水稻窄卷叶突变体nrl7的鉴定与基因定位

叶片的形态是理想株型的重要性状, 叶片适度卷曲能提高水稻(Oryza sativa)群体的光能利用率, 研究控制水稻叶片形态的相关基因能够进一步丰富株型理论。该研究在粳稻品系C275的群体中发现了1株自然变异的窄卷叶突变体nrl7(narrow rolled leaf 7)。与野生型相比, 突变体的叶片变窄且向内卷曲; 该突变体叶片连接中脉的泡状细胞严重变形, 中脉与小叶脉之间的维管束数量均减少至1个。此外, 突变体nrl7的株高、实粒数和实粒重均降低或减少, 分别为野生型的88.46%、69.77%和68.98%, 差异达极显著水平。叶片卷曲导致单叶光合速率减弱, 与野生型相比, 突变体的光合速率降低了17%, 达极显著水平。突变体nrI7叶片的气孔导度、胞间CO₂浓度和蒸腾速率则与野生型相比无明显变化。利用图位克隆的方法将目的基因定位于水稻第3染色体短臂上的分子标记RM5444和MM1300之间, 物理距离约为185.14 kb。研究结果为该基因的克隆和进一步的功能分析奠定了基础。     

一个显性卷叶突变体z2的遗传分析与精细定位

叶片的适度卷曲对水稻理想株型育种具有重要意义。在水稻T-DNA插入突变体库中获得一个叶片外卷突变体z2,突变体表型出现在分蘖期;与野生型相比,农艺性状无明显差异,光合作用效率高于野生型。对突变体和野生型的石蜡切片研究表明,突变体叶片泡状细胞数量(8-9个)明显多于野生型(4-5个)。z2卷叶性状遗传稳定,由一对显性核基因控制。以z2纯合突变体为母本,籼稻Dular为父本进行杂交构建F2代定位群体,利用图位克隆的方法,将该基因初定位于水稻第2号染色体的In Del1812与In Del1870标记之间,物理距离为580 kb。     

一个水稻内颖退化突变体的形态特征及基因的精确定位

水稻产量和品质受花器官发育的直接影响,因此对水稻颖花发育机理的研究将有助于水稻产量提高和品质的改良。文章利用60Coγ射线辐照亲本8PW33(籼稻背景)获得一个性状能稳定遗传的内颖退化突变体(编号:MU102),并对其农艺性状和花器官进行了观察和分析。结果显示,相对于野生型,该突变体的株高、每穗总粒数及剑叶宽均显著增加,而结实率则显著降低,差异均达显著水平。解剖镜下观察表明,该突变体内颖退化,外颖弯曲呈现镰刀状,其余器官与野生型表型基本一致。扫描电镜观察显示,突变体与野生型叶片维管束的结构组成以及外颖表皮细胞组成、排列均正常,没有明显差异;与野生型相比,突变体内颖表皮细胞排列较为紧密,推测可能是内颖收缩退化导致的。遗传分析显示该突变性状是由隐性单基因控制,并命名为pd2。利用实验室现有的SSR分子标记将PD2基因定位于水稻第9号染色体上,通过进一步扩大群体和开发新的Indel标记,将PD2基因定位在2个Indel标记之间,两者间的物理距离大约是82 kb。在该物理区间内有一个已经克隆的内颖发育基因REP1,经过测序和比对分析,推测REP1与PD2为等位基因。     

黄瓜矮生突变体C1056的茎解剖结构及其生理特性分析

该研究以黄瓜矮生突变体C1056和野生型CCMC为材料,对其主要生理特性、叶绿体超微结构以及茎显微结构进行了观察、测定和比较分析,以探讨黄瓜株高调控机理并挖掘新的矮化种质,为黄瓜的矮化育种提供依据。结果显示:(1)突变体C1056的株高较野生型极显著变矮,且叶色加深、叶脉加粗、叶尖内卷、叶片皱缩,但茎粗、节间数与野生型无显著差异,而节间长度极显著低于野生型。(2)茎横切显微结构显示,突变体的维管束数量与野生型无显著差异,但导管直径缩小;纵切结果显示,突变体茎节间细胞长度变短,细胞变小,细胞数目略有补偿。(3)与野生型相比,突变体的叶绿素和类胡萝卜素含量均有不同程度的下降,叶绿素/类胡萝卜素和叶绿素a/b的比值明显增高。(4)突变体叶绿素荧光各参数与野生型相比无明显变化;突变体的净光合速率较野生型降低8%,气孔导度、蒸腾速率较野生型分别提高15%和10%,但差异均不显著,而胞间CO2浓度显著高于野生型。(5)透射电镜观察结果发现,与野生型相比,突变体的叶肉细胞比较小,叶绿体所占细胞面积明增大,且叶绿体形状为半圆形和纺锤形,部分非正常结构的叶绿体的大部分基质、基粒片层未完全分化且不清晰,垛叠不整齐。研究表明,黄瓜矮生突变体C1056的矮化主要因其节间长度缩短以及细胞变小所致,且突变体的叶绿体结构受到一定程度的影响,但并未明显影响其光合能力。     

