Free proline contents in two different groups of rice mutants resistant to hydroxy-L-proline

Abstract

In four rice (Oryza sativa L.) mutants resistant to hydroxy-L-proline (Hyp), HYP101, HYP203, HYP205 and HYP210, and in their original variety, Nipponbare, free proline and Hyp contents in the seeds and in the 14-day-old seedlings have been determined. The four mutants can be divided into two groups: HYP101 and HYP203 are classified as to recessive gene and the levels of free proline are similar to that of the original variety; the second group includes mutants HYP205 and HYP210 where the Hyp resistance is transmitted heterozygously and, both in the seeds and in the seedlings, a remarkable increase in free proline content is observed. In particular, free proline contents in the seeds of HYP205 and HYP210 are, respectively, 24 and 12 times that of the original variety. Hyp is detected only in the seedlings cultured with Hyp solution. In the Hyp resistant seedlings of HYP205 and HYP210, Hyp contents are twice that of the original variety and less than half in the seedlings of HYP101 and HYP203. Hyp resistance and differential proline levels are also evident in the callus initiated from the mutants. This suggests that the Hyp resistant mutants are good genetic markers both in planta and in vitro. The Hyp mutants are also discussed with regard to stress resistance.

Development of AFLP-derived STS markers for the selection of 5-methyltryptophan-resistant rice mutants

“…Solid arrows Mutant-specific amplification products. Amplification conditions for each STS marker are described in Table 4 Table 5 cumulates the corresponding free amino acid, while a recessive gene-controlled mutant does not (Mori et al 1989). All of the M 4 lines derived from each of the seven resistant PM lines gave an acceptable fit to a 1:2 ratio of the homozygous resistant for the segregating lines (from c 2 =0.29, 0.75>P>0.50 of PM-7 to c 2 =1.46, 0.25>P>0.10 of PM-6) ( Table 5).…”

Selection of hydroxyproline-resistant proline-accumulating mutants of cauliflower (brassica oleracea var. botrytis)

“…This approach was first applied to plants by Widholm (1972aWidholm ( , 1972b, who isolated tryptophanproducing lines of tobacco by selecting for resistance to 5-methyltryptophan . Amino acid analogue-resistant mutants which overproduce the specific amino acid have been found in bacteria (Czonka, 1981 ;Sugiura & Kisumi, 1985) as well as plants (Widholm, 1976 ;Kueh & Bright, 1982 ;Van Swaaij et al ., 1986 ;Mori et al ., 1989) . It has been reported that free proline-accumulating cell lines resistant to a proline analogue show increased resistance to stresses such as salt (Riccardi et al ., 1983) and freezing (Van Swaaij et al ., 1986, 1987 .…”