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Title: [Relationships of wheat seed vigor with enzyme activities and gene expression related to seed germination under stress conditions.].
Author: Chen LT, Sun AQ, Yang M, Chen LL, Ma XL, Li ML, Yin YP.
Journal: Ying Yong Sheng Tai Xue Bao; 2017 Feb; 28(2):609-619. PubMed ID: 29749170.
Abstract:
This study aimed to analyze the enzyme activities and gene expression differences related to seed germination in different wheat genotypes, and to clarify the relationship between seed vigor and the related enzyme activities as well as gene expression under stress germination conditions. We measured seed vigor, total soluble sugar content, soluble protein content, α-amylase activity, cysteine protease activity and gene expression of the related enzymes of four wheat cultivars under drought, artificial aging and cold soaking stress. Results showed that drought, artificial aging and cold soaking stress affected seed vigor to some extent. Under different germination conditions, total soluble sugar content showed an increasing trend with small amplitude at first and then decreased with small amplitude and after that increased rapidly again, while soluble protein content in the four cultivars gradually decreased with germination time. The α-amylase activity of the four cultivars showed a rising trend on the whole, but that of Yunong 949 and Lunxuan 061 declined after germinating for 60 hours after cold soaking stress. Cysteine protease activity decreased at first and then increased as a whole. However, under drought stress condition, cysteine protease activity of Yunong 949, Yumai 49-198 and Lunxuan 061 increased at first and then decreased and finally increased again. The α-AMY (α-amylase gene) expression levels increased at first and then decreased as a whole under different germination conditions. The expression level of α-AMY in Lunxuan 061 after cold soaking stress was higher than that of CK, while the α-AMY expression levels in four cultivars under other stress germination conditions were lower than that of CK. The expression level of CP (cysteine protease gene) showed an increasing trend. No significant difference of CP expression level was found in Chang 4738 between artificial aging treatment and CK. The CP expression levels in the four cultivars under other stress conditions were higher than that of CK. The results demonstrated that there was no direct relationship between the enzyme activities and gene expression levels of α-amylase and cysteine protease under different germination conditions. The α-amylase activity and total soluble sugar content had an extremely significant positive correlation, but the correlation between cysteine protease activity and soluble protein content was not significant. The α-amylase activity significantly positively correlated with vigor index under standard germination condition. However, the α-amylase activity had no significant correlation with vigor index under stress conditions. After cold soaking stress, cysteine protease activity significantly positively correlated with vi-gor index during seed germination, but the correlation was not significant under standard germination, drought stress and artificial aging. 分析不同基因型小麦品种逆境萌发过程中种子萌发相关酶活性及基因表达差异,明确在逆境条件下,种子活力与种子萌发相关酶活性及基因表达量的关系.通过标准发芽试验和逆境(冷浸、人工老化、干旱胁迫)发芽试验,测定4个小麦品种种子活力、萌发过程中可溶性总糖和可溶性蛋白含量、α-淀粉酶活性、半胱氨酸蛋白酶活性及相关基因表达量.结果表明:干旱、人工老化和冷浸胁迫3种逆境对种子活力都有一定影响.不同萌发条件下,可溶性总糖含量呈现先小幅度升高后小幅度降低再迅速升高的趋势;而可溶性蛋白含量随着萌发时间的延长呈现逐渐下降的趋势.α-淀粉酶活性整体呈现逐渐升高的趋势,但在冷浸胁迫处理后,豫农949和轮选061的α-淀粉酶活性在萌发60 h后出现下降.半胱氨酸蛋白酶活性整体呈先降低后升高的趋势,但在干旱胁迫条件下,豫农949、豫麦49-198和轮选061的半胱氨酸蛋白酶活性呈现先升高后降低再升高的趋势.不同逆境萌发条件下,α-AMY(α-淀粉酶基因)表达量整体呈先上升后下降的趋势.冷浸胁迫处理后,轮选061的α-AMY表达量高于对照,在其他逆境萌发条件下,4个品种的α-AMY表达量均低于对照;人工老化处理后,长4738的CP(半胱氨酸蛋白酶基因)表达量与对照差异不显著,在其他逆境萌发条件下,4个品种的CP表达量均高于对照.种子萌发期间,不同萌发条件下α-淀粉酶和半胱氨酸蛋白酶活性与其基因表达并没有直接关系,α-淀粉酶活性与可溶性总糖含量达到显著正相关,半胱氨酸蛋白酶活性与可溶性蛋白含量的相关性不显著.在标准发芽条件下,α-淀粉酶活性与活力指数呈显著正相关,而在逆境萌发过程中,其相关性不显著.冷浸胁迫处理后,半胱氨酸蛋白酶活性与活力指数呈显著正相关,但在标准发芽、干旱胁迫、人工老化处理后,其相关性不显著.

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