Chongqing Key Laboratory of Economic Plant Biotechnology, Collaborative Innovation Center of Special Plant Industry in Chongqing, Chongqing Engineering Research Center for Special Plant Seedling, Institute of Special Plants, Chongqing University of Arts and Sciences, 402160, Yongchuan, China.
Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, 400715, Beibei, Chongqing, China.
BMC Plant Biol. 2022 Oct 12;22(1):486. doi: 10.1186/s12870-022-03868-3.
The timing of bud break is very important for the flowering and fruiting of longan. To obtain new insights into the underlying regulatory mechanism of bud break in longan, a comparative analysis was conducted in three flower induction stages of two longan varieties with opposite flowering phenotypes by using isobaric tags for relative and absolute quantification (iTRAQ).
In total, 3180 unique proteins were identified in 18 samples, and 1101 differentially abundant proteins (DAPs) were identified. "SX" ("Shixia"), a common longan cultivated variety that needs an appropriate period of low temperatures to accumulate energy and nutrients for flower induction, had a strong primary inflorescence, had a strong axillary inflorescence, and contained high contents of sugars, and most DAPs during the bud break process were enriched in assimilates and energy metabolism. Combined with our previous transcriptome data, it was observed that sucrose synthase 6 (SS6) and granule-bound starch synthase 1 (GBSSI) might be the key DAPs for "SX" bud break. Compared to those of "SX", the primary inflorescence, axillary inflorescence, floral primordium, bract, and prophyll of "SJ" ("Sijimi") were weaker. In addition, light, rather than a high sugar content or chilling duration, might act as the key signal for triggering bud break. In addition, catalase isozyme 1, an important enzyme in the redox cycle, and RuBisCO, a key enzyme in the Calvin cycle of photosynthetic carbon assimilation, might be the key DAPs for SJ bud break.
Our results present a dynamic picture of the bud break of longan, not only revealing the temporal specific expression of key candidate genes and proteins but also providing a scientific basis for the genetic improvement of this fruit tree species.
龙眼开花结果对芽休眠期的时间要求非常严格。为深入了解龙眼芽休眠的调控机制，本研究以两个开花表型相反的龙眼品种的三个诱导开花阶段为材料，采用相对和绝对定量同位素标记（iTRAQ）技术进行比较分析。
在 18 个样本中共鉴定到 3180 个独特蛋白质，其中有 1101 个差异丰度蛋白（DAP）。“石硖”（SX）是一种常见的龙眼栽培品种，需要适宜的低温期来积累开花所需的能量和养分，其具有较强的一级花序，有较强的腋生花序，并且含糖量较高，在芽休眠过程中，大多数 DAP 富集在同化产物和能量代谢中。结合我们之前的转录组数据，观察到蔗糖合酶 6（SS6）和颗粒结合淀粉合酶 1（GBSSI）可能是“SX”芽休眠的关键 DAP。与“SX”相比，“四季蜜芒”（SJ）的一级花序、腋生花序、花原基、苞片和先出叶较弱。此外，光而不是高糖含量或低温持续时间可能是触发芽休眠的关键信号。此外，作为氧化还原循环中的重要酶的过氧化氢酶同工酶 1 和光合作用碳同化卡尔文循环中的关键酶核酮糖-1,5-二磷酸羧化酶/加氧酶（RuBisCO）可能是 SJ 芽休眠的关键 DAP。
本研究结果提供了龙眼芽休眠的动态图，不仅揭示了关键候选基因和蛋白质的时间特异性表达，还为该果树品种的遗传改良提供了科学依据。
