Development Of Molecular Markers For Fruit Bitter In Luffa

Luffa is one of the important Curcurbitaceae crops.There are two cultivated subspecies in China,ridge gourd[Luffa acutangula?L.?Roxb.]and sponge gourd[Luffa cylindrica?L.?Rome.].Ridge gourd is cultivated mainly in southern China.Bitterness in fruits occurs in hybrid of the two subspecies and sometimes in angular gourds,which is harmful to the health of consumers and need to be excluded during breeding.In this study,a genetic map was constructed and the gene for fruit bitterness was mapped using SSR and SRAP molecular marker techniques based on a backcross population of angular gourd4-0-0-0 and sponge gourd 48-1-0-0.The main results are as follows:1.Fruit bitterness of 4-0-0-0,48-1-0-0,48-1-0-0×4-0-0-0 F₁ and 87 BC₁ plants of[?48-1-0-0×4-0-0-0?×48-1-0-0]were evaluated by a panel of taster.The results showed that two parental fruits were not bitter,the F₁ fruits were bitter and the BC₁ population segregated with a ratio of 1:1 for bitter and non-bitter fruits.This confirmed that a single dominant gene for fruit bitterness existed in the angular gourd species.2.90 polymorphic SSR markers and 36 robust and polymorphic SRAP markers on two parents were obtain after screening 192 SSRs which were developed in our lab or published in papers and 324 SRAP primer combinations.The polymorphic markers were amplified on 87 individual plants of the BC₁ population.A molecular linkage map was constructed and 111 markers including 78 SSRs and 32 SRAPs were integrated into 12linkage groups,covering a genetic distance of 775.41 cM with the average marker distance of 6.99 cM.The length of single linkage groups ranged from 27.11 to 96.14 cM which contained 4¹8 markers.3.The fruit bitter gene bt was mapped within marker SGE292 and SGC196 on linkage group 3,whose genetic distances were 6.08 and 3.11 cM,respectively.These two markers could be used as the molecular markers for tagging bt gene.