טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBoris Wasserman
SubjectGenetics of Melon's Fruit Flesh Carotenoids Biosynthesis
DepartmentDepartment of Biology
Supervisors Full Professor Horwitz Benjamin
Dr. Yaakov Tadmor


Abstract

Carotenoids are substances of orange, yellow, red color, and also colorless, absorbing light in the visible or UV regions of the spectrum. In plants carotenoids carry out a number of important functions, including protection of the photosynthetic apparatus from oxidative damage, light harvesting, and also add color to flowers, to fruits and vegetables raising their food value. Carotenoids in fruits have greater importance, where they positively influence human health and add color to fruit flesh.

The purpose of this study was to characterize biosynthesis of carotenoids in melon fruit flesh.

The analysis of the carotenoid contents in fruits of the Newe-Yaar  melon collection has shown that the greatest contents of carotenoids was in cultivars with orange flesh. Cultivars with green flesh contained a much smaller amount of carotenoids, the majority of cultivars with white and cream fruits flesh did not reveal measurable amounts of carotenoids. HPLC analysis showed that b-carotene and lutein are basic carotenoids in melon fruit flesh. The spectral analysis of carotenoid extracts from flesh of melon fruits showed that orange cultivars can be divided into 4 groups according to their b-carotene and z-carotene content.

In samples of fruits from different types of melon cultivars the level of transcription of genes connected with biosynthesis of carotenoids was followed by Northern blot analysis. No major differences were found in the level of transcription of these genes in fruit flesh. Thus, transcriptional regulation of these genes cannot explain the difference in accumulation of carotenoids between cultivars with orange, green and cream fruit flesh. The level of transcription of the genes connected with biosynthesis of carotenoids, apparently, is not the main factor determining accumulation of carotenoids in melon fruit flesh.

The analysis of heritability of fruit flesh color in fruits of RIL (recombinant inbred lines)  PI414723 x Dulce F6 population showed that in a population there is a consecutive change in the contents of carotenoids. The potential number  of genes influencing fruit flesh color in population PI x Dulce has been ascertained by means of bulk segregation analysis with use of SSR markers. 4 out of a total of 26 SSR markers were found to be linked to fruit color in the PI x Dulce population.

This work created the plant material and the genetic data that increased our understanding of carotenoids biosynthesis in melon's fruit flesh and set essential infrastructure for future detailed studies in this field.