Development of a Thermosensitive Genetic Male Sterile Line for Hybrid Breeding through Ovary Culture in Rice (Oryza sativa L.)

Abstract

Unpollinated young ovaries from the F1 plants of the cross between UPRI 95-140, a TGMS donor, and UPRI 95-117, a good plant type line of indica rice were pretreated at 8°C for 14 days and cultured onN6 medium supplemented with lactoprotein hydrolysate 500 mg l-1 2,4-D 4.0 mg l-1 NAA 2.0 mg l-1 and BA 1.0 mg l-1. Five calli with 0.5% of callus induction were obtained. Four of these calli gave complete green plantlets possible of spontaneous dihaploids while the remaining one gave partially green plantlets onMS plant regeneration medium supplemented with casein acid hydrolysate 500 mg l-1, NAA 0.5 mg l-1 and BA 1-5 mg l-1. One of the regenerated green plantlets was identified with thermosensitive genetic male sterility (TGMS) trait. The spikelet fertility transformation of this plant was closely related to mean minimum daily and mean average daily temperatures of the 15-d thermosensltive stage prior to 5 days of heading. It presented complete spikelet sterility between May 1 and Sept 5 and 0.5 to 12.3% and 0.5 to 41.5% of seed set between Sept 18 and Nov 1, 1995 and March 10 to april 27, 1996, respectively at Pantnagar in the northern India. And the line in H2 present homogenous performance with optimum spikelet fertility transformation in Wet season, 1996. This line is being used to develop two-line heterotic hybrids.