Identification of BABY BOOM and LEAFY COTYLEDON genes in sweet pepper (Capsicum annuum L.) genome by their partial gene sequences

Abstract

Haploid plant production via anther culture is a valuable tool to rapidly create pure lines for plant breeding programs. Some sweet pepper (Capsicum annuum L.) varieties produce embryogenic anther culture readily, while others do not respond at all. The switching of microspore developmental program from gametophyte-to sporophytetype is regulated by transcription factors like BABY BOOM (BBM) and LEAFY COTYLEDON (LEC). Genes encoding these transcription factors have not been found in sweet pepper yet. The sequences of BBM and LEC from other plants, annotated in National Center for Biotechnology Information (NCBI), were used to design degenerative primers for conservative regions in these genes and to amplify BBM-and LEC-like sequences from genomic DNA of sweet pepper by PCR. The PCR products were cloned and sequenced. Sequence comparison revealed high similarity between the isolated sequences and those annotated in NCBI for BBM and LEC1. The obtained sequences were subjected to bioinformatics analyses to determine the exon-intron structure. Exons were translated in protein products in silico. The protein blast of the pepper BBM in the NCBI database revealed presence of an AP2-type functional domain, which is typical for the BBM family. The pepper LEC sequence was found to carry CBFD-NFYB-HMF motif, typical for the LEAFY COTYLEDON gene product family. RT-PCR confirmed high levels of expression of the BBM and LEC genes at the early stages of direct embryos development in anther culture. Expression of the two genes was not detected either in mature pepper plants or in non-embryogenic anthers. The two genes were detected in genomes of 14 pepper varieties, some of which do not respond with formation of direct embryos. We assume that differences in responses between varieties should be attributed not to presence/absence of two genes, but to their interaction with other genes' products and different factor like micro-RNAs involved in the regulation of their expression.

Transcriptional identification and characterization of differentially expressed genes associated with embryogenesis in radish (Raphanus sativus L.)

“…Several members in the AP2/ERF family had also been reported to be involved in microspore-, somatic- and zygotic embryogenesis 32 . In this study, the radish orthologs of APETALA2 ( AP2 , negatively controlling cell proliferation during seed development), AINTEGUMENTA ( ANT , expressing in the primordia of cotyledons) and BABY BOOM ( BBM , promoting cell proliferation and morphogenesis during embryogenesis) were differentially expressed during radish embryogenesis and seed development, consistent with their actions in Arabidopsis thaliana 17 , Brassica napus 16 , Capsicum annuum 37 and Elaeisguineensis 38 . These findings suggested that these TFs potentially participate in the specific process embryogenesis and early seedling development in radish 9 .…”

Signaling Overview of Plant Somatic Embryogenesis

“…Another key regulator of plant cell totipotency is BBM . BBM can induce embryogenesis in differentiated cells and could be a vital factor in plant embryogenesis development (Irikova et al, 2012). BBM triggers a set of genes like LEC1 and LEC2 , as well as ABI3 and the FUS3 network, which together activate SE (Horstman et al, 2017).…”

Gene expression and metabolite profiling of gibberellin biosynthesis during induction of somatic embryogenesis in Medicago truncatula Gaertn

“…BABY BOOM (BBM) was originally isolated from Brassica embryogenic microspore cultures; when ectopically expressed in Arabidopsis , induced spontaneous SE [ 100 ]. Although BBM was proven to be capable of inducing SE in numerous plant species [ 57 , 101 , 102 ], only few authors focus on BBM utility as a suitable marker to monitor SE progress [ 60 , 103 ]. Our results confirmed transcriptional induction of MtBBM only in callus of the embryogenic M9-10a line, which is consistent with results from Theobroma cacao SE where expression of TcBBM was significantly higher in undifferentiated embryogenic callus, compared to non-embryogenic callus.…”