Search

Pod size is a key agronomic trait that influences peanut yield greatly. However, our understanding of the mechanisms underlying pod size is limited. In this study, we employed a segregating population derived from a cross between the small-pod line ND_S and the large-pod line ND_L to map quantitative trait loci (QTL) associated with pod size. Initial mapping performed using bulk segregant analysis revealed a candidate interval on chromosome A05 referred to as qPSW05. We refined this interval to a 256.9 kb genomic region using newly developed molecular markers. Through sequence and expression analyses, we identified the candidate gene AhXE45GC, which encodes an AN1 zinc finger protein. We discovered a 33-bp insertion in the intron of AhXE45GC in ND_S. Accessions that lack this insertion, such as ND_L, had significantly larger pods than those with the insertion, including ND_S. To facilitate marker-assisted selection for peanut pod size, we developed a molecular marker associated with this polymorphism. This marker could provide a valuable genetic resource for breeding high-yielding peanut varieties. [ABSTRACT FROM AUTHOR]

Peanut (Arachis hypogaea L.) is an important oil crop. Oleic acid is a major factor that determines the quality of peanuts. Therefore, the high oleic and high oleic to linoleic acid ratio are the target traits in an advanced peanut breeding program. This study provided an extensive evaluation of the genetic and physical characteristics as well as disease resistance of 220 high oleic peanut varieties in China. Notably, these varieties clustered into five major categories based on their traits. A majority of these varieties have been bred using interspecific hybridization or selected from mutants of self-crossed parents, with the main parent varieties being Kaixuan 016 and CTWE. Analysis of disease resistance showed that most high oleic peanut varieties could resist two or three diseases. However, those varieties with resistance to multiple diseases were relatively scarce. Moreover, some high oleic peanut varieties showed no disease resistance or inadequate testing. The results further indicate that the genetic basis for high oleic peanut breeding is insufficient, highlighting the need for its further development. Importantly, our findings lay a critical foundation for future high oleic peanut breeding and promote better understanding of the genetic and trait diversity offered by these varieties. [ABSTRACT FROM AUTHOR]

Peanut (Arachis hypogea L.) bacterial wilt (BW) is a devastating disease caused by Ralstonia solanacearum that results in severe yield and quality losses. Plant defensins are short cysteine-rich peptides with antimicrobial activity. The role of defensin genes (AhDef) in peanut is unclear. A genome-wide investigation of AhDef genes was undertaken, and 12 identified AhDef genes were classified into two groups containing the gamma-thionin domain formed by four disulfide pairs: Cys1-Cys8, Cys2-Cys5, Cys3-Cys6, and Cys4-Cys7. In silico analysis revealed that AhDef genes showed highly conserved architectural features and contained cis-elements associated with phytohormone signaling and defense responses. A highly resistant cultivar, H108 (R) and a susceptible accession, H107 (S) were tested by R. solanacearum inoculation. H108 (R) showed fewer symptoms than H107 (S) owing to inhibition of bacterial reproduction and spread in the vascular bundles of roots and stems. In a transcriptomic expression profile, AhDef genes, particularly AhDef1.6 and AhDef2.2, were up-regulated in H108 (R) compared with H107 (S) under R. solanacearum infection and phytohormone treatment. Subcellular localization showed that the AhDef1.6 and AhDef2.2 proteins were both expressed specifically on the plasma membrane. Overexpression of protein fusion AhDef2.2-YFP in Nicotiana benthamiana and peanut leaves increased resistance to R. solanacearum, suggesting its role in response to BW infection. AhDef2.2 may be valuable for peanut resistance breeding. [ABSTRACT FROM AUTHOR]