人工老化的甜玉米种子活力、生理特性和遗传多样性的变化

Changes of vigor, physiological characteristics and genetic diversities of artificially aged sweet corn seeds

【目的】研究人工老化处理对甜玉米Zea mays L.saccharata Sturt.种子活力、生理特性和遗传多样性的影响,为甜玉米种子贮藏及大田生产提供参考。【方法】以甜玉米品种‘农甜88’和‘农甜99’为试验材料,采用人工老化的方法处理玉米种子,沙床发芽法检测种子的发芽势、发芽率、发芽指数和活力指数。测定了种子的脱氢酶(Dehydrogenase,DHA)活性、过氧化物酶(Peroxidase,POD)活性、相对电导率(Relative electrical conductivity,REC)和丙二醛(Malondialdehyde,MDA)含量,采用SRAP标记检测不同处理时间种子的遗传多样性,分析种子生理指标和遗传多样性与种子活力的关系。【结果】随老化时间的增加,2个品种种子的发芽势、发芽率、发芽指数、活力指数、DHA活性和POD活性逐渐降低,而REC和MDA含量则逐渐升高。老化处理6 d后,‘农甜88’和‘农甜99’种子的发芽势、发芽率、发芽指数、活力指数、DHA活性、POD活性分别比对照下降18.32%和43.15%、10.73%和15.38%、19.43%和23.60%、41.85%和45.70%、69.78%和71.74%、52.02%和71.60%;浸泡24 h的REC分别比对照提高了33.68%和27.68%,MDA含量分别比对照提高了41.50%和47.08%。老化处理使种子的遗传多样性下降,老化处理6 d后,‘农甜88’和‘农甜99’等位基因数、有效等位基因数、基因多样性分别比对照下降29.35%和23.58%、25.00%和20.00%、96.99%和83.35%。相关性分析发现,2个品种老化种子浸出液的REC和MDA含量均与种子活力各性状呈显著或极显著负相关,DHA和POD活性均与种子活力各性状呈显著或极显著正相关。【结论】随老化时间的增加,2个甜玉米品种种子的活力以及DHA、POD活性逐渐降低、REC和MDA含量逐渐升高;种子老化处理降低了种子遗传物质的多样性;‘农甜88’种子耐老化能力强于‘农甜99’。

【Objective】To identify the effects of artificial aging on vigor,physiological characteristics and genetic diversities of sweet corn(Zea mays L.saccharata Sturt.)seeds,and provide a reference for sweet corn seed storage and field production.【Method】‘Nongtian88’and‘Nongtian99’were selected as experimental materials and their seeds were treated using the method of artificial aging.The germination potential,germination rate,germination index and vigor index were measured using the method of germination in sand bed.The dehydrogenase(DHA)activity,peroxidase(POD)activity,relative electrical conductivity(REC)and malondialdehyde(MDA)content of artificially aged seeds were measured.The genetic diversity of artificially aged seeds was detected using SRAP,and the relationships between physiological characteristics,genetic diversities and seed vigor were analyzed.【Result】With the increase of aging time,seed germination potentials,germination rates,germination indexes,vigor indexes,DHA activities and POD activities of two cultivars decreased gradually,while the RECs and MDA contents increased gradually.Compared to the control(CK),the germination potentials,germination rates,germination indexes,vigor indexes,DHA activities and POD activities of‘Nongtian88’and‘Nongtian99’seeds decreased by18.32%and43.15%,10.73%and15.38%,19.43%and23.60%,41.85%and45.70%,69.78%and71.74%,52.02%and71.60%respectively after aging treatment for six days.The RECs of‘Nongtian88’and‘Nongtian99’seeds after soaking for24hours increased by33.68%and27.68%respectively than that of CK,and MDA contents increased by41.50%and47.08%respectively than that of CK.Compared to CK,the seed genetic diversities decreased after artificial aging treatment,the allele numbers,effective allele numbers and gene diversities of‘Nongtian88’and‘Nongtian99’seeds decreased by29.35%and23.58%,25.00%and20.00%,96.99%and83.35%respectively after aging treatment for six days.The correlation analysis showed that the RECs and MDA contents of aged seeds of two cultivars were significantly or highly significantly negatively correlated with vigor indexes,while DHA and POD activities were significantly or highly significantly positively correlated with seed vigor indexes.【Conclusion】With the increase of artificially aging time,the seed vigor indexes,DHA and POD activities of two sweet corn cultivars decrease gradually,while the RECs and MDA contents increase gradually.Artificial aging results in the decrease of seed genetic diversity.‘Nongtian88’seed has stronger aging resistant ability than‘Nongtian99’.