Kwon Young Hyun, Lee Seung Youn, Rhie Yong Ha
Agriculture and Life Science Research Institute, Kangwon National University, Chuncheon 24341, Republic of Korea.
Department of Smart Horticultural Science, Andong National University, Andong 36729, Republic of Korea.
Plants (Basel). 2025 Jan 17;14(2):251. doi: 10.3390/plants14020251.
Morphophysiological dormancy (MPD) is considered one of the most primitive dormancy classes among seed plants. While extensive studies have examined the occurrence of endo-β-mannanase in seeds with physiological dormancy (PD) or non-dormancy, little is known about the activity of this enzyme in seeds with MPD. This study aimed to investigate the temporal and spatial patterns of endo-β-mannanase activity during dormancy break and germination. The research focused on , a species with deep simple MPD, by monitoring its morphological and biochemical characteristics under natural field conditions. Seeds were buried in the field and exhumed monthly over a year. Key parameters measured included germination, embryo elongation, endosperm weakening, and endo-β-mannanase activity in the exhumed seeds. Scanning electron microscopy was employed to observe structural changes in the endosperm. For the first three months after burial in May, endo-β-mannanase activity was undetectable, and the underdeveloped embryo exhibited minimal elongation. Starting in September, the embryo began to grow, accompanied by increased endo-β-mannanase activity in the micropylar endosperm. Erosion of the endosperm cell wall was observed in the lateral regions surrounding the embryo, whereas the micropylar endosperm showed no obvious signs of collapse or damage. The increase in enzyme activity coincided with moderate temperatures and a corresponding increase in embryo length. During the winter months, embryo elongation ceased for 2-3 months, and enzyme activity declined. However, as germination resumed in early March, enzyme activity increased again. This was followed by micropylar endosperm rupture and the completion of germination. The seasonal pattern of endo-β-mannanase activity observed in seeds with deep simple MPD was distinct from that of seeds with PD, MD, or non-deep MPD, highlighting the unique mechanisms underlying dormancy break and germination in .
形态生理休眠（MPD）被认为是种子植物中最原始的休眠类型之一。虽然已有大量研究探讨了内切-β-甘露聚糖酶在具有生理休眠（PD）或非休眠种子中的存在情况，但对于该酶在具有MPD种子中的活性却知之甚少。本研究旨在探究休眠打破和萌发过程中内切-β-甘露聚糖酶活性的时空模式。该研究聚焦于一种具有深度简单MPD的物种，通过在自然田间条件下监测其形态和生化特征来展开。种子被埋于田间，一年内每月进行挖掘。测量的关键参数包括挖掘出的种子的萌发、胚伸长、胚乳弱化以及内切-β-甘露聚糖酶活性。采用扫描电子显微镜观察胚乳的结构变化。5月埋入后的前三个月，未检测到内切-β-甘露聚糖酶活性，发育不全的胚伸长极少。从9月开始，胚开始生长，伴随珠孔端胚乳中内切-β-甘露聚糖酶活性增加。在胚周围的外侧区域观察到胚乳细胞壁的侵蚀，而珠孔端胚乳未显示出明显的塌陷或损伤迹象。酶活性的增加与适度温度以及胚长度的相应增加同时出现。在冬季的几个月里，胚伸长停止2至3个月，酶活性下降。然而，随着3月初萌发恢复，酶活性再次增加。随后是珠孔端胚乳破裂并完成萌发。在具有深度简单MPD的种子中观察到的内切-β-甘露聚糖酶活性的季节性模式与具有PD、MD或非深度MPD的种子不同，突出了该物种休眠打破和萌发背后的独特机制。
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