Department of Biology, Fiji National University , Fiji, Fiji Islands.
Department of Biotechnology, Vignan University , Vadlamudi, India.
Plant Signal Behav. 2021 Mar 4;16(3):1865687. doi: 10.1080/15592324.2020.1865687. Epub 2020 Dec 23.
Noni ( L.), a tropical, medicinal plant of the family Rubiaceae utilized since 2000 y ago by the Polynesians, is currently facing a major challenge in production vis-a-vis climate change. The worldwide average temperatures continue to fluctuate, resulting in extremely cold winters and hot summers that reduce plant productivity. Photosynthetic apparatus is an exceptionally sensitive component to estimate the degree of damage at contrasting temperatures. The present study was aimed to evaluate the temperature stress response of Noni plant using the chlorophyll a fluorescence OJIP transients (OJIP transients). Results showed the declined photosynthetic pigment pool and reduced functional and structural integrity of the photosynthetic apparatus under very low- and high-temperature treatments. Drastically lower yield parameters such as φ(Po) and φ(Eo), efficiency ψ(Eo) and performance indices - PI and PI, and accumulation of inactive reaction centers were observed. Consecutively, a lower level of calculated electron transport from PSII to PSI was observed. In contrast, the enhanced δRo indicates that PSI is more thermo-tolerant as compared to PSII. Additionally, very low and high temperatures cause an increase in antenna size (ABS/RC) and the decrease in the amplitude of I to P phase of fluorescence transient. Overall, the photosynthetic apparatus of leaf tissue was more sensitive to low and high temperatures than the developing fruit. The findings of the present study demonstrated the potential role of thylakoid components of the photosynthetic apparatus, which might be crucial in regulating the temperature stress response in the Noni plant, and thereby crop improvement.
诺丽（Morinda citrifolia L.），茜草科药用植物，2000 多年前被波利尼西亚人应用于医疗。如今，该植物的生产正面临气候变化带来的重大挑战。全球平均气温持续波动，导致冬季极寒、夏季酷热，降低了植物的生产力。光合作用系统是评估不同温度下损伤程度的一个非常敏感的组件。本研究旨在利用叶绿素 a 荧光 OJIP 瞬变（OJIP 瞬变）评估诺丽植物对温度胁迫的响应。结果表明，在极低温和高温处理下，光合色素池减少，光合机构的功能和结构完整性降低。产量参数如φ（Po）和φ（Eo）、效率ψ（Eo）和性能指数 - PI 和 PI 以及非活性反应中心的积累明显降低。随后，观察到从 PSII 到 PSI 的电子传递水平降低。相反，δRo 的增加表明 PSI 比 PSII 更耐热。此外，极低和高温会导致天线大小（ABS/RC）增加和荧光瞬变 I 到 P 相的幅度减小。总的来说，叶片组织的光合作用系统对低温和高温的敏感性高于发育中的果实。本研究的结果表明，光合作用系统类囊体组件可能在调节诺丽植物对温度胁迫的响应方面发挥重要作用，从而实现作物改良。
