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Glutinous rices have none or negligible amounts of amylose content and opaque
endosperm appearance. Non glutinous rices may have high (>24%), intermediate
(20-24%), low (10-19%) and very low (<10%) amylose content. Varieties with
high, intermediate and low amylose content generally have translucent
appearance. However, those with very low amylose content have dull or lazy
appearance.
In order to study the effect of amylose content on endosperm appearance, we examined the F\1\ seeds from the crosses of IR29 (a glutinous variety) and IR37307-8 (a very low amylose variety with dull endosperm) with varieties having high, intermediate and low amylose contents (Table 1). The F\1\ seeds as well as those of parents were harvested, dried, dehulled and milled in Wig- L-Bug. The endosperm appearance was scored phenotypically as opaque, dull, or translucent. Individual grains were analyzed for amylose content. Results were as follows:
Table 1. Endosperm appearance and amylose content in parents and their
hybrids.
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Cross Endosperm appearance* Amylose content
(P\1\/P\2\) (in percent)
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P\1\ P\1\/P\2\ P\2\/P\1\ P\2\ P\1\ P\1\/P\2\ P\2\/P\1\ P\2\
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IR29/IR37307 O O D O 0.10 1.11 3.06 7.48
IR29/IR3351 O D D T 0.10 5.70 6.10 12.23
IR29/IR24 O D T T 0.10 5.53 12.76 14.88
IR29/IR24632 O T T T 0.10 20.87 22.43 21.90
IR29/BPI121-407 O T T T 0.10 22.92 22.40 24.58
IR29/IR8 O T T T 0.10 23.88 27.54 27.51
IR37307/IR3351 D D D T 7.48 11.20 7.92 12.23
IR37307/IR24 D D T T 7.48 6.86 12.88 14.88
IR37307/IR24632 D D T T 7.48 17.45 16.50 21.90
IR37307/BPI121-407 D D T T 7.48 13.93 18.65 24.58
IR37307/IR8 D T T T 7.48 23.92 26.88 27.51
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*D-dull T-translucent O-opaque
Crosses with IR29
When this glutinous variety was crossed as female with different non-waxy
varieties of varying amylose content, the F\1\ seeds did not have translucent
endosperm in all cases as reported earlier. In crosses with low and very low
amylose content varieties as pollen parents, the F\1\ endosperm appearance was
dull. However, the endosperm appearance of F\1\ seeds was translucent, when
varieties with intermediate and high amylose contents were used as pollen
parents (Table 1). Therefore complete xenia effect was shown only in crosses
with varieties of intermediate and high amylose content.
Crosses with IR37307-8
No information is available on the appearance of F\1\ endosperm when a dull
endosperm variety is used as female. In the present study the crosses with low
and intermediate amylose varieties as pollen parents, the appearance of F\1\
endosperm was dull. However, when high amylose variety was used as pollen
parent, the resulting F\1\ seeds had transliucent endosperm.
In rice, like other cereals, the non-waxy pollen has been reported to show xenia effect (Nagai, 1958; Ghos, Chatge and Subramanyan, 1960). This study shows that xenia effect is not a universal phenomenon. The cross of a waxy and a low amylose non-waxy varieties, produced seeds with dull endosperm which could be easily distinguished from translucent as well as opaque endosperm. The results indicate that the potence of a gene to produce xenia effect depends on the amylose content of the pollen parent.
References
Ghosh, R.L. M., M.B. Ghatge and V. Subramanyan, 1960. Rice in India. Indian Council of Agricultural Research, New Delhi.
Nagai, I., 1958. Japonica rice: its breeding and culture. Yokendo, Tokyo, 843 pp.
