Prapa Sripichitt

Improved Method for Anther Culture of an Indica Rice Cultivar of Thailand

At present, anther culture is a powerful tool for plant breeding. Anther culture offers the possibility to rapidly obtain the genetically diverse haploids or homozygous doubled haploids from Fl hybrids (Gosal et al., 1997). However, the use of anther culture as a routine technique for breeding of indica rice is extremely limited by the poor induction of androgenic calli and subsequent plant regeneration. The average frequency of green plant regeneration from cultured anthers of indica rice was only 1% in comparison with the 10% of japonica rice (Hu, 1985). Extensive works have been made on various factors influencing the anther culture efficiency of indica rice (Reddy et al., 1985) . Chu et al. ( 1997) developed the medium for the anther culture of javanica and tropical japonica rice varieties. In this report, we describe that the Chu medium is effective for the green plant regeneration from microspore-derived calli of an indica rice cultivar, Chinat 1, in Thailand.

Development of specific simple sequence repeat (SSR) markers for non-pollen type thermo-sensitive genic male sterile gene in rice ( Oryza sativa L.)

A key factor of two-line hybrid rice production is the development of thermo-sensitive genic male sterility (TGMS) lines. In this study, a TGMS line showing non-pollen type thermo-sensitive genic male sterility was used. Crossing between TGMS line (female parent) and normal pollen varieties; CNT1 and PTT1 (male parent) were performed and F 1 and F 2 populations were develop for each crosses. The phenotypic segregation ratio, 3:1 (fertile: sterile pollens) observed in F 2 populations of TGMS/CNT1 and TGMS/PTT1 crosses confirmed that the non-pollen type thermo-sensitive genic male sterility is controlled by a single recessive gene. The bulk segregant analysis (BSA) using simple sequence repeat (SSR) markers were deployed to identify the location and genetic effect of this gene. We have generated new set of SSR markers to identify progenies carrying TGMS gene in a cross TGMS/PTT1. The TGMS gene was located on chromosome 2 with 0.0 cM distance from T2 marker. This TGMS gene was located in the same region of previous identified tmsX gene. It might be the same allele of this gene of 2 different lines. This marker could be used for marker assisted backcrossing to transfer TGMS gene for developing female parent in two line hybrid rice system. Key words: Hybrid rice, thermo-sensitive genic male-sterile, non-pollen type, molecular marker, marker assisted backcrossing.