SUPEROXIDE DISMUTASE FAMILY GENES IN WATERMELON AND THEIR RESPONSES TO DIFFERENT ABIOTIC STRESSES

• A total of 8 SOD genes from watermelon were identified and bioinformatically analyzed. • The SOD proteins from watermelon and other different plant species can be classified into five groups consistent with their metal cofactors. • ClSOD genes exhibited distinctive tissue-specific and abiotic stress responsive expression patterns. Superoxide dismutase (SOD) is an important enzyme in the antioxidant system of plants and plays a vital role in stress responses by maintaining the dynamic balance of reactive oxygen species (ROS) concentrations. Genome-wide analysis of the SOD gene family in various plant species has been conducted but little is known about this gene family in watermelon (Citrullus lanatus). Here, eight SOD genes were identified in the watermelon genome and are designated ClCSD1-5, ClFSD1-2 and ClMSD according to their metal cofactors. Phylogenetic analysis shows that SOD proteins from various plant species can be classified into five groups and members in the same group possess the same metal cofactor and similar subcellular localizations. Expression analysis of the ClSOD genes indicates that they had tissue-specific expression patterns with high expression in different tissues including the leaves, flowers and fruit. In addition, the expression of ClSOD genes differed appreciably under salinity, drought and abscisic acid (ABA) treatments, indicating that they may be involved in ROS scavenging under different abiotic stresses via an ABA-dependent signaling pathway. These results lay the foundation for elucidating the function of ClSOD genes in stress tolerance and fruit development in watermelon.     

南洋楹无性系抗寒性研究

【目的】南洋楹属典型热带树种,抗寒性较差,严重制约其推广应用。开展南洋楹无性系抗寒性评价,对于提高其造林成效、拓广其栽培区域具有重要意义。【方法】以生长较好的9个南洋楹无性系组培苗为研究对象,通过系列低温处理,观测幼苗叶片形态变化,分析测定叶片相对电导率(REC)、脯氨酸(PRO)含量以及超氧化物歧化酶(SOD)的活性,揭示南洋楹无性系在低温胁迫下的生理响应,并进行无性系抗寒性评价。【结果】在2℃时,所有无性系均出现不同程度落叶;0℃时所有无性系均出现顶芽死亡,其抗寒性差异主要表现在0~2℃温度区间;9个无性系的REC随温度降低呈单调上升和先上升后下降再上升的2种变化趁势,属于后者的无性系抗寒性更强,0℃下S5、S7的REC最低;PRO含量随温度降低整体上呈现递增趁势,TL18、S7、S5、A8的PRO含量增幅最大,均在1倍以上;SOD活性在同一温度下无性系之间差异显著,但随温度降低无明显变化规律。应用REC进行聚类分析,将9个无性系分为3类,S7、S5、TL18抗寒性最强,A8抗寒性最差,其它6个无性系抗寒性居中。【结论】建议生产上推广S7、S5和TL18无性系。     

日本大耳白兔抗氧化物酶活性增龄性变化研究

选择日本大耳白兔,按年龄分为幼年、青年、老年三组,分别测定动脉血血清SOD、MDA、GSH—px活性水平,以探讨日本大耳白兔抗氧化物酶活性增龄性变化。结果显示：随着年龄的增长,血清SOD活性在中年期以前是随增龄而增加,青年组显著高于幼年CR（P〈0．05,P〈0．01）,在中年期以后是随增龄而降低,老年组明显低于青年组（P〈0．05,P〈0．01）;血清MDA含量是随增龄而增加,老年组明显高于青年组和幼年组（P〈0．05,P〈0．01）,青年组明显高于幼年CR（P〈0．05）;血清GSH—px活性随增龄而降低,老年组显著低于青年组和幼年组（P〈0．01）,青年组显著低于幼年组（P〈0．05,P〈0．01）。机体在衰老过程中体内自由基生成增加。抗氧化物酶活性全面降低可能是加速机体衰老的原因之一。     

两种诱雄剂对黄瓜植株保护酶类活性的影响

通过测定AgNO_3和Ag_2S_2O_3两种诱雄剂对黄瓜雌性系h154,151和普通系h002植株保护酶类活性的影响,结果表明,茎尖中的POD,CAT活性较对照都有所升高,处理48 h时酶活性达到最高,POD活性增幅分别为164-4%,133.5%,241.5%和23.1%,16.5%,57.2%;CAT活性增幅分别为91.3%,95.7%,113.5%和69.6%,64.3%,82.4%。AgNO_3处理黄瓜幼苗后SOD活性先下降,后升高,处理120 h时,SOD活性达到最高,增幅分别为75.3%,65.2%,30.7%和27.2%,36.9%,16.2%。     

