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Peanut (Arachis hypogaea L.) is one of the important cash crops in China, and about 40% of peanuts are used for food production. The sucrose content was positively correlated with the flavor and taste of peanut and its products, thus increasing sucrose content in kernel was significant for the promotion of peanut quality. In this study, two F2:3 populations (NYBPXSYT5-1 and 19-1934XJHT1) were constructed to investigate the genetic model of sucrose content, and analyze the correlations between sucrose content with oil content, protein content, and other seed traits. The results showed that the sucrose contents of peanut kernel in two populations were continuously distributed and abundantly varied, and the transgressive segregation phenomenon were observed. In the two populations, sucrose content was significantly negatively correlated with oil content but significantly positively correlated with protein content. However, the correlations between sucrose content and kernel length, kernel width, and 100-kernel weight were inconsistent. The genetic analysis in two populations showed that the sucrose content in peanut kernel was mainly regulated by two pairs of main genes with the additive effect and dominant effect. There was the interaction between the two main genes, as well as the additive effect. This study initially reveals the genetic regulation of sucrose content in peanut kernels, which is beneficial for the breeding of edible peanut varieties and the cultivation of special varieties. [ABSTRACT FROM AUTHOR]

In order to understand pathogenicity of Athelia rolfsii to different peanut varieties, six strains with high, moderate and weak virulence were inoculated on resistant and susceptible varieties in the field, occurrence of disease was investigated every week after inoculation. The results showed that the optimal time for investigation was 14 days after inoculation. There was no significant difference in disease index among cultivars inoculated by highly virulent strains ZY2 and SQ1, and weakly virulent strain GP3-1, respectively, but there was significant difference of those inoculated by moderately virulent strains (HA, H1-3 and BL1-1). The disease indices of varieties by strain GP3-1 was low; and was high by strains ZY2 and SQ1. All tested peanut varieties were susceptible to the highly virulent strains ZY2 and SQl.The disease indices between resistant and susceptible varieties showed significant difference among moderately virulent strains. One peanut variety with broad-spectrum resistance to multiple moderately virulent strains was identified. [ABSTRACT FROM AUTHOR]

Very-long-chain fatty acids (VLCFAs) have high application value in the fields of industry, medicine and food. Previous research has proved that total content of VLCFAs in the Arachis species is significantly higher than that in cultivated peanuts. In this study, contents of VLCFAs were determined in RIL population derived from the cross between Zhonghua 5 and ICGV86699 with wild species consanguinity. Board phenotypic variations of total very-long-chain fatty acid content ranging from 4.99% to 10.33% was observed among the RILs. Five lines with high total very-long-chain fatty acid content were identified, of them, the highest content of ZJ011 is 9.82%. Based on the previously constructed genetic map, 20 QTLs with 3.72%-15.66% phenotypic variation explained (PVE) were repeatedly detected, and were mainly located on chromosomes A04, B04 and B06. The results lay a molecular and material foundation for the improvement of oil quality. [ABSTRACT FROM AUTHOR]

Sucrose content of peanut seeds is an important quality indicator for edible peanuts. In this study, we analyzed the main gene plus multigene genetic model for sucrose content based on peanut recombinant inbred lines from continuous generation populations, and investigated the effects of environmental factors on sucrose content based on the investigation of phenotypic variation of different varieties in various geographical locations. The results revealed that 4 main genes plus additive-epistasis (4MG-AI) was the optimal model in all three generations of the RIL population. The heritabilities of the main genes ranged from 80.8% to 96.1%, indicating a high degree of heritability for peanut sucrose content. Among the four main genes, the 1st and the 2nd main gene explained the phenotypes 30%-52.2% and 25.1%-29.6%, respectively, while the third and fourth pairs of main effect genes explained the phenotypes at smaller rates. Based on the stability analysis of sucrose content of nine peanut materials, including Zhonghua 16, in five different environments, it was found that the coefficients of variation ranged from 17.39% to 39.08%, and that the stability of different materials varied. The environmental stability of sucrose content was varied across different varieties. This study showed that peanut sucrose content is a quantitative trait with high heritability, but it is also affected by environmental factors. The germplasms or varieties with high sucrose content and environmental stability were suggested to be further screened for genetic breeding and functional gene discovery in future breeding. [ABSTRACT FROM AUTHOR]

