Molecular markers for sex determination in papaya (Carica papaya L.)

Abstract

We have developed molecular markers tightly linked to Sex1, the gene that determines plant sex in papaya ( Carica papaya L.). Three RAPD products have been cloned and a portion of their DNA sequenced. Based on these sequences SCAR primers were synthesized. SCAR T12 and SCAR W11 produce products in hermaphrodite and male plants and only rarely in females. SCAR T1 produces a product in all papayas regardless of plant sex. SCAR T12 and SCAR W11 showed no recombination in a population of 182 F2 plants from a 'SunUp' by 'Kapoho' cross. Based on these results a PCR-based technique for rapidly and accurately determining the sex of papaya plants was developed using either W11 or T12 to detect the hermaphrodite or male allele and T1, which amplifies a product regardless of sex type, as a positive control. The sexing technique, using SCAR T12 and SCAR T1 as a positive control, was used to correctly predict hermaphrodite papaya plants in a population of seedlings with an overall accuracy of 99.2%.

PCR Detection Assay for Sex Determination in Papaya Using Scar Marker

“…The reason may be that the specifi c chromosomal region for sex type determination in papaya shares an identical segment of the Y chromosome of males and hermaphrodite plants and is absent in females. This result is consistent with the expected result and as reported by DEPUTY et al (2002). LIU et al (2004) identifi ed the male specifi c (MSY) region in hermaphrodite and male papaya plants and found that some sequences of this region are common in both male and hermaphrodite plants.…”

“…The reaction profi le of this SCAR marker assay was optimized by modifying the earlier mentioned protocol (DEPUTY et al 2002) through a change of the concentrations of PCR ingredients, such as a decrease in MgCl 2 concentration, an increase in the concentration of dNTPs, primers, DNA and Taq polymerase. Amplifi ed fragment of 800 bp were obtained in hermaphrodite and male papaya plants only, but not in female plants.…”

“…However, DEPUTY et al (2002) reported SCAR markers that are specifi c for male and hermaphrodite plants in a large number of plants. DEPUTY et al (2002) cloned three RAPD-PCR products showing linkage to the gene that determines fl ower sex, Sex1, in papaya. Two of these RAPD products, T12 and T1, had been previously mapped to 7 cM fl anking the Sex1 gene.…”

“…In this paper the SCAR marker W11 (DEPUTY et al 2002) was initially tested among dioecious and gynodieoecious cultivars and was later used to determine the sex of 84 seedlings of an intergeneric cross of Carica papaya × Vasconcella caulifl ora containing a mixture of male, female and hermaphrodite plants.…”

Molecular confirmation of sex in regenerated plantlets of spine gourd (Momordica dioica Roxb. Ex. wild) by using RAPD markers

“…Sex determination in papaya by using PCR based RAPD molecular marker was reported by several authors from various countries like in Japan (Ursaki et al, 2002), Hawaii (Deputy et al, 2002), Brazil (Lemos et al, 2002) and India (Parasnis et al, 1999). In Salix viminalis (Alstrom-Rapaport et al, 1998), Encephalartos natalensis (Prakash & Staden, 2006), Borassus flabellifer , Simmondsia chinensis (Agrawal et al, 2007) and Pandanus fasciculalris (Vinod et al, 2007) also sex is determined by using PCR based RAPD molecular marker.…”