＇, ‘ Zhengdan 23＇, ‘ Jidan 8＇ and‘ Huayu 13＇ preformed relatively stronger resistance to corn borer. In the ear stage of corn, five corn varieties of ‘ Xundan 20＇, ‘ Qidan 1 ＇, ‘ Zhongke 4＇, ‘ Nongda 108＇ and ＇ Ludan 6018＇ showed relatively stronger resistance to corn borer. The comprehensive resistances of ten corn varieties to corn borer in the whorl stage and the ear stage successively were ‘Zhongnongda 311’ 〉 ‘Zbong, ke 4＇ 〉 ‘Jidan 8＇ 〉 ‘ Zhengdan 23＇ 〉‘Zhengdan 958＇ 〉 ‘ Qidan 1＇ 〉 ‘ Zhongdi 985＇ 〉 ‘Nongda108＇ 〉 ‘Liyu16＇ 〉‘Denghai3＇.

Accumulation Characteristics and Resistance to Heavy Metal Contamination of Agaricus bisporus Varieties in Shanxi Province,China

In order to evaluate the accumulation characteristics of heavy metals in the cultivars of Agaricus bisporus in Shanxi Province and to select the varieties with high resistances to heavy metal pollution, atomic absorption spectrophotometer and the atomic fluorescence spectrophotometer were used as the determination methods to compare the heavy metal contents and accumulation characteristics of 6 different varieties. The results showed that 3 heavy metal elements （lead, chromium and cadmium） were tested in the 6 varieties of A. bisporus , all of which were contaminated by heavy metals, but basically no beyond the national standards for food safety. In general, these varieties had less quality risk and could be eaten safely. The accumulation characteristics of heavy metals in these varieties were analyzed, and the varieties were screened according to the resistance to heavy metals pollution. The results showed that variety No. 1 and No. 6 were the varieties with strong comprehensive resistance to the 3 types of heavy metal pollution, and variety No. 3 was a species with weak comprehensive ability in resisting heavy metal pollution.

Resistance Evaluation of Dominant Varieties against Rice Blast (Magnaporthe oryzae) and Bacterial Blight (Xanthomonas oryzae pv. oryzae) in Guangzhou, China

The resistance of dominant rice varieties in Guangzhou against rice blast(Magnaporthe oryzae)and bacterial blight(Xanthomonas oryzae pv.oryzae)were evaluated by artificial inoculation and field natural blast nursery identification.Among 11 varieties tested,seven varieties showed resistance to rice blast,accounting for 63.6%;two varieties were highly resistant,accounting for 18.2%;three varieties were resistant,accounting for 27.3%;two varieties were moderately resistant,accounting for 18.2%;four varieties were susceptible(moderately susceptible),accounting for 36.4%.Varieties showed different resistance against the prevailing pathotype IV of bacterial blight;one variety was resistant,accounting for 9.1%;three varieties were moderately resistant,accounting for 27.3%;five varieties were moderately susceptible,accounting for 45.5%;one variety was susceptible,accounting for 9.1%;one variety was highly susceptible,accounting for 9.1%;all varieties tested showed susceptible to the virulent pathotype V.Huanghuazhan,Yuejingsimiao 2 and Fengxiuzhan showed resistance against both bacterial blight(pathotype IV)and rice blast,accounting for 27.3%.It is helpful to reduce the production risk by extending such dominant rice varieties with good resistance to rice blast and bacterial blight.

Mechanism of rice variety resistance to the yellow stem borer,Scirpophaga incertulas (Walker)

Yellow stem borer(YSB),Scir-pophaga incertulas(Walker)has be-come the main rice insect pest onceagain along the Changjiang Riversince 1990s.Unfortunately,no ricevariety with resistance to YSB hasbeen reported so far.Japonica Zhen-dao 2 with moderate resistance toYSB was found.In 10 rice vari-eties with different resistance levels,YSB individuals showed distinct de-velopmental rates,and the asyn-chronous development even occurredin the same rice variety.In this

Screening of Winter Rape Varieties Suitable for Northern Guangxi

[Objective] The study was conducted to provide a reference for develop- ment of fine winter rape varieties in northern Guangxi. [Method] In 2012 and 2013, 11 winter rape varieties were evaluated in northern Guangxi using randomized com- plete block design, Data such as yield and diseases were collected and analyzed. [Result] Among all the 11 varieties tested, the highest yield was recorded in variety Chuanzao NHl105. Dadi 95, FDl102, Chuanzao NHl105 and SWUl112 exhibited disease resistance better than Qinghai 131. [Conclusion] The winter rape varieties of FD105 and Qianza J102 were found suitable for planting in northern Guangxi.

Evaluation and screening for resistance of some varieties(lines)to major diseases and insect pests of rice

During 1984-1988,2,231 varieties(lines)from International Rice Testing Program(IRTP)were evaluated and screened for resistance to riceblast(Bl),bacterial blight(BB),sheath blight

Identification of Molecular Markers for a Aphid Resistance Gene in Sorghum and Selective Efficiency Using These Markers

In this study, an F2 segregated population obtained by hybridization between the aphid-sensitive sorghum strain Qiansan and aphid-resistant cultivar Henong 16 was used to establish an aphid-resistant pool and an aphid-sensitive pool. 192 pairs of AFLP （amplified fragment length polymorphism） marker primers were screened in these pools using BSA （bulked segregant analysis）. Three pairs of EcoR I-CTG/Mse I-CCT, EcoR I-CTG/Mse I-CAT, and EcoR I-AGT/Mse I-CCC showed linkage with aphis resistance. EcoR I-CTG/Mse I-CCT-475, EcoR I-CTG/Mse I-CAT-390, and EcoR I-AGT/Mse I-CCC- 350 （E42/M52-350） were mapped within 6, 10, and 13 cM distances with the aphid-resistant gene by using Mapmaker 3.0 software. The bands amplified by EcoR I-CTG/Mse I-CCT-475 and EcoR I-CTG/Mse I-CAT-390 were extracted, cloned, and sequenced. Specific primers of SCAR （sequence characterized amplified regions） were then designed from these bands. A specific band of 300 bp was amplified by a pair of SCAR primers designed based on the sequence obtained from the EcoR I-CTG/Mse I-CAT-390 marker. The SCAR marker was named SCAS0. The marker was used to detect the F2, BC1, and F2：3 populations. The selective efficiency was 86.8, 91.1, and 86.3% in the BC1, F2, and F2：3 populations, respectively. The average selective efficiency was 88.2%.

