Fadón Erica, Herrera Sara, Herrero María, Rodrigo Javier
INRES - Gartenbauwissenschaft, Universität Bonn, Bonn, Germany.
Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Zaragoza, Spain.
Tree Physiol. 2021 Apr 8;41(4):619-630. doi: 10.1093/treephys/tpaa063.
Male meiosis in temperate fruit trees occurs in the anthers once a year, synchronized with the seasons. The alternation of dormant and growth cycles determines the optimum moment for the male gametophyte formation, a process sensitive to both cold and warm temperatures. This ensures pollen viability and subsequent reproduction success that guarantee fruit production. In this work, we explore how male meiosis is framed by seasonality in sweet cherry. For this purpose, the dormant phases, male meiosis and blooming dates were established in four cultivars with different flowering dates and chilling requirements over 7 years. The chilling and heat requirements for each cultivar were empirically estimated, and chilling and heat temperatures were quantified according to the Dynamic and Growing Degree Hours (GDH) models, respectively. Endodormancy was overcome approximately a fortnight earlier during the colder winters than during the milder winters. Against our initial hypothesis, these differences were not clearly reflected in the time of male meiosis. The period between chilling fulfillment and meiosis lasted several weeks, during which a high amount of GDH accumulated. Results showed that male meiosis is conditioned by endodormancy but especially by warm temperatures, during the forcing period. This differs from what has been described in other related species and creates a framework for further studies to understand the strategies of synchronizing dormancy with seasons.
温带果树的雄配子减数分裂每年在花药中发生一次，与季节同步。休眠和生长周期的交替决定了雄配子体形成的最佳时刻，这一过程对寒冷和温暖温度都很敏感。这确保了花粉的活力以及随后的繁殖成功，从而保证果实产量。在这项研究中，我们探究了甜樱桃中雄配子减数分裂是如何受季节性影响的。为此，在7年时间里，对4个花期和需冷量不同的品种确定了休眠期、雄配子减数分裂期和开花日期。根据经验估算了每个品种的需冷量和需热量，并分别根据动态和生长度日（GDH）模型对冷量和热量进行了量化。在较寒冷的冬季，内休眠大约比在较温和的冬季提前两周解除。与我们最初的假设相反，这些差异在雄配子减数分裂时间上并未明显体现出来。从冷量满足到减数分裂的这段时间持续了几周，在此期间积累了大量的生长度日。结果表明，雄配子减数分裂受内休眠的制约，但在催芽期尤其受温暖温度的影响。这与其他相关物种中所描述的情况不同，并为进一步研究理解休眠与季节同步的策略创造了一个框架。