拟南芥干旱相关突变体的远红外筛选及基因克隆

干旱胁迫是影响植物生长发育的主要限制因素之一。到目前为止, 许多研究都仅关注于植物对干旱反应的信号转导网络, 而对其中一些很重要的中间成分却知之甚少。保卫细胞定位于植物叶片的表皮中, 控制二氧化碳的吸收以及水分的散失, 已经成为一种高度特化的细胞体系, 可用来研究植物早期干旱信号转导机制。控制气孔的开度在提高植物的抗旱性方面具有重要意义。通过使用远红外热成像仪检测植物叶片表面温度的微小差异, 我们成功地筛选并获得了拟南芥(Arabidopsis thaliana)干旱敏感突变体doi1。在干旱胁迫条件下, 该突变体表现为叶面温度低于野生型, 且失水率比野生型高。利用TAIL-PCR技术成功克隆到该突变体基因NCED3, 并利用RT-PCR方法验证了TAIL-PCR结果的可靠性。     

拟南芥叶片数目变化突变体对营养生长时相转变的影响

拟南芥(Arabidopsis thaliana)的营养生长可以分为2个阶段: 幼龄期与成熟期。由幼龄期向成熟期的转变(VPC)与叶片的形态学特征、茎顶端分生组织(SAM)形状、远轴面表皮毛的出现以及SPL家族转录因子表达水平的变化相关。研究表明, 造成这种转变的信号来源于叶原基。该研究利用2种莲座叶数目改变了的突变体和对野生型切除叶片的方法, 分析了叶片数目对VPC的影响。结果表明, 莲座叶数目的减少推迟了VPC的发生; 而莲座叶数目增多突变体amp1-1并未使VPC的发生提前, 推测叶源信号的产生受到了光合作用的影响。     

一个大豆理想株型突变体it1的表型和生理鉴定

突变体是基因功能研究和品种改良的重要材料。本研究对一个中品661 EMS诱变的株型突变体(it1)进行了表型和生理鉴定,旨在为该突变体的利用提供参考。结果表明:与野生型相比,突变体株型紧凑,节间缩短,叶片变小呈深绿色且皱缩;突变体高度降低为野生型的2/3,但节间数目与野生型无显著差别,说明it1株高降低是由每个节间长度缩短造成的,与节间数目无关;突变体的分枝数、荚数、粒数、叶柄长度及夹角、百粒重等产量性状均显著或极显著低于野生型。与野生型相比,突变体叶片叶绿素相对含量和木质素的含量显著高于野生型。本研究结果为控制突变相关基因的定位、图位克隆和功能分析以及育种利用提供了优良种质和理论依据。     

水稻无蜡质叶片突变体wcl1的图位克隆

从水稻T-DNA插入突变体库中筛选获得1份叶片表皮无蜡质的突变体wcl1(Wax Crystal-Sparse Leaf 1),突变体wcl1有如下主要特征:一是突变体叶片角质层蜡质减少,二是突变体的干旱敏感性高于野生型。通过图位克隆技术,克隆了wcl1基因,其编码酮酯酰辅酶A(LOC_OS09g25850),在突变体中LOC_OS09g25850基因的第10个外显子处鸟嘌呤(G)突变为胸腺嘧啶(T)导致转录提前终止,经分析表明突变体wcl1是一个wsl2基因的等位突变体。     

