The curious chromosomes of a curious fruit

Mar 09, 2009

Incipient sex chromosomes have been found in New Zealand's eponymous export, the kiwifruit. Researchers writing in the open access journal BMC Genomics have mapped the kiwifruit genome and pin-pointed the sex-determining locus.

It has previously been suggested that, among the plant's small (<1um) chromosomes, lie a pair of X/Y-like chromosomes that result in its dioecism. Now a team led by Lena Fraser and colleagues at the New Zealand Institute for Plant and Food Research has confirmed this suggestion by mapping the genome of the golden kiwifruit.

The genome has been mapped with 644 microsatellite markers from three genetic libraries (two from the New Zealand Institute for Plant and Food Research and one from the University of Udine, Italy). These showed 29 linkage groups, represented expression of 587 genes, and revealed that sex-linked sequence characterised amplified region (SCAR) markers and the flower sex phenotype were mapping to a subtelomeric region that bears the hallmarks of an early sex-determining locus.

The mapping of this sex-determining locus to a subtelomeric region fits with previous published work on and also the authors own observations. Whilst studying kiwifruit karyotypes, the research team observed that in the pollen mother cells undergoing one of the 29 pairs of chromosomes did not pair tightly in a region close to one end. An absence of pairing means that the male-specific region on the Y is inherited as a unit, maintaining . Based on the they have now defined for this non-recombining sex-determining region, the authors suggest that at least two linked genes on the putative are responsible for dioecy: one suppressing pistil formation and one for pollen development.

Of more than 60 species of Actinidia (kiwifruit), only two have been widely cultivated so far, and there is potential for breeding new varieties. All Actinida species are dioecious, and the authors say they are likely to have similar sex-determining regions. The authors work in producing female, male and consensus for the golden kiwifruit, A. chinensis and identifying the sex-determining region may provide the key to fully exploiting this relatively recent cultivar.

According to Fraser, 'The gene-rich map we have constructed will be a valuable resource for quantitative trait loci analyses to identify markers related to traits of importance in breeding new and novel kiwifruit for the markets of the world.'

More information: A gene-rich linkage map in the dioecious species Actinidia chinensis (kiwifruit) reveals putative X/Y sex-determining chromosomes, Lena G Fraser, Gianna K Tsang, Paul M Datson, H NIHAL De Silva, Catherine F Harvey, Geoffrey P Gill, Ross N Crowhurst and Mark A McNeilage, (in press), http://www.biomedcentral.com/bmcgenomics/

Source: BioMed Central

Explore further: Breakthrough study discovers six changing faces of 'global killer' bacteria

add to favorites email to friend print save as pdf

Related Stories

Red kiwi poised to make a healthy debut

Nov 09, 2005

First there was green, then yellow and now red-fleshed kiwifruit. A team of researchers in Italy and New Zealand has found that a newly developed variety of red-fleshed kiwifruit contain anthocyanins, bright red pigments ...

Genetic data promises new future for kiwi fruit

Jul 31, 2008

Kiwifruit lovers can look forward to new, novel forms of their favourite fruit thanks to the release this week of crucial genetic data which fruit breeders say will help them naturally breed new varieties with increased health ...

Evolution of the Sexes: What a Fungus Can Tell Us

Jan 09, 2008

Fungi don't exactly come in boy and girl varieties, but they do have sex differences. In fact, a new finding from Duke University Medical Center shows that some of the earliest evolved forms of fungus contain clues to how ...

X chromosome exposed

May 29, 2008

Researchers from the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, and the EMBL-European Bioinformatics Institute (EMBL-EBI) in Hinxton, UK, have revealed new insights into how sex chromosomes are regulated. ...

How do you know whether you are male or female?

Dec 27, 2007

New research published online this week in the open-access journal PLoS Biology investigates this basic and much-studied question in the fruit fly, and comes to a surprising new conclusion.

Recommended for you

Plants prepackage beneficial microbes in their seeds

21 hours ago

Plants have a symbiotic relationship with certain bacteria. These 'commensal' bacteria help the pants extract nutrients and defend against invaders – an important step in preventing pathogens from contaminating fruits and ...

User comments : 0