四氯乙烯和镉联合胁迫对草鱼SOD和POD活性影响

为了考察超氧化物歧化酶(SOD)和过氧化物酶(POD)是否可以作为四氯乙烯(PCE)和镉(Cd2+)联合污染生物指标,采用静水生物测试法,研究了PCE和Cd2+联合胁迫对草鱼(Ctenopharyngodon idellus)肝胰脏、肾脏和鳃组织SOD以及肝胰脏、肾脏POD的影响。结果表明:(1)PCE和Cd2+复合污染胁迫时,草鱼肝胰脏SOD随着时间变化呈现"降低-升高-降低"的变化趋势,且最高浓度组始终低于对照;(2)肾脏SOD在所有暴露浓度组随着时间变化呈现"降低-升高-降低"的变化趋势,除最低浓度组在120 h显著高于对照外,其他均显著低于对照;(3)鳃组织SOD也呈现"降低-升高-降低"的变化趋势,但始终低于对照;(4)高浓度组(1/4TU和1/2TU)草鱼肝胰脏和肾脏POD活性随着暴露时间变化呈"降低-升高-降低"的变化趋势,但肝胰脏和肾脏的POD活性始终显著低于对照(P0.05);(5)草鱼鳃组织SOD活性明显低于肝胰脏和肾脏。PCE和Cd2+分别破坏了酶的蛋白结构和诱导了鱼体细胞膜的脂质过氧化,二者联合污染比单一污染加剧了草鱼的毒性效应。     

Callose and β‐1,3‐glucanase inhibit Phytophthora cinnamomi in a resistant avocado rootstock

Phytophthora root rot (PRR) of avocado, caused by Phytophthora cinnamomi, is a significant threat to sustainable production wherever the crop is grown. Resistant rootstocks in combination with phosphite applications are the most effective options for managing this disease. Recently, the mechanisms underpinning PRR resistance have been investigated by the avocado community. Here, biochemical assays and confocal and scanning electron microscopy were used to investigate early defence responses in PRR resistant and ‐susceptible avocado rootstocks. Zoospore germination and subsequent hyphal growth for the pathogen were significantly inhibited on the surface of resistant avocado roots. When penetration occurred in the resistant R0.06 rootstock, callose was deposited in the epidermal cells, parenchyma and cortex of roots. In addition, β‐1,3‐glucanase was released early (6 h post‐inoculation, hpi) in response to the pathogen, followed by a significant increase in catalase by 24 hpi. In contrast, susceptible R0.12 roots responded only with the deposition of lignin and phenolic compounds incapable of impeding pathogen colonization. In this study, PRR resistance was attributed to a timely multilayered response to infection by P. cinnamomi.     

不同油茶品种叶片3种保护酶活性分析

[目的]测定不同油茶品种健康叶片中的3种保护酶活性,为油茶抗病性、抗逆性机理研究提供参考依据.[方法]采用紫外—可见分光光度计法,测定岑软3号油茶、博白大果油茶、普通油茶、岑软2号油茶、香花油茶和陆川油茶6个油茶品种叶片的过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性.[结果]6个品种油茶叶片的POD活性排序为普通油茶>(博白大果油茶和岑软3号油茶)>(岑软2号油茶、香花油茶和陆川油茶),CAT活性排序为岑软3号油茶>(普通油茶、博白大果油茶和岑软2号油茶)>(香花油茶和陆川油茶),SOD活性排序为陆川油茶>岑软3号油茶>(博白大果油茶、普通油茶、岑软2号油茶和香花油茶).[结论]以油茶健康叶片中POD、CAT和SOD活性高低可判断油茶的抗病性或抗逆性强弱.     

淹水胁迫对苦瓜幼苗生长、丙二醛含量和SOD活性的影响

以台湾玉华苦瓜(Momordica charantia L.)为试材,研究淹水时间对苦瓜幼苗生长、丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性的影响。结果表明,淹水4 d时,玉华苦瓜幼苗的各项指标与对照差异不显著;淹水8 d后,株高显著低于对照,MDA含量、SOD活性显著高于对照;淹水12 d后,株高、叶片数显著低于对照,MDA含量、SOD活性显著高于对照。说明玉华苦瓜对涝渍胁迫的抵抗能力有限,生理受到伤害,生长受到抑制。     

蓝莓离体繁育新梢形态与抗氧化酶对营养元素的应答

为了研究营养元素硝酸铵、硝酸钾、葡萄糖酸钙对蓝莓离体繁育的影响,以蓝莓‘夏普蓝’继代增殖苗为试材,就添加了不同浓度的硝酸铵、硝酸钾、葡萄糖酸钙的改良培养基对蓝莓离体增殖的新梢形态及体内超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化物酶(Peroxidase,POD)、过氧化氢酶(catalase,CAT)活性的影响情况进行了试验研究。试验结果表明:当培养基中硝酸铵的浓度为600 mg·L~(-1)、硝酸钾的浓度为400 mg·L~(-1)、葡萄糖酸钙的浓度为600 mg·L~(-1)时,新梢植株发育良好,植株长势健壮,颜色正常;发育正常的新梢其SOD活性间不存在明显差异,其POD活性间不存在明显差异,其CAT活性间也不存在明显差异;而且其SOD、POD、CAT活性均明显高于发育不正常的新梢。分析结果表明:矿质营养元素能调节蓝莓不定芽抗氧化酶活性;而稳定、平衡的抗氧化酶活性又能促进不定芽的发育。