Map-based cloning of LPD, a major gene positively regulates leaf prickle development in eggplant

A critical gene for leaf prickle development (LPD) in eggplant was mapped on chromosome E06 and was confirmed to be SmARF10B through RNA interference using a new genetic transformation technique called SACI developed in this study Prickles on eggplant pose challenges for agriculture and are undesirable in cultivated varieties. This study aimed to uncover the genetic mechanisms behind prickle formation in eggplant. Using the F₂ and F_2:3 populations derived from a cross between the prickly wild eggplant, YQ, and the prickle-free cultivated variety, YZQ, we identified a key genetic locus (LPD, leaf prickle development) on chromosome E06 associated with leaf prickle development through BSA-seq and QTL mapping. An auxin response factor gene, SmARF10B, was predicted as the candidate gene as it exhibited high expression in YQ's mature leaves, while being significantly low in YZQ. Downregulating SmARF10B in YQ through RNAi using a simple and efficient Agrobacterium-mediated genetic transformation method named Seedling Apical Cut Infection (SACI) developed in this study substantially reduced the size and density of leaf prickles, confirming the role of this gene in prickle development. Besides, an effective SNP was identified in SmARF10B, resulting in an amino acid change between YQ and YZQ. However, this SNP did not consistently correlate with prickle formation in eight other eggplant materials examined. This study sheds light on the pivotal role of SmARF10B in eggplant prickle development and introduces a new genetic transformation method for eggplant, paving the way for future research in this field.