O小孢子发生失败（减数前或期间） Abnormality happens before or during meiosis ▲进入减数分裂前液泡化、解体Meiocytes degenerated before meiosis:番i(tomato)、 豌豆(pea)和玉米(maize) 28 28 ○小孢子发生失败（减数前或期间） Abnormality happens before or during meiosis ▲进入减数分裂前液泡化、解体 Meiocytes degenerated before meiosis：番茄(tomato) 、 豌豆(pea)和玉米(maize)