The contents of fat and sucrose are important factors to peanut quality, and revealing their hereditary properties is critical to improve the quality in peanut. In this study, the analysis of embryo, cytoplasm, and maternal effects for fat and sucrose contents in peanut seed were conducted by using general genetic model. Five peanut lines with significantly different fat and sucrose contents were selected as parents for incomplete diallel crosses. The results indicated that the fat content was mainly controlled by embryo additive effect, followed by maternal additive effect. The sucrose content was primarily governed by maternal additive effect. Correlation analysis showed that there was a significantly negative correlation between fat and sucrose contents in peanut seed (r = -0.886**), which was mostly managed by embryo additive and cytoplasmic effects. Predicted genetic effects suggested that 18-1951 with high fat content and JHT1 with high sucrose content were superior donor parents for improving the contents of fat and sucrose in peanut, respectively. [ABSTRACT FROM AUTHOR]

Cold temperature and cold damage is one of the important abiotic stress factors restricting the development of peanut industry. The ability of peanut varieties to tolerate cold at germination stage is an important guarantee to determine the uniformity of seeding emergence, high yield, and high quality. In this research, 62 peanut varieties with different genotypes were comprehensively assessed for cold tolerance at germination stage by using comprehensive index value, weight, membership function value, and D-value of each variety. The results showed that the higher the D-value, the stronger the cold tolerance, and vice versa. The 62 varieties were divided into five categories by systematic cluster analysis: the first category was high cold-tolerant, the second was cold-tolerant, the third was intermediate cold-tolerant, the fourth was sensitive, and the fifth was highly sensitive. Correlation analysis revealed that the correlations between oleic acid content and D-value and other four indexes of cold tolerance did not reach a significant level, indicating that the acid content of peanut oil had nothing to do with the cold tolerance in peanut germination stage. A significant positive correlation between each relative index value and D-value indicated that there was consistency among the relative index values of cold tolerance in peanut germination stage. The analysis of its relative index characteristic value, contribution value, and weight demonstrated that the relative germination rate could be used as the positive index of cold tolerance identification in peanut bud period, that is, the greater the relative germination rate, the stronger its cold tolerance at germination stage, and vice versa. Five varieties with high cold-tolerance were selected, and the relative germination rate as the evaluation index of cold-tolerance in peanut germination stage was established in this study, providing basic materials and efficient assessing methods for the quick assessment of cold-tolerant peanut germplasm in peanut germination stage, cultivation of new varieties with cold-tolerance and related theoretical researches. [ABSTRACT FROM AUTHOR]

Breeding and application of peanut cultivars with desirable resistance to Aspergillus flavus is crucial for integrated management of aflatoxin contamination. Most peanut germplasm lines identified as resistant to A. flavus infection or aflatoxin production possess small pod or seed with relatively low yield potential. In this study, a total of 188 recombinant inbreed lines (RILs) population derived from Zhonghua 16 x J11 were assessed for their resistance to A. flavus infection and consequent aflatoxin production. The yield-related traits including 100-pod weight and 100-seed weight were also investigated among the RILs. The results revealed that variations of percent seed infection index (PSII) and aflatoxin content (AFT) in the RILs were much wider than those of their two parents. Eight lines with resistance to seed infection, nine lines with resistance to aflatoxin production were identified from the RILs. A special line with large pod and resistance to both seed infection and aflatoxin production was identified, which could be potential for further resistance improvement in peanut. [ABSTRACT FROM AUTHOR]

