Generation and analysis of drought stressed subtracted expressed sequence tags from safflower (Carthamus tinctorius L.)

Drought is the most crucial environmental factor that limits productivity of many crop plants. Exploring novel genes and gene combinations is of primary importance in plant drought tolerance research. Stress tolerant genotypes/species are known to express novel stress responsive genes with unique functional significance. Hence, identification and characterization of stress responsive genes from these tolerant species might be a reliable option to engineer the drought tolerance. Safflower has been found to be a relatively drought tolerant crop and thus, it has been the choice of study to characterize the genes expressed under drought stress. In the present study, we have evaluated differential drought tolerance of two cultivars of safflower namely, A1 and Nira using selective physiological marker traits and we have identified cultivar A1 as relatively drought tolerant. To identify the drought responsive genes, we have constructed a stress subtracted cDNA library from cultivar A1 following subtractive hybridization. Analysis of similar to 1,300 cDNA clones resulted in the identification of 667 unique drought responsive ESTs. Protein homology search revealed that 521 (78 %) out of 667 ESTs showed significant similarity to known sequences in the database and majority of them previously identified as drought stress-related genes and were found to be involved in a variety of cellular functions ranging from stress perception to cellular protection. Remaining 146 (22 %) ESTs were not homologous to known sequences in the database and therefore, they were considered to be unique and novel drought responsive genes of safflower. Since safflower is a stress-adapted oil-seed crop this observation has great relevance. In addition, to validate the differential expression of the identified genes, expression profiles of selected clones were analyzed using dot blot (reverse northern), and northern blot analysis. We showed that these clones were differentially expressed under different abiotic stress conditions. The implications of the analyzed genes in abiotic stress tolerance are discussed in our study.

Phenotypic characters of rice landraces reveal independent lineages of short-grain aromatic indica rice

Rice landraces are lineages developed by farmers through artificial selection during the long-term domestication process. Despite huge potential for crop improvement, they are largely understudied in India. Here, we analyse a suite of phenotypic characters from large numbers of Indian landraces comprised of both aromatic and non-aromatic varieties. Our primary aim was to investigate the major determinants of diversity, the strength of segregation among aromatic and non-aromatic landraces as well as that within aromatic landraces. Using principal component analysis, we found that grain length, width and weight, panicle weight and leaf length have the most substantial contribution. Discriminant analysis can effectively distinguish the majority of aromatic from non-aromatic landraces. More interestingly, within aromatic landraces long-grain traditional Basmati and short-grain non-Basmati aromatics remain morphologically well differentiated. The present research emphasizes the general patterns of phenotypic diversity and finds out the most important characters. It also confirms the existence of very unique short-grain aromatic landraces, perhaps carrying signatures of independent origin of an additional aroma quantitative trait locus in the indica group, unlike introgression of specific alleles of the BADH2 gene from the japonica group as in Basmati. We presume that this parallel origin and evolution of aroma in short-grain indica landraces are linked to the long history of rice domestication that involved inheritance of several traits from Oryza nivara, in addition to O. rufipogon. We conclude with a note that the insights from the phenotypic analysis essentially comprise the first part, which will likely be validated with subsequent molecular analysis.

Functions for rice RFL in vegetative axillary meristem specification and outgrowth

Roles for the transcription factor RFL in rice axillary meristem development were studied. Its regulatory effects on LAX1, CUC1, and OsPIN3 reveal its functions in axillary meristem specification and outgrowth.Axillary meristems (AMs) are secondary shoot meristems whose outgrowth determines plant architecture. In rice, AMs form tillers, and tillering mutants reveal an interplay between transcription factors and the phytohormones auxin and strigolactone as some factors that underpin this developmental process. Previous studies showed that knockdown of the transcription factor gene RFL reduced tillering and caused a very large decrease in panicle branching. Here, the relationship between RFL, AM initiation, and outgrowth was examined. We show that RFL promotes AM specification through its effects on LAX1 and CUC genes, as their expression was modulated on RFL knockdown, on induction of RFL:GR fusion protein, and by a repressive RFL-EAR fusion protein. Further, we report reduced expression of auxin transporter genes OsPIN1 and OsPIN3 in the culm of RFL knockdown transgenic plants. Additionally, subtle change in the spatial pattern of IR4 DR5:GFP auxin reporter was observed, which hints at compromised auxin transport on RFL knockdown. The relationship between RFL, strigolactone signalling, and bud outgrowth was studied by transcript analyses and by the tillering phenotype of transgenic plants knocked down for both RFL and D3. These data suggest indirect RFL-strigolactone links that may affect tillering. Further, we show expression modulation of the auxin transporter gene OsPIN3 upon RFL:GR protein induction and by the repressive RFL-EAR protein. These modified forms of RFL had only indirect effects on OsPIN1. Together, we have found that RFL regulates the LAX1 and CUC genes during AM specification, and positively influences the outgrowth of AMs though its effects on auxin transport.

