Comparative analyses of root developmental adaptation to phosphate starvation in tomato

Inorganic phosphate (Pi) is the major form of P imported by plant roots from the soil and is a critical nutrient for plant growth. Therefore, Pi deficiency could result in crop yield losses. Modulating root system architecture (RSA) is one of the most important strategies of plants to mitigate Pi limitation and further ensure yield stability for crops. However, the mechanisms underlying root developmental adaptation responses to Pi-starvation are still not fully understood. In this work, we explore the morphological and transcriptional adaptations in roots of Solanum lycopersicum cv. M82 (M82), a tomato wild relative S. pennellii (Penn), and a set of introgression lines (ILs) of Penn into M82. M82 and most individuals in the IL population adapted their RSA to Pi deficiency through inhibition of primary root growth and enhanced lateral root development. In contrast, the wild relative Penn did not respond to Pi deficiency. Moreover, IL1.4, one genotype within the introgression line (IL) mapping population, produced more lateral roots than M82 under both Pi-deficient and Pi-sufficient conditions, suggesting that a subset of genes from Penn (genomic bin d-1J) in IL1.4 may positively regulate the development of lateral roots. Through RNA-seq analysis, we identified transcriptional responses of M82, Penn and IL1.4 response to Pi-deficient treatment.