[Objectives]This study aimed to analyze the relationship between soybean DREB（dehydration responsive element-binding protein）transcription factor gene GmDREB8 and drought stress, which laid a foundation for the study of the molecular mechanism of DREB transcription factors participating in soybean drought stress and provided new gene resources for soybean drought tolerant transgenic breeding. [Methods]The soybean variety ’Tianlong 1’ was used as experiment material. Quantitative real time polymerase chain reaction（RT-qPCR）was used to analyze the expression patterns of 10 DREB genes induced by drought treatment, as well as the differential expression of GmDREB8 in different soybean tissues and plant hormones. Bioinformatics methods were used to analyze the conserved motif and subcellular localization prediction of GmDREB8. Subcellular localization of GmDREB8 protein was carried out by Agrobacterium tumefaciens mediated tobacco transient expression system. Arabidopsis with heterologous expression of GmDREB8 and soybean plants silenced by VIGS（virus induced gene silencing）technology were used to analyze the function of GmDREB8 in Arabidopsis and soybean under drought stress. [Results]Ten DREB genes were induced to express under drought stress, and most of their expression patterns were different. GmDREB8 was screened and cloned, which was located on soybean chromosome 17 and contained an AP2 domain with a molecular weight of 19.79×10~3 and isoelectric point of 9.76. GmDREB8 gene was induced by plant hormones abscisic acid（ABA）and salicylic acid（SA）. GmDREB8 protein was located in the nucleus. The root length of transgenic Arabidopsis heterologous expressing GmDREB8 was more inhibited than wild type（WT）under different concentrations of mannitol, and it was more sensitive to drought stress. Compared with empty plasmid control group, the leaves of GmDREB8 silent soybean lines had lower relative conductivity, relative water loss rate, malondialdehyde（MDA）content and higher free proline（Pro）content after drought treatment, as a result of stronger drought tolerance. [Conclusions]GmDREB8 can negatively regulate the drought tolerance of plants.

近年来,南方水稻抽穗灌浆期低温寡照天气发生频率明显增加,为探明其对稻米品质的影响,在水稻灌浆结实期不同时间段（1～7 d、8～14d、15～21d、22～28d、29～35d）设置低温弱光复合胁迫（LW）、单一弱光（WN）、单一低温处理（LN）和常温常光（NN）4个处理,研究低温弱光复合胁迫对稻米加工品质、外观品质、蒸煮食味品质、RVA谱特征值等的影响。结果表明,不同处理方式间的垩白米率、垩白大小和垩白度均表现为LW＞LN＞WN＞NN,且灌浆结实期各阶段的复合胁迫均较对照NN差异极显著或显著,除了2016年灌浆结实1～7d的垩白度外,灌浆结实21d内的复合胁迫与单一弱光、低温差异也显著或极显著,单一胁迫低温、弱光在灌浆结实21d内较对照NN差异极显著或显著,其中单一低温与弱光在部分处理下差异达显著水平,灌浆结实21d后,复合胁迫与单一弱光、低温部分差异显著,弱光与低温无显著差异。不同处理间的糙米率、精米率和整精米率均表现为NN＞WN＞LN＞LW,其中,灌浆结实21d内,复合胁迫及单一低温、弱光较对照NN差异极显著或显著,灌浆结实21d后,部分时间段差异显著或极显著。低温弱光复合胁迫及单一胁迫对加工品质影响程度按大小依次为整精米率、精米率、糙米率,且灌浆结实21d内处理的影响大。对蒸煮食味品质,低温弱光复合胁迫极显著或显著降低了稻米的直链淀粉含量、胶稠度、外观、黏度和食味值,显著或极显著提高了蛋白质含量和硬度,单一胁迫低温、弱光表现与复合胁迫相同的影响,且灌浆结实21d内,除2016年的胶稠度,单一低温、弱光较对照NN差异显著或极显著,单一低温、弱光较复合胁迫差异也多显著或极显著。从水稻RVA谱特征值来看,低温弱光复合胁迫及单一胁迫造成稻米的峰值黏度、热浆黏度与崩解值下降,最高黏度、消减值与峰值时间上升,除灌浆结实29～35 d的崩解值外,复合胁迫较对照NN差异达极显著或显著水平,部分指标的低温、弱光较对照NN差异也达显著水平。总之,灌浆结实期各时间段的低温弱光复合胁迫及单一胁迫造成稻米品质不同程度下降,且以灌浆结实21d内复合胁迫的影响较大。