Molecular Plant Breeding 2016, Vol.7, No.28, 1
-
18
1
Review Article Open Access
Genetics of Sex Chromosomes and Sex-linked Molecular Markers in Papaya
(
Carica papaya
L.)
Priyanka
1
, Anurag Yadav
2
, Upendra Nath Dwivedi
1
, Kusum Yadav
1
1 Department of Biochemistry, University of Lucknow, Lucknow, India
2 Department of Microbiology, College of Basic Science & Humanities, S.D. Agricultural University, S.K. Nagar, Dist. Banaskantha, Gujarat, India
Corresponding authors Email:
anukusum@gmail.com
Molecular Plant Breeding, 2016, Vol.7, No.28 doi
Received: 08 May, 2016
Accepted: 09 Aug., 2016
Published: 12 Aug., 2016
Copyright © 2016
Priyanka et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Priyanka, Anurag Y., Upendra N.D., and Kusum Y., 2016, Genetics of sex chromosomes and sex-linked molecular markers in papaya (
Carica papaya
L.),
Molecular Plant Breeding, 7(28): 1-18 (doi
Abstract
Papaya (
Carica papaya
L.) is an edible tropical fruit crop which has several medicinal and nutritional benefits. Sex type
determination is more complicated in trioecious papaya at early seedling stage. Many hypothesis and research have been done to
understand the genetics of sex determination. Various methods based on morphological, cytological traits and isozyme based markers
have been utilized for sex identification, but none of these were efficient to solve the problem of sex identification in papaya at early
seedling stage. Hence, sex-linked molecular markers including RAPDs, ISSRs and AFLPs have been developed in papaya and some
advanced molecular markers like SSRs and SNPs have been developed in other plant species for sex identification, which indicated
that these markers could also be utilized to differentiate male, female and hermaphrodite plants at early seedling stages in papaya.
Keywords
Papaya; Sex chromosomes; Sex-linked markers
Introduction
Papaya (
Carica papaya
L.) is an edible tropical fruit crop which has several medicinal and nutritional benefits. It
is diploid (2n=9), dicotyledonous plant with a small genome size of 372 Mbp (Arumuganathan and Earle, 1991;
Damasceno et al., 2009; Araujo et al., 2010). It is believed to be originated from Central and South America.
Papaya belongs to the order Brassicales and family Caricaceae. It is closely related to the genus V
asconcellea
. It
shared a common ancestor with the member of order Brassicales e.g.
Arabidopsis thaliana
(Ming et al., 2008).
Papaya is short lived, semi-woody, herbaceous and perennial plant that can be grown upto 10 m in height and
produces fruits in nine to ten months from germinating period. It exhibits palmately-lobed leaves and clustered at
the top of plant (Morton, 1987; OECD, 2005).
Papaya fruit is found to be most nutritious and ranked first among 35 commonly used fruits according to the
percentage of US recommended daily allowances for antioxidant vitamins (A, C and E), thiamine, folate,
riboflavin, niacin, potassium, iron, calcium and fibre (Chandrika et al., 2003; Ming et al., 2008). It is low in
calories, fat and sodium and contains no starch. The fresh fruit is mainly consumed but it is also used in drinks,
jams and as a dried and crystallized fruit candy. The entire plant produces a proteolytic enzyme, papain (EC:
3.4.22.2) which is commonly used in food processing to tenderize meat, clarify beer and juice (chillproofing),
produce chewing gum, and coagulate milk. Papain can also be used in wide range of medical applications such as
to help in digestion, reduce swelling, in fever and in treatment of ulcers (Aravind et al., 2013). In addition, it is
also utilized for making soap, shampoo, lotions, skin care products and toothpastes in pharmaceutical/chemical
industries (Morton, 1987). It is used as important fruit model crop owing to their numerous seed production and
small genome size.
Papaya is trioecious species with three sex types: male, female and hermaphrodite. Among these sex types,
hermaphrodite plants are preferred for commercial cultivation in tropical regions due to their pyriform shaped
fruits (Magdalitan and Mercado, 2003), while female plants are grown mainly for papain production (Parasnis et
al., 1999, 2000). Male plants are not useful for economic purposes as they do not produced fruits and hence they
