Incompatibility Mechanism in Interspecific Peanut Hybrids1
- T. M. Halward and
- H. T. Stalker2
Mechanisms of incompatibility among interspecific peanut(Arachis spp.) hybrids were investigated in an attempt to determine efficient methods for the introgression of germplasm from diploid Arachis species (2n = 20) into A. hypogaea L. (2n = 40). Hexaploid interspecific hybrids (2n = 60) with restored fertility were used in a backcross program, in reciprocal, with diploid Arachis species in an attempt to rapidly reduce the chromosome number from 2n = 60 to 2n = 40. All attempts to cross hexaploids and diploids failed to produce viable hybrids. The proposed mechanisms for such failure are: (i) lack of pollen germination on the stigma or restricted pollen tube growth (in crosses using diploid A. cardenasii as the female parent), and (ii) endosperm degeneration and/ore mbryo abortion( in all other crosses examined). When A. cardenasii Krap. et Greg. nom. nud. (coll. GKP 10017) (2n = 20) was used as a female parent, no pegs (the basal portion of the gynoecium that grows by the activity of an intercalary meristem and carries the fertilized ovule into the soil) werep roduced. When A . duranensis Krap. et Greg. nom. nud. (coll. K 7988) (2n = 20) or batizocol Krap. et Greg. (col l. K 9484 (2n = 20) was used as a female, very few pegs were produced and the hybride mbryosa bortedw ithin 10 days after pollination. When either of the two hexaploidh ybrids(A. hypogaea ✕ A. batizocoi or A. hypogaea ✕ A. cardenasii was used as a female, peg development was more frequent,b ut all developed pods contained tiny, shrivelled, black seeds. Embryo rescue techniques were applied as a means for overcoming embryo abortion. The seeds were successfully germinated in culture and shoots and roots were initiated.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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