水稻赤霉素代谢关键酶基因表达的检测分析

赤霉素(GA)与水稻矮化突变体的产生有密切的关系.根据GenBank数据库中水稻赤霉素代谢关键酶基因的cDNA序列,在保守序列区域设计引物,经过反应条件优化,建立了相对定量RT-PCR双标准曲线检测方法,并对中9B及其体细胞无性系矮化突变体SV9B的相关基因表达情况进行了检测.结果表明,该方法设计的引物特异性强,所构建的标准曲线相关性好,实验具有很高的可信度,可以应用于水稻赤霉素相关突变体的研究.     

盐胁迫下宁夏枸杞苯丙烷代谢相关基因差异表达分析北大核心CSCD

为探究盐胁迫条件下宁夏枸杞苯丙烷代谢相关基因差异表达规律,以不同浓度NaCl(0,100,200,300 mmol/L)处理的水培宁夏枸杞幼苗为研究材料,利用高通量测序技术和qRT-PCR对盐胁迫下宁夏枸杞苯丙烷代谢相关基因差异表达进行分析,同时对该途径中关键酶活性及产物含量进行测定。结果表明,(1)宁夏枸杞在不同浓度NaCl处理下共有58个苯丙烷代谢相关基因差异表达,且随着盐胁迫程度的增加大部分基因表达水平上调或不变;(2)随着NaCl浓度的增加,宁夏枸杞叶片抗氧化酶SOD、POD、CAT的活性均下降,而酚类物质、类黄酮和木质素的含量在100 mmol/L NaCl处理下均显著积累。研究发现,宁夏枸杞可能通过调控苯丙烷代谢相关基因上调表达,增加酚类物质、类黄酮和木质素的合成,来清除过多活性氧和提升细胞壁强度以适应盐胁迫;宁夏枸杞可耐受的NaCl浓度在100~200 mmol/L之间。     

不同形态氮素培养下水稻叶片中蛋白质差异表达

硝态氮除作为主要氮源外,还作为一种潜在的信号物质,在植物生长发育过程中起着重要作用,其作用方式的直接性或间接性近年来成为了研究热点。利用双向电泳（2-DE）技术,对不同形态氮素（NO3^-与NH4^＋）培养的水稻叶片蛋白表达谱进行了比较分析,结果在硝态氮和铵态氮培养的叶片中分别分辨出26个和6个增量表达蛋白。质谱分析结合数据库检索鉴定出11个蛋白,其中7个硝态氮上调的蛋白为：光系统Ⅱ放氧复合蛋白1（N1）、抗性相关蛋白MLA13（N2）、光系统Ⅱ23kD多肽（N3）、翻译激活因子（N5）、光系统Ⅱ放氧复合蛋白2前体（N8）、未知蛋白（N17）和泛素载体蛋白（N18）;4个铵态氮上调蛋白为：ATP合酶β亚基（A1）、转氨酶（A3）和两个功能未知的蛋白（A5,A6）。上述研究结果有助于了解水稻适应不同氮素营养时的生物化学基础及可能的生物学意义,同时也为深入阐明水稻响应NO3^-与NH4^＋信号的反应提供了蛋白水平的证据。     

不同海拔生境条件下水稻叶片及茎鞘氮素含量的变化

本文报道生长在不同海拔生境条件下(云南省元江、玉溪、昆明、大理、丽江)的水稻叶片及茎鞘氮素含量的变化。所获得的主要结果如下: 1.自然生境条件下,水稻叶片和茎鞘的氮素含量随着生育期的进展而变化,有一个由高到低的下降趋势。而前期低海拔地区的含量比高海拔地区的高,成熟期则是海拔越高其叶片含氮量也越高,茎鞘含氮量的情形与叶片相反。 2.穗肥施用时期不同,对叶片和茎鞘氮素含量的影响不同,在低和较低海拔地区施用时期越晚,成熟期残存于叶片及茎鞘的氮素就越多;而且海拔高的地区的含量也高。在冷凉的高海拔地区丽江以颖花分化期追肥比幼穗分化和减数分裂期施用则黄熟期保持较高的含氮量。     

