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Analysis of Genes for Stigma Coloration in Rice - IRRI books

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Effects <strong>of</strong> dwarf genes<br />

on rice root elongation<br />

H. Kitano and Y. Futsuhara<br />

The effects <strong>of</strong> dwarf genes on root elongatlon at the seedlmg stage were exam<strong>in</strong>ed <strong>in</strong><br />

18 near-isogenlc dwarf l<strong>in</strong>es that were bred at the Plant Breedmg Institute <strong>of</strong> Hokkaido<br />

University us<strong>in</strong>g Shiokarl as the recurrent parent (K<strong>in</strong>oshlta and Sh<strong>in</strong>bashi 1982).<br />

Seedl<strong>in</strong>gs <strong>of</strong> the l<strong>in</strong>es and Shlokari were grown <strong>for</strong> 10d after germlnatlon by soil culture<br />

<strong>in</strong> the greenhouse and by hydroponics <strong>in</strong> a growth cablnet at 28 °C. Thereafter, data<br />

on shoot, sem<strong>in</strong>al root, and nodal root lengths and on number <strong>of</strong> roots were recorded.<br />

In addition, average nodal root length and total root length were calculated from the<br />

mean values <strong>of</strong> the measurements <strong>of</strong> root characters. Table 1 shows the results <strong>of</strong> the<br />

soil culture experiment. Except In a few l<strong>in</strong>es, shoot and/or root growth <strong>in</strong>hibition by<br />

each dwarf gene showed a slmilar tendency <strong>in</strong> the two cultural condltions. The l<strong>in</strong>es<br />

were classified <strong>in</strong>to four categories: Group A hav<strong>in</strong>g a prom<strong>in</strong>ent decrease <strong>in</strong> root<br />

length and shoot length (d-1, d-10, d-11, d-13, d-27), Group B hav<strong>in</strong>g a greater<br />

decrease In shoot length than <strong>in</strong> root length (d-18 k , d-35, d-b), Group C hav<strong>in</strong>g a<br />

greater decrease In root length than <strong>in</strong> shoot length (d-3, 4, 5, d-7, d-14, d-17, and<br />

Group D composed <strong>of</strong> resldual l<strong>in</strong>es (d-2, d-6, d-12, d-30, d-47, d-a). Although it is<br />

confrrmed that d-7 and d-27 significantly decrease radicle length <strong>in</strong> the mature<br />

embryonic stage (Kamglma and Watanabe 1985), <strong>in</strong> this experiment reduclble effects<br />

by these dwarf genes could not be detected on sem<strong>in</strong>al root elongatlon after<br />

germmatlon. On the other hand, excised root tips <strong>of</strong> the isogenic l<strong>in</strong>es were cut at 1 cm<br />

from the top <strong>of</strong> the sem<strong>in</strong>al root <strong>of</strong> seedl<strong>in</strong>gs at 6 d after germ<strong>in</strong>ation and cultured on<br />

White's medlum <strong>for</strong> 21 d at 26 °C <strong>in</strong> the dark. The root growth responses <strong>of</strong> the 18 l<strong>in</strong>es<br />

were compared wlth that <strong>of</strong> Shiokari. The results <strong>of</strong> this experiment were conslderably<br />

different from those gwen above, suggest<strong>in</strong>g that dwarf gene action on root growth is<br />

affected by shoot growth.<br />

These results reveal that the expression <strong>of</strong> dwarf genes on root elongation varies<br />

remarkably.<br />

References cited<br />

Kamijima O, Watanabe K (1985) Effect <strong>of</strong> dwarf genes on size and cellular characteristics <strong>of</strong><br />

embryonic organs <strong>in</strong> near-isogenic l<strong>in</strong>es <strong>of</strong> rice. Jpn. J. Breed. 35:243-254.<br />

K<strong>in</strong>oshita T, Sh<strong>in</strong>bashi N (1982) Identification <strong>of</strong> dwarf penes and their character expression <strong>in</strong><br />

the isogenic background. Jpn. J. Breed. 32:219-231.<br />

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