Identification of BABY BOOM homolog in bread wheat

Modern breeding practice of small grain cereals necessitates the development of an efficient system for the large scale and reproducible production of the doubled haploid (DH) lines. It is believed that among the available DH generation techniques, only isolated microspore culture (IMC) can satisfy the demand of public and private breeding programs. Unfortunately, the IMC method is prone to several challenges that jeopardizes its large scale adoption. One of the approaches to limit the variation in DH plant production and increase the efficiency of the method is manipulation of embryogenesis-related genes. Here we set up a study to map BABY BOOM in a bread wheat genome. The gene is one of the morphogenic regulators of somatic embryogenesis in plants. To achieve this task, we used amino acid sequences of Zea mays BBM-like proteins. TaBBM homoeologs were mapped to chromosomes 6AL, 6BL and 6DL. Amino acid sequence analysis revealed the presence of two AP2 domains and bbm-1 motif in the A and D copies and only one AP2 domain and bbm-1 motif in the B copy. This, along with the absence of both gene expression and predictable TATA-box, suggests that TaBBM-gB is a pseudogene. The expression pattern of the identified A and D homoeologs was similar to that for the BBM-like genes in other species and presence of the transcript was detected in an embryogenic microspore population. Identification of the TaBBM homolog can have application in elevating the efficiency of DH production, tissue culture, plant transformation and genome editing for wheat improvement.