Development of very early flowering and normal fruiting plum with fertile seeds
Inventors
Srinivasan, Chinnathambi • Scorza, Ralph • Callahan, Ann • Dardick, Chris
Assignees
US Department of Agriculture USDA
Publication Number
US-8633354-B2
Publication Date
2014-01-21
Expiration Date
2030-04-15
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Abstract
To produce early flowering genotypes, plum (Prunus domestica) was transformed with the poplar (Populus trichocarpa) Flowering Locus T1 (PtFT1) gene. Ectopic expression of 35S::PtFT1 Induced early flowering in vitro from transgenic plantlets within two months of transformation. When the transgenic plum plants were rooted and transferred to soil and grown in posts in the growth chamber, a number of additional lines flowered. Normal flowering and fruiting were observed in the greenhouse within one year of transformation. While dormancy was not necessary for growth or fruiting, FT plums were still winter hardy and floral bud set and flowering responded normally to changes in temperature. By manipulating a single gene, temperate tree crops can be effectively engineered for cultivation in new growing areas and for entirely new modes of agricultural production that are continuous, sustainable, and adaptable to climate change.
Core Innovation
The invention is the development of transgenic plum genotypes that flower very early and continually produce normal fruits and fertile seeds within six to twelve months. This is achieved by ectopically expressing the poplar (Populus trichocarpa) Flowering Locus T1 gene (PtFT1) in plum (Prunus domestica). The expression of PtFT1 induces early flowering in vitro from transgenic plantlets within two months of transformation, with normal flowering and fruiting observed within one year after transfer to soil and growth in controlled conditions.
The problem being addressed is the long juvenile period of three to eight years that severely limits traditional breeding and genetic improvement of Prunus fruit trees. This slow breeding cycle, along with environmental constraints such as chilling and dormancy requirements, restricts where and how these temperate fruit crops can be grown. Shortening the juvenile period and enabling early and continual flowering in Prunus can drastically reduce breeding time, space, and cost, enabling improved cultivars and continuous fruit production adaptable to climate change.
By manipulating a single gene, PtFT1, temperate tree crops like plum can bypass environmental cues such as chilling and day length to flower and fruit continuously. These transgenic plants are capable of producing ripe fruits with fertile seeds and exhibit altered growth habits. The invention provides methods for transforming Prunus plants with PtFT1, regenerating early and continually flowering plants, and accelerating breeding cycles for new cultivar development, thus offering sustainable and climate-independent agricultural production systems.
Claims Coverage
The claims cover multiple inventive features related to transforming Prunus plants with the Populus trichocarpa PtFT1 gene to induce early and continual flowering and fruit production, describing methods, plant characteristics, and breeding approaches.
Method of producing early and continually flowering Prunus plants
Transforming regenerable Prunus tissue with a recombinant construct comprising PtFT1 cDNA under regulatory elements, culturing and regenerating transgenic plantlets, rooting and acclimating them, planting in controlled conditions, and selecting plants exhibiting early and continual flowering phenotype.
Use of constitutive and CaMV 35S promoters for PtFT1 expression
Employing one or more regulatory elements such as a constitutive promoter operably linked to PtFT1 cDNA, specifically including the CaMV 35S promoter, for inducing early and continual flowering in transgenic Prunus plants.
Early flowering transgenic Prunus plants with specific growth habits
Transgenic Prunus plants transformed with PtFT1 exhibiting extensive lateral shoot production and a range of growth patterns including branched upright, combined upright and bushy, or bushy and recumbent growth compared to non-transgenic controls.
Method of producing transgenic Prunus plants that also yield ripe fruits with fertile seeds
Transforming Prunus tissue with PtFT1, regenerating transgenic plants exhibiting early and continual flowering, pollinating with compatible cultivars, and selecting plants producing ripe fruit with fertile seeds.
Accelerated breeding cycle enabled by PtFT1 transgenic Prunus plants
Using early and continually flowering transgenic plants expressing PtFT1 to produce ripe fruit and fertile seeds, germinating progeny to continue breeding cycles year-round, thereby substantially shortening the breeding time compared to non-transgenic Prunus.
Method of obtaining improved cultivars in shorter time
Crossing PtFT1 transgenic Prunus plants exhibiting early and continual flowering and fertile fruit production with non-transformed plants having new desired traits, and selecting progeny lacking the PtFT1 transgene for conventional breeding to acquire improved non-transgenic cultivars.
Continuous fruit production in protected structures
Growing PtFT1 transgenic Prunus plants in large numbers in protected environments such as greenhouses to enable continuous fruit production, independent of external seasonal cues.
Characteristics of PtFT1 transgenic Prunus plants and their progeny
Plants or progeny containing the PtFT1 recombinant construct exhibit early flowering, shortened juvenile period, new flowering structures, segregation of early flowering and non-flowering progeny with non-transgenic individuals, distinct branched and bushy or recumbent growth patterns, and broader climate adaptability for fruit production compared to controls.
The patent claims comprehensively cover the genetic transformation of Prunus with PtFT1 to induce early and continual flowering and fruiting, methods for producing and selecting such transgenic plants, their unique growth characteristics, their use to significantly accelerate breeding cycles and produce improved cultivars, and applications for continuous fruit production adaptable to diverse growing conditions.
Stated Advantages
Significantly reduces the long juvenile period of plum trees from years to months, enabling faster breeding and genetic improvement.
Allows continual and early flowering and fruit production independent of environmental cues such as chilling and day length.
Enables cultivation of temperate tree crops in new growing areas and under climates affected by climate change.
Facilitates climate-independent and sustainable fruit production in protected environments like greenhouses.
Improves breeding efficiency by producing fertile seeds quickly and allowing accelerated genetic crosses and selection.
Documented Applications
Accelerated breeding of Prunus cultivars to obtain new improved varieties more rapidly.
Year-round continuous fruit production in protected structures such as greenhouses.
Cultivation of temperate tree fruit crops in regions with insufficient chilling or varying climates.
Use as a genetic tool to shorten juvenile phases for functional analysis of genes involved in fruit development.
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