Genetic mechanism and chromosomal location of pollen-specific gene(s) in Gossypium

Genetic manipulation of plant reproduction is limited by the lack of knowle dge on genes controlling gametophyte development. We have combined the powe r of haploid analysis with the advanced technique of confocal laser scannin g microscopy to identify and understand the genetic mechanism of pollen dev elopment in cotton A study was made on the differential effects of specific chromosomal deficiencies on the morphology of mature cotton pollen, Pollen of the two tetraploid species (G. hirsutum L, and G, barbadense L,) were: found to he morphologically distinct. Confocal microscopy was used to const ruct a three-dimensional image of the fluorochrome-stained pollen grains. C ytogenetically deficient stocks of cotton were used for locating genes for pollen development to chromosomes and chromosome arms. Results indicated th at the pollen size and spine pattern were significantly different between T M-1 (G. hirsutum) and 3-79 (G, barbadense), Comparative analysis of pollen morphology of parental and interspecific hybrid, monosomic, and monotelodis omic plants indicated that gene(s) responsible for pollen spine development were located on the long arm of chromosome 12. The segregating nature of p ollen morphological features indicated that the gametophytic gene(s) of the microspore partially controlled the pollen size and spine formation during pollen grain development.