水稻条纹病毒胁迫下的水稻全基因组表达谱

水稻条纹叶枯病由水稻条纹病毒(Rice stripe virus, RSV)引起,对我国水稻生产危害严重.为了明确RSV侵染对水稻基因表达谱的影响,采用Affymetrix水稻全基因组芯片对RSV接种后出现条纹症状第7天的武育粳3号水稻病叶和相应的健康叶片进行了全基因组表达谱分析,得到3 517个差异基因,其中2 002个表达上调,1 515个表达下调.根据TIGR数据库注释(http://www.tigr.org/tdb/e2k1/osa1/)和MIPS基因功能分类标准(http://mips.gsf.de/projects/funcat)将差异基因归类为15个功能类别,多数差异基因与植物防御、信号传导及蛋白质、碳水化合物的代谢相关,一些转录因子的表达也发生了明显的变化.代谢途径分析表明,RSV侵染后磷酸戊糖途径、类黄酮合成途径和芸苔素合成途径的相关基因表达明显增强,赤霉素合成途径相关基因的表达受到了抑制.     

不同胁迫条件下化感与非化感水稻PAL多基因家族的差异表达

水稻苯丙氨酸解氨酶(PAL)调控酚酸类化感物质的合成代谢。编码PAL的基因是一个基因家族,包含至少11个基因成员,并受不同环境条件的调控。为了明确PAL基因家族中调控水稻化感作用的特定基因成员,本研究运用实时荧光定量PCR技术分析了低氮及稗草胁迫条件下强化感水稻PI312777与非化感水稻Lemont中根系的11个PAL成员基因的表达差异。结果表明,低氮和稗草胁迫条件下,PI312777和Lemont中的 PAL4和PAL10均不表达,其余9个PAL基因成员发生了不同程度的表达变化。其中,PAL11均上调表达,其分别在低氮处理和稗草胁迫的PI312777中上调3.29倍和1.07倍,而在相同处理下的Lemont中上调3.92倍和1.08倍;PAL3和PAL9则仅在低氮和稗草胁迫条件下的PI312777中上调表达,低氮胁迫分别为1.83倍和2.66倍,稗草胁迫为1.46倍和2.65倍;而这两个基因在相同处理下的Lemont中表达下调,低氮胁迫下调1.05和1.24倍,稗草胁迫下调1.14和1.16倍,推测PAL3和PAL9可能与胁迫初期调控水稻化感作用有关。     

不同氮素水平下CO_2倍增对转Bt棉花氮素代谢的影响

通过开顶式CO_2气室研究了盛蕾期转Bt棉花新棉33~B及其对照亲本DP5415的生长势和氮素代谢特征对土壤氮素水平(100和200 mg N·kg~(-1))和CO_2浓度倍增(750和375μl·L~(-1))的生理生态响应.结果表明:CO_2浓度升高可显著提高2种棉花的株高和茎粗,增加生物产量;氮素水平提高可显著增加转Bt棉花的株高、茎粗,以及茎和蕾的鲜质量,而对亲本棉花DP5415的影响不显著;对照棉花DP5415的谷氨酰胺合成酶(GS)活力随大气CO_2浓度的升高而显著降低,随氮素营养的提高而升高,转Bt棉花新棉33~B在低氮条件下,GS活力随大气CO_2浓度的升高而显著增加;大气CO_2浓度升高及氮素营养的增加使盛蕾期转Bt棉花的硝酸还原酶(NR)活力显著增加,DP5415的NR活力也随大气CO_2浓度的升高而显著提高;大气CO_2浓度对2种棉花的亚硝酸还原酶(NiR)活力都有明显的抑制作用,其中,高CO_2浓度条件下,DP5415的NiR活力还随氮素营养的增加而显著下降.可见,大气CO_2浓度升高下,土壤氮素水平变化对转Bt棉花的生长势影响显著,但对其氮素代谢生理的影响较对照亲本棉花小.生产中(尤其是高浓度CO_2环境下),应进一步加强转Bt棉花的氮肥优化管理.

