| NP839, NP883, and NP880: new sources of fertility restoration
in male sterile wheat R. K. MIRI, J. S. AMAWATE and H. K. JAIN Division of Genetics, Indian Agricultural Research Institute, New Delhi, India The pioneering work of KIHARA (1951, 1963), FUKASAWA (1958), WILSON and Ross (1962) and SCHMIDT, JOHNSON and MAAN (1962) on cytoplasmic-nuclear interactions in wheat has opened up possibilities of commercial exploitation of heterosis in this important cereal crop. A stable cytoplasmic-genetic male sterility and fertility restoration system whereby the pollen production in breeding lines can be switched "off" or "on" at will is one of the pre-requisites for successful production of hybrid wheat. Our extensive studies on the mechanism of T. timopheevi system of cytoplasmic male sterility and fertility restoration with ten varieties of wheat including C303. C306. Sharbati Sonora, Lerma Rojo, S310, Kalyansona, PV18, NP830, NP875 and Sonalika involving more than two thousand lines. F1 plants and backcross progenies led us to the conclusion that these varieties can be classified into three categories: varieties carrying modifiers (fertility restoring) of strong, action, those carrying such modifiers of weak action and varieties without such modifiers (MIRI 1966, 1968. MIRI et al. 1970). OEHLER and INGOLD (1966) reported a commercial variety "Primepi" carrying a dominant gene for fertility restoration and PORTER and MERKLE (1967) found fertility restoring genes in a composite population of world collection of common wheat. Our recent findings reported here show that the Indian wheat varieties NP 839, NP 883 and NP 880 carry genes which fully restore fertility and support the hypothesis proposed by us earlier (MIRI et al. 1970) It is now suggested that a systematic study should be undertaken of the so far identified hexaploid wheat varieties, carrying fertility restorer genes, to find how many different loci are involved, which may then be numbered as R1, R2, R3 etc. as has already been done by wheat rust geneticists for black, brown and yellow rusts. The most promising of the fertility restorer genes can then be used for the development of hybrid wheat. Twenty-nine varieties (Table 1) were crossed as pollen parents with completely male sterile Kalyansona lines W-12-67-4, W-12-67-2, W-12-67-25, W-11-67-31 and W-11-67- 25, carrying T. timopheevi cytoplasm, during the 1968 crop season. The F1 progenies from these crosses were grown in pots in the 1969 season and plants were classified for male fertility on the basis of the development of anthers and seed set on bagged ears. Sixteen F1 plants obtained from the cross W-12-67-4 x NP839, twenty-three F1 plants from the cross W-12-67-2 x NP883 and five F1 plants from the cross W-12-67-4 x NP880, were completely fertile. Kalyansona is a dwarf (Norin) wheat selected from breeding material developed initially in Mexico by BORLAUG and his colleagues. It is ten to fifteen days later in maturity compared with NP839, NP883 and NP880, all of which are tall Indian varieties. All the F1 plants were tall and early maturing and the head type of Kalyansona appeared to be partially dominant. The complete fertility observed in the F1 plants suggests that these three varieties carry fertility restoring genes. The F1 progenies derived from the crosses with twenty-six other varieties showed varying degrees of male fertility (Table 1). |
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