Morphophysiological and transcriptomic analyses during the development of microspores and megaspores in Orobanche coerulescens

The findings revealed that the flower development process of <i>O. coerulescens</i> could be categorized into six stages. Mature pollen was tricellular, with downy ornamentation and pores on the outer wall. The embryo sac was the monosporangiate polygonum type, and the ovule was inverted. The megaspores developed and matured about 15 days later than the microspores. The soluble sugar level of the flower buds decreased initially and then increased during development, whereas the starch level showed an opposite trend. The levels of strigolactone, auxin, and gibberellins gradually increased throughout the development process. The key genes regulating phytohormone synthesis during the development of microspores and megaspores were identified as <i>ALDHs</i> (Aldehyde Dehydrogenases). In contrast, the key genes regulating phytohormone signaling included <i>TIR1</i> (Transport Inhibitor Response 1) and <i>IAA3</i> (Indole-3-acetic Acid Inducible 3), and the key TF was <i>ARF5</i> (AUXIN RESPONSE FACTOR 5). The findings of this study enhanced the understanding of <i>O. coerulescens</i> biology, providing theoretical references for regulating its reproduction, implementing biological control measures, maintaining its population, and optimizing resource utilization.