FK506-binding protein (FKBP) genes have been found to play vital roles in plant development and abiotic stress responses. However, limited information is available about this gene family in wheat (Triticum aestivum L.). In this study, a total of 64 FKBP genes were identified in wheat via a genome-wide analysis involving a homologous search of the latest wheat genome data, which was unevenly distributed in 21 chromosomes, encoded 152 to 649 amino acids with molecular weights ranging from 16 kDa to 72 kDa, and was localized in the chloroplast, cytoplasm, nucleus, mitochondria, peroxisome and endoplasmic reticulum. Based on sequence alignment and phylogenetic analysis, 64 TaFKBPs were divided into four different groups or subfamilies, providing evidence of an evolutionary relationship with Aegilops tauschii, Brachypodium distachyon, Triticum dicoccoides, Arabidopsis thaliana and Oryza sativa. Hormone-related, abiotic stress-related and development-related cis-elements were preferentially presented in promoters of TaFKBPs. The expression levels of TaFKBP genes were investigated using transcriptome data from the WheatExp database, which exhibited tissue-specific expression patterns. Moreover, TaFKBPs responded to drought and heat stress, and nine of them were randomly selected for validation by qRT-PCR. Yeast cells expressing TaFKBP19-2B-2 or TaFKBP18-6B showed increased influence on drought stress, indicating their negative roles in drought tolerance. Collectively, our results provide valuable information about the FKBP gene family in wheat and contribute to further characterization of FKBPs during plant development and abiotic stress responses, especially in drought stress.

Key cereal crops, including wheat, rice and maize, supply nearly 50% of the world’s caloric intake, with starch constituting over 70% of the grain weight. However, the regulatory mechanisms underlying starch synthesis are poorly understood. In this study, we identify a transcription factor TaPIL1-5D, which binds to the promoters of ADP-glucose pyrophosphorylase small subunit 1 (TaAGPS1a−7A), granule-bound starch synthase I (TaGBSSI−4A), and branching enzyme II b (TaBEIIb-2D). Similarly, its homologous OsPIL11 and ZmPIL1 also activate the expression of the AGPS1, BEIIb, and GBSSI, and positively regulates grain starch synthesis. TaPIL1-5D and ZmPIL1 improve grain yields in two successive years. Nine alleles of TaPIL1-5B form three distinct haplotypes (Hap1-3), while TaPIL1-5B-Hap1 is repressed due to its binding by the transcriptional repressor TaBZR1.1. Additionally, TaPIL1-5B interacts with TaPIL1-5D in the nucleus, enhancing its transcriptional activation. Collectively, our study enriches the starch regulatory network and provides a promising tool for improving starch content.