Subjects: Biology >> Botany >> Applied botany submitted time 2023-07-13 Cooperative journals: 《广西植物》
Abstract： Climate change has been observed to increase the frequency and intensity of drought, which can adversely affect plant growth and development. Therefore, it is crucial to quantify plant xylem resistance to embolism, particularly in the context of global climate change, to study the process of plant response to drought. In this study, we aimed to evaluate the drought tolerance of Rhododendron cultivars and select those with strong drought resistance by using three species of shrub rhododendrons, namely Rhododendron × pulchrum ‘zihe’, Rhododendron × hybridum ‘yangmeihong’ and Rhododendron simsii, as the materials. Optical techniques were used to construct embolism vulnerability curves in petal and leaf tissues and petal and leaf anatomical structural traits were also measured. The correlation between xylem hydraulic function and anatomical structural traits were also analyzed. The results were as follows: (1) The P12, P50 and P88 values (water potential values corresponding to the occurrence of 12%, 50% and 88% embolism) of petals in Rhododendron × pulchrum ‘zihe’, Rhododendron × hybridum ‘yangmeihong’ and Rhododendron simsii were higher than those of leaves. (2) The embolism vulnerability of petal and leaf tissues varied among the three species, and the speed of petal and leaf embolism occurrence did not coincide, which may be an important characteristic of hybridized horticultural flowering plants. (3)The correlation analysis between P50 values and their morphological characteristics showed that the P50 values of leaves were negatively correlated with leaf palisade tissue thickness, and the P50 values of petals were positively correlated with petal thickness. In conclusion, the study suggests that the petal embolism vulnerability of the three shrubs of Rhododendron is higher than that of the leaves, and the plants preferentially sacrifice the petals to protect the leaves under drought stress. Furthermore, the embolism vulnerability may be related to the leaf palisade tissue thickness and petal thickness. Our findings provide a scientific basis for selecting and configuring tree species of Rhododendron plants in arid areas, and lay the foundation for screening and cultivating drought-resistant Rhododendron varieties.
Subjects: Biology >> Botany >> Applied botany submitted time 2020-10-20 Cooperative journals: 《广西植物》
Abstract：为了理解紫花苜蓿叶绿体基因组密码子偏好性的使用模式，该文以紫花苜蓿叶绿体基因组中筛选到的49条蛋白质编码序列为研究对象，利用CodonW、CUSP、CHIPS、SPSS等软件对其密码子的使用模式和偏好性进行分析。结果表明：紫花苜蓿叶绿体基因的第3位密码子的平均GC含量为26.87%，有效密码子数（ENC）在40.6～51.41之间，多数密码子的偏好性较弱。相对同义密码子使用度（RSCU）分析发现，RSCU＞1 的密码子数目有30个，以A、U结尾的有29个，说明了紫花苜蓿叶绿体基因组A或U出现的频率较高。中性分析发现，GC3与GC12的相关性不显著，表明密码子偏性主要受到自然选择的影响；而ENC-plot 分析发现一部分基因落在曲线的下方及周围，表明突变也影响了部分密码子偏性的形成。此外，有17个密码子被鉴定为紫花苜蓿叶绿体基因组的最优密码子。紫花苜蓿叶绿体基因组的密码子使用的偏好性可能受到自然选择和突变的共同作用。该研究将为紫花苜蓿叶绿体基因工程的开展和目标性状的遗传改良奠定基础。
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