The technology and applications of microarrays of immobilized DNA or oligonucleotides are reviewed. DNA arrays are fabricated by high-speed robotics on glass or nylon substrates, for which labeled probes are used to determine complementary binding allowing massively parallel gene expression and gene discovery studies. Oligonucleotide microarrays are fabricated either by in situ light-directed combinational synthesis or by conventional synthesis followed by immobilization on glass substrates. Sample DNA is amplified by the polymerase chain reaction (PCR), and a fluorescent label is inserted and hybridized to the microarray. This technology has been successfully applied to the simultaneous expression of many thousands of genes and to large-scale gene discovery, as well as polymorphism screening and mapping of genomic DNA clones.
Based on early genetic studies of inter‐ and intra‐specitlc crosses in cotton, the genes for increased plant pubescence, H1 and H2 are independently inherited. More recent studies with aneuploids of Gossypium hirsutum L. showed that the H1 and H2 genes and the Sm2 gene (that removes trichomes from the plant) all are located on chromosome 6, and that the H2 and Sm2 are located in the long arm of the chromosome. The H2 gene was mapped 4 units from the centromere. Based on the latter data, the three genes may either be closely linked or alleles. In this study, we used aneuplolds to show that the H1 and Sm2 genes also are located 4 map units from the centromere in the long arm of chromosome 6. In addition to the cytogenetic approach, we also studied the F2 populations of the three crosses of H1 ✕ H2, H1 ✕ Sm2, and Sm2 ✕ H2 and found that the three genes segregated as alleles. In view of these results, a revised nomenclature for the smooth‐halriness genetlcal system in cotton is needed.
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