Transcriptome approach to understand the potential mechanisms of resistant and susceptible alfalfa(Medicago sativa L.) cultivars in response to aphid feeding

Plant breeding for resistance to agricultural pests is an essential element in the development of integrated crop management systems, however, the molecular and genetic mechanisms underlying resistance are poorly understood. In this pilot study, we conducted a transcriptomic analysis of a resistant （R） and susceptible （S） variety of alfalfa, with （＋A） or without （-A） aphids （totally four treatments）. We used the resistant cultivar Zhongmu t and the susceptible cultivar Soca. A total of 3 549 mRNAs were differentially expressed, of which 1 738 up-regulated and 1 307 down-regulated genes were identified in S＋A/S-A plants, while 543 up-regulated and 331 down-regulated genes were identified in the R＋A/R-A plants. KEGG analysis mapped 112 and 546 differentially expressed genes to 8 and 17 substantially enriched pathways for Zhongmu 1 and Soca, respectively. Six shared pathways were linked to plant resistance traits, including phenylpropanoid biosynthesis associated with salicylic acid synthesis, and linoleic acid metabolism associated with both jasmonic acid and flavonoid biosynthesis. Ultimately, we proposed a preliminary regulatory mechanism of alfalfa cultivar resistance response to aphids feeding based on transcriptome analyses and published documents.

Study on Adaptability of Introduced Pear Varieties

[Objectives]To study the adaptability of introduced pear.[Methods]Five pear varieties,"Aidang"pear,"Taiwan Zaomi"pear,"Cuiguan"pear,"Tianjin Yali"pear and"Zaosheng Xinshui"pear,were introduced.Then,using these five varieties,the phenology of pear trees,various characters of fruit,stress resistance(heat tolerance and cold tolerance)of varieties were studied.[Results]The plants of 5 varieties of pear trees grew fast and were robust;in late March,it went into the flowering period;"Aidang"pear fruit had a certain number of stone cells;"Taiwan Zaomi"pear had the highest sweetness;"Cuiguan"pear had the largest fruit;these five varieties of pear trees had good water resistance,heat resistance and cold resistance.[Conclusions]This study can provide a reference for the introduction of pear trees,and can also provide a practical basis for the large-scale planting of pear trees.

Genetic and Association Mapping Study of English Grain Aphid Resistance and Tolerance in Bread Wheat Germplasm

English grain aphid （EGA） is a destructive insect pest of wheat. To identify the loci associated with EGA resistance and tolerance, 70 bread wheat accessions mainly from central Asia were evaluated for EGA resistance and tolerance traits at two locations, and genotyped with 51 SSR markers. Totally, three accessions showed high or moderate levels resistance and 17 genotypes displayed highly or moderately tolerate to EGA. Genetic diversity of these lines was investigated also. After 97 SSR loci which evenly covered all wheat chromosomes were scanned for association, four SSR loci were significantly associated with EGA resistance and four with EGA tolerance. After association analysis was conducted with dynamic aphid densities, we found four loci Xgwm192b, Xgwm391, Xbarc98, and Xgwm613b were detected continuously at different growing stages of wheat. In addition, the loci of EGA resistance/tolerance and Russian wheat aphid resistance were compared. The results generated in this study would be helpful for utilization of the EGA resistance/tolerance germplasm, and for development of mapping populations in EGA resistance breeding programs.

Susceptibility to Insecticides and Ecological Fitness in Resistant Rice Varieties of Field Nilaparvata lugens Stl Population Free from Insecticides in Laboratory

A population of rice brown planthopper （BPH） Nilaparvata lugens collected from a paddy field in Hangzhou was successively reared on susceptible rice Taichung Native 1 （TN1） in a laboratory free from insecticides for more than 14 generations. The changes in susceptibility to insecticides and ecological fitness on different resistant rice varieties were monitored in each generation. The resistance ratio to imidacloprid sharply declined with the succession of rearing generations without insecticides from 359.94-fold at F1 to 6.50-fold at F14 compared with the susceptible strain, and the resistance ratio to chlorpyrifos was from 9.90-fold at F1 to 5.94-fold at F14. Nymphal duration and weights of newly hatched female adults were significantly affected by rice variety, generation and their interactions, but nymphal survival was significantly affected by the generation only. The ratio of brachypterous adults in males was affected by the generation and generation × variety interaction, whereas no difference was found in females. Nymphal duration extended with increasing generations, and the female nymphal duration was shorter in the susceptible variety TN1 than those in the resistant varieties IR26 and IR36. In addition, the female adult weight in TN1 was higher than those in IR26 and IR36. These results indicated that the resistance of field BPH population to insecticides was reversed after several generations of no-exposure to insecticides, and the ecological fitness in TN1 was higher than those in IR26 and IR36. These findings suggested the rational and reduced use of insecticides in combination with the manipulation of resistant rice varieties would be effective for BPH management.