Determinação de atividade antioxidante, compostos fenólicos totais e teor de resveratrol em cinco cultivares brasileiras de Arachis hypogaea L. com a utilização de duas metodologias extrativas

O amendoim A. hypogaea L. é a quarta oleaginosa mais consumida no mundo e suas sementes são altamente energéticas, com grandes quantidades de lipídios, proteínas, vitaminas e carboidratos. Diversas atividades farmacol��gicas já foram observadas em extratos de raízes, folhas e sementes, sendo a principal delas a atividade antioxidante. Neste trabalho, foi realizada a comparação entre duas metodologias (por maceração e assistida por micro-ondas) para a extração de compostos antioxidantes, incluindo o resveratrol. Também foi realizada a comparação entre extratos de diferentes órgãos de cultivares brasileiras (IAC 886, IAC Caiapó, IAC Tatu ST, IAC 8112 e IAC 99-1) quanto à atividade antioxidante, por DPPH, ao teor de compostos fenólicos, por Folin-Ciocalteu, e ao teor de resveratrol, por HPLC. Por fim, foram estabelecidos protocolos de cultura de tecidos para explantes de sementes, visando à produção de calos e plantas in vitro para posterior dosagem de compostos de interesse, tendo em vista a possibilidade de modulação das condições in vitro. As melhores condições determinadas para a extração por maceração de antioxidantes de A. hypogaea foram 80% de etanol em água como solvente, trituração com almofariz e pistilo, 50 mL solvente por grama de material vegetal seco, 120 minutos de incubação e dois estágios de extração. As melhores condições para a extração de resveratrol assistida por micro-ondas foram o uso de 37 mL de solvente/g material vegetal seco, com agitação de 1200 rpm por 15 minutos, a 37C. De uma maneira geral, os extratos de raízes e oriundos de micro-ondas apresentaram maior atividade antioxidante (até 92,36 2,71%), teor de compostos fenólicos (até 54,15 1,39 mg EAG/g extrato) e teor de resveratrol (até 1,614 0,356 mg/g extrato). Dentre as cultivares estudadas, IAC Tatu e IAC 99-1 foram as que apresentaram os teores mais elevados. Brotos e calos friáveis foram obtidos a partir de cotil��dones, eixos embrionários e fol��olos embrionários cultivados em meios suplementados com BAP e picloram, respectivamente.

