水稻花器官突变体apl (abnormal palea and lodicules) 的表型分析与基因初定位

水稻(Oryza sativa)是重要的粮食作物, 其花器官的正常起始及形态建成直接影响水稻的产量。为了深入分析水稻小花发育的调控机理, 从已构建的水稻EMS诱变突变体库中筛选获得了一个花器官异常发育的突变体apl (abnormal palea and lodicules)。与野生型相比, apl突变体小花的内稃膨大, 浆片伸长或转换成稃状结构, 雄蕊数目减少, 表明APL基因可能参与调控水稻内稃、浆片和雄蕊等多轮花器官属性的建成。遗传学分析表明, 该突变体性状受1个隐性单基因控制。通过图位克隆, 将APL基因初步定位于1号染色体上。该工作为深入研究APL基因在水稻花器官形态建成中的作用机制奠定了基础。     

一个新的水稻花器官数目突变体fon(t)的鉴定及分析

水稻花器官数目突变体 fon(t)是在单倍体与二倍体的杂交 F2代发现的,经过多代种植,已稳定遗传。以 fon(t)为父本,以日本晴、93?11 和 R527 为母本配制杂交组合进行遗传分析,根据 F2代表型及χ2测验结果表明,该突变体的性状是由单隐性基因控制的。因为对花器官数目突变体曾有报道如 fon1、fon2 和 fon3,所以该突变体暂定名为 fon(t)。该突变体导致内外稃开裂,花器官外露;雄蕊和雌蕊的数目均增多,雄蕊一般 6~9 枚,雌蕊 1~2 枚;浆片同源转化为类内稃的结构;个别的花器官中还出现花丝上伸出类柱头的结构,浆片上部同源转化为类柱头或者类雄蕊的结构。研究结果表明,fon(t)基因可能影响水稻第三、四轮花器官的数目以及第二轮浆片的发育。     

绵竹花形态结构及雌、雄配子体的发育研究

对绵竹（Bambusa intermedia Hsueh et Yi）花器官的形态结构进行解剖观察,其花序属于无限花序,每个假小穗基部都生有潜伏芽。小花类型为开放型,基本结构包括内、外稃各1枚,浆片3枚,雄蕊6枚,雌蕊1枚,柱头羽毛状三分叉。小花中各结构的发育顺序为外稃→内稃→浆片→雄蕊→雌蕊。小穗中小花的发育顺序是由基部向顶部。子房1室,胚珠倒生,侧膜胎座,双珠被。药壁具4层细胞,有大量的败育情况出现。     

水稻颖花开裂SRS突变体的鉴定

利用扫描电镜观察了水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）颖花开裂突变体ＳＲＳ（ｓｐｌｉｔ ｒｉｃｅ ｓｐｉｋｅｌｅｔ）花器官形态发生过程,该突变体表现为内外稃变软变长,不抱合,外稃基部又着生一颖花,浆片呈稃片状,但是雌雄蕊着生位置和形态表现正常。利用ＳＲＳ突变体为父本,“窄叶青８号”为母本配制杂交组合,其Ｆ２代群体中正常与突变植株的分离比例为３：１,表明该突变性状是由单隐性基因控制的。作为对照,同     

一份条斑和颖花异常水稻双突变体的形态特征和细胞学观察

在水稻遗传转化过程中发现一个不含外源基因的条斑和颖花异常的双突变体。该突变体的茎、叶、穗出现条斑。在分蘖盛期,一些叶片开始分岔或卷曲;花器官数目增多,表现为多内外稃,叶片状浆片,或浆片增大,雌雄蕊增多,颖花开裂。透射电镜对叶片白色组织细胞超微结构观察,发现细胞壁内陷,质体结构异常,不能发育出正常叶绿体所具有的片层和类囊体。叶绿素总含量和净光合速率明显低于野生型。突变体绿色组织部分中的细胞生长正常,但细胞较大。利用扫描电镜对花器官形态发生过程进行观察,雄蕊原基发育严重不同步,原基大小也不一样;心皮原基较小。     

