Simultaneous chromosome G-banding and in situ hybridization of RFLP markers in maize
--Song, Y; Ren, N; Mao, N; and Liu, L

The technique of simultaneous G-banding and in situ hybridization (ISH) has been developed in plants for the first time. Using this technique with RFLP markers, umc58 was localized onto 1L3 (chromosome 1, long arm, the third band from the centromere to the end of the arm), 5L5 and 9L6; and umc65 was localized onto 6L1 and 8L7. It was shown that umc58 and umc65 hybridize to triplicated and duplicated sequences respectively (Figs. 1 and 2). These two markers separately showed hybridization sites near the centromere of the long arm in chromosomes 1 and 6, corresponding basically to their sites in the genetic map. It was deduced that umc58 probably was near Helminthosporium carbonum susceptibility genes (hm1 and hm2), as hybridization sites of umc58 in chromosomes 1 and 9 are those at which the genes localize.

Figure 1. The mitotic chromosomes showing hybridization sites of the tested probes. In all the figures the small arrow denotes the hybridization site and the large arrow denotes the centromere. (a) Late prophase chromosomes showing a site with probe umc58 at 1L3. (b) Late prophase chromosomes showing a site with probe umc58 at 5L5. (c) Late prophase chromosomes showing a site with probe umc58 at 9L6. (d) Early metaphase chromosomes showing a site with probe umc65 at 6L1. (e) Early metaphase chromosomes showing a site with probe umc65 at 8L7.

Figure 2. G-banded idiograms showing the physical location of the RFLP markers. The top numeral is the number of the chromosome. (a) G-banded idiogram of chromosomes 1, 5 and 9 showing sites with probe umc58 at 1L3, 5L5 and 9L6 respectively. (b) G-banded idiogram of chromosomes 6 and 8 showing sites with probe umc65 at 6L1 and 8L7 respectively. 

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