Abstract：

By using open-top chambers, this paper studied the physiological and ecological re-sponses of transgenic Bt cotton cv. 33~B and its parent line non-transgenic cotton cv. DP5415 in their growth potential and nitrogen metabolism to doubled CO_2 concentration (750 μl·L~(-1) vs.375 μl·L~(-1)) and nitrogen fertilization level (200 mg N·kg~(-1)vs. 100 mg N·kg~(-1)). Doubled CO_2 concentration promoted the height-and stem growth and the biomass production of the two eultivars significantly, whereas doubled N fertilization level only had significant positive effects on 33~B. The leaf glutamine synthetase activity (GSA) of DP5415 decreased significantly under doubled CO_2 concentration but increased significantly under doubled N fertilization level, while the GSA of 33~B was significantly higher under doubled CO_2 concentration and low nitrogen fertili-zation level. Both the doubled CO_2 concentration and the doubled nitrogen fertilization level in-creased the leaf nitrate reductase activity (NRA) of 33~B significantly, and the NRA of DP5415 also had a significant increase under doubled CO_2 concentration. Doubled CO_2 concentration had significant inhibitory effects on the leaf nitrite reductase activity (NiRA) of both 33~B and DP5415. The NiRA of DP5415 decreased significantly under doubled CO_2 concentration and N fertilization level. All the results suggested that under doubled CO_2 concentration, N fertilization level had significant effects on the growth potential of transgenic Bt cotton but lesser effects on its nitrogen metabolism, compared with the control non-transgenic cotton. Therefore, in the planting of transgenic Bt cotton, especially,under elevated CO_2 condition, optimized N fertilization should be made.     

抑制表达谷氨酸合酶基因对水稻碳氮代谢的影响

提高水稻的氮素利用率对农业生产极为重要,水稻谷氨酸合酶（GOGAT,EC1．4．1．14）被认为具有提高水稻氮素利用率的潜力,但该酶在水稻中的功能以及其对碳氮代谢的影响一直未被系统的报道．本研究以抑制表达谷氨酸合酶基因的转基因水稻为材料,结合谷氨酸合酶基因家族全生育期表达谱数据,研究该基因家族在水稻体内的功能及其对碳氮代谢的影响．结果表明,谷氨酸合酶家族基因成员的表达模式各不相同,具有明显的组织和器官特异性,表明其在体内行使着不同的功能．与野生型相比,抑制表达谷氨酸合酶基因的转基因植株的分蘖数、地上部干重以及单株产量显著下降．同时,转基因植株叶片中的硝酸盐、部分游离氨基酸、叶绿素、糖、糖磷酸以及吡啶核苷酸含量也显著降低,但游离铵、仅一酮戊二酸以及异柠檬酸含量上升．分析表明,谷氨酸合酶在水稻的碳氮代谢过程中扮演着重要角色,是水稻氮素高同化过程中必不可少的因子．     

锥栗种仁转录组及淀粉和蔗糖代谢相关酶基因的表达分析

本研究采用高通量测序技术对淀粉积累高峰期的锥栗种仁进行转录组测序分析,对得到的Unigene进行功能注释、分类及代谢通路分析,并进一步通过实时定量PCR方法分析了7个与淀粉和蔗糖代谢相关酶基因在锥栗种仁发育过程中的表达特征。结果显示:de novo组装后共获得53629条Unigene序列,序列平均长度为746 bp;通过与其他核酸、蛋白质数据库的Blast搜索比对,共26739条Unigene序列获得基因注释,占All-Unigene的49.86%;与COG数据库比对后将其注释的14413条Unigene序列划分成25类;GO功能注释的33926条Unigene基因共分成细胞组分、分子功能和生物过程3大类58个分支;与KEGG数据库比对结果注释的5277条Unigene序列划分为116条代谢通路;7个与淀粉和蔗糖代谢相关酶基因表达量变化趋势中,CH.29636(淀粉合成酶,SS),CH.11971(淀粉分支酶,SBE)两个基因随着种仁的发育呈现逐渐上升的趋势,而其余5个基因(CH.31302、CH.33690、CH.19238、CH.30128、CH.13088)表达量随着种仁的发育呈先上升后下降的趋势,该结果与锥栗种仁发育期淀粉和蔗糖的变化规律一致。这些信息为锥栗果实品质形成相关功能基因的研究提供了重要依据。     

不同氮素水平下水稻生育后期叶片和籽粒的蛋白质组学

以超级杂交水稻“两优培九”为试验材料,运用蛋白质双向电泳技术研究了水稻生育后期不同氮素水平下（正常供氮水平的1/2,20 mg·L^-1;正常供氮水平,40 mg·L^-1;正常供氮水平的2倍,80 mg·L^-1）叶片和籽粒蛋白质组水平的变化,并鉴定分析了其差异蛋白质点（共鉴定出16个叶片蛋白质、9个弱势粒蛋白质、4个强势粒蛋白质）的生物功能.结果表明：生育后期氮素是通过影响与光合有关的酶的活化、CO₂的活化及光系统单位和电子传递链构成来影响和调节植物的光合作用;氮素可促进弱势粒中与能量合成和生长相关酶的表达;高氮水平不利于强势粒淀粉的合成,但充足的氮素对水稻物质累积及代谢具有重要作用.因此,在生育后期合理运用氮肥对提高水稻剑叶光合性能、增强源的功能、延缓功能性早衰及强化籽粒灌浆具有积极作用.     

