Maize Genetics Cooperation Newsletter vol 81 2007

 

 

Cheonan, KOREA

National Livestock Research Institute, RDA

GWACHEON, KOREA

Ministry of Science & Technology

DAEJEON, KOREA

Chungnam National University

 

Inheritance of ear shank length in maize (Zea mays L.)

--Ji, HC; Lee, JK; Choi, GJ; Kim, KY; Seong, BR; Seo, S; Kim, SH; Lee, HB

 

       The ear shank in maize corresponds to the lower portion of the lateral branch and comprises several nodes and shortened internodes.  The inheritance of ear shank length was investigated in sweet corn inbreds Ia453sh2 (with a long shank) and Hi38c1 (a tropical Hawaiian super sweet, with the brittle1 gene and a short shank).  Ear shank lengths of the parent lines were 4.59 cm (Hi38c1) and 13.25 cm (Ia453sh2).  The ear shank length of F1 hybrids was 14.66 cm, while the length of F2 lines was 12.69 cm (Fig. 1).  The ear shank lengths in BC1 and BC2 were 8.88 cm and 15.32 cm, respectively.  The average coefficients of variation (CV) were as follows:  P1 40%, P2 27%, F1 35%, F2 52%, BC1 56%,
 

P1            P2             F1             F2           BC1          BC2
 
 


Figure 1.  Distribution of ear shank length in parents, F1, F2 and Backcross (BC1, BC2) generations.  F1, F2 and BC1 and BC2 populations were derived from the parental inbreds Hi38-71 (short shank) and Ia453sh2 (long shank).  P1: Hi38-71, P2: Ia453sh2.

 

BC2 39%.  These results were analyzed by the Generation Mean Analysis (GMA) Method modified from Mather and Jinks (1977).  Generation mean analysis of the six generations (Table 1) revealed a highly significant additive effect.  The aa [additive x additive] and dd [dominance x dominance] effects were not significant but ad [additive x dominance] effects were significant.

 

Table 1.  Estimates of additive (a), dominance (d), and interaction parameters for the cross Hi38c1(bt) x Ia453sh2.

 

Parameter+

Estimate (�SE)

t test

 

m

12.69�0.27

 

18.36

**

a

-6.44�0.43

 

-6.39

**

d

3.38�1.42

 

0.97

NS

aa

-2.36�1.38

 

-0.69

NS

ad

-2.11�0.45

 

-2.03

*

dd

1.12�2.13

 

0.22

NS

+m=midpoint, a=additive effect, d=dominance effect, aa=additive x additive effect, ad=additive x dominance effect, dd=dominance x dominance effect

*, **, NS; levels of significance.

 

       Broad-sense heritability was 60.51% and narrow-sense heritability was 58.5%.  The estimated minimum number of gene loci, using the Castle and Wright formula, was 0.54.  Therefore, ear shank length might depend on a single gene acting without any dominance effect, but more study is needed on the relationship between ear shank length and other characters.

 

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of authors.