用Rim2超级家族分子指纹鉴别杂交水稻及预测杂种优势

选用5对Rim2引物对21份籼稻和20份粳稻材料进行了DNA指纹扩增,共扩增出38条谱带,其中多态性谱带26条,多态性水平为69.64%;粳稻平均多态性水平为56.67%,明显高于籼稻。根据Nei’s遗传距离计算获得的聚类树状图表明,参试21份籼稻材料聚为6组,20份粳稻材料聚为7组。亲缘关系分析表明,Rim2分子指纹可以区分多数的籼稻或粳稻材料,且显示出材料的遗传特征。考察部分籼稻和粳稻杂交组合的产量对照优势与双亲间遗传距离的关系,发现杂交粳稻的遗传距离与杂交优势表现出相关性,而杂交籼稻无此相关性。     

回交高代选择导入系的纹枯病抗性与抗旱性的遗传重叠研究

利用来自抗旱性较好的供体亲本（BG300和BG304）、具有两种遗传背景（IR64和特青）的水稻高代回交（BC2）抗旱选择导入系，通过人工接种的方法鉴定纹枯病抗性，考察纹枯病抗性与抗旱性之间可能存在的遗传重叠。通过与受体亲本的纹枯病抗性表现比较发现，具有特青背景的抗旱选择导入系倾向于纹枯病抗性的降低，而IR64背景的抗旱选择导入系则倾向于纹枯病抗性的增强。基于基因型与表型的方差分析共鉴定到6个与纹枯病抗性相关的位点，其中QSbr6在不同供体和背景的两个群体中分别检测到，而QSbr10则在同一供体的两个遗传背景下均检测到；有3个位点（QSbr6、QSbr8和QSbr10）与同一群体中检测到的抗旱性位点位置相近，很可能是两种抗性重叠的遗传基础。尽管方差分析的方法在选择导入系的非选择目标性状相关位点的鉴定中存在相当程度的偏低估计，本研究所检测到的纹枯病抗性位点，特别是那些与抗旱性重叠位点的分子标记以及相关的抗性株系仍将为进一步的水稻纹枯病抗性和抗旱性的多抗性育种和深入的遗传重叠研究提供有用的信息和材料。     

水稻发育温度效应的非线性模型及其应用

水稻完成某一生育期所需的有效积温常因环境而异，表明广泛应用的线性积温法需要修正。分析表明，日最低温度比日最高温度效应更显著，说明发育速率与温度间呈非线性关系。于是，本文提出了一个具有较好预测性的非线性温度效应模型。它较其他非线模型的优点在于其参数的生物学意义清晰。对积温的不稳定性，它解释为：有效积温     

水稻亲本遗传分化程度与籼粳杂种优势的关系

本文利用两套材料,即来自一个籼／粳交（圭６３０／０２４２８）的双单倍体（ＤＨ）系和另一组由多种类型的籼、粳组成的对照组,从分子水平上研究了水稻亲本的遗传分化程度。在此基础上探讨了亲本的遗传分化程度与籼粳杂种优势的关系。两套测交Ｆ１群体的结果一致表明,亲本遗传分化程度对穗数和千粒重的影响相对较小,但是对每穗结实粒数和结实率这两项体现育性的指标影响较大。当亲本遗传分化综合指数ＴＤｊ值为２０￣２５时,育     

烟酰胺腺嘌呤二核苷酸(NAD)合成途径和水稻叶片早衰

叶片是植物进行光合作用的主要场所,其衰老由内源遗传发育信号和外界环境胁迫所启动,是一个非常复杂有序的调控过程。烟酰胺腺嘌呤二核苷酸(nicotinamide adenine dinucleotide,NAD)是脱氢酶的辅酶,在糖酵解、糖异生、三羧酸循环以及呼吸链等代谢中发挥着不可替代的作用。最新研究表明,水稻NAD生物合成参与调控沉默信息调控因子Sirtuins的生物活性、组蛋白H3K9去乙酰化、植物激素茉莉酸(JA)和叶片衰老。本文综述了有关水稻叶片衰老的细胞生理特征、Sirtuins酶活、NAD生物合成以及水稻早衰的OsSRT1-NAD调控途径和OsSRT1-Me OH-JA调控途径,以期阐明水稻叶片衰老的分子机理及其调控途径,为高产育种提供相应的理论参考。     

水稻紫鞘染色体片段代换系Z519的鉴定及PSH1候选基因分析

花青素是广受人们喜爱的植物色素,在食品加工、杂种纯度鉴定中具有重要的作用。本研究鉴定了一个以日本晴为受体、优良紫鞘恢复系R225为供体亲本的紫鞘水稻染色体片段代换系Z519。Z519共含有16个代换片段,分布于除第10染色体外的其他11条染色体,平均长度为6.85 Mb。Z519在芽鞘3 mm时鞘尖呈现紫色,其后在叶鞘、叶缘、茎维管束和柱头等部位出现紫色线条,而日本晴各部位均为绿色。Z519叶鞘中花青素含量极显著高于日本晴,剑叶中没有显著差异。与受体日本晴相比,Z519的株高显著降低,千粒重、主穗总粒数和实粒数显著增加,有效穗数、主穗长和结实率无显著差异。进一步以日本晴与Z519杂交产生的F1和F2群体对紫鞘基因进行了遗传分析和分子定位。该紫鞘表型受显性单基因控制,位于第1染色体In Del标记L03和SSR标记L01之间37.8 kb的区域,被命名为PSH1。对该区间进行候选基因预测和测序,Z519在一个编码质体ATP/ADP转运蛋白的LOC_Os01g45910基因第一外显子的第238~252碱基的GTG重复区又多插入了GTG 3个碱基,导致增加了一个甘氨酸。q RT-PCR结果进一步表明其表达量在Z519中明显降低,初步确定LOC_Os01g45910是PSH1的候选基因。该研究为PSH1调控花青素的分子机制奠定了良好基础。     

