甘肃野生草地早熟禾内源激素含量的变化与无融合生殖率的关系研究

为探究甘肃野生草地早熟禾无融合生殖率与内源激素之间的关系,以8个不同无融合生殖率的甘肃野生草地早熟禾种质为试验材料,采集不同发育时期的新鲜小穗样品,测定玉米素(ZT)、吲哚-3-乙酸(IAA)、玉米素核苷(ZR)、赤霉素(GA₃)和脱落酸(ABA)的含量,并分析了内源激素含量与无融合生殖发生的关系。结果表明:ZT和ZR在小穗发育初期呈现出下降趋势,在抽穗后2 d最低,之后ZT逐渐上升而ZR在开花期达到峰值后又开始下降,GA₃和IAA均表现出先增加后下降的趋势,但GA₃在抽穗后2 d达到峰值,IAA则是在开花期含量最高;研究发现,在小穗发育初期,无融合生殖率较低的材料(甘南、清水、肃南和兰州)ABA激素水平无显著变化,相反无融合生殖率较高的材料(陇西、秦州、定西和陇南)的ABA含量均呈现出逐渐下降的趋势,所有材料开花期至乳熟期均出现猛增,之后又急剧下降。相关性分析结果表明:无融合生殖率与ZT、ZR、ABA、(ZT+ZR)/IAA和(ZT+ZR)/ABA呈显著正相关,与GA₃、IAA/ABA和GA₃/ABA呈显著负相关,与IAA无显著相关性。因此,高ZT、ZR和低ABA含量、高(ZT+ZR)/IAA和(ZT+ZR)/ABA比值更可能促进胚珠向无融合生殖途径发育,高GA₃含量可能促进胚珠向有性生殖途径发育。

The relationship between endogenous hormone content and apomixis rate of wild Kentucky bluegrass in Gansu Province

To investigate the relationship between apomixis rate and endogenous hormone levels in Kentucky bluegrass, eight wild Kentucky bluegrass strains with different apomixis rates, collected in Gansu Province, were studied. Fresh spikelets were harvested at different development stages, and the contents of zeatin (ZT), indole-3-acetic acid (IAA), trans-zeatin-riboside (ZR), gibberellin (GA₃) and abscisic acid (ABA) were determined, and the relationship between apomixis development and endogenous hormone levels analyzed. It was found that: ZT and ZR contents showed a downward trend during early spikelet development, and were lowest 2 days after heading, then ZT content gradually increased and ZR content began to decline after peaking at flowering stage. GA₃ and IAA showed a trend of first increasing and then declining, but GA₃ content reached a peak 2 days after heading, while IAA content was highest during the flowering stage. In addition, during the early stages of spikelet development, there was no significant change in ABA levels in genotypes with low apomixis (Gannan, Qingshui, Sunan and Lanzhou), but showed a decreasing trend in highly-apomictic genotypes (Longxi, Qinzhou, Dingxi and Longnan). However, ABA levels sharply increased from flowering to milk ripening, and then decreased sharply in two genotypes. Correlation analysis showed that the apomixis rate was positively correlated with ZT, ZR, ABA, (ZT+ZR)/IAA and (ZT+ZR)/ABA; negatively correlated with GA₃, IAA/ABA and GA₃/ABA; but failed to correlate with IAA. Therefore, high ZT, ZR and low ABA contents, (ZT+ZR)/IAA and (ZT+ZR)/ABA ratio are associated with promotion of apomictic ovule development, while high GA₃ content appears to promote ovule development by the sexual pathway.