Study of the phenomenon of antidromy with diploid and haploid maize --Rotarenco, VA, Maslobrod, SN The phenomenon of antidromy, which is noticed with many species of plants and particularly well marked in grasses, was described by G. Maclosky (1895; 1896). The antidromy phenomenon consists of the periodic change of spirally - rolled up leaf tubes counterclockwise (leftness) and clockwise (rightness) with every new stalk's node. According to the data by Sulima (1970) left (L) and right (D) leaves of most gramineous plants alternate on the stalk with exceptional consistency. The exception to the antidromy rule is maize.

Together with the right antidromy plants (symmetrical) there are some plants of maize with an infringed antidromy (asymmetrical). The latter have an infringed alternation of L and D leaves on the stalk's nodes, which determines leftness and rightness of plants: L-plants appear to have an abundance of L-leaves, frequently repeating on several nodes after the other; D-plants on the contrary were noted to have a superfluous forming of D-leaves also repeating on several successive nodes. Zone of antidromy infringement is situated as a rule on the nodes from an ear to the panicle of a maize plant (Sulima,1970).

We wished to determine the amount of infringed antidromy (asymmetrical plants) on the diploid and haploid levels. We studied the character of alternation of L and D leaves on the nodes from the ear to the panicle. Diploids and their haploid analogues of two homozygous lines (092 and Rf-7) and also the synthetic population (SP), no less than 200 plants of every variant, were used. The results are presented in Table 1.

Table 1. Part of asymmetrical plants (with an infringed antidromy) on diploid (2n) and haploid (n) levels.
 
Genotype Number of asymmetrical plants, (%)
  2n n
092 6.8 37.0
Rf-7 6.6 27.7
SP(population) 25.4 41.5

Sulima supposed that the infringements of antidromy with maize were not only harmless or indifferent for the species, but were even useful. According to his hypothesis, antidromy infringements on a maize stalk are a sort of filter regulating the flow of metabolites between the panicle and the ear. This filter should be considered as an evolutionarily expedient mechanism of regulation of the direction of the main flow of metabolites with its reorientation to the middle of the stalk, where the main consumer of substances, the ear is situated. Sulima and colleagues have analyzed 12 male (without ears) and 9 female (without panicles) forms of maize. Male forms had 30% and female