An analysis of the quantity and diversity of messenger RNAs from pollen and shoots of Zea mays

Summary The mRNAs of the mature pollen grain of Zea mays and of vegetative shoots were analyzed by comparing the kinetics of hydridization between homologous and heterologous reactions of cDNA to poly-(A)RNA in excess. The total complexity of pollen poly-(A)RNA i s 2.4×10⁷ nucleotides, whereas in the seedling shoot it is 4.0×10⁷ nucleotides. This corresponds to 24,000 different sequences in pollen and about 31,000 diverse mRNAs in shoots. The mRNAs in pollen can be divided into three abundance classes that constitute 35%, 49% and 15% of the total mRNAs having complexities of 2.1×10⁵, 6.4×10⁶ and 1.8×10⁷ nucleotides, respectively. Estimates have been made of the number of copies of each sequence per pollen grain or shoot cell, and also of the pollen mRNA sequences shared with those of the shoot.