水稻ygl80黄绿叶突变体的遗传分析与目标基因精细定位

通过化学诱变获得遗传稳定的水稻黄绿叶突变体ygl80。与野生型亲本10079相比,ygl80突变体在苗期和孕穗期叶片叶绿素分别下降76.64%和54.59%,类胡萝卜素含量分别下降53.85%和41.18%,成熟期株高、每株有效穗数、每穗着粒数、穗长和千粒重分别减少14.8%、16.5%、21.3%、9.1%和7.4%。遗传分析表明,ygl80的突变性状由1对隐性核基因控制。利用(ygl80/浙辐802) F₂作为定位群体, 将突变基因定位在第5染色体长臂InDel标记C2和C3之间,遗传距离分别为0.24 cM 和0.39 cM,两标记之间的物理距离约为90 kb,此区间内包含11个预测基因。基因组序列分析发现,ygl80突变体在编码叶绿素合酶的YGL1(LOC_Os05g28200)基因编码区第5027碱基处(位于第14外显子),碱基C突变为碱基T,使编码蛋白序列第348位的脯氨酸(Pro)突变成亮氨酸(Leu)。该基因是已报道的水稻ygl1黄绿叶突变基因的等位基因。ygl80突变体在整个生育期都表现为黄绿叶,而ygl1突变体在苗期叶片黄化,中期慢慢转绿,后期叶色以及总叶绿素和类胡萝卜素的含量接近野生型,这可能是YGL1基因编码的叶绿素合酶蛋白的氨基酸不同突变位点造成的。     

剪根稻苗移栽后叶鞘3H-同化物的运转分配特点

用3H同位素示踪方法研究了剪根稻苗移栽后叶鞘同化物的运转分配特点。结果表明,剪根处理稻苗各器官干重均低于对照,而3H-同化物的比活度却高于对照,标记后10d多数器官高出对照1倍左右,分蘖高2倍,新根高4倍。剪根处理发根节和新根的放射性总活度和3H-同化物的分配比例均高于对照,意味着其新根的发生更加依赖于主茎叶鞘物质输出。     

Methane emission from two Indian soils planted with different rice cultivars

In a greenhouse study, methane emissions were measured from two diverse Indian rice-growing soils planted to five rice cultivars under similar water regimes, fertilizer applications and environmental conditions. Significant variations were observed in methane emitted from soils growing different cultivars. Total methane emission varied between 8.04 and 20.92gm^–2 from IARI soil (Inceptisol) and between 1.47 and 10.91gm^–2 from Raipur soil (Vertisol) planted to rice. In all the cultivars, emissions from IARI soil were higher than from Raipur soil. The first methane flux peak was noticed during the reproductive phase and the second peak coincided with the grain-ripening stage of the rice cultivars. Received: July 7, 1996     

Evolution of dinitrogen and nitrous oxide from the soil to the atmosphere through rice plants

Summary It is commonly assumed that a large fraction of fertilizer N applied to a rice (Oryza sativa L.) field is lost from the soil-water-plant system as a result of denitrification. Direct evidence to support this view, however, is limited. The few direct field, denitrification gas measurements that have been made indicate less N loss than that determined by ¹⁵N balance after the growing season. One explanation for this discrepancy is that the N₂ produced during denitrification in a flooded soil remains trapped in the soil system and does not evolve to the atmosphere until the soil dries or is otherwise disturbed. It seems likely, however, that N₂ produced in the soil uses the rice plants as a conduit to the atmosphere, as does methane. Methane evolution from a rice field has been demonstrated to occur almost exclusively through the rice plants themselves. A field study in Cuttack, India, and a greenhouse study in Fort Collins, Colorado, were conducted to determine the influence of rice plants on the transport of N₂ and N₂O from the soil to the atmosphere. In these studies, plots were fertilized with 75 or 99 atom % ¹⁵N-urea and ¹⁵N techniques were used to monitor the daily evolution of N₂ and N₂O. At weekly intervals the amount of N₂+N₂O trapped in the flooded soil and the total-N and fertilized-N content of the soil and plants were measured in the greenhouse plots. Direct measurement of N₂+N₂O emission from field and greenhouse plots indicated that the young rice plant facilitates the efflux of N₂ and N₂O from the soil to the atmosphere. Little N gas was trapped in the rice-planted soils while large quantities were trapped in the unplanted soils. N losses due to denitrification accounted for only up to 10% of the loss of added N in planted soils in the field or greenhouse. The major losses of fertilizer N from both the field and greenhouse soils appear to have been the result of NH₃ volatilization.