水稻砷污染及其对砷的吸收和代谢机制

水稻是当今世界大部分地区(尤其是东南亚)的主要的粮食作物之一,同时也是砷(As)进入食物链的主要途径之一。日益严重的水稻田As污染,不但影响了稻米的产量和品质,而且通过食物链威胁着人体健康。如何减少水稻地上部(尤其是米粒)As的含量和降低其毒性,及提高水稻As耐性是亟需解决的世界食品安全问题。深入了解水稻对As的吸收、积累和代谢的生理及分子生物学机制是解决水稻As污染的关键途径。综述国内外研究,对今后深入研究提出建议。     

QTLs and epistasis for seminal root length under a different water supply in rice (Oryza sativa L.)

To identify the genetic background of seminal root length under different water-supply conditions, a recombinant inbred (RI) population consisting of 150 lines, derived from a cross between an indica lowland rice, IR1552, and a tropical japonica upland rice, Azucena, was used in both solution culture (lowland condition) and paper culture (upland condition). Quantitative trait loci (QTLs) and epistatic loci for seminal root length were analyzed using 103 restriction fragment length polymorphism (RFLP) markers and 104 amplified fragment length polymorphism (AFLP) markers mapped on 12 chromosomes based on the RI population. One QTL for seminal root length in solution culture (SRLS) and one for seminal root length in paper culture (SRLP) were detected on chromosomes 8 and 1, and about 11% and 10% of total phenotypic variation were explained, respectively. The QTL for SRLP on chromosome 1 was very similar with the QTL for the longest nodal root referred to in a previous report; this QTL may be phenotypically selectable in a breeding program using paper culture. Five pairs of epistatic loci for SRLS were detected, but only one for SRLP, which accounted for about 60% and 20% of the total variation in SRLS and SRLP, respectively. The results indicate that epistasis is a major genetic basis for seminal root length, and there is a different genetic system responsible for seminal root growth under different water supply conditions. Received: 26 May 2000 / Accepted: 19 October 2000     

Discrimination of nitrogen isotopes during absorption of ammonium and nitrate at different nitrogen concentrations by rice (Oryza sativa L.) plants

Studies of uptake of ionic sources of N by two hydroponically grown rice (Oryza sativa L.) cultivars (paddy‐field‐adapted Koshihikari and dryland‐adapted Kanto 168) showed that the magnitude of the nitrogen isotope fractionation (?) for uptake of NH₄⁺ depended on the concentrations of NH₄⁺ and cultivar (averaging –6·1‰ for Koshihikari and –12·0‰ for Kanto 168 at concentrations from 40 to 200 mmol m^?3 and, respectively, –13·4 and –28·9‰ for the two cultivars at concentrations from 0·5 to 4 mol m^?3). In contrast, the ? for uptake of NO₃^? in similar experiments was almost insensitive to the N concentration, falling within a much narrower range (+3·2‰ to –0·9‰ for Koshihikari and –0·9‰ to –5·1‰ for Kanto 168 over NO₃^? concentrations from 0·04 to 2 mol m^?3). From longer term experiments in which Norin 8 and its nitrate‐reductase deficient mutant M819 were grown with 2 or 8 mol m^?3 NO₃^? for 30 d, it was concluded that the small concentration‐independent isotopic fractionation during absorption of this ion was not related to nitrate reductase activity.     

