Studies of some induced morphological mutants

--V. K. Chaudhary and J. L. Minocha

Besides male-sterile mutants which have been reported elsewhere other morphological variants/mutants were obtained in M2 generation. These mutants were viable (pistillate, pygmy, multitillering and red cob) and non-viable (albino, staminate and vegetative). Their characteristics are given in Table 1. The EMS treatments of 0.1% for 24, 48 and 72 hrs produced more of such morphological mutants than the treatment of EMS, 0.2% concentration for a corresponding time of treatment. The number of pistillate variants was much higher in all three treatments of EMS in a 0.1% concentration. Ethidium bromide, which is considered a potent cytoplasmic mutagen, in a 0.1% concentration induced more mutants than the treatment of 0.2% given for 24, 48 and 72 hrs. This treatment produced a higher number of pygmy and pistillate mutants than other mutants. More multitillering mutants were obtained after the treatment with EB (0.2%) than any treatment of EMS. The appearance of these morphological mutants as well as albino seedlings gives an indication of EB being nuclear in its nature. Treatment with streptomycin at 0.1 and 0.2% concentrations for 48 hrs produced mostly multitillering mutants as compared to the other treatments.

Table 1. Characteristic features of some induced morphological mutants.

Normal seed set was observed in these viable mutants. The non-viable mutants did not give seed set hence no further study. The albino seedlings in M2 could not survive and hence no further study. Their occurrence has been reported elsewhere. The viable morphological mutants were further analysed in M3 and subsequent generations. As pistillate and multitillering mutants were without male inflorescence, these were crossed to the control (CM400) as pollen parent. The resulting progeny in M3 generation were phenotypically normal looking like the control. Upon selfing such plants in M3 their progeny exhibited segregation in M4 generation. Out of 780 seeds sown in each case, in one, 552 normal and 180 pistillate mutants were recorded, whereas in another 534 normal and 192 multitillering mutants, providing an indication for these characters being monogenically controlled. Pygmy mutants bred true in M3 and subsequent generations. Male-sterile mutants could set seed when crossed with the control pollen and the result has been reported elsewhere.

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