Indica Genotypes Research Articles

Development of a technique for in vitro unpollinated ovary culture in rice, Oryza sativa L.

A simple and efficient technique for in vitro unpollinated ovary culture in rice which is also applicable for indica genotypes was developed for breeding and genetic studies. Sampling explants at the auricle distance of 7–12 cm between the two uppermost leaves of a tiller, providing a chilling pretreatment and ovaries with 1/3 of the hulls intact gave optimum response to culture. For callus induction with the spontaneous breaking of ovaries, N6 media supplemented with NAA (2 mg/l) and DMSO (0.6–0.8%) gave a mean PCI value of 3.8% and range of 0.8–12.5% among genotypes. Media combining 2,4,5-T or 2,4-D with NAA in N6 medium also has reasonably good callus induction. For calli induced inside, 2,4-D (0.2–0.5 mg/l), NAA (2 mg/l) and KT (1 mg/l) contained media were superior. The maximum green plant regeneration (PPR) of 77.3% was found with the medium containing NAA 0.25 mg/l, IAA 0.5 mg/l and KT 2.0 mg/l. Significant genotype, medium and their interaction effects for per cent ovary survival and callus induction were observed.

Phenylacetic acid stimulation of direct shoot formation in anther and somatic tissue cultures of rice (Oryza saliva L.)

AbstractThe effect of phenylacetic acid (PAA) on rice (Oryza saliva L.) anther culture was investigated with six genotypes, using 2,4‐D as control. In the two‐step culture protocol, replacing 2, 4‐D with PAA in the induction medium did not influence callus induction but significantly improved the shoot differentiation from callus, particularly in the indica cultivar Teqing. The anther‐derived calli of all genotypes regenerated shoots directly on the callus induction medium containing PAA. Most of the directly‐regenerated plantlets had well‐developed root systems and were therefore readily transplanted into soil. The improved shoot differentiation potential and the frequency of direct regeneration depended on genotype, basal medium and PAA concentration. The one‐step green shoot regeneration frequencies obtained were 1.98% with the indica cultivar ‘129’, 1.5% with the indica × japonica hybrid ‘Teqing/02428’ (F1), and 1.98% with the indica × indica hybrid ‘Waiyin 2/C.B.’ (F1). The PAA‐based one‐step method was most effective on the anther culture of indica genotypes. Three DH populations have been constructed from hybrids (F1) via one‐step culture. PAA also enhanced the one‐step plantlet formation in rice somatic tissue culture.