Abstract
Multiple projects were conducted to investigate the potential for developing a breeding program utilizing species of Catalpa Scop. and Chilopsis D. Don. The efficacy of oryzalin was evaluated for inducing polyploidy and restoring fertility in the sterile, intergeneric hybrid xChitalpa tashkentensis Elias & Wisura [Catalpa bignonioides Walt. x Chilopsis linearis (Cav.) Sweet] 'Pink Dawn'. Submerging meristems in 150 μM oryzalin for up to 24 hours was effective at inducing tetraploids and cytochimeras. Pollen from the diploid cultivar was non-viable, but pollen from the polyploid stained and germinated as well as pollen from progenitor taxa. Polyploid xChitalpa were self-compatible yielding tetraploids when self pollinated and triploids when crossed with C. bignonioides, but reciprocal crosses with Chilopsis taxa failed. To increase recovery of triploids, we investigated germination of ovules and embryos at various harvest dates on Schenk and Hildebrandt (SH) basal salts supplemented with various medium components. Germination of triploid [(polyploid xChitalpa) x C. bignonioides] and tetraploid (selfed polyploid xChitalpa) embryos was greatest at 7 weeks after pollination on SH with 20 g•L⁺¹ sucrose and ≥ 1 μM gibberellic acid (GA₃). Triploids [Chilopsis linearis x (polyploid xChitalpa)] germinated < 5%. Additional studies were conducted to screen diverse taxa for resistance to powdery mildew (PM), Erysiphe elevata (Burr.) U. Braun & S. Takam, and catalpa sphinx larvae (CSL), Ceratomia catalpae (Boisduval). Twenty-four taxa from Catalpa (section Catalpa Paclt and Macrocatalpa Grisebach), Chilopsis, and xChitalpa were screened in 2004-05 for susceptibility to PM. Disease incidence and severity were recorded to calculate area under the disease progress curves (AUDPC) for each year. North American Catalpa spp. in sect. Catalpa, Chilopsis, and xChitalpa taxa were all moderate to highly susceptible to PM. Chinese Catalpa spp. in sect. Catalpa and West Indian sect. Macrocatalpa were resistant to PM. Hybrids among North American and Chinese Catalpa spp. in sect. Catalpa varied in susceptibility, indicating inheritance of partial resistance to PM. A no-choice feeding study conducted with CSL in 2005 found no differences in survival or growth of larvae reared on taxa from both sections of Catalpa, Chilopsis, and xChitalpa. Future breeding of xChitalpa can utilize the identified sources of resistance for PM; however, a source of resistance to CSL was not found. Triploids are generally infertile and may be deployed by breeders to limit invasive potential of introduced ornamentals. However, inheritance of ornamental traits can be complex at higher ploidy levels. Inheritance of two mutant foliage types, variegated and purple, was investigated for diploid, triploid and tetraploid tutsan (Hypericum androsaemum L.). Fertility of progeny was evaluated with pollen viability tests, percent fruit set, and germinative capacity of seed from specific crosses. Segregation ratios were determined for diploids in reciprocal di-hybrid F₁, F₂, BC[subscript 1P1], and BC[subscript 1P2] families and selfed F₂s with the parental phenotypes and triploid and tetraploid F₂s. Diploid di-hybrid crosses fit the expected 9:3:3:1 ratio for a single, simple recessive gene for both traits, with no evidence of linkage. A novel phenotype representing a combination of parental phenotypes was recovered. Data from backcrosses and selfing also supported the recessive model. Both traits behaved as expected at the triploid level; however, at the tetraploid level the number of variegated progeny increased, with segregation ratios between random chromosome and random chromatid assortment models. We propose the gene symbol var (variegated) and pl (purple leaf) for the variegated and purple alleles, respectively. Triploid pollen stained moderately well, but pollen germination was low. Triploid plants demonstrated extremely low male fertility and no measurable female fertility (no viable seed production). Research presented herein demonstrates the feasibility of manipulating ploidy levels for breeding desirable ornamental traits including non-invasiveness.
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Claims 20
Claim · model-written summary
Oryzalin treatment induced tetraploids and cytochimeras in xChitalpa.
- Taxon
- xChitalpa tashkentensis Elias & Wisurae1
- Treatment
- 150 μM oryzalin for up to 24 hourse0
- Outcome
- inducing tetraploids and cytochimerase0
Not reportedComparatorDirection
Verbatim
e0“Submerging meristems in 150 μM oryzalin for up to 24 hours was effective at inducing tetraploids and cytochimeras.”
e1“xChitalpa tashkentensis Elias & Wisura”
Claim · model-written summary
Diploid cultivar pollen was nonviable.
Verbatim
e0“Pollen from the diploid cultivar was non-viable”
e1“xChitalpa tashkentensis Elias & Wisura”
Claim · model-written summary
Polyploid pollen stained and germinated as well as progenitor pollen.
Verbatim
e0“pollen from the polyploid stained and germinated as well as pollen from progenitor taxa”
e1“xChitalpa tashkentensis Elias & Wisura”
Claim · model-written summary
Self pollination of polyploid xChitalpa yielded tetraploids.
Verbatim
e0“Polyploid xChitalpa were self-compatible yielding tetraploids when self pollinated”
Claim · model-written summary
Crosses of polyploid xChitalpa with C. bignonioides yielded triploids.