融安黄竹小穗和小花的形态发育

运用扫描电镜对融安黄竹Dendrocalamus ronganensis的小穗和小花的发生发育及形态结构进行了研究。其小穗的发育过程是: 小穗原基→第一颖片原基→第二颖片原基→第一朵小花的外稃原基→第一朵小花原基→第二朵小花的外稃原基→第二朵小花原基。小穗为由2个颖片和1-2朵小花组成的假小穗。其小花发育的过程是: 内稃原基→雄蕊原基→雌蕊原基。内稃在发生上由彼此独立的两个突起形成, 随着发育逐渐愈合。观察结果支持内稃是双起源的说法。雄蕊原基近两轮发生。雌蕊原基由小花原基的中央部分直接发育而成。在小花的发育过程中, 未观察到鳞被原基的发生。该种的小花是无花被的, 结构较为简化, 为外稃和内稃包裹的雄蕊和雌蕊组成的结构。与近缘类群做比较, 探讨了小穗和小花在竹亚科中的演化。     

FaesAP2B基因在甜荞长雌蕊长雄蕊突变体lpls的表达分析

为弄清甜荞（Fagopyrum esculentum Moench.）长雌蕊长雄蕊突变体lpls花和籽粒发育调控的分子机制,从甜荞中克隆出1个长1 788 bp的AP2同源基因的cDNA序列,命名为FaesAP2B（GenBank登录号为MK290847.1）。序列结构分析表明：FaesAP2B基因包含1个长1 380 bp的完整开放阅读框（Open Reading Frame,ORF）,编码1个由459个氨基酸残基组成的AP2/ERF家族转录因子,该转录因子含有2个高度保守的AP2结构域,第1个AP2结构域前还存在1个由10个氨基酸残基组成的核定位信号区。用qPCR检测FaesAP2B基因在甜荞lpls突变体根、茎、幼叶、花被片、雄蕊、雌蕊以及发育4 d的果实共7种器官中表达的组织特异性显示：FaesAP2B在甜荞突变体lpls营养组织和生殖结构中均有表达,但其在花器官和果实等生殖结构中的表达量明显高于营养组织,且在雄蕊中的表达量最高,极显著高于其在其他6种组织中的表达量（LSD,P<0.01）,同时,FaesAP2B在花被片、雌蕊和发育4 d的果实中的表达量均极显著高于其在根、茎和叶等营养器官中的表达量（LSD,P<0.01）,但该基因在其根、茎、叶间的表达量无显著性差异。推测该基因可能主要参与调控甜荞lpls突变体花和果实的发育。     

蝴蝶兰PhalPI基因的克隆及在花器官突变体中的表达分析

为深入研究兰科植物花器官发育的调控机理,从蝴蝶兰花瓣中克隆了一个B类MADS-box转录因子PhalPI（GenBank登录号为KY020416）。序列分析表明,该基因的cDNA全长为944 bp,含完整的开放阅读框,可编码210个氨基酸,属于BGLO/PI蛋白家族,与蝴蝶兰属的PhPI10和PeMADS6基因关系最近;表达模式分析表明,PhalPI基因在生殖器官中表达,在营养器官中不表达,在授粉后的子房中,该基因的表达水平降低。在5种花器官突变体中,PhalPI基因在萼片唇瓣化突变体的萼片和蕊柱中表达水平明显升高;在雄蕊花瓣化突变体的萼片和侧瓣中表达水平降低,在其唇瓣和蕊柱中显著升高;在侧瓣合柱化突变体的蕊柱中,PhalPI基因的表达也发生了显著升高;PhalPI基因表达的改变与花器官形态的突变相关;而在侧瓣唇瓣化和侧瓣花药化突变体中,PhalPI基因的表达水平没有变化。推测该基因在决定蝴蝶兰侧瓣和唇瓣的发育中起重要的调控作用。     