药用野生稻复合体（稻属）的分子系统发育与进化研究

稻属（Oryza L.）隶属于禾本科（Gramineae）Ehrhartoideae亚科的稻族（Oryzeae），包括两个栽培种（亚洲栽培稻O. sativa和非洲栽培稻O. glaberrima）和大约20多个野生种，广布于热带亚洲、非洲、大洋洲、中美洲和南美洲。药用野生稻复合体（O. officinalis complex）是稻属中最大、也是最复杂的一个复合体，共包括9个种，含有5种染色体组类型（B、C、BC、CD 和E）。作为栽培稻品质改良的重要基因库，药用野生稻复合体在稻属中具有重要的地位。但是，相似的形态和重叠的地理分布使部分物种的分类和鉴定一直较为困难;种内染色体组构成和倍性的不同更增加了分类鉴定的复杂性。这种情况阻碍了对这些野生稻遗传优势的有效利用。另外，由于物种间断分布和缺乏明确的二倍体亲本等原因，药用野生稻复合体内的异源多倍体起源一直存在争议。本文通过细胞核乙醇脱氢酶基因（Adh）和nrDNA的内转录间隔区（ITS）限制性片段长度多态性（RFLP）分析;叶绿体matK 基因、trnL 内含子和trnL-trnF 基因间隔区、核基因Adh和GPA1以及核糖体DNA ITS片段等序列比较的方法，对药用野生稻复合体中染色体组和物种的鉴定、种间系统发育关系，以及异源多倍体CCDD物种的起源和多倍体ITS的分子进化等进行了研究。主要研究结果如下： 1． 利用核Adh 基因限制性片段长度多态性，检测了来自国际水稻研究所基因库的64份药用野生稻复合体的样品。结果证明，所有O. rhizomatis样品都是含C染色体组的二倍体，所有O. minuta样品都是含BC 染色体组的四倍体。但是，种子库中鉴定为O. officinalis、O. punctata和O. eichingeri的样品中，同时都发现了含C染色体组的二倍体和含BC染色体组的四倍体。四倍体的O. officinalis只在印度分布，而且曾被描述为另一个种O. malampuzhaensis。 四倍体的O. punctata，也被一些学者称为O. schweinfurthiana，被发现和其二倍体一样分布广泛。值得注意的是，有两个曾被作为O. officinalis 四倍体的样品实际上是含有CD染色体组的物种O. latifolia。我们的结果增进了对国际水稻研究所种子库中部分野生稻样品染色体组构成的理解, 纠正了以往对药用野生稻复合体样品的错误鉴定，为今后进一步研究和利用这部分资源提供了种质编目的重要基础。 2． 对稻属中代表不同地理分布区的、含CD染色体组的11个样品（包括77个克隆）的ITS片段进行了测序。基于这些ITS序列的限制性片段长度多态性，提出一个快速而可靠的区分稻属CD 染色体组物种的方法。这个方法的具体步骤是：（1）利用通用引物扩增ITS 片段;（2）利用限制性内切酶FokI和/或DraⅢ消化PCR扩增产物;（3）用1%的琼脂糖胶电泳并根据消化产物的片段长度多态性来区分不同物种。 3． 利用包括两个叶绿体片段（matK和 trnL-trnF）、nrDNA内转录间隔区（ITS）和三个核基因（Adh1、Adh2和GPA1）的同源序列分析，探讨了药用野生稻复合体中二倍体物种和它们所代表的染色体组之间的系统发育关系。