Paternal plastid inheritance in alfalfa: plastid nucleoid number within generative cells correlates poorly with plastid number and male plastid transmission trength

A previous study on alfalfa determined that the number of plastids/generative cell does not necessarily correlate with male plastid transmission strength in a given genotype. The objectives of the present study were to learn (1) whether plastid nucleoid number/generative cell is comparable to the number of plastids/generative cell, and (2) whether plastid nucleoid number/generative cell correlates with known male plastid transmission behavior in three alfalfa genotypes. Our results, which were based upon 150 generative cells examined by DAPI/epifluorescence microscopy, indicate that the mean plastid nucleoid number/generative cell is much less than the mean number of plastids/generative cell in genotype 7W (60 nucleoids/264 plastids) and genotype 301 (54 nucleoids/165 plastids). In genotype MS-5, mean plastid nucleoid number/generative cell (45) is similar to the mean number of plastids/generative cell (65). The significantly fewer plastid nucleoids/generative cell in MS-5, compared to that of 7W and 301, correlates positively with the relatively poor male plastid transmission strength of this genotype. However, the difference between the mean number of plastid nucleoids/generative cell in 7W and 301 is not significant, yet 301 is a much stronger transmitter of male plastids than is 7W.