水稻长颖壳突变体的形态发生、解剖结构观察及其遗传鉴定

长颖壳花器官突变体从野生稻(Oryza nivara Sharma et Shastry)和栽培稻(Oryza sativa subsp. indica Kato)杂交后代材料中获得。该突变体的内外稃变长、呈叶状,且顶端表现不同程度的开裂;每朵颖花的雄蕊1~10枚不等;雌蕊1~3枚不等;子房上柱头1~5个不等;有的颖花形成雄蕊/雌蕊嵌合体;子房处常附有瘤状物;此突变体结实率为18.2%;花粉可育率为62.46%。利用扫描电镜观察了该突变体花器官形态发生过程,并经遗传分析鉴定该突变性状由单隐性基因(暂命名为lh)控制。本文讨论了lh基因和以前鉴定的其他突变体基因之间的关系,通过表型分析推测,突变体基因可能影响花器官数目同时具有拟南芥B类基因的部分功能。     

新小竹花形态结构及雌、雄配子体的发育研究

新小竹(Neomicrocalamus prainii)是一种小型攀援竹类,笋秆两用型竹种。该研究通过形态观察和石蜡切片的方法对新小竹花器官形态及解剖结构特征进行观察与描述,为研究竹类植物的生殖生物学提供新的理论信息。结果显示:(1)新小竹的花序为无限花序,没有小穗柄,成熟小穗平均长度为2.98 cm;每个小穗约有4～6朵小花,其中3～5朵为可育小花,顶端均有1朵不育小花;小穗基部有2～4个苞片;小穗轴每节长约0.52 cm。(2)新小竹的可育小花包括1片内稃、1片外稃、3枚浆片(浆片2大1小,边缘光滑)、6枚雄蕊和1枚雌蕊;雄蕊呈梭型,雌蕊羽毛状柱头三裂。(3)新小竹成熟花粉粒多为二核,具1个萌发孔;花药具有4个药室,花药壁由表皮、药室内壁、中层和绒毡层4层结构组成,绒毡层为腺质型;花药发育过程还存在多种异常情况。(4)新小竹子房一室,侧膜胎座,倒生胚珠,双珠被;大孢子母细胞由1个孢原细胞直接发育而成,合点端1个大孢子分化成为功能大孢子,由功能大孢子经过有丝分裂形成多核胚囊,直至发育成熟。研究表明,新小竹雄配子体存在发育异常现象,但大部分发育正常,其结实率低不仅与内在因素有关,外部环境也可能是导致其结实率低的重要因素。     

Characterization of the Rice Floral Organ Number Mutant fon3

A spontaneous rice mutant named floral organ number 3 (fon3) had major mutations in floral organ numbers. Genetic analysis indicated thatfon3 acted as a single recessive gene. Microscopic observation showed that the number of floral organs infon3 increased centripetally. For example, the number of pistils was the more frequently increased than organs in the outer whorls. Homeotic conversion of lodicules and glumes into palea/lemma-like organs was observed in some flowers. Scanning electron microscopy observation showed that the size of flower meristems was maintained the same or similar until the lemma primordium started to differentiate, at which time the floral meristem became enlarged, suggesting abnormal development of the inner whorls of rice florets. The relationship offon3 with other similar rice mutants is discussed.     

Characterization of the Rice Floral Organ Number Mutant fon3

A spontaneous rice mutant named floral organ number 3 (fon3) had major mutations in floral organ numbers. Genetic analysis indicated that fort3 acted as a single recessive gene. Microscopic observation showed that the number of floral organs infon3 increased centripetally. For example, the number of pistils was the more frequently increased than organs in the outer whorls. Homeotic conversion of lodicules and glumes into palea/lemma-like organs was observed in some flowers. Scanning electron microscopy observation showed that the size of flower meristems was maintained the same or similar until the lemma primordium started to differentiate, at which time the floral meristem became enlarged, suggesting abnormal development of the inner whorls of rice florets. The relationship of fort3 with other similar rice mutants is discussed.     

