Maize Genetics Cooperation Newsletter vol 84 2010

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

 

callusogenesis, somatic embryogenesis and plant regeneration in F1 hybrids of maize.

 

Climenco O.A, Kravchenko A.N., Jacota A.G.

 

Institute of Plant Genetics and Physiology

Chisinau, Republic of Moldova

 

The purpose of this study was to determine heritability and correlation of such characters as  callusogenesis, somatic embryogenesis and plant regeneration. 20 hybrids F1  (Co125 x P502, Co125 x MK390, Co125 x MK159, Co125 x MK01, Co125 x P101, 092 x P502, 092 x MK390, 092 x MK159, 092 x MK01, 092 x P101, A239 x P502, A239 x MK390, A239 x MK159, A239 x MK01, A239 x P101, 459 x P502, 459 x MK390, 459 x MK159, 459 x MK01, 459 x P101) were used as experimental material. Tissue cultures were initiated from 12-13 day-old immature embryos. The data were processed by analysis of variance (Statgraphics Plus 5.1) and coefficients of heritability (h2) for the characters under study were calculated. For the comparison of the relationships between the processes of calusogenesis, somatic embryogenesis and plant regeneration correlation coefficients were determined among parental   inbred lines as well as among hybrid combinations.

              Highly significant differences of the frequency of embryogenic callus formation and plant regeneration process among F1 hybrids were found out. Such combinations as A239 x P502 and A239 x MK159 proved to be the best for somatic embryogenesis (83,58% and 86,89%, respectively). However, A239 x MK159 hybrid had much lower frequency of plant regeneration process than that of A239 x P502 hybrid (34,96% and 76,54%, respectively).  It was also found out that hybrid combination 092 x P502 had rather high frequency of the processes under study (somatic embryogenesis – 73,39% and plant regeneration – 67,78%). In addition, in 4 hybrid combinations the processes of somatic embryogenesis and plant regeneration were not observed.

              Correlation analysis showed that for all the inbred lines (parental forms for F1 hybrids) between the somatic embryogenesis and plant regeneration processes a positive correlation was found (r = 0,69  P<0,05). At the same time, for F1 hybrids a positive relationship (r = 0,44  P<0,05) between callus formation and somatic embryogenesis was determined. A similar relationship exists between callusogenesis and plant regeneration (r = 0,48  P<0,05). However, the correlation between somatic embryogenesis frequency and plant regeneration frequency was much stronger ( r = 0,95  P<0,001) than that of parental lines. Among F1 hybrids a strong negative correlation (r = -0,87  P<0,001) was observed between embryogenic callus formation  and non-embryogenic callus formation. It should be noted that the somatic embryogenesis  and plant regeneration  also negatively correlated with non-embryogenic callus formation ( r = -0,43  P<0,05 and r = -0,56  P<0,01, respectively). Embryogenic  callus formation was  positively correlated (r = 0,66 P<0,001) with plant regeneration.

              Heritability for the processes under study was estimated on the basis of two-factor analysis of variance. Coefficients of heritability are presented in table 1. It was shown that male parent and interaction of both parents had the highest values of heritability for callusogenesis, somatic embryogenesis and plant regeneration processes. Female parent had the lowest heritability value and this coefficient was significant only for non-embryogenic callus formation process.

Table 1

Coefficients of heritability for the characters under study.

Character

h2  for female parent    

  h2  for male parent         

 h2 for interaction of both parents

Embryogenic callus formation

-

0,47***

0,32*

Non-embryogenic callus formation

0,26***

0,35***

0,31***

Plant regeneration

-

0,47***

0,41***

* - P<0,05  ** - P<0,01   *** - P<0,001

 

Taking into account relatively high heritability values of male parent,  heritability coefficients of  male parent for each hybrid combination were calculated on the basis of single-factor analysis of variance (table 2). It should be noted that the highest values of male parent heritability were registrated in case when inbred line A239 was used as a female parent.

Table 2

Heritability corfficients  (h2)  of male parent in F1 hybrids.

 

female parent

male

parent

characters

Embryogenic callus formation

Non-embryogenic callus formation

Plant regeneration

 

 

Co 125

p502

 

 

0,692*

 

 

0,665*

 

 

0,731*

MK390

MK159

MK01

P101

 

 

092

p502

 

 

0,396*

 

 

0,366*

 

 

0,438*

MK390

MK159

MK01

P101

 

 

A239

p502

 

 

0,773**

 

 

0,823**

 

 

0,919**

MK390

MK159

MK01

P101

 

 

459

p502

 

 

0,293*

 

 

0,538*

 

 

0,888*

MK390

MK159

MK01

P101

* - P<0,05  ** - P<0,01

 In contrast, the lowest coefficients of heritability for the processes under study were observed when inbred line 092 was used as a female parent. The lowest value of male parent heritability for embryogenic callus formation was noted when 459 inbred line was used as  a female parent.

Thus, these results can be used in the elaboration of new and improved methods of obtaining maize regenerants.