Liu Juan, Chen Li-Yu, Zhou Ping, Liao Zhenyang, Lin Hai, Yu Qingyi, Ming Ray
FAFU and UIUC Joint Center for Genomics and Biotechnology, Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education; Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology; College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Chinese Academy of Sciences, Wuhan Botanical Garden, Wuhan, 430074, China.
Hortic Res. 2021 Jul 1;8(1):147. doi: 10.1038/s41438-021-00581-4.
Sex types of papaya are controlled by a pair of nascent sex chromosomes, but molecular genetic mechanisms of sex determination and sex differentiation in papaya are still unclear. We performed comparative analysis of transcriptomic profiles of male and female floral buds at the early development stage before the initiation of reproductive organ primordia at which there is no morphological difference between male and female flowers. A total of 1734 differentially expressed genes (DEGs) were identified, of which 923 showed female-biased expression and 811 showed male-biased expression. Functional annotation revealed that genes related to plant hormone biosynthesis and signaling pathways, especially in abscisic acid and auxin pathways, were overrepresented in the DEGs. Transcription factor binding motifs, such as MYB2, GAMYB, and AP2/EREBP, were enriched in the promoters of the hormone-related DEGs, and transcription factors with those motifs also exhibited differential expression between sex types. Among these DEGs, we also identified 11 genes in the non-recombining region of the papaya sex chromosomes and 9 genes involved in stamen and carpel development. Our results suggested that sex differentiation in papaya may be regulated by multiple layers of regulation and coordination and involved transcriptional, epigenetic, and phytohormone regulation. Hormones, especially ABA and auxin, transcription factors, and genes in the non-recombination region of the sex chromosome could be involved in this process. Our findings may facilitate the elucidation of signal transduction and gene interaction in sex differentiation of unisexual flowers in papaya.
番木瓜的性别类型由一对新生的性染色体控制,但番木瓜性别决定和性别分化的分子遗传机制仍不清楚。我们对雄性和雌性花芽在生殖器官原基起始之前的早期发育阶段的转录组图谱进行了比较分析,此时雄性和雌性花在形态上没有差异。共鉴定出1734个差异表达基因(DEG),其中923个表现出雌性偏向表达,811个表现出雄性偏向表达。功能注释显示,与植物激素生物合成和信号通路相关的基因,尤其是脱落酸和生长素通路中的基因,在差异表达基因中占比过高。转录因子结合基序,如MYB2、GAMYB和AP2/EREBP,在激素相关差异表达基因的启动子中富集,具有这些基序的转录因子在不同性别类型之间也表现出差异表达。在这些差异表达基因中,我们还在番木瓜性染色体的非重组区域鉴定出11个基因,以及9个参与雄蕊和心皮发育的基因。我们的结果表明,番木瓜的性别分化可能受多层调控和协调的影响,涉及转录、表观遗传和植物激素调控。激素,尤其是脱落酸和生长素、转录因子以及性染色体非重组区域的基因可能参与了这一过程。我们的发现可能有助于阐明番木瓜单性花性别分化中的信号转导和基因相互作用。