Constitutive expression of Arabidopsis LEAFY or APETALA1 genes in citrus reduces their generation time.
Citrus trees have a long juvenile phase that delays their reproductive development by between 6 and 20 years, depending on the species. With the aim of accelerating their flowering time, we transformed juvenile citrus seedlings to constitutively express the Arabidopsis LEAFY (LFY) or APETALA1 (AP1) genes, which promote flower initiation in Arabidopsis. Both types of transgenic citrus produced fertile flowers and fruits as early as the first year, notably through a mechanism involving an appreciable shortening of their juvenile phase. Furthermore, expression of AP1 was as efficient as LFY in the initiation of flowers, and did not produce any severe developmental abnormality. Both types of transgenic trees flowered in consecutive years, and their flowering response was under environmental control. In addition, zygotic and nucellar derived transgenic seedlings had a very short juvenile phase and flowered in their first spring, demonstrating the stability and inheritance of this trait. These results open new possibilities for domestication, genetic improvement, and experimental research in citrus and other woody species.
Departamento de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, Moncada, 46113 Valencia, Spain.
L
L
Peña
M
M
Martín-Trillo
J
J
Juárez
J A
JA
Pina
L
L
Navarro
J M
JM
Martínez-Zapater
D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D002957:Citrus / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D015870:Gene Expression; D005818:Genetic Engineering / Q000379:methods; D005822:Genetic Vectors / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D026161:MADS Domain Proteins; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018514:Plant Structures / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D012098:Reproduction / Q000235:genetics / Q000502:physiology; D012231:Rhizobium / Q000235:genetics; D012621:Seasons; D013997:Time Factors; D014157:Transcription Factors; D014170:Transformation, Genetic; D019076:Transgenes / Q000235:genetics*; D019737:Transplants
C091535:AP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; D010940:Plant Proteins; D014157:Transcription Factors