Prasad C T Manjunath, Kodde Jan, Angenent Gerco C, de Vos Ric C H, Diez-Simon Carmen, Mumm Roland, Hay Fiona R, Siricharoen Sasiwimon, Yadava Devendra K, Groot Steven P C
Bioscience, Wageningen Plant Research, Wageningen University and Research, Wageningen, Netherlands.
Laboratory of Molecular Biology, Wageningen University and Research, Wageningen, Netherlands.
Front Plant Sci. 2022 Dec 1;13:1050411. doi: 10.3389/fpls.2022.1050411. eCollection 2022.
Seed aging during storage results in loss of vigor and germination ability due to the accumulation of damage by oxidation reactions. Experimental aging tests, for instance to study genetic variation, aim to mimic natural aging in a shorter timeframe. As the oxidation rate is increased by elevating the temperature, moisture, and oxygen levels, this study aimed to (1) investigate the effect of experimental rice seed aging by an elevated partial pressure of oxygen (EPPO), (2) elucidate the mechanism of dry-EPPO aging and (3) compare aging under dry-EPPO conditions to aging under traditional moist-controlled deterioration (CD) conditions and to long-term ambient storage. Dry seeds from 20 diverse rice accessions were experimentally aged under EPPO (200 times higher oxygen levels), at 50% relative humidity (RH), along with storage under high-pressure nitrogen gas and ambient conditions as controls. While no decline in germination was observed with ambient storage, there was significant aging of the rice seeds under EPPO storage, with considerable variation in the aging rate among the accessions, with an average decline toward 50% survival obtained after around 21 days in EPPO storage and total loss of germination after 56 days. Storage under high-pressure nitrogen gas resulted in a small but significant decline, by an average of 5% germination after 56 days. In a second experiment, seven rice seed lots were stored under EPPO as compared to a moist-CD test and two different long-term ambient storage conditions, i.e., conditioned warehouse seed storage (CWSS) and traditional rice seed storage (TRSS). Untargeted metabolomics (with identification of lipid and volatile compounds profiles) showed a relatively high increase in levels of oxidized lipids and related volatiles under all four storage conditions. These compounds had a high negative correlation with seed viability, indicating oxidation as a main deteriorating process during seed aging. Correlation analysis indicated that EPPO storage at 50% RH is more related to aging under TRSS at 60% and CD-aging at 75% ERH rather than CWSS at 40% ERH. In conclusion, aging rice seeds under EPPO conditions is a suitable experimental aging method for analyzing variation among seed lots or genotypes for longevity under storage.
种子在储存过程中老化，由于氧化反应造成的损伤积累，导致活力和发芽能力丧失。例如，用于研究遗传变异的实验老化试验旨在在较短时间内模拟自然老化。由于通过提高温度、湿度和氧气水平可加快氧化速率，本研究旨在：（1）研究通过提高氧气分压（EPPO）对水稻种子进行实验老化的效果；（2）阐明干EPPO老化的机制；（3）比较干EPPO条件下的老化与传统湿控劣变（CD）条件下的老化以及长期环境储存下的老化情况。来自20个不同水稻品种的干燥种子在EPPO（氧气水平高200倍）、相对湿度（RH）50%的条件下进行实验老化，同时以高压氮气储存和环境条件储存作为对照。虽然环境储存未观察到发芽率下降，但EPPO储存条件下水稻种子出现了显著老化，不同品种间老化速率差异较大，EPPO储存约21天后平均存活率降至50%左右，56天后发芽率完全丧失。高压氮气储存导致发芽率小幅但显著下降，56天后平均发芽率下降5%。在第二个实验中，将七个水稻种子批次在EPPO条件下储存，并与湿CD试验以及两种不同的长期环境储存条件（即有条件仓库种子储存（CWSS）和传统水稻种子储存（TRSS））进行比较。非靶向代谢组学（鉴定脂质和挥发性化合物谱）显示，在所有四种储存条件下，氧化脂质和相关挥发性化合物的水平相对大幅增加。这些化合物与种子活力呈高度负相关，表明氧化是种子老化过程中的主要劣变过程。相关性分析表明，50%RH下的EPPO储存与60%RH下的TRSS储存和7%ERH下的CD老化更为相关，而非40%ERH下的CWSS储存。总之，EPPO条件下老化水稻种子是一种适用于分析不同种子批次或基因型在储存期间寿命差异的实验老化方法。
