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| 海带配子体高温耐受性评价指标体系构建及其在种质资源耐高温性状评价中的应用 |
| Construction of an Evaluation Index System for High-Temperature Tolerance in Kelp Gametophytes and Its Application in Evaluating High-Temperature Tolerance Traits in Germplasm Resources |
| 投稿时间：2025-03-28 修订日期：2025-05-07 |
| DOI： |
| 中文关键词: 海带 高温耐受性 相对生长率 叶绿素荧光 种质资源 |
| 英文关键词: Saccharina japonica Heat tolerance Relative growth rate Chlorophyll fluorescence Germplasm resources |
| 基金项目:中央高校基本科研业务费(202262001)；中国海洋大学教师科研启动经费(862201013155)；中国海洋大学英才计划科研启动经费（862401013149）和山东省重点研发计划(良种工程)(2022LZGC004)共同资助。 |
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| 中文摘要: |
| 相比于海带的原产地,中国养殖区的环境温度更高,尤其是在中国南方养殖区,高温胁迫是造成海带减产和病害的重要诱因之一。因此,耐高温是海带良种培育的重要育种目标。然而,目前海带耐高温性状尚无精准的评价指标体系,不同品种品系之间的高温耐受性还缺乏系统的综合评价和比较。本研究以100份不同年代、地区的海带配子体为材料,涵盖我国40多年来主要的养殖品种和品系,综合生长、光合生理指标系统评价它们的高温耐受性,旨在构建海带配子体高温耐受性评价指标体系并筛选出耐高温配子体材料。结果显示,在25℃高温胁迫时,中国南方海带配子体的相对生长率、最大光合效率、实际光合效率等参数均高于北方,表明中国南方海带配子体具备更强的抗高温能力。我们发现从20世纪80年代至21世纪20年代,海带配子体的高温耐受性呈现出逐步增强的趋势。综合生长和叶绿素荧光指标构建了海带配子体耐高温评价模型,即配子体耐高温综合评价值(H值),并基于H值对100份配子体材料进行耐高温类型划分,筛选得到耐高温型的种质材料3份。总之,本研究构建了海带配子体高温耐受性的评价模型,并首次对我国40多年以来的海带品种品系的高温耐受性进行了系统评价和比较,获得一批耐高温的优良种质,对海带种质创新和良种培育具有重要意义。 |
| 英文摘要: |
| Saccharina japonica is an important economic alga in China, and the kelp cultivated in China is derived from wild populations in Japan. The environmental temperature in Chinese cultivation areas is higher than that of kelp’s native habitat. In particular, in the southern farming areas of China, high-temperature stress is one of the key factors contributing to yield reduction and diseases in kelp. Therefore, heat tolerance is an important breeding objective in developing superior kelp varieties. The high-temperature tolerance of kelp gametophytes is closely related to that of sporophytes. Evaluating the high-temperature tolerance of gametophytes and selecting heat-resistant ones for hybrid breeding are crucial for developing new kelp varieties with enhanced heat tolerance.However, at present there is no precise evaluation index system for kelp's high-temperature tolerance traits, and there is still a lack of systematic and comprehensive evaluation and comparison of high-temperature tolerance among different varieties and strains.In this study, 100 samples of kelp gametophytes collected from different years and regions were used, covering the major cultivation varieties and strains in China over the past 40 years. Their high-temperature tolerance was comprehensively evaluated using growth and photosynthetic physiological indicators, with the aim of establishing an evaluation index system for high-temperature tolerance in kelp gametophytes and screening for high-temperature tolerant gametophyte materials.
By observing the relative growth rates of kelp gametophytes at 15°C, 25°C, 26°C, and 27°C, it was determined that their lethal temperature is 27°C, and 25°C was chosen as the high-temperature stress condition for kelp gametophytes.Then, the relative growth rate and photosynthetic parameters (Fv/Fm、Y(Ⅱ)、Jmax and PARsat) of the kelp gametophytes were measured under conditions of 15°C and 25°C, respectively.The results showed that under high-temperature stress at 25°C, both the growth and photosynthetic parameters of the kelp gametophytes exhibited a significant decline. Moreover, the coefficients of variation for these parameters increased before and after high-temperature stress, indicating that under high-temperature stress, the previously consistent performance among different strains began to diverge. The distribution of each parameter became more dispersed, and the differences between strains increased. Integrating relative growth rate and chlorophyll fluorescence parameters, the heat tolerance of kelp gametophytes spanning more than 40 years was evaluated and compared from multiple dimensions.The results revealed that after high-temperature stress, the kelp gametophytes from the most recent 20s exhibited the highest relative growth rate, with the smallest decrease compared to their growth rate at the optimal temperature. This may be attributed to the fact that the sea water temperature in the primary cultivation areas of farmed kelp in our country is higher than that in their natural distribution regions, which continuously enhances the high-temperature tolerance in the offspring of these cultured populations.After high-temperature stress, the kelp gametophyte materials from the 1980s experienced a larger decline in the photosynthetic parameters Fv/Fm, Y(II), and Jmax compared to those from other decades, indicating that high-temperature stress had the greatest impact on their photosynthesis. This may be because the gametophytes from the 1980s were stored under low-temperature and weak-light conditions for the longest period, making them relatively more sensitive to high-temperature stress. In recent years, the rapid increase in temperature and the pursuit of higher yields in production may have contributed to the enhanced heat tolerance observed in kelp gametophyte growth during the 2020s. However, changes in photosynthetic capacity may require a longer period of acclimation and accumulation. Overall, from the 1980s to the 2020s, the heat tolerance of kelp gametophytes has shown a gradual increasing trend.
This study also comprehensively and systematically evaluated the differences in heat tolerance by comparing the growth and photosynthetic parameters of kelp gametophyte clones from different regions.Under high-temperature stress, the kelp gametophytes from southern China exhibited the highest relative growth rate and the smallest reduction in growth; moreover, their photosynthetic parameters Fv/Fm, Y(Ⅱ), and Jmax declined less compared to those from northern China, indicating that their photosynthesis was less affected by high-temperature stress.Overall, kelp gametophytes in southern China exhibit stronger heat tolerance than those in northern China, possibly because the selective pressure of the high-temperature environment on kelp sporophytes has been genetically transmitted to the gametophyte cells.
Integrating growth and chlorophyll fluorescence parameters, a heat tolerance evaluation model for kelp gametophytes was established—referred to as the comprehensive heat tolerance evaluation value (H value). Based on the H value, 100 gametophyte samples were classified by heat tolerance type, and three heat-tolerant germplasm materials were selected.
In summary, this study developed an evaluation model for high-temperature tolerance in kelp gametophytes and, for the first time, systematically evaluated and compared the high-temperature tolerance of kelp varieties and strains in China over the past 40 years. A collection of superior high-temperature tolerant germplasm materials was obtained, which is of great significance for kelp germplasm innovation and the breeding of superior varieties. |
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