To explore the roles of FAD2s in response to cold stress in peanut, we cloned seven AhFAD2 genes from normal oleate peanut ZH16 and high oleate peanut ZH413, respectively. The results of qRT-PCR showed that the expression patterns of FAD2 genes were similar in ZH16 and ZH413. AhFAD2-1A/B was highly expressed in flower and developing seed, AhFAD2-3A/B was mainly expressed in leaf and stem, and AhFAD2-4A/B was expressed specifically in root and flower, indicating that AhFAD2 genes played their respective roles in different developmental stages and tissues of peanut. At 6 days after inducing under 15 °C, the germination rate of ZH16 was significantly decreased while that of ZH413 was not significantly affected. The expression of both AhFAD2-1A/B and AhFAD2-4A/B were induced by cold stress. The expression of AhFAD2-1A/B was significantly up-regulated at 6 DAI in ZH16, while at 1 DAI in ZH413, suggesting that AhFAD2-1A/B was induced by cold more quickly in high oleate peanut. Furthermore, the expression of AhFAD2-4A/B was significantly up-regulated at 3 DAI in ZH16 and then decreased, while it was increased immediately and maintained at high level for six days in ZH413. Based on these results, we speculate that up-regulation of AhFAD2-4A/B may compensate the function of AhFAD2-1A/B that is deactivated under cold stress in high oleate peanut, and the deactivation of AhFAD2-1A/B is not the most important factors affecting peanut cold tolerance. This study provides a theoretical basis in breeding of high oleate peanut with high tolerance to cold stress, and the theoretical support for extension of high oleate peanut in both high latitude and high altitude regions. [ABSTRACT FROM AUTHOR]

Ten peanut lines developed by Oil Crops Research Institute (CAAS, Wuhan, China) were evaluated for resistance and yield loss to peanut stem rot caused by Sclerotium rolfsii under natural disease condition and by artificial inoculation. Results indicated that the wilting rates of these lines ranged from 11.0% to 50.0% under natural disease condition and 7 lines had the wilting rates lower than 30. 0%. Peanut yield and wilting rate were significantly negative correlated (r= -0.73,P < 0.05). The wilting rates of these lines (from 66.1% to 94.0%), at two weeks post inoculation in the artificial inoculation experiment,were lower than those (from 66.1% to 97.4%) before harvest, all these lines were susceptible to infection by S. rolfsii. The peanut yield was negatively related with wilting rate by artificial inoculation with the correlation coefficient of -0.85 (P <0.05). The peanut yield loss was higher than 91.7% for all these lines after artificial inoculation. One tolerant line 16 - A13440 was identified. [ABSTRACT FROM AUTHOR]

Peanut virus diseases can cause mosaic and dwarf symptoms on peanut plants and influence peanut's production. Reverse transcription PCR(RT-PCR)was used to detect peanut viruses in 12 peanut samples collected from Gaocheng, Hebei Province. Results revealed that only Peanut stripe virus (PStV) was detected in the 90% of the collected samples with mosaic and dwarf symptom. The coat protein gene (cp) of PStV of two isolates were sequenced, and their sizes were 864 base pairs. Sequence analysis showed that the sequences of Gaocheng isolates shared 94.4%-99.2% and 94.7%-99.7% similarities at nucleotide level and 95.5%-99.7% and 95.8%-100.0% at amino acid level with those of other PStV strains. These isolates shared closer relationship with Chinese and USA isolates compared with Chinese Taiwan, Thailand and Vietnam isolates by phylogenetic analysis of CP nucleotide sequence. [ABSTRACT FROM AUTHOR]

Pod traits including pod length and width, seed length and width, 100-pod weight, and 100-seed weight of a high yield and high oil content novel peanut cultivar Zhonghua 16 and 8 related parental lines in its breeding pedigree were investigated. The results indicated that the pod length, 100 - pod weight and 100 - seed weight of Zhonghua 16 were lower than the corresponding data of the immediate parental genotypes, Zhonghua 5 and 8130 respectively, but higher than the corresponding means of all 8 parental lines respectively. The pod width and seed width of Zhonghua 16 were higher than that of the 8 parental lines in the pedigree respectively. The seed length of Zhonghua 16 were higher than that of the Zhonghua 5 and 8130 and the average of the 8 parents respectively. Based on the results of PCR analysis using 136 polymorphic SSR primers, 64. 1% and 87. 3% polymorphic bands of 8130 and Zhonghua 5 were identified in Zhonghua 16. Besides, there were some bands in Zhonghua 16 which were absent in both direct parents 8130 and Zhonghua 5. Certain candidate SSR markers related to the pod traits were identified including 5 markers related to 100 - pod weight, 4 related to 100 - seed weight, 3 related to pod length and 3 related to seed length. Several SSR bands related to large pod including IPAHM606 - 1, IPAHM531-1, GA8 - 2, 1B9 - 4 and HAS0428 - 2 were observed to have been inherited from the parents to Zhonghua 16. [ABSTRACT FROM AUTHOR]