Abstract
In citrus, a classical method of studying crossovers and segregation distortion (SD) is the genetic analysis of progenies. A new strategy combining fluorescence-activated cell sorting and whole genome amplification of haploid pollen nuclei with a large set of molecular markers, offers the opportunity to efficiently determine the frequency of crossovers and the identification of SD without the need to generate segregating populations. Here we have analyzed meiotic crossover events in a pollen nuclei population from “Eureka” lemon and the allelic SD was evaluated in a pollen nuclei population from a clementine × sweet orange hybrid (“CSO”). Data obtained from the “CSO” pollen nuclei population were compared to those obtained from genotyping of a segregating population (“RTSO”) arising from a hand-made sexual hybridization between diploid non apomictic selected tangor (mandarin × sweet orange; “RTO” tangor) as female parent pollinated with “CSO” tangor as male parent. The analysis of crossovers rates on chromosome 1 revealed the presence of up to five crossovers events on one arm and four on the corresponding other arm, with an average of 1.97 crossovers per chromosome while no crossover events were observed in five “Eureka” lemon pollen nuclei. The rate of SD observed in “CSO” pollen nuclei (13.8%) was slightly lower than that recovered in the “RTSO” population (20.7%). In the pollen nuclei population, SD was found on linkage group (LG) 2, while the “RTSO” population showed SD on LGs 2 and 7. Potential male gametic selection mechanisms were distinguished in pollen grains, while in the population, mechanisms of gametophytic selection and/or zygotic selection were observed. This methodology is a very useful tool to facilitate research focused on the reproductive biology of citrus and study the mechanisms that affect crossovers and SD.
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Claims 9
Claim · model-written summary
Chromosome 1 showed up to five crossovers on one arm and four on the other.
- Outcome
- crossovers eventse0
- Value
- five crossovers events on one arm and four on the corresponding other arme0
CitrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“up to five crossovers events on one arm and four on the corresponding other arm”
t0“citrus hybrids”
Claim · model-written summary
Average crossovers per chromosome were 1.97.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an average of 1.97 crossovers per chromosome”
t0“citrus hybrids”
Claim · model-written summary
Five Eureka lemon pollen nuclei had no observed crossover events.
Verbatim
e0“no crossover events were observed in five “Eureka” lemon pollen nuclei”
t0“citrus hybrids”
Claim · model-written summary
Segregation distortion was 13.8% in CSO pollen, slightly lower than 20.7% in RTSO progeny.
- Material
- “CSO”e0
- Outcome
- rate of SDe0
- Direction
- slightly lowere0
- Value
- 13.8%e0
- Qualifier
- 20.7%e0
- Comparator
- “RTSO” populatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of SD observed in “CSO” pollen nuclei (13.8%) was slightly lower than that recovered in the “RTSO” population (20.7%)”
t0“citrus hybrids”
Claim · model-written summary
Segregation distortion in CSO pollen was found on linkage group 2.
- Outcome
- SD was found on linkage group (LG) 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the pollen nuclei population, SD was found on linkage group (LG) 2”
t0“citrus hybrids”
Claim · model-written summary
Segregation distortion in RTSO progeny was found on linkage groups 2 and 7.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the “RTSO” population showed SD on LGs 2 and 7”
t0“citrus hybrids”
Claim · model-written summary
The pollen data distinguished possible male gametic selection mechanisms.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Potential male gametic selection mechanisms were distinguished in pollen grains”
t0“citrus hybrids”
Claim · model-written summary
The progeny showed gametophytic and/or zygotic selection mechanisms.
- Outcome
- mechanisms of gametophytic selection and/or zygotic selectione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mechanisms of gametophytic selection and/or zygotic selection were observed”
t0“citrus hybrids”
Claim · model-written summary
Single pollen genotyping was useful for research on citrus reproductive biology and segregation distortion.
- Outcome
- very useful toole0
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This methodology is a very useful tool to facilitate research focused on the reproductive biology of citrus and study the mechanisms that affect crossovers and SD”