独立和合并的基因系统发育树都显示了一致的结果，即C染色体组和B染色体组的亲缘关系要比它们和E染色体组的近。三个含C染色体组的二倍体中，O. officinalis 和O. rhizomatis表现出较近的亲缘关系。值得注意的是，在O. eichingeri种内，尽管基于多基因的数据支持来自斯里兰卡的样品和来自非洲的样品聚成一个分支，但是较低的支持率表明, 两个地区的样品之间存在着较高的遗传分化。 4． 稻属中含CD染色体组的物种特产于拉丁美洲，包括O. alta、 O. grandiglumis 和O. latifolia。由于具有相同的染色体组类型、相似的形态特征和重叠的地理分布，这3个物种间的系统发育关系一直存在争论。另外，因为美洲大陆上没有含C和D染色体组的二倍体物种存在，对这些含CD染色体组物种的可能起源也有不同的假设被提出。使这个问题更具挑战性的是，尽管开展了世界范围的收集，至今仍没有找到含D 染色体组的二倍体物种。在本研究中，代表含C、CD和E染色体组以及含G染色体组的外类群共7个物种，共15份样品的2个叶绿体片段（matK和trnL-trnF）和3个核基因（Adh1，Adh2 和 GPA1）部分片段被测序。基于简约法、距离法和最大似然法的系统发育分析都充分支持含CD染色体组的物种起源于一次杂交事件的推论，并且显示，在物种形成时，含C染色体组的物种（O. officinalis 或O. rhizomatis 而非O. eichingeri）可能承担了母本，而含E染色体组的物种（O. australiensis）则可能承担了父本。另外，CCDD物种间非常一致的系统发育关系表明，非常大的分歧存在于 O. latifolia 和其它两个种（O. alta和O. grandiglumis）之间，这个结果倾向于将后两个种处理为同种或同种下不同分类群。 5． 基于178个克隆序列比较，探讨了ITS在稻属多倍体中的致同进化及其系统学意义。研究发现稻属异源四倍体的ITS存在不同形式的进化方式：首先，非洲BBCC四倍体O. eichingeri和O. punctata 的ITS片段同时保留了双亲拷贝，而且系统发育研究表明，二倍体的O. eichingeri和O. punctata 可能是这两个四倍体的直接祖先;其次，亚洲四倍体O. malampuzhaensis和O. minuta 的ITS仅定向保留母本ITS拷贝;另外，美洲CCDD四倍体的ITS序列发生了双向致同进化，即O. alta和O. grandiglumis的ITS位点一致化成C染色体组类型，而O. latifolia一致化成 D/E 染色体组类型。我们的研究进一步表明在利用ITS片段进行系统发育分析时，特别是涉及异源多倍体时必须慎重。 6． 利用栽培稻的微卫星引物，对含B/C染色体组的6个物种，157个体的SSR位点进行扩增。结果在这些亲缘关系稍远的野生稻中得到7个SSR位点，其中5个位点表现出多态性。比较BB、CC和BBCC物种SSR位点的每位点平均等位基因数A、多态位点百分率P和期望杂合度He ，3项指标发现，四倍体物种的遗传多样性，总体上要高于二倍体物种;二倍体物种内部，O. officnalis的遗传变异最大。另外，以遗传相关性为标准，讨论了B/C染色体组物种间的系统发育关系，同时推测了现存二倍体物种和4个BBCC四倍体物种的遗传关系。