两种温度下模拟氮沉降对陆稻与稗草竞争的影响

在昼/夜温度为35 ℃/25 ℃和30 ℃/20 ℃条件下,研究了模拟氮沉降对稗草和陆稻生长及竞争关系的影响.结果表明：35 ℃/25 ℃条件下,每年输入4 g·m^-2氮处理,稗草和陆稻地上部分生物量分别比对照增加29.18%和27.80％,稗草吸收氮和磷量分别增加87.33%和49.73%,而陆稻吸收氮和磷量无显著变化.在30 ℃/20 ℃条件下,每年输入2、4、6 g·m^-2氮处理后,稗草地上部分生物量分别比对照增加48.99％、72.68％和36.18％,分蘖数分别增加111.11％、122.22％和144.44％,稗草植株氮和磷吸收量分别增加108.88％、129.22%、134.29％和16.53％、65.05%、22.47%,而陆稻均无显著变化.在30 ℃/20 ℃条件下,氮沉降显著增加了稗草与陆稻地上部分生物量的比值,但在35 ℃/25 ℃条件下影响不显著.表明氮沉降增加可能会提高稗草而降低陆稻的竞争力,而且在温度较低的情况下,这种趋势更明显.     

Molecular mapping of the cnx2 locus involved in molybdenum cofactor biosynthesis in rice (Oryza sativa L.)

Molybdenum cofactor (Moco) is essential for nitrate reductase (NR), xanthine dehydrogenase (XDH), and aldehyde oxidase to perform their catalytic functions in plants. Moco biosynthesis is a complex process involving many genes. Little is known about the genetics and molecular aspects of Moco biosynthesis in plants and other eukaryotes. In rice, we previously isolated a Moco mutant C25 with a mutation in the CNX2 gene from a mutagenized indica cultivar IR30 and characterized its biochemical properties. This mutant was crossed with a japonica cultivar, Norin 8, to investigate the linkage of cnx2 to restriction fragment length polymorphism (RFLP) and cleaved amplified polymorphic sequence (CAPS) markers. Chlorate resistance was used to trace the cnx2 mutation because of its cosegregation with the loss of NR and XDH activities observed earlier. RFLP and CAPS analyses show the location of the cnx2 locus on the long arm of chromosome 4. It is mapped between RFLP markers C513 and C377 with a distance of 9.5 and 13.1 cM, respectively. It is also linked with CAPS marker RA0738 at a distance of 30.3 cM. Received: 25 June 2000 / Accepted: 31 August 2000     

RFLP mapping of the genes controlling hybrid breakdown in rice (Oryza sativa L.)

 Complementary recessive genes hwd1 and hwd2 controlling hybrid breakdown (weakness of F₂ and later generations) were mapped in rice using RFLP markers. These genes produce a plant that is shorter and has fewer tillers than normal plants when the two loci have only one or no dominant allele at both loci. A cultivar with two dominant alleles at the hwd1 locus and a cultivar with two dominant alleles at the hwd2 locus were crossed with a double recessive tester line. Linkage analysis was carried out for each gene independently in two F₂ populations derived from these crosses. hwd1 was mapped on the distal region of rice genetic linkage map for chromosome 10, flanked by RFLP markers C701 and R2309 at a distance of 0.9 centiMorgans (cM) and 0.6 cM, respectively. hwd2 was mapped in the central region of rice genetic linkage map for chromosome 7, tightly linked with 4 RFLP markers without detectable recombination. The usefulness of RFLP mapping and map information for the genes controlling reproductive barriers are discussed in the context of breeding using diverse rice germplasm, especially gene introduction by marker-aided selection.     

A comparison of nitrate transport in four different rice(Oryza sativa L.) cultivars

