I. Rice species and conservation

G. S. KHUSH, D. S. MULTANI, G. V. VERGARA and D. S. BRAR

International Rice Research Institute, P. O. Box 933, Manila, Philippines

A new species of rice, Oryza indandamanica was described by J. L. Ellis (Ellis 1985) of Botanical Survey of India from the Andaman and Nicobar group of islands in Bay of Bengal. Senior author visited the type locality of the new species on the Rutland island in November 1987 and collected the seeds. It was grown at IRRI and compared with Oryza granulata and O. meyeriana. Morphologically the three species are closely related. In fact, O. indandamanica is difficult to distinguish with O. granulata (Khush and Jena 1989).

We crossed O. granulata (Acc 104503) with O. indandamanica and 2 F1 plants were obtained by the high embryo rescue technique. The F1 plants were so similar to the parents that we had to resort to isozyme analysis to confirm their hybrid nature. Two taxa show allelic polymorphism at five isozyme loci. The F1 plants showed the two parental and hybrid bands for Sdh-1 (Fig. 1) and Amp-1 (Fig. 2). These observations confirmed the hybrid nature of these plants.

The F1 plants showed regular meiosis (Fig. 3) with 12 pairs. No univalents or other abnormalities were observed in 57 PMC'S examined. The pollen fertility of the hybrid was 41% as compared to 74% and 71% for O. granulata and O. indandamanica. These observation show that O. indandamanica and O. granulata have identical genomes. On the basis of genome homology and morphological similarity, O. indandamanica cannot be considered an independent species. It is

Fig. 1. Zymogram showing Sdh-1 isozyme pattern in parents: Oryza indandamanica (P1), O. granulata (P2), and F1 hybrid.

Fig. 2. Zymogram showing Amp-1 isozyme pattern in parents: O. indandamanica (P1). O. granulata (P2) and F1 hybrid.

Fig. 3. A P.M.C.from the F1 of O.granulata X O.indandamanica showing normal pairing (12 bivalents) at diakinesis.

just an ecotype of O. granulata.

References

Ellis, J. L., 1985. O. indandamanica Ellis, a new rice plant from islands of Andamans. Bull. Bot. Surv. India 27: 225-227.

Khush, G. S. and K. K. Jena, 1989. Biosystematic status of O. indanamanica Ellis. In S. Iyama and G. Takeda (eds.), Proc. 6th Intern. Congress SABRAO, p. 1179-182. Organ. Committee, Tokyo.