Expression pattern analysis of key genes related to anther development in a mutant of male-sterile Betula platyphylla Suk.

Abstract

Male-sterile mutants are ideal materials for studying the gene regulatory pathway of anther development. Here, the cytological morphology of mutant and wild-type anthers during the whole development stage was analyzed. At the microspore developmental stage, the tapetum cells of two types of mutants (mutant male inflorescences (MM), normal-like male inflorescences (NLM) showed additional vacuoles and a reduced cytoplasm, while the wild-type tapetum cells began to degenerate. Before pollination, compared with formed mature pollen grains in wild-type male inflorescences, collapsed microspores were discovered in mutants. Based on the transcriptome data of wild-type male inflorescence (NM) and mutant MM, ten key differentially expressed genes (ABORTED MICROSPORES (AMS), MYB38, MALE STERILITY 1 (MS1), MYB32, ODORANT1 (ODO1), QUARTET3 (QRT3) and CYTOCHROME P450 77A3 (CYP77A3), ATP-Binding Cassette Transporter G26 (ABCG26), FIL1, LIPID-TRANSFER PROTEIN 14 (LTP14)) related to anther development were selected for further study. Furthermore, MYB32, MYB38, AMS, MS1, and ABCG26 were highly expressed at the tetrad stage in MM and NLM, along with ODO1, QRT3, and CYP77A3, which were significantly upregulated at the tetrad stage in NLM, FIL1 and LTP14 were upregulated at the tetrad stage in MM. These events suggested that these genes may accelerate the abortion process in mutant birch anther. Tissue-specific expression analysis of ten genes indicated diverse spatiotemporal expression patterns. QRT3 and CYP77A3 were expressed in all five tissues, including leaves, stems, roots, female inflorescences, and male inflorescences, while the other eight genes had high transcription levels during male development, indicating that these genes may play different roles in these developmental processes. These results facilitate further investigation of the functional and molecular mechanisms underlying anther and microspore development in Betula platyphylla.