As rice can use both nitrate (NO3-) and ammonium (NH4+), we have tested the hypothesis that the shift in the pattern of cultivars grown in Jiangsu Province reflects the ability of the plants to exploit NO3- as a nitrogen (N) source. Four rice cultivars were grown in solution culture for comparison of their growth on NO3- and NH4+ nitrogen sources. All four types of rice,Xian You 63 (XY63), Yang Dao 6 (YD), Nong Keng 57 (NK) and Si You 917 (SY917), grew well and produced similar amounts of shoot biomass with 1 mmol/L NH4+ as the only N source.However, the roots of NK were significantly smaller in comparison with the other cultivars. When supplied with 1 mmol/L NO3-, YD produced the greatest biomass; while NK achieved the lowest growth among the four cultivars. Electrophysiological measurements on root rhizodermal cells showed that the NO3--elicited changes in membrane potential (ΔEm) of these four rice cultivars were significantly different when exposed to low external NO3- (＜1 mmol/L); while they were very similar at high external NO3- (10 mmol/L). The root cell membrane potentials of YD and XY63 were more responsive to low external NO3- than those of NK and SY917. The ΔEm values for YD and XY63 rhizodermal cells were almost the same at both 0.1 mmol/L and 1 mmol/L NO3-;while for the NK and SY917 the values became larger as the external NO3- increased. For YD cultivar, ΔEm was measured over a range of NO3- concentrations and a Michaelis-Menten fit to the data gave a Km value of 0.17 mmol/L. Net NO3- uptake depletion kinetics were also compared and for some cultivars (YD and XY63) a single-phase uptake system with first order kinetics best fitted the data; while other cultivars (ND and SY917) showed a better fit to two uptake systems. These uptake systems had two affinity ranges: one had a similar Km in all the cultivars (0.2 mmol/L); the other much higher affinity system (0.03 mmol/L) was only present in NK and SY917. The expression pattern of twelve different NO3- transporter genes was tested using specific primers, but only OsNRT1.1 and OsNRT2. 1 expression could be detected showing significant differences between the four rice cultivars. The results from both the physiological and molecular experiments do provide some support for the hypothesis that the more popular rice cultivars grown in Jiangsu Province may be better at using NO3- as an N source.     

不同环境下水稻谷粒重发育的杂种优势和遗传相关性分析

选用9个不同类型的水稻品种(系),按双列杂交设计(6×5)配成两套亲本和F12个世代的遗传材料,采用数量性状的加性、显性遗传模型、发育遗传模型比较分析了水稻谷粒重发育的杂种优势和遗传相关性。结果表明,早季在谷粒充实前期(1～12d)群体平均优势较小,中后期(13～28d)正向优势趋于明显,在谷粒充实的全过程均表现较小的负向群体超亲优势;晚季则在谷粒充实前中期(1～18d)表现正向群体平均优势。后期(19～28d)优势不明显,在谷粒充实前期(1～12d)表现正向群体超亲优势,之后转为明显的负向群体超亲优势,表明晚季谷粒发育的杂种优势表现较之早季更有利于提高籽粒充实质量,不同发育时期谷粒重之间以及与最终谷粒重之间的遗传相关分析表明,早季以显性相关为主,晚季以加性相关为主,随着发育进程的推进,相关趋于密切。     

Effects of the activities of key enzymes involved in starch biosynthesis on the fine structure of amylopectin in developing rice (Oryza sativa L.) endosperms

The dynamic changes of the activities of enzymes involving in starch biosynthesis, including ADP-glucose pyrophosphorylase (AGPase), soluble starch synthases (SSS), starch branching enzyme (SBE) and starch debranching enzymes (DBE) were studied, and changes of fine structure of amy- lopectin were characterized by isoamylase treatment during rice grain development, using trans anti-waxy gene rice plants. The relationships between the activities of those key enzymes were also analyzed. The amylose synthesis was significantly inhibited in transgenic Wanjing 9522, but the total starch content and final grain weight were less affected as compared with those of non-transgenic Wanjing 9522 rice cultivar. Analyses on the changes of activities of enzymes involving in starch bio- synthesis showed that different enzyme activities were expressed differently during rice endosperm development. Soluble starch synthase is relatively highly expressed in earlier stage of endosperm de- velopment, whilst maximal expression of granule-bound starch synthase (GBSS) occurred in mid-stage of endosperm development. No obvious differences in changes of the activities of AGPase and SBE between two rice cultivars investigated, except the DBEs. Distribution patterns of branches of amy- lopectin changed continually during the development of rice grains and varied between two rice culti- vars. It was suggested that amylopectin synthesis be prior to the synthesis of amylose and different enzymes have different roles in controlling syntheses of branches of amylopectin.     

Azoxystrobin induces lignification-related enzymes and phenolics in rice (Oryza sativa L.) against blast pathogen (Pyricularia grisea)

Abstract

This study was conducted to analyse the induction of lignification-related enzymes and phenolic content in rice to blast disease caused by Pyricularia grisea using azoxystrobin. The severity of rice blast was reduced (70% over control) through treatment by azoxystrobin. This reduction in disease severity was mainly associated with induction of host defense mechanisms by azoxystrobin. Increased production of secondary metabolite – phenolic and lignification – related enzymes, namely, peroxidase (POD), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) were observed in rice plants treated with azoxystrobin.