Apple ( Borkh.) holds a prominent position among global temperate fruit crops, with flowering playing a crucial role in both production and breeding. This review delves into the intricate mechanisms governing apple flowering amidst the backdrop of climate change, acknowledging the profound influence of external and internal factors on biennial bearing, flower bud quality, and ultimately, fruit quality. Notably, the challenge faced in major apple production regions is not an inadequacy of flowers but an excess, leading to compromised fruit quality necessitating thinning practices. Climate change exacerbates these challenges, rendering apple trees more susceptible to crop failure due to unusual weather events, such as reduced winter snowfall, early spring cold weather, and hailstorms during flowering and fruit setting. Altered climatic conditions, exemplified by increased spring warming coupled with sub-freezing temperatures, negatively impact developing flower buds and decrease overall crop production. Furthermore, changing winter conditions affect chilling accumulation, disrupting flower development and synchronicity. Although the physiological perception of apple flowering has been reviewed in the past, the genetic, epigenetic, and multi-omics regulatory mechanisms governing floral induction and flowering are still rarely discussed in the case of apple flowering. This article comprehensively reviews the latest literature encompassing all aspects of apple flowering, aiming to broaden our understanding and address flowering challenges while also laying a solid foundation for future research in developing cultivars that are ideally adapted to climate change.

中文翻译：

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气候变化背景下苹果（Malus × Domestica Borkh.）开花机制的见解：遗传和表观遗传因素的探索

苹果（Borkh.）在全球温带水果作物中占有重要地位，其开花在生产和育种中都发挥着至关重要的作用。这篇综述深入研究了气候变化背景下苹果开花的复杂机制，承认外部和内部因素对两年结果、花芽质量以及最终果实质量的深远影响。值得注意的是，主要苹果产区面临的挑战不是花朵不足，而是花朵过多，导致果实品质受损，需要间伐措施。气候变化加剧了这些挑战，使苹果树更容易因异常天气事件而歉收，例如冬季降雪量减少、​​早春寒冷天气以及开花和坐果期间的冰雹。气候条件的改变，例如春季变暖加剧和低于冰点的温度，对正在发育的花蕾产生负面影响并降低作物总体产量。此外，冬季条件的变化会影响寒冷的积累，扰乱花朵的发育和同步性。尽管过去对苹果开花的生理感知进行了综述，但在苹果开花的情况下，控制花诱导和开花的遗传、表观遗传和多组学调控机制仍然很少讨论。本文全面回顾了涵盖苹果开花各个方面的最新文献，旨在扩大我们的理解并解决开花挑战，同时也为未来开发最适合气候变化的品种的研究奠定坚实的基础。