稻属的系统发育基因组学研究

稻属（OrvzaL���）是禾本科(Poaceae)中的重要植物类群，包含20多个野生种和两个栽培种，共有十个基因组类型，即A，B，C，E，F，G，BC，CD，HJ和HK，蕴藏了极为丰富的遗传资源，是水稻遗传改良的重要基因库。考虑到该属现存物种中的多倍体都是由二倍体杂交起源的，因此，弄清二倍体基因组之间的进化关系对于正确理解整个稻属的进化历史至关重要，同时也为稻属及其近缘类群的进化生物学、比较基因组学和功能基因学研究等提供了一个重要的工作基础。迄今，对稻属各基因组之间的系统发育关系还没有一致的结论，特别是对A、B和C基因组三者之间的关系，以及稻属基部类群的归属问题还存在争议。本研究选取来自不同二倍体基因组的6个稻属物种为研究对象，以近缘属Leersia中的L���tisserantti作外类群，通过对基因组水平的多基因序列数据的详尽分析，探讨了稻属二倍体基因组之间的亲缘关系问题，基因树与基因树之间冲突的机理，以及利用基因组水平的多基因序列做系统发育分析的方法，主要研究结果如下。 利用已完成的水稻两亚种（O．sativaL���ssp. indica和O．sativaL���ssp.japonica）的全基因组序列，筛选并扩增出遍布核基因组12条染色体的142个单拷贝核基因片段。通过对全部基因位点的合并分析，我们得到了一棵有完全分辨并得到显著统计支持的系统树。分别提取各基因的外显子区、内含子区和第三密码子进行合并建树时发现，除了合并外显子区的MP分析以外，所得系统树的树形均不变，说明这棵树基本上不会因为选取基因组不同区域或碱基位点而改变，尽管不同区域或碱基位点受到不同的选择约束力。以基因为单位进行放回式抽样也强烈支持合并建树的分析结果，表明多基因合并序列的系统发育估计并没有受到少数特殊基因的支配。为了考察基因组内物种取样对建树的影响，我们增加了2个A基因组物种以及C基因组的另外两个物种，随机选取其中的62个基因位点进行扩增和测序（增加的O．sativa的序列来自BGI-RIS数据库）。将全部II个物种62个基因位点的序列合并建树分析，得到基因组之间的进化关系均未改变。我们进一步评估了合并数据的系统误差，结果发现，合并数据的系统发育重建也未受到系统误差的影响。综上所述，本研究通过系统发育基因组学方法所得到的系统树反映了类群真实的进化关系。 为了深入探讨以往研究中出现相互矛盾的系统发育关系的原因，我们对142个基因位点分别做了单独的建树分析，并用系统发育网络方法分析了数据中基因之间系统发育信息矛盾的集中位置及其矛盾程度。基于单基因的建树分析及系统误差分析，我们排除了随机误差和系统误差直接造成基因之间信息冲突的可能性。基于溯祖理论( Coalescence theory)的进一步分析表明，稻属进化过程中发生了两次世代间隔较短的连续分化事件，由于祖先居群较大引起基因的谱系分选，进而使得在利用现有物种基因序列来重建这些分化事件时基因树不能正确反映物种树，且呈现出基因组水平的基因树冲突现象。这两次间隔较短的连续分化事件分别对应了稻属中两次物种快速分化过程，整个稻属基因组的多样性几乎都是在这两次物种快速分化过程中形成的。随机抽样分析表明，需要大量的分子序列数据才能正确分辨稻属二倍体基因组的系统发育关系（若取95%的概率，则至少需要120个基因或50kb的随机碱基位点）。本研究用基因组水平的多基因合并数据克服了谱系分选对构建系统树所带来的“噪音”，在存在广泛单基因系统发育信息矛盾的前提下获得了对物种树的正确估计，这充分证明系统发育基因组学方法在解决快速分化类群的进化关系问题中有着巨大潜力和广阔的应用前景。 基于本文所采用的142个核基因，我们初步探讨了利用多基因序列数据构建系统树时如何进行模型选择和插入缺失编码等问题，并评估了数据缺失对基因组水平系统发育重建的影响。结果表明，对合并数据而言，混合模型比单一模型能更好的拟合数据的进化模式;找到合并数据中异质性的根源并做出适当的数据分割是成功运用混合模型的关键;某些模型成分在提高模型对数据的适合度上发挥着重要作用，尤其要考虑位点之间以及谱系之间的突变速率异质性。我们认为，在设置模型时，最复杂的不一定是最好的，把握数据中最重要的进化特征远比简单的增加模型的复杂度重要。插入缺失的编码分析表明，编码后显著增加了对A基因组和B基因组聚为一枝的支持，但对稻属基部类群的分辨状况改善不明显。另外，我们通过去除数据缺失比例较大的类群来降低数据缺 失对系统发育推断的影响，结果所得的系统发育关系不变，支持率也仅有极微小的变化，说明基因组水平的多基因数据由于具有丰富的系统发育信息，因而对数据缺失具有很好的缓冲能力。

