Significance of consensus CYC‐binding sites found in the promoters of both ChCYC and ChRAD genes in Chirita heterotricha (Gesneriaceae)

Abstract CYC‐like genes are widely conserved in controlling floral dorsoventral asymmetry (zygomorphy) through persistent expression in corresponding domains in core eudicots. To understand how CYC‐like gene expression is maintained during flower development, we selected Chirita heterotricha as a material and isolated the promoter sequences of the ChCYC1C and ChCYC1D genes, homologs of CYC, by inverse polymerase chain reaction. Further promoter analyses led to the identification of a putative cis‐regulatory element in each promoter matching the consensus DNA binding site for Antirrhinum CYC protein: GGCCCCTC at ?165 for ChCYC1C, and GGCCCCCC at ?163 for ChCYC1D. This indicates that both the ChCYC1C and ChCYC1D genes have probably evolved autoregulatory loops to sustain their expression in developing flowers. We also isolated the coding and promoter sequences of the ChRAD gene, a homolog of Antirrhinum RAD. Promoter analysis showed that the ChRAD gene promoter also contained a putative CYC‐binding site (GGCCCAC at ?134). Therefore, ChRAD is likely a direct target of the ChCYC1 genes, which is similar to Antirrhinum RAD. These results imply that the establishment of floral zygomorphy in Chirita may have been achieved by the evolution of an autoregulatory loop for CYC‐like genes, which was probably accompanied by simultaneous co‐option of the RAD‐like gene into their regulatory network.     

Significance of consensus CYC-binding sites found in the promoters of both ChCYC and ChRAD genes in Chirita heterotricha (Gesneriaceae)

CYC-like genes are widely conserved in controlling floral dorsoventral asymmetry (zygomorphy) through persistent expression in corresponding domains in core eudicots. To understand how CYC-like gene expression is maintained during flower development, we selected Chirita heterotricha as a material and isolated the promoter sequences of the ChCYCIC and ChCYCID genes, homologs of CYC, by inverse polymerase chain reaction. Further promoter analyses led to the identification of a putative cis-regulatory element in each promoter matching the consensus DNA binding site for Antirrhinum CYC protein: GGCCCCTC at-165 for ChCYC1C, and GGCCCCCC at-163 for ChCYCID. This indicates that both the ChCYCIC and ChCYC1D genes have probably evolved autoregulatory loops to sustain their expression in developing flowers. We also isolated the coding and promoter sequences of the ChRAD gene, a homolog of Antirrhinum RAD. Promoter analysis showed that the ChRAD gene promoter also contained a putative CYC-binding site (GGCCCAC at -134). Therefore, ChRAD is likely a direct target of the ChCYC1 genes, which is similar to Antirrhinum RAD. These results imply that the establishment of floral zygomorphy in Chirita may have been achieved by the evolution of an autoregulatory loop for CYC-like genes,which was probably accompanied by simultaneous co-option of the RAD-like gene into their regulatory network.     

中国广西石灰岩地区苦苣苔科一新种——鹿寨唇柱苣苔

描述了中国广西石灰岩地区苦苣苔科(Gesneriaceae)1新种--鹿寨唇柱苣苔(Chirita luzhaiensis Yah Lin,Y.S.Huang & W.B.Xu).该种与桂林唇柱苣苔(Chirita gueilinensis W.T.Wang)相似,但叶面被长柔毛和短柔毛,花药无毛,花丝近基部膝状弯曲,退化雄蕊3枚,无毛,花期12月至次年1月可与后者区别.目前,鹿寨唇柱苣苔仅见于广西鹿寨县中渡镇的两个石灰岩山洞中.     

黄花牛耳朵(苦苣苔科)的传粉生物学

通过野外观察和繁育系统的实验,对黄花牛耳朵(Chirita lutea Yan Liu et Y.G.wei)的传粉生物学进行了研究.结果表明,黄花牛耳朵的花期从7月初至8月底,单株花期约35～47 d,单花化期约6～10 d,花的开放无固定的时间.在花期内花粉活性约80%,柱头可授性约75%～90%.花粉/胚珠比率(P/O)为1 215.73±266.13.柱头在花药散粉时已生长至花筒口部,明显高于花药,便于接受异花花粉.黄花牛耳朵不存在无融合生殖,高度白交亲和,但较难发生自动的白花授粉,产生种子主要依靠传粉媒介.自然授粉的结实率明显低于人工授粉的结实率,存在传粉限制,蜜蜂(Apidae sp.)、方头泥蜂(Crabro sp.)、无垫蜂(Ameglla sp.)是主要的传粉者.     

New Plants of Gesneriaceae from Guangxi of China (Cont. I)

Five new species of Gesneriaceae from Guangxi of China are described and illustrated. They are Oreocharis heterandra , Didymostigma leiophyllum , Chirita macrodonta ,C. macrorhiza and C. liujiangensis.     

广西唇柱苣苔属(苦苣苔科)一新变种——光华唇柱苣苔

记载了广西苦苣苔科Gesneriaceae一新变种——光华唇柱苣苔Chirita tribracteata、W．T.Wang var.zhuana Z．Y．Li,Q．Xing＆Y．B．Li。该变种与原变种不同在于叶大而厚,边缘具圆齿或牙齿,叶柄具宽翅,苞片宽倒卵形或倒披针形,有锯齿,花冠淡紫色,喉部具黄色纵纹。