The male fertility of primary and further generation dihaploids ofSolanum tuberosum

Abstract

Male sterility in dihaploids of Solamtm tttberosum is often a barrier to their utilization in breeding and gcnetical studies. Although the male I'ertility of primary dihaploids (obtained directly from tetraploids) was generally low, a few were produced by the author which produced seed when used as pollen parents on female fertile dihaploids. The population of further generation dihaploids (from dihaploid intercrosses) produced from them showed a marked improvement in male fertility. Comparative data from measurements of different aspects of male fertility in dihap[oids are presented. These showed that the weight of pollen per anther, the percentage of (iodine) stainable pollen and the number of seeds per berry were greater in further generation dihaploids than in primary dihaploids.It is suggested that interspecilic crosses using dihaploids are not necessarily useful for increasing male fertility in diploid potatoes. The advantages of breeding at the diploid level within S. tuherosum are discussed. Rare male-fertile dihaploids could be used to generate diploids with a high frequency of male fertility. These could then be used to cross with any other Ilowering dihaploids to combine characters at the diploid level, so exploiting the simpler genetic ratios associated with disomic inheritance.

Advances in Haploid Production in Higher Plants

“…Intense selection at the diploid level and the subsequent reconstitution of tetraploids are therefore essential. The major concern of using primary dihaploids in breeding is connected to their low fertility levels, especially in terms of male gametes (De Maine 1997). Therefore the production of further generation of dihaploids (i.e.…”

“…Therefore the production of further generation of dihaploids (i.e. inter-dihaploids) via 2x x 2x crosses is considerably difficult (De Maine 1997;Schwarzfischer et al 2002). Only highly selected dihaploid clones with high fertility can be crossed sexually.…”

Improving main agronomic characters of dihaploids with 2n gametes by means of sexual hybridisation and anther culture of potato (Solarium tuberosum)

“…Such improvement used to be achieved by careful selection of parents for 2x (dihaploid)-2x (wild species) crosses (Hermunstad & Peloquin 1985) or by selection at the 2x level (Veilleux & Lauer 1981;De Jong et al 1982;Iwanaga 1980Iwanaga , 1985Werner & Peloquin 1991) or through both procedures because the 2n gamete was controlled by a single recessive gene (Mok & Peloquin 1975b;Okwuagwu & Peloquin 1981;Iwanaga 1984;Jonhanson et al 1986;. However, these methods are not efficient because infertility often occurs with crosses between diploids with 2n gametes and other dihaploids (Maine 1997). Even if some berries could be harvested, they do not have enough seeds and often contain both diploid and tetraploid seeds.…”