Development of a transgenic early flowering pear (Pyrus communis L.) genotype by RNAi silencing of PcTFL1-1 and PcTFL1-2.
Trees require a long maturation period, known as juvenile phase, before they can reproduce, complicating their genetic improvement as compared to annual plants. 'Spadona', one of the most important European pear (Pyrus communis L.) cultivars grown in Israel, has a very long juvenile period, up to 14 years, making breeding programs extremely slow. Progress in understanding the molecular basis of the transition to flowering has revealed genes that accelerate reproductive development when ectopically expressed in transgenic plants. A transgenic line of 'Spadona', named Early Flowering-Spadona (EF-Spa), was produced using a MdTFL1 RNAi cassette targeting the native pear genes PcTFL1-1 and PcTFL1-2. The transgenic line had three T-DNA insertions, one assigned to chromosome 2 and two to chromosome 14 PcTFL1-1 and PcTFL1-2 were completely silenced, and EF-Spa displayed an early flowering phenotype: flowers developed already in tissue culture and on most rooted plants 1-8 months after transfer to the greenhouse. EF-Spa developed solitary flowers from apical or lateral buds, reducing vegetative growth vigor. Pollination of EF-Spa trees generated normal-shaped fruits with viable F1 seeds. The greenhouse-grown transgenic F1 seedlings formed shoots and produced flowers 1-33 months after germination. Sequence analyses, of the non-transgenic F1 seedlings, demonstrated that this approach can be used to recover seedlings that have no trace of the T-DNA. Thus, the early flowering transgenic line EF-Spa obtained by PcTFL1 silencing provides an interesting tool to accelerate pear breeding.
Institute of Plant Sciences, Agricultural Research Organization, P.O. Box 6, 50250 Bet-Dagan, Israel.
Aviad
A
Freiman
Lyudmila
L
Shlizerman
Sara
S
Golobovitch
Zeev
Z
Yablovitz
Raia
R
Korchinsky
Yuval
Y
Cohen
Alon
A
Samach
Elisabeth
E
Chevreau
Pierre-Marie
PM
Le Roux
Andrea
A
Patocchi
Moshe A
MA
Flaishman
D001483:Base Sequence; D003433:Crosses, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D035264:Flowers / Q000235:genetics* / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant / Q000235:genetics; D005838:Genotype; D040582:Inheritance Patterns / Q000235:genetics; D027845:Malus / Q000235:genetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D010641:Phenotype; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D031989:Pyrus / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013696:Temperature
D004269:DNA, Bacterial; D018744:DNA, Plant; D010940:Plant Proteins; D012333:RNA, Messenger; C036483:T-DNA