金樱子与现代月季远缘杂交的生殖生物学特性

The characteristics of reproductive biology in the distant crosses between Rosa laevigata and Rosa hybridas

为了揭示蔷薇原种金樱子与现代月季品种间远缘杂交常不能结实的原因,以现代月季品种‘芦王特’、‘歌林娇红’、‘同情’、‘白雪山’为母本,二倍体野生蔷薇原种金樱子为父本,开展远缘人工定向杂交,测定父本花粉活力,研究授粉后花粉在柱头萌发形态以及胚胎发育等生殖生物学特性。结果发现,与以上4个月季品种杂交时父本金樱子的花粉活力分别为8.0%、22.0%、63.7%、39.8%;‘同情’人工授粉后2 h平均每个柱头上萌发花粉数分别有8.1粒,其他品种均未在柱头上观察到花粉萌发;授粉后4h平均每个柱头上萌发花粉数分别为17.6、21.9、11.7、12.0粒;到授粉后12 h时数量达到最多,分别为23.4、60.4、40.3、34.4粒;随后萌发数量急剧下降,且大部分花粉管细短、弯曲并停留在柱头表面。另外,4个月季品种授粉后每个柱头上的花粉萌发率均先升后降;在授粉10天后观察到的子房中含有的球形胚异常降解,金樱子与‘同情’及‘白雪山’的杂交胚胎中可观察到鱼雷形及子叶形胚,但后期出现胚胎异常降解。杂交时使用的父本花粉活力并不低,但授粉24 h之后的花粉管出现异常以及受精后胚胎大量败育可能是导致金樱子远缘杂交不结实的重要因素。

Seeds are seldom obtained in the distant hybridization between R.hybridas and R.laevigata,which seriously influences utilization of excellent genes from R.laevigata.With an aim to reveal the factors leading to infertility in the crosses between modern rose varieties（female parent） and R.laevigata（male parent）,we carried out the artificial orientation hybridization between diploid wild species in rosa—R.laevigata and four R.hybridas,which are ＇Luwangte＇、＇Gelin Jiaohong＇、＇Belle de Londres＇ and ＇Mount Shasta＇,tested pollen viability of male parent,examined germination behavior of pollen grains on the stigmas after pollination,and observed embryo development.It was found that before the four R.hybridas pollinating,the pollen viability of male parent was respectively 8.0%、22.0%、63.7%、39.8%.No pollen grains germinated on the stigmas 2 h after pollination except for the stigmas of ＇Belle de Londres＇ with 8.1,and respectively 17.6、21.9、11.7、12.0 pollen grains germinated on each stigma of the four varieties at 4 h after pollination;At 12 h after pollination,the number reached the highest value,which were 23.4、60.4、40.3、34.4 respectively;Subsequently,the number was quickly decreased,most pollen tubes were thin,short and curved,stayed on the stigmas＇ surface and failed to enter ovaries.In addition,during different time after pollination,average germinating rate on each stigma was increased first and then decreased.At 10 d after pollination,many globular embryo in ovaries began to degenerate,torpedo and cotyledonary embryos can be observed in the two crosses between R.laevigata and the two R.hybridas,which are ＇Belle de Londres＇ and ＇Mount Shasta＇,but in the later phase,these embryos degenerated.These results suggest that the male pollen viability was not low,but 24 h after pollination,most germinated pollen grains on the stigmas were abnormal before fertilization,and degeneration of a large number of embryos after fertilization,which may be the main factors resulting in infertility in the cross.