Morphological and SCAR marker development for early sex determination in Pointed gourd Trichosanthes dioica Roxb

Abstract

Pointed gourd (Trichosanthes dioica Roxb., 2n=2x=22), a perennial vegetable crop and commonly known as parwal/patal, have Indo-Malayan origin. It is said to be native of South East Asia and probably the Northern and Eastern states of India especially of West Bengal, Assam and Bihar. It has high economic value with export potential. It is mainly cultivated along the riverine belts of Bihar. Pointed gourd (Trichosanthes dioica Roxb) is an economically important cucurbit and is extensively propagated through vegetative means, viz; vine and root cuttings. The plant s dioecious in nature and its vegetative mode of propagation makes its reproduction and multiplication labour intensive. Dioecy represents an inconvenience in pointed gourd breeding since at present there are only few reports distinguishing male and female plants prior to flowering. The use of molecular marker provides a quick and reliable identification of sex types in plants. RAPD (Random amplified polymorphic DNA) has been used previously for determining the gender of plants before flowering. The SCAR marker is one of the stable markers, generally derived from RAPD increase effectiveness of RAPD marker by selecting and redesigning primers whose priming sites occur in target sequence(s) of gene or organism at optimum distance. Therefore, the present study was undertaken to identify marker associated with male and female sex expression trait in T. dioica Roxb. followed by development of SCAR. The screening of genomic DNA samples representative of male and female plants of pointed gourd with RAPD was used to discover sex specific PCR amplification product. A total 40 RAPD primers were used for RAPD analysis, out of which 20 primers gave good results. Among these 20 primers, OPC-04 amplified a band of 400 bp specific to female lines. This RAPD marker was eluted, sequenced and the sequence was used to design primers for SCAR marker. From the sequence, a set of two SCAR primers (N6Fn and N7Fn) was designed to allow amplification of female specific region But,