Verbatim
e0“triploids when crossed with C. bignonioides”
e1“Polyploid xChitalpa were self-compatible yielding tetraploids when self pollinated and triploids when crossed with C. bignonioides”
Claim · model-written summary
Reciprocal crosses with Chilopsis taxa failed.
Verbatim
e0“reciprocal crosses with Chilopsis taxa failed”
e1“Polyploid xChitalpa were self-compatible yielding tetraploids when self pollinated and triploids when crossed with C. bignonioides, but reciprocal crosses with Chilopsis taxa failed.”
Claim · model-written summary
Triploid embryo germination was greatest at seven weeks under the specified culture medium.
Verbatim
e0“Germination of triploid [(polyploid xChitalpa) x C. bignonioides] and tetraploid (selfed polyploid xChitalpa) embryos was greatest at 7 weeks after pollination on SH with 20 g•L⁺¹ sucrose and ≥ 1 μM gibberellic acid (GA₃).”
Claim · model-written summary
Tetraploid embryo germination was greatest at seven weeks under the specified culture medium.
Verbatim
e0“Germination of triploid [(polyploid xChitalpa) x C. bignonioides] and tetraploid (selfed polyploid xChitalpa) embryos was greatest at 7 weeks after pollination on SH with 20 g•L⁺¹ sucrose and ≥ 1 μM gibberellic acid (GA₃).”
Claim · model-written summary
Triploids from Chilopsis linearis crosses germinated below 5%.
- Taxon
- Chilopsis linearis
Chilopsis linearise0 - Outcome
- germinatede0
- Direction
- <e0
- Value
- 5%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Triploids [Chilopsis linearis x (polyploid xChitalpa)] germinated < 5%.”
Claim · model-written summary
North American Catalpa taxa were moderate to highly susceptible to powdery mildew.
Verbatim
e0“North American Catalpa spp. in sect. Catalpa, Chilopsis, and xChitalpa taxa were all moderate to highly susceptible to PM.”
e1“powdery mildew (PM), Erysiphe elevata”
Claim · model-written summary
Chilopsis taxa were moderate to highly susceptible to powdery mildew.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“North American Catalpa spp. in sect. Catalpa, Chilopsis, and xChitalpa taxa were all moderate to highly susceptible to PM.”
e1“powdery mildew (PM), Erysiphe elevata”
Claim · model-written summary
xChitalpa taxa were moderate to highly susceptible to powdery mildew.
Verbatim
e0“North American Catalpa spp. in sect. Catalpa, Chilopsis, and xChitalpa taxa were all moderate to highly susceptible to PM.”
e1“powdery mildew (PM), Erysiphe elevata”
Claim · model-written summary
Chinese Catalpa species were resistant to powdery mildew.
Verbatim
e0“Chinese Catalpa spp. in sect. Catalpa and West Indian sect. Macrocatalpa were resistant to PM.”
e1“powdery mildew (PM), Erysiphe elevata”
Claim · model-written summary
West Indian Macrocatalpa taxa were resistant to powdery mildew.
Verbatim
e0“Chinese Catalpa spp. in sect. Catalpa and West Indian sect. Macrocatalpa were resistant to PM.”
e1“powdery mildew (PM), Erysiphe elevata”
Claim · model-written summary
North American and Chinese Catalpa hybrids varied in powdery mildew susceptibility.
.jpg?width=60){kind=small}
CatalpaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Hybrids among North American and Chinese Catalpa spp. in sect. Catalpa varied in susceptibility, indicating inheritance of partial resistance to PM.”
e1“powdery mildew (PM), Erysiphe elevata”
Claim · model-written summary
Catalpa, Chilopsis and xChitalpa taxa did not differ in larval survival or growth.
- Taxon
- Catalpa, Chilopsis, and xChitalpae0
- Interactor
- Ceratomia catalpae
Ceratomia catalpaee1pest - Outcome
- survival or growth of larvaee0
- Direction
- no differencese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A no-choice feeding study conducted with CSL in 2005 found no differences in survival or growth of larvae reared on taxa from both sections of Catalpa, Chilopsis, and xChitalpa.”
e1“Ceratomia catalpae (Boisduval)”
Claim · model-written summary
Diploid tutsan foliage traits fit a recessive unlinked gene model.
Verbatim
e0“Diploid di-hybrid crosses fit the expected 9:3:3:1 ratio for a single, simple recessive gene for both traits, with no evidence of linkage.”
e1“tutsan (Hypericum androsaemum L.)”
Claim · model-written summary
Tetraploid tutsan had more variegated progeny, with intermediate segregation ratios.
Verbatim
e0“at the tetraploid level the number of variegated progeny increased, with segregation ratios between random chromosome and random chromatid assortment models.”
e1“tutsan (Hypericum androsaemum L.)”
Claim · model-written summary
Triploid tutsan showed extremely low male fertility.
Verbatim
e0“Triploid plants demonstrated extremely low male fertility and no measurable female fertility (no viable seed production).”
e1“tutsan (Hypericum androsaemum L.)”
Claim · model-written summary
Triploid tutsan showed no measurable female fertility or viable seed production.
Verbatim
e0“Triploid plants demonstrated extremely low male fertility and no measurable female fertility (no viable seed production).”
e1“tutsan (Hypericum androsaemum L.)”