Origin and domestication of papaya Y^h chromosome

Abstract

Sex in papaya is controlled by a pair of nascent sex chromosomes. Females are XX, and two slightly different Y chromosomes distinguish males (XY) and hermaphrodites (XY h ). The hermaphrodite-specific region of the Y h chromosome (HSY) and its X chromosome counterpart were sequenced and analyzed previously. We now report the sequence of the entire male-specific region of the Y (MSY). We used a BAC-by-BAC approach to sequence the MSY and resequence the Y regions of 24 wild males and the Y h regions of 12 cultivated hermaphrodites. The MSY and HSY regions have highly similar gene content and structure, and only 0.4% sequence divergence. The MSY sequences from wild males include three distinct haplotypes, associated with the populations' geographic locations, but gene flow is detected for other genomic regions. The Y h sequence is highly similar to one Y haplotype (MSY3) found only in wild dioecious populations from the north Pacific region of Costa Rica. The low MSY3-Y h divergence supports the hypothesis that hermaphrodite papaya is a product of human domestication. We estimate that Y h arose only ∼4000 yr ago, well after crop plant domestication in Mesoamerica >6200 yr ago but coinciding with the rise of the Maya civilization. The Y h chromosome has lower nucleotide diversity than the Y, or the genome regions that are not fully sex-linked, consistent with a domestication bottleneck. The identification of the ancestral MSY3 haplotype will expedite investigation of the mutation leading to the domestication of the hermaphrodite Y h chromosome. In turn, this mutation should identify the gene that was affected by the carpel-suppressing mutation that was involved in the evolution of males.

Domestication and Genetics of Papaya: A Review

“…Further evidence is offered by the origin of the Y h chromosome in cultivated hermaphrodite individuals of papaya (VanBuren et al, 2015). By sequencing the entire male-specific region of the Y chromosome and comparing it with the previous sequences of the hermaphrodite-specific region of the Y h chromosome, (Wang et al, 2012), VanBuren et al (2015) found that the Y h chromosome possess lower nucleotide diversity as compared to the Y.…”

“…Cultivars can inbred, resulting in stable characteristics across generations (Manshardt, 1992). For gynodioecious cultivated papaya, it has been reported that two-thirds of the plants correspond to hermaphrodites and onethird to female plants, though dioecious cultivars exist (VanBuren et al, 2015). Sex determination for the three types of papaya, female, male, and hermaphrodite plants, is genetically regulated by the pairing of sex chromosomes (Carvalho and Renner, 2012), through a sex-linked region that behaves like an XY sex chromosome.…”

“…Sex determination for the three types of papaya, female, male, and hermaphrodite plants, is genetically regulated by the pairing of sex chromosomes (Carvalho and Renner, 2012), through a sex-linked region that behaves like an XY sex chromosome. For male and hermaphrodite individuals, sex is controlled by slightly different Y chromosome regions: Y h in hermaphrodites and Y in males (VanBuren et al, 2015). Female plants produce flowers and fruits all year round in tropical regions; however, in subtropical areas, despite continuous flowering, fruit set is decreased during drier seasons (Gonsalves, 1998).…”

Resistencia de Vasconcellea cauliflora al Virus de la mancha anular de la papaya-potyvirus (PRSV-P) y su introgresión en Carica papaya

“…La especie Carica papaya silvestre se encuentra extendida en bosques tropicales que van de México hasta Costa Rica (Chávez-Pesqueira et al, 2014). La versión hermafrodita de C. papaya cultivada es producto de la domesticación por grupos étnicos de México, presumiblemente los mayas (VanBuren et al, 2015).…”

“…Carica papaya wild species are widely distributed in tropical forests from Mexico up to Costa Rica (Chávez-Pesqueira et al, 2014). The hermaphrodite version of C. papaya currently sown is the result of domestication by Mexican ethnic groups, presumably the Mayas (VanBuren et al, 2015).…”