水稻光敏色素A和B的突变对气孔发育和OsAQP基因表达的影响

OsAQP是在水稻叶片保卫细胞中高表达的液泡膜型水通道基因,为研究该基因在水稻发育过程中的表达与光敏色素光信号通路的关系,观察统计了日本晴、光敏色素突变体phyA和phyB 3个水稻品种的生长发育特征,比较了开花时间、叶片气孔密度、气孔器长等指标,并采用半定量RT-PCR以及实时定量PCR技术检测OsAQP基因在3种材料不同时期叶片中的表达特性。结果显示,光敏色素突变体phyB叶片的气孔密度、气孔器长度均低于同时期的日本晴和光敏色素突变体phyA水稻,说明光敏色素B及其相关信号可能与气孔的发育关系密切;表达模式分析显示,OsAQP基因在3个水稻品种的叶片中具有不同的表达特性,并伴随发育时期呈现下降的趋势。本研究结果说明水稻光敏色素B以及相关信号不仅与气孔的发育有关,而且可能通过与光敏色素A及相关信号通路共同调节OsAQP基因的表达,参与气孔开闭的调节。     

拟南芥干旱突变体远红外成像技术的筛选和特性鉴定

利用化学诱变剂甲基磺酸乙酯(EMS)对模式植物拟南芥(Arabidopsis thaliana)进行化学诱变获得突变体筛选群体。在干旱胁迫下,以叶片的温度差异为筛选指标,利用远红外成像技术进行突变体的筛选,获得了对干旱不敏感突变体dri1(drought-insensitive 1)和敏感突变体drs1(drought-sensitive 1)。实验结果表明dri1和drs1为单基因隐性突变,气孔密度同野生型无差异,而叶片温度、气孔开度和叶片失水率则有明显改变。在MS培养基上的种子萌发实验表明在ABA、甘露醇和NaCl胁迫下dri1萌发率要比野生型高,而drs1则比野生型低。对突变基因的研究有待进一步进行。     

A detailed analysis of the leaf rolling mutant sll2 reveals complex nature in regulation of bulliform cell development in rice (Oryza sativa L.)

Bulliform cells are large, thin‐walled and highly vacuolated cells, and play an important role in controlling leaf rolling in response to drought and high temperature. However, the molecular mechanisms regulating bulliform cell development have not been well documented. Here, we report isolation and characterisation of a rice leaf‐rolling mutant, named shallot‐like 2 (sll2). The sll2 plants exhibit adaxially rolled leaves, starting from the sixth leaf stage, accompanied by increased photosynthesis and reduced plant height and tiller number. Histological analyses showed shrinkage of bulliform cells, resulting in inward‐curved leaves. The mutant is recessive and revertible at a rate of 9%. The leaf rolling is caused by a T‐DNA insertion. Cloning of the insertion using TAIL‐PCR revealed that the T‐DNA was inserted in the promoter region of LOC_Os07 g38664. Unexpectedly, the enhanced expression of LOC_Os07 g38664 by the 35S enhancer in the T‐DNA is not responsible for the leaf rolling phenotype. Further, the enhancer also exerted a long‐distance effect, including up‐regulation of several bulliform cell‐related genes. sll2 suppressed the outward leaf rolling of oul1 in the sll2oul1 double mutant. We conclude that leaf rolling in sll2 could be a result of the combined effect of multi‐genes, implying a complex network in regulation of bulliform cell development.     

Rolling-leaf14 is a 2OG-Fe (II) oxygenase family protein that modulates rice leaf rolling by affecting secondary cell wall formation in leaves

As an important agronomic trait, leaf rolling in rice (Oryza sativa L.) has attracted much attention from plant biologists and breeders. Moderate leaf rolling increases the amount of photosynthesis in cultivars and hence raises grain yield. Here, we describe the map-based cloning of the gene RL14, which was found to encode a 2OG-Fe (II) oxygenase of unknown function. rl14 mutant plants had incurved leaves because of the shrinkage of bulliform cells on the adaxial side. In addition, rl14 mutant plants displayed smaller stomatal complexes and decreased transpiration rates, as compared with the wild type. Defective development could be rescued functionally by the expression of wild-type RL14. RL14 was transcribed in sclerenchymatous cells in leaves that remained wrapped inside the sheath. In mature leaves, RL14 accumulated mainly in the mesophyll cells that surround the vasculature. Expression of genes related to secondary cell wall formation was affected in rl14-1 mutants, and cellulose and lignin content were altered in rl14-1 leaves. These results reveal that the RL14 gene affects water transport in leaves by affecting the composition of the secondary cell wall. This change in water transport results in water deficiency, which is the major reason for the abnormal shape of the bulliform cells.     

