what is the role of gibberellins in plants
Gibberellin Gibberellins (GAs) are plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development and leaf and fruit senescence.[1] GAs are one of the longest-known classes of plant hormone. It is thought that the (albeit unconscious) selective breeding of crop strains that were deficient in GA synthesis was one of the key drivers of the "green revolution" in the 1960's,[2] a revolution that is credited to have saved over a billion lives worldwide.[3]
Microspore In seed plants the microspores develop into pollen grains each containing a reduced, multicellular male gametophyte.[5] The megaspores, in turn, develop into reduced female gametophytes that produce egg cells that, once fertilized, develop into seeds. Pollen cones or microstrobili usually develop toward the tips of the lower branches in clusters up to 50 or more. The microsporangia of gymnosperms develop in pairs toward the bases of the scales, which are therefore called microsporophylls. Each of the microsporocytes in the microsporangia undergoes meiosis, producing four haploid microspores. These develop into pollen grains, each consisting of four cells and a pair of external air sacs. The air sacs give the pollen grains added buoyancy that helps with wind dispersal.[3]