A genetic analysis of low‐temperature‐sensitive sterility in indica‐japonica rice hybrids

Abstract

Low-temperature-sensitive steriUty has become one of the major obstacles in indica-japonica hybrid rice breeding. The objectives of this paper were to evaluate the extent of the fertility reduction and to determine the genetic basis of low-temperature-sensitive sterility. Seventeen varieties were crossed in various ways to produce 21 F|S including 16 indica-japonica hybrids. Fertility of the F]S and their parents was examined under both high and low temperature conditions. Considerable reduction in spikelet fertility was observed under low-temperature conditions in the majority of the indica-japonica hybrids having at least one wide compatibility parent. However, the extent of fertility reduction varied greatly, depending on the parental genotypes. Data from five pairs of reciprocal crosses indicated that the cytoplasm had no effect on fertility reduction. The more-or-less bimodal distribution of the fertihty segregation of one BCiF, and two F^ populations under low-temperature conditions suggested that the lowtemperature-sensitive sterility was controlled by only one or a few genes. It was also shown that the low-temperature-sensitivity is not related to wide compatibility. We conclude that it is possible to develop indicajaponica hybrids with wide compatibility and also insensitivity to the low-temperature conditions.

Male and female gamete abortions, and reduced affinity between the uniting gametes as the causes for sterility in an indica/japonica hybrid in rice

“…japonica. These three varieties are regarded as typical indica or japonica, and were recommended and used as testers for compatibility analyses (Liu et al 1996). Nanjing 11 was crossed with Akihikari to produce an inter-subspecific hybrid, and with IR36 to produce an intra-subspecific hybrid.…”

“…It is known that the majority of the indica/japonica hybrids are partly sterile, with the spikelet fertility mostly in the range of 30-60% (Liu et al 1996). It has also been observed that strong heterosis exists in many indica/japonica hybrids in both vegetative and reproductive growth, which has attracted the attentions of rice breeders for several decades (Yang et al 1962;Chu et al 1964;Yuan 1987).…”

Estimating the outcrossing rate of barley landraces and wild barley populations collected from ecologically different regions of Jordan

“…Parzies et al (2000) reported higher outcrossing rates under fluctuating rainfall conditions. Light intensity has been shown to modify the outcrossing rate in other self-pollinated species such as wheat (Demotes-Mainard et al 1995) and rice (Li et al 1996). Low population density reduced outcrossing in the cross-pollinated crop Cuphea laminuligera (Krueger and Knapp 1991).…”

The relevance of outcrossing for the dynamic management of genetic resources in predominantly selfing Triticum aestivum L. (bread wheat)

“…f was estimated by the maximum likelihood method proposed by Li and Horovitz (1953) (Nelson et al, 1995a,b (Li et al, 1996) and winter wheat (Demotes-Mainard et al, 1995). Demotes-Mainard et al (1995) (Fisher, 1958 (David et al, 1993;Ronfort and Couvet, 1995).…”