浅绿叶水稻突变体的特性与遗传分析

在簇生稻与粳稻日本晴杂交后代F8世代中发现一个能稳定遗传的浅绿叶色突变体(pgl,pale green leaf)。与野生型相比,突变体pgl株高、剑叶宽、主穗粒数和千粒重均显著下降。从幼苗开始,突变体pgl叶片都表现为浅绿色。在苗期和抽穗期突变体叶片的叶绿素含量都极显著低于野生型,其中叶绿素b的含量极低,仅为0.002~0.003 mg/g,突变体pgl表现为叶绿素b的缺失。在分蘖期与齐穗期,突变体pgl的净光合作用速率与野生型相当。叶绿体超微结构观察表明突变体pgl的叶绿体基质片层和堆叠层数较少。遗传分析发现浅绿叶色表型由一对隐性细胞核基因控制。采用BSA法,通过全基因组SNP芯片分析,浅绿叶色基因pgl被定位于水稻第10染色体上的22806614~23000408区间,与R1022900951CA标记紧密连锁。突变体pgl与另外3个浅绿叶色突变体(W1、Y406和Y45)的等位性检测结果表明浅绿叶色基因pgl与突变体W1的浅绿叶色基因为等位基因。对pgl的候选基因LOC_Os10g41780(叶绿素a加氧酶,chlorophyll a oxygenase)的序列比对发现,在突变体pgl中,LOC_Os10g41780在第2507和3136位碱基处分别发生1个T的缺失和T变成C的替换。分析发现,第3136位碱基位于第9外显子内,其碱基T变C的替换导致其编码的精氨酸变成色氨酸。本研究鉴定的突变体pgl和W1为LOC_Os10g41780的新变异,为阐明浅绿叶色形成的分子机理和光合作用机理的研究提供了特异资源。     

<Emphasis Type="Italic">NARROW LEAF 7</Emphasis> controls leaf shape mediated by auxin in rice

Elucidation of the genetic basis of the control of leaf shape could be of use in the manipulation of crop traits, leading to more stable and increased crop production. To improve our understanding of the process controlling leaf shape, we identified a mutant gene in rice that causes a significant decrease in the width of the leaf blade, termed narrow leaf 7 (nal7). This spontaneous mutation of nal7 occurred during the process of developing advanced backcrossed progeny derived from crosses of rice varieties with wild type leaf phenotype. While the mutation resulted in reduced leaf width, no significant morphological changes at the cellular level in leaves were observed, except in bulliform cells. The NAL7 locus encodes a flavin-containing monooxygenase, which displays sequence homology with YUCCA. Inspection of a structural model of NAL7 suggests that the mutation results in an inactive enzyme. The IAA content in the nal7 mutant was altered compared with that of wild type. The nal7 mutant overexpressing NAL7 cDNA exhibited overgrowth and abnormal morphology of the root, which was likely to be due to auxin overproduction. These results indicate that NAL7 is involved in auxin biosynthesis. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under accession numbers AB354301 and AB354302.     

CLD1/SRL1 modulates leaf rolling by affecting cell wall formation,epidermis integrity and water homeostasis in rice

Leaf rolling is considered as one of the most important agronomic traits in rice breeding. It has been previously reported that SEMI‐ROLLED LEAF 1 (SRL1) modulates leaf rolling by regulating the formation of bulliform cells in rice (Oryza sativa); however, the regulatory mechanism underlying SRL1 has yet to be further elucidated. Here, we report the functional characterization of a novel leaf‐rolling mutant, curled leaf and dwarf 1 (cld1), with multiple morphological defects. Map‐based cloning revealed that CLD1 is allelic with SRL1, and loses function in cld1 through DNA methylation. CLD1/SRL1 encodes a glycophosphatidylinositol (GPI)‐anchored membrane protein that modulates leaf rolling and other aspects of rice growth and development. The cld1 mutant exhibits significant decreases in cellulose and lignin contents in secondary cell walls of leaves, indicating that the loss of function of CLD1/SRL1 affects cell wall formation. Furthermore, the loss of CLD1/SRL1 function leads to defective leaf epidermis such as bulliform‐like epidermal cells. The defects in leaf epidermis decrease the water‐retaining capacity and lead to water deficits in cld1 leaves, which contribute to the main cause of leaf rolling. As a result of the more rapid water loss and lower water content in leaves, cld1 exhibits reduced drought tolerance. Accordingly, the loss of CLD1/SRL1 function causes abnormal expression of genes and proteins associated with cell wall formation, cuticle development and water stress. Taken together, these findings suggest that the functional roles of CLD1/SRL1 in leaf‐rolling regulation are closely related to the maintenance of cell wall formation, epidermal integrity and water homeostasis.