一个水稻畸形颖壳突变体ah的鉴定及其突变性状的遗传分析

水稻畸形颖壳突变体ah是双胚苗品系W2555中自然突变产生的。该突变体的内外稃畸形,退化;雄蕊雌蕊化,雌蕊败育;浆片同源转化为类内外稃的结构,推测该突变体可能影响B功能基因的正常发育。与野生型相比,突变体的小穗分支稀疏,每级枝梗上颖花数目减少,一般为4～6朵;小穗顶端的颖花经常不能成熟,表现为颖花始终泛白,不能转绿,因此该突变也影响花序分生组织的发育。进一步的研究证明,该突变体的发育受外界环境的影响。突变性状的遗传分析表明,该突变体由单隐性基因控制。     

Crinkly4 receptor-like kinase is required to maintain the interlocking of the palea and lemma, and fertility in rice, by promoting epidermal cell differentiation

The palea and lemma are unique organs in grass plants that form a protective barrier around the floral organs and developing kernel. The interlocking of the palea and lemma is critical for maintaining fertility and seed yield in rice; however, the molecules that control the interlocking structure remain largely unknown. Here, we showed that when OsCR4 mRNA expression was knocked down in rice by RNA interference, the palea and lemma separated at later spikelet stages and gradually turned brown after heading, resulting in the severe interruption of pistil pollination and damage to the development of embryo and endosperm, with defects in aleurone. The irregular architecture of the palea and lemma was caused by tumour-like cell growth in the outer epidermis and wart-like cell masses in the inner epidermis. These abnormal cells showed discontinuous cuticles and uneven cell walls, leading to organ self-fusion that distorted the interlocking structures. Additionally, the faster leakage of chlorophyll, reduced silica content and elevated accumulation of anthocyanin in the palea and lemma indicated a lesion in the protective barrier, which also impaired seed quality. OsCR4 is an active receptor-like kinase associated with the membrane fraction. An analysis of promoter::GUS reporter plants showed that OsCR4 is specifically expressed in the epidermal cells of paleas and lemmas. Together, these results suggest that OsCR4 plays an essential role in maintaining the interlocking of the palea and lemma by promoting epidermal cell differentiation.     

Identification and fine mapping of a mutant gene for palealess spikelet in rice

In grass, the evolutionary relationship between lemma and palea, and their relationship to the flower organs in dicots have been variously interpreted and wildely debated. In the present study, we carried out morphological and genetic analysis of a palealess mutant (pal) from rice (Oryza sativa L.), and fine mapping the gene responsible for the mutated trait. Together, our findings indicate that the palea is replaced by two leaf-like structures in the pal flowers, and this trait is controlled by one recessive gene, termed palealess1 (pal1). With a large F2 segregating population, the pal1 gene was finally mapped into a physical region of 35 kb. Our results also suggest that the lemma and palea of rice are not homologous organs, palea is likely evolutionarily equivalent to the eudicot sepal, and the pal1 should be an A function gene for rice floral organ identity.     

CURVED CHIMERIC PALEA 1 encoding an EMF1‐like protein maintains epigenetic repression of OsMADS58 in rice palea development

Floral organ specification is controlled by various MADS‐box genes in both dicots and monocots, whose expression is often subjected to both genetic and epigenetic regulation in Arabidopsis thaliana. However, little information is known about the role of epigenetic modification of MADS‐box genes during rice flower development. Here, we report the characterization of a rice gene, CURVED CHIMERIC PALEA 1 (CCP1) that functions in palea development. Mutation in CCP1 resulted in abnormal palea with ectopic stigmatic tissues and other pleiotropic phenotypes. We found that OsMADS58, a C‐class gene responsible for carpel morphogenesis, was ectopically expressed in the ccp1 palea, indicating that the ccp1 palea was misspecified and partially acquired carpel‐like identity. Constitutive expression of OsMADS58 in the wild‐type rice plants caused morphological abnormality of palea similar to that of ccp1, whereas OsMADS58 knockdown by RNAi in ccp1 could rescue the abnormal phenotype of mutant palea, suggesting that the repression of OsMADS58 expression by CCP1 is critical for palea development. Map‐based cloning revealed that CCP1 encodes a putative plant‐specific EMBRYONIC FLOWER1 (EMF1)‐like protein. Chromatin immunoprecipitation assay showed that the level of the H3K27me3 at the OsMADS58 locus was greatly reduced in ccp1 compared with that in the wild‐type. Taken together, our results show that CCP1 plays an important role in palea development through maintaining H3K27me3‐mediated epigenetic silence of the carpel identity‐specifying gene OsMADS58, shedding light on the epigenetic mechanism in floral organ development.