不同年代推出的冬小麦(Triticun aestivum L)品种农艺性状以及光合生理生态特性

本文探讨了五十年来北京地区广泛推广的17个冬小麦(Triticun aestivum L)品种在品种改良的过程中农艺性状和某些光合特性的变化趋势。从中选出形态、产量和推出年代差异最大的3个冬小麦品种：京冬8号、农大139和燕大1817，种植在相同的环境条件下，进一步研究与冬小麦产量提高有关的生理生态特性，以及它们的气体交换特性对于外界环境变化的响应。本试验于1999-2001年在北京农林科学院试验农场（39o09’N, 116o04’E）进行。结果如下： 1. 在冬小麦品种改良的过程中，小麦品种的经济产量、收获指数、千粒重提高，而生物产量、株高、单株穗数、单株籽粒产量和穗长降低。籽粒产量与株高、穗数极显著负相关，与穗粒重、收获指数、千粒重极显著正相关。株高与穗长、单株籽粒产量、穗数显著正相关，而与收获指数和千粒重极显著负相关。收获指数与穗数极显著负相关，而与千粒重极显著正相关。说明株高降低、收获指数提高和千粒重的提高对于冬小麦品种改良过程中产量的提高起重要作用。 2. 随品种推出年代的延迟，各品种苗期-拔节期的净光合速率（PN）、 气孔导度（gs）、蒸腾速率（ E）、量子产率（Fv/Fm）均呈增加的趋势，水分利用率（WUE）呈降低的趋势。在孕穗期-蜡熟期，旗叶的PN也随品种推出年代而呈增大的趋势，而在成熟期呈减小的趋势。gs在孕穗期-灌浆期增大，在蜡熟期和成熟期减小;各个时期的E均呈递增趋势;而WUE呈降低趋势。旗叶的Fv/Fm在孕穗期和开花期呈递增的趋势，而在成熟期下降。在苗期至孕穗期，PN、 E均与产量显著正相关;在拔节始期和孕穗期gs与产量显著正相关（R=0.616, 0.499, P<0.05），在苗期-拔节期、开花期和成熟期，WUE与历史产量和试验产量显著负相关（P<0.05, 或P<0.001），在苗期和拔节期Fv/Fm与产量正相关（P<0.05）。在冬小麦品种的改良过程中，其光合作用的改良不仅表现在净光合速率上，而且还表现在荧光动力学参数Fv/Fm上， 即PSII的原初光能转化效率有所提高。 3. 孕穗期至灌浆期，高产品种京冬8号旗叶的PN、gs、E、叶绿素含量和水分含量均最高，而水分利用率（WUE）较低，且具有较高的光呼吸和较低的暗呼吸，其旗叶的叶比重也较高。京冬8号（上世纪90年代推出）叶片气体交换的日变化表现为：在拔节期，全天的净光合速率均最高，而后随生育进程差异变小，通常上午较高，而在中午和下午较低。其旗叶Fv/Fm的变化趋势与净光合速率相似。燕大1817（上世纪40年代推出）的光合作用的午休现象较不明显，且在下午恢复较快，说明它可能具有一定的抗光抑制能力。孕穗至灌浆期是冬小麦籽粒形成和充实的关键时期，此时，叶片光合产物充足与否直接影响千粒重。进一步研究它们“源库”关系的结果表明，京冬8号“源库”关系协调，能够充分发挥“源“和“库”的潜力，且具有最高的收获指数、穗粒重和千粒重，而其它两个品种燕大1817和农大139都存在提高其品种产量潜力的限制因素。因此我们认为，高产品种的高产不仅因为其叶片具有较高的光合速率和较低的暗呼吸消耗，而且有较大的“库”容量和收获指数。 4. 当CO2浓度从360增加到720 µmol.mol-1时，单位叶面积的净光合速率和叶片的水分利用率 随CO2浓度升高而升高。但不同品种差异很大，京冬8号PN 和WUE最高，增加最多，分别提高了173 %和81 %;其次为农大139（上世纪70年代推出），燕大1817增加最少，分别提高了76 %和65 %。E随CO2 浓度的增加而提高;农大139和燕大1817的gs随CO2浓度的增大而减小，而京冬8号则增大。京冬8号和农大139旗叶胞间CO2浓度（Ci） 随CO2 浓度的增加而增大，而燕大1817 的Ci先增大，而后又急剧降低，且京冬8号的Ci最低，燕大1817 最高。在高CO2浓度下，京冬8号的光合速率显著高于其它两个品种，而Ci却低于其它两个品种，说明京冬8号的光合潜力高于其它两个品种。灌浆期高产品种京冬8号旗叶在田间不同自然光强下，净光合速率都是最高的（差异最大时，比燕大1817提高24.8 %）。因此，冬小麦光合作用的潜力，也在一定程度上得到改良。

Growth performance, recovery rate and fish yield of GIFT strain at various water depths under rice-fish culture systems

Effect of water depth on recovery rate, growth performance and fish yield of GIFT in the rice-fish production systems was studies in experimental plots of 123 m2 with a pond refuge of I meter deep which covered 10% of the total land area. Mortality rate of fish was very low ranging from 0.81-1.63%. However, at harvest, recovery rate ranged from 76.69-82.93% with the highest recovery at 11-15 em of water depth. Significantly the highest absolute growth (99.97) and specific growth rate (2.42%) were found at 21-25 cm water depth. The same treatment also produced significantly higher fish yield (909.76 kg/ha) although statistically similar to the fish yield (862.60 kg/ha) obtained at ll-15 em of water depth. Results also suggested that higher water depth can produce bigger fish but no significant effects of water depth was found on fish yield in the treatments 11-15 cm and 21-25 cm water depths of this experiment.

