Mishina Kohei, Morita Minami, Matsumoto Sora, Sakuma Shun
Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan.
Plants (Basel). 2024 Dec 23;13(24):3600. doi: 10.3390/plants13243600.
Successful pollination and fertilization are crucial for grain setting in cereals. Wheat is an allohexaploid autogamous species. Due to its evolutionary history, the genetic diversity of current bread wheat () cultivars is limited. Introducing favorable alleles from related wild and cultivated wheat species is a promising breeding strategy for resolving this issue. However, wide hybridization between bread wheat and its relatives is hampered by the presence of suppressor genes and difficulties in crossing. Optimized methods for observing pollen tubes are essential for understanding the mechanism of crossability between wheat and its relatives. Here, we improved the crossing procedure between bread wheat and rye () and established an optimized protocol for visualizing pollen tube behavior. Crossing via detached spike culture significantly enhanced crossing efficiency and phenotypic stability. A combination of canonical aniline blue staining and optimized clearing and sectioning allowed us to visualize pollen tube behavior. The proportion of rye pollen tubes reaching the micropyle was lower than that for pollen tubes germinated on the stigmatic hair, explaining why the hybrid seed-setting rate was approximately 75% instead of 100%. This method sheds light on wide hybridization through deeper visualization of the insides of pistils.
成功的授粉和受精对于谷物的结实至关重要。小麦是一种异源六倍体自花授粉物种。由于其进化历史，当前面包小麦（）品种的遗传多样性有限。从相关野生和栽培小麦物种中引入有利等位基因是解决这一问题的一种有前景的育种策略。然而，面包小麦与其近缘种之间的远缘杂交受到抑制基因的存在和杂交困难的阻碍。优化的观察花粉管的方法对于理解小麦与其近缘种之间的可杂交性机制至关重要。在这里，我们改进了面包小麦和黑麦（）之间的杂交程序，并建立了一个优化的方案来观察花粉管行为。通过离体穗培养进行杂交显著提高了杂交效率和表型稳定性。经典苯胺蓝染色与优化的透明和切片相结合，使我们能够观察花粉管行为。到达珠孔的黑麦花粉管比例低于在柱头毛上萌发的花粉管比例，这解释了为什么杂种结实率约为75%而不是100%。这种方法通过更深入地观察雌蕊内部，为远缘杂交提供了新的见解。
