Leaf stomatal characteristics and key agronomic traits of intersectional peanut F1 hybrids between Huayu 665 and Arachis paraguariensis

The cultivated peanut is a globally important crop, valued for its oil, food, and feed uses, but has a narrow genetic base. High stress resistance, good-quality and high-yield factors residing in wild species constitute valuable resources for genetic improvement of the peanut cultigen. Some wild species are used as groundcovers, while others utilized as potted plants. Previous studies have focused on compatible wild relatives, but there is a lack of research on the use of incompatible Arachis species. This study aimed to investigate the hybrids produced from a cross between the peanut cultivar Huayu 665 and the incompatible species Arachis paraguariensis, enhancing our understanding of distant hybridization. Ture F₁ intersectional hybrids were identified by transposon element marker pairs. Leaf stomata were observed, and main agronomic traits were investigated. The F₁ hybrids exhibited significantly fewer large stomata (14.78 per mm²) and longer stomata (26.52 μm) on the abaxial leaf epidermis compared to the female parent, Huayu 665, which had 20.56 per mm² and 16.86 μm, respectively. Compared to Huayu 665, the F₁ hybrids exhibited a longer first pair of lateral branches, a wider range of seed set, and more branches, but produced fewer pods per plant. A hybrid with a plant type similar to the female parent was identified. The authenticity of the hybrids was confirmed through molecular, anatomical, and morphological analyses. The hybrid resembling the cultigen may accelerate the utilization of incompatible wild species in peanut breeding. However, its chromosome composition is yet to be determined. To avoid missing true hybrid identification in peanut remote crosses, use of molecular markers distributed across different chromosomes of the wild species was proposed.