Flower bulbs protect faithful chromosome segregation in Lycoris meiosis under heat stress

Heat stress disrupts chromosome segregation during meiosis and induces aneuploid gametes in plants, which leads to sterility and thus poses a severe threat to reproduction in plants. Lycoris is a group of bulbous flowering plant species, which hosts a special reproductive development trait; i.e., its male meiosis occurs in flower buds within underground bulbs. Lycoris blooms in hot summer, a question thus being asked: whether the bulbs protect pollen mother cells (PMCs) from heat and thereby confer thermotolerance of meiosis in Lycoris . Heat does not affect meiotic chromosome segregation in PMCs in Lycoris flower buds developing inside the intact bulbs. In contrast, isolated flower buds cultured ex vivo in medium from two diploid Lycoris species showed severe defects in meiotic chromosome configuration and segregation under heat. Moreover, callose cell wall thickness exhibits different alteration patterns during meiosis within and beyond Lycoris species, which, additionally, reveals a negative association with faithful chromosome segregation under heat. Our study suggests that bulbs protect meiotic stability, especially chromosome organization and double-strand break repair, in Lycoris under high temperatures.