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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]

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]

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]