The investigation of the differentiation and development of inflorescenees and flowers in Ailanthus ahissima(Mill.)Swingle(Simaroubaceae)using light microscopy(LM)and scanning electron microscopy(SEM)suggests:1)Flower...The investigation of the differentiation and development of inflorescenees and flowers in Ailanthus ahissima(Mill.)Swingle(Simaroubaceae)using light microscopy(LM)and scanning electron microscopy(SEM)suggests:1)Flower bud differentiation of A.altissima occurs in early April on a panicle bearing many flowers;2)The sequence of floral development proceeds from calyx primordia to corolla primordia to stamen primordia and finally to carpel primordia.Five sepal primordia are initiated spirally and asynchronously.Five petal primordia form nearly simultaneously and grow more slowly than the stamen primordia.The ten stamens are alternately arranged in two whorls;the two whorls develop simulta-neously.The 5-carpellate gynoecium grows quickly.3)In hermaphrodites,the five carpels adhere to each other to form the style and stigma;in staminate flowers,in late developmental stages,the five carpels are sterile and fertile stamens differentiate into anthers and filaments.In this paper,we focus on the morphological transition from bisexual to unisexual flower development in A.altissima.We observed that the primordia of staminate flowers are initiated in nearly the same way as in hermaphrodite flowers(although the time of initiation of each organ is different).The stamen and carpel primerdia initiate simultaneously in both hermaphrodite and staminate flowers.The formation of reproductive structures is due to the differen-tiation in the course of development of the floral primordia that form the anthers and filaments and/or styles,stigmas,and ovaries.The formation of staminate flowers is due to suppression of the development of the gynoecium in A.altissima.The mechanism of transition from bisexual to unisexual flowers will only be clarified by further study.展开更多
The diversity of plant architecture is determined by axillary meristems (AMs). AMs are produced from small groups of stem cells in the axils of leaf primordia and generate vegetative branches and reproductive inflores...The diversity of plant architecture is determined by axillary meristems (AMs). AMs are produced from small groups of stem cells in the axils of leaf primordia and generate vegetative branches and reproductive inflorescences . Previous studies identified genes critical for AM development that function in auxin biosynthesis, transport, and signaling. barren stalkl (ba1), a basic helix-loop-helix transcription factor, acts downstream of auxin to control AM formation. Here, we report the cloning and characterization of barren stalk2 (ba2), a mutant that fails to produce ears and has fewer branches and spikelets in the tassel, indicating that ba2 functions in reproductive AM development. Furthermore, the ba2 mutation suppresses tiller growth in the teosinte branchedl mutant, indicating that ba2 also plays an essential role in vegetative AM development. The ba2 gene encodes a protein that co-localizes and heterodimerizes with BA1 in the nucleus . Characterization of the genetic interaction between ba2 and ba1 demonstrates that ba1 shows a gene dosage effect in ba2 mutants, providing further evidence that BA1 and BA2 act together in the same pathway. Characterization of the molecular and genetic interaction between ba2 and additional genes required for the regulation of ba1 further supports this finding. The ba1 and ba2 genes are orthologs of rice genes, LAX PANICLE1 (LAX1) and LAX2, respectively, hence providing insights into pathways controlling AMs development in grasses.展开更多
基金This research was supported by a Scholarshipfrom the Scientific Research Foundation for Returned Overseas Chinese ScholarsScientific Research Foundation of Nankai University+3 种基金Science and Technology of Maintain of Ecological System And Adaptability Management on the Interlaced Belt of Northern Grassland and Agriculture and Animal(2007CB106802)Scientific Research Foundation of State Forestry Adminis-trationof the P.R.China("948"item)"Observation Technological Indraught of Characters of Soil Water and Heat in Arid Area"(2006-4-02)Scientific Research Foundation of Tianjin(07JCYBJC12400,07JCYBJC12500)
文摘The investigation of the differentiation and development of inflorescenees and flowers in Ailanthus ahissima(Mill.)Swingle(Simaroubaceae)using light microscopy(LM)and scanning electron microscopy(SEM)suggests:1)Flower bud differentiation of A.altissima occurs in early April on a panicle bearing many flowers;2)The sequence of floral development proceeds from calyx primordia to corolla primordia to stamen primordia and finally to carpel primordia.Five sepal primordia are initiated spirally and asynchronously.Five petal primordia form nearly simultaneously and grow more slowly than the stamen primordia.The ten stamens are alternately arranged in two whorls;the two whorls develop simulta-neously.The 5-carpellate gynoecium grows quickly.3)In hermaphrodites,the five carpels adhere to each other to form the style and stigma;in staminate flowers,in late developmental stages,the five carpels are sterile and fertile stamens differentiate into anthers and filaments.In this paper,we focus on the morphological transition from bisexual to unisexual flower development in A.altissima.We observed that the primordia of staminate flowers are initiated in nearly the same way as in hermaphrodite flowers(although the time of initiation of each organ is different).The stamen and carpel primerdia initiate simultaneously in both hermaphrodite and staminate flowers.The formation of reproductive structures is due to the differen-tiation in the course of development of the floral primordia that form the anthers and filaments and/or styles,stigmas,and ovaries.The formation of staminate flowers is due to suppression of the development of the gynoecium in A.altissima.The mechanism of transition from bisexual to unisexual flowers will only be clarified by further study.
基金the National Science Foundation Plant Genome Research Program IOS-1114484/0820729 to P.M.and S.M.and NSF PGRP IOS-1546873 to P.M.
文摘The diversity of plant architecture is determined by axillary meristems (AMs). AMs are produced from small groups of stem cells in the axils of leaf primordia and generate vegetative branches and reproductive inflorescences . Previous studies identified genes critical for AM development that function in auxin biosynthesis, transport, and signaling. barren stalkl (ba1), a basic helix-loop-helix transcription factor, acts downstream of auxin to control AM formation. Here, we report the cloning and characterization of barren stalk2 (ba2), a mutant that fails to produce ears and has fewer branches and spikelets in the tassel, indicating that ba2 functions in reproductive AM development. Furthermore, the ba2 mutation suppresses tiller growth in the teosinte branchedl mutant, indicating that ba2 also plays an essential role in vegetative AM development. The ba2 gene encodes a protein that co-localizes and heterodimerizes with BA1 in the nucleus . Characterization of the genetic interaction between ba2 and ba1 demonstrates that ba1 shows a gene dosage effect in ba2 mutants, providing further evidence that BA1 and BA2 act together in the same pathway. Characterization of the molecular and genetic interaction between ba2 and additional genes required for the regulation of ba1 further supports this finding. The ba1 and ba2 genes are orthologs of rice genes, LAX PANICLE1 (LAX1) and LAX2, respectively, hence providing insights into pathways controlling AMs development in grasses.
