Identification of molecular markers linked to male sterility in onion (Allium cepa L.)

Abstract

Onion is one of the most important vegetable crops. Onion hybrids are very popular. Male sterility has been utilized for the production of F1 hybrids. Molecular markers help us to identify a male sterile and maintainer line which facilitates early development of F1 hybrids with stable male sterility system. Keeping this in view, the present study was conducted in onion. Studies on morphological and floral characters of male sterile (A), maintainer (B) and male parent (C) lines have showed significant differences for different parameters. Molecular characterization of these lines using RAPD marker could not differentiate the genotypes successfully. However Dendrogram and PCA analysis clustered the genotypes accurately. The first cluster consisting of MS-65 and MS-48 group and the second cluster consisting of MLT group. This result has also in agreement with the morphological character, as multiplier onions are different from single onions. A marker was identified which could able to classify male sterile (A) and male fertile (B) genotypes by using ORF 725 primers. Among the male sterile and maintainer lines tested with ORF 725 marker, the lines MS-65(A and B), PBR (A and B), Rose onion (A and B) were successfully differentiated by amplifying both forward and reverse primers to produce two bands in male sterile(A) and one band in male fertile (B) lines. This marker was not able to differentiate A and B lines of Arka Pragati, MS-48 and MLT group. Among F1 hybrids tested, the F1 451 (MS-65 x Sel-13) produced two bands but 394(MS-65 x PBR) and 452(MS-48 x Sel-14) produced single bands indicating these are lacking stable cytoplasmic male sterility. This is because male sterile lines used in these hybrids are not stabilized. This may be also due to the N-cytoplasmic contamination of Scytoplasmic hybrid seed lot.