4个种子数量差异明显的甜橙品种的胚珠发育观察

Observation of Ovule Development Processing in Four Sweet Orange Cultivars with Obviously Different Seed Numbers

采用4个遗传背景高度一致而种子数量明显差异的甜橙品种为材料,从花后25d到花后185d,分阶段对胚珠发育过程进行了显微观测分析,以寻找柑桔种子发育和数量形成的关键期。结果显示,在花后25d和35d时,同一品种单果间胚珠数量无明显差异,但品种间胚珠数量存在显著差异。在花后35d时,单果内胚珠可区分为明显发育胚珠（ODO）和滞后发育胚珠（DLO）,并且ODO数量在品种间也存在显著差异。在后续观察中,各品种ODO数量有小幅波动,但平均数与成熟果实中的最终种子数基本一致,表明种子数量在花后35d胚珠明显分化时已确定。品种间的ODO总体发育趋势和最后大小基本一致。DLO发育启动时间晚、发育时间更短,其最终大小仅约成熟种子的1/10~1/6。

Four sweet orange cultivars with obviously different number of seeds were used as mate- rials to observe and analyze the development process of ovules with microscopic observation in the stages from 25 DAF （Days After Flowering） to 185 DAF, aiming to reveal the critical period of seeds formation, and to provide a reference for breeding, production, and molecular biology re- search. Results showed that there were no significant differences on ovule number and size among the fruits of 25 DAF and 35 DAF from the same variety, but significantly different among the varie- ties. At 35 DAF, the ovules in examined individual fruits could be differentiated into obviously de- veloped ovules （ODO） and develop-lagged ovules （DLO）, and the numbers of ODO were signifi- cantly different among varieties. In the follow-up observations, the numbers of ODO fluctuated in a narrow range in each cultivar, and was nearly equivalent to the final number of seeds in ripe fruits of each cultivar. Similar trends on ovule size and final ovule size of ODO were found among varie- ties, but DLO appeared later, the development time was shorter, and the final size was only 1/6 to 1/10 of the mature seeds.