Duplication and independent selection of cell-wall invertase genes GIF1 and OsCIN1 during rice evolution and domestication

Background: Various evolutionary models have been proposed to interpret the fate of paralogous duplicates, which provides substrates on which evolution selection could act. In particular, domestication, as a special selection, has played important role in crop cultivation with divergence of many genes controlling important agronomic traits. Recent studies have indicated that a pair of duplicate genes was often sub-functionalized from their ancestral functions held by the parental genes. We previously demonstrated that the rice cell-wall invertase (CWI) gene GIF1 that plays an important role in the grain-filling process was most likely subjected to domestication selection in the promoter region. Here, we report that GIF1 and another CWI gene OsCIN1 constitute a pair of duplicate genes with differentiated expression and function through independent selection. Results: Through synteny analysis, we show that GIF1 and another cell-wall invertase gene OsCIN1 were paralogues derived from a segmental duplication originated during genome duplication of grasses. Results based on analyses of population genetics and gene phylogenetic tree of 25 cultivars and 25 wild rice sequences demonstrated that OsCIN1 was also artificially selected during rice domestication with a fixed mutation in the coding region, in contrast to GIF1 that was selected in the promoter region. GIF1 and OsCIN1 have evolved into different expression patterns and probable different kinetics parameters of enzymatic activity with the latter displaying less enzymatic activity. Overexpression of GIF1 and OsCIN1 also resulted in different phenotypes, suggesting that OsCIN1 might regulate other unrecognized biological process. Conclusion: How gene duplication and divergence contribute to genetic novelty and morphological adaptation has been an interesting issue to geneticists and biologists. Our discovery that the duplicated pair of GIF1 and OsCIN1 has experiencedsub-functionalization implies that selection could act independently on each duplicate towards different functional specificity, which provides a vivid example for evolution of genetic novelties in a model crop. Our results also further support the established hypothesis that gene duplication with sub-functionalization could be one solution for genetic adaptive conflict.

Effect of stocking density on growth and yield of GIFT tilapia under rice-fish production system

The study was conducted at the Central Experimental Station, Philippine Rice Research Institute, Maligaya, Science City of Munoz, Nueva Ecija, Philippines during the wet season to determine the suitable stocking density(s) for better growth and yield of fish under rice-fish production systems. Recovery rate of GIFT tilapia in different stocking densities ranged from 75.74 to 83.47%. Among different treatments, rice +5,000 fingerlings/ha and rice +10,000 fingerlings/ha resulted in the highest recovery rate of 83.33% and 83.47%, respectively. The lowest recovery rate of 75.75% was obtained from rice +20,000 fingerlings/ha, but similar to that was obtained (78.56%) from rice +15,000 fingerlings/ha. Significantly higher rate of gain in body weight and that of specific growth rate were recorded in the treatment from rice +5,000 fingerlings/ha, while other treatments resulted in similar absolute and specific growth rate. Fish yield increased significantly with relatively higher stocking densities, but higher densities produced maximum number of smaller fishes and also lower recovery rate.

Introducing tilapia (GIFT) with shrimp (Penaues monodon) in brackishwater rice-shrimp system: impact on water quality and production

Mixed rearing of tilapia (Genetically Improved Farmed Tilapia, GIFT) with shrimp (Penaeus monodon) in brackishwater rice-shrimp system was assessed for its impact on dry season's shrimp production. The experiment was conducted in pre-selected farmer's field located at Paikgacha Upazila of Khulna district and designed with three different densities (treatment) of GIFT, viz, 0.3, 0.4 and 0.5/m² with a constant stocking density of shrimp at 3/m². Each treatment had three replications. There had a set of control treatment where GIFT was not stocked. Results of the experiment revealed that tilapia did not exert any significant effect (p>0.05) on the water quality variables, even on survival rate of shrimp (p>0.05) under farm level condition in rice-shrimp rotational system, but a density dependent negative effect (P<0.05) on the growth of shrimp led apparently lower production rate of shrimp. Though tilapia provided the major augment of total production (p<0.05) in the respective treatments than in monoculture of shrimp, but not that of the economic return. However, economic loss due to sudden shrimp crop failure might be partially minimized by the tilapia crop.