Molecular Biology Program, New Mexico State University, Las Cruces, New Mexico, United States of America.
HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, United States of America.
PLoS One. 2023 Feb 16;18(2):e0281805. doi: 10.1371/journal.pone.0281805. eCollection 2023.
In perennial plants such as pecan, once reproductive maturity is attained, there are genetic switches that are regulated and required for flower development year after year. Pecan trees are heterodichogamous with both pistillate and staminate flowers produced on the same tree. Therefore, defining genes exclusively responsible for pistillate inflorescence and staminate inflorescence (catkin) initiation is challenging at best. To understand these genetic switches and their timing, this study analyzed catkin bloom and gene expression of lateral buds collected from a protogynous (Wichita) and a protandrous (Western) pecan cultivar in summer, autumn and spring. Our data showed that pistillate flowers in the current season on the same shoot negatively impacted catkin production on the protogynous 'Wichita' cultivar. Whereas fruit production the previous year on 'Wichita' had a positive effect on catkin production on the same shoot the following year. However, fruiting the previous year nor current year pistillate flower production had no significant effect on catkin production on 'Western' (protandrous cultivar) cultivar. The RNA-Seq results present more significant differences between the fruiting and non-fruiting shoots of the 'Wichita' cultivar compared to the 'Western' cultivar, revealing the genetic signals likely responsible for catkin production. Our data presented here, indicates the genes showing expression for the initiation of both types of flowers the season before bloom.
在山核桃等多年生植物中，一旦达到生殖成熟，就会有遗传开关被调控，以确保每年都能进行花的发育。山核桃是雌雄异株的，同一棵树上既有雌花又有雄花。因此，定义专门负责雌花序和雄花序（柔荑花序）起始的基因是极具挑战性的。为了了解这些遗传开关及其时间调控，本研究在夏季、秋季和春季，从一个雌先型（威奇塔）和一个雄先型（西部）山核桃品种中，分析了柔荑花序的开花和侧芽的基因表达。我们的数据表明，同一枝条上当前季节的雌花会对雌先型‘威奇塔’品种的柔荑花序产生负面影响。而前一年的果实产量对‘威奇塔’品种的同一枝条次年的柔荑花序产量有积极影响。然而，前一年的结实或当年的雌花产量对雄先型（西部品种）品种的柔荑花序产量没有显著影响。RNA-Seq 结果表明，与‘西部’品种相比，‘威奇塔’品种的结实和非结实枝条之间存在更多的差异，揭示了可能与柔荑花序产生有关的遗传信号。我们这里提供的数据表明，在开花前的那个季节，有一些基因开始表达，从而启动这两种花的形成。
