3. Genetical classification of existing dwarf-gene sources of hsien rice in China

Yong-Gen LU, Guo-Chang WANG and Ren-HUA WANG

South China Agricultural University, Guangzhou, China

Genetic analysis of eight dwarf-statured cultivars of hsien (indica) rice in China (Table 1) was carried out in Guangzhou, China. The analysis was carried out to determine: 1) the mode of inheritance of dwarf-stature in different dwarfs; 2) allelic relationships among various dwarfs; 3) genetical classification of dwarfs.

The main results obtained are summarized as follows:
1. Tallness is incompletely dominant to the dwarfness of all dwarfs tested except Zhaiyeqing 8, Aizhongshuitiangu and Zhuchi.
2. The dwarfness of Aijiaonante, Aizizhan, Dijiaowujian (Dee-geo-woo-gen), Guangchang mutant, Zhaiyeqing 8 and Zhuchui is controlled by a major recessive gene. In addition, a set of modifiers with positive or negative effects is involved.
3. The dwarfness of both Aizhongshuitiangu and Fubaoai 21 is conditioned by minor genes and is under polygenic control.
4. Based on the results of the transgressive segregation, the strength of modifier effect might be Zhuchui>Guangchang mutant> Aizizhan> Aijiaonante> Fubaoai 21.
5. Based on the mode of inheritance of dwarfness and allelic relationships among the dwarfs, the existing dwarf-gene sources of hsien rice in China may be classified into two categories and four groups, as shown in Table 1.

Table 1. Classification of eight dwarf Hsien cultivars according 
         to their genetic control
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              Seasonal                                  Modifier
Cultivar                 Maturity  Origin  Dwarfing 
              type                         gene            genes
________________________________________________________________
Dijiaowujian  Early cr.  Late      Taiwan  DGWG      Positive3   
(Dee-geo-
woo-gen)

Zhuchui       Late crop  Medium    Guangdong  "           "
Aizizhan      Early crop  Late     Guangxi    "      Negative4  
Aijaonante    Early crop  Early    Guangdong  "           "
Guangchang 
mutant        Early crop  Medium   GAAS1      "           "
Zhaiyeqing 8  Early crop  Medium   GAAS2   Independent Positive3
                                             of DGWG 
Aizhongshui- 
tianku        Late crop   Late     Indonesia  minor genes 
Fubaoai 21    Late crop   Medium   Guangdong
________________________________________________________________ 
1. Guangdong Academy of Agricultural Sciences, radiation-induced mutant from Guangchang 13.

2. Bred by GAAS with a dwarfing gene from Hualong-Shuitiangu, an Indonesian native cultivar.

3. Strongly positive and weakly negative effect in the mode of transgressive segregation.

4. Weakly positive and strongly negative effect in the mode of transgressive segregation.

References

Lu, Y. G., S. X. Zheng, Z. B. Li and R. H. Wang, 1979. A study on the phenotypic expression and genetic transmission of dwarf-gene sources of early hsien rice in China. Acta Genetica Sinica 6(3): 311-321.

Lu, Y. G., G. C. Wang and R. H. Wang, 1987. A study on phenotypic expression and genetic transmission of four dwarf-gene sources of hsien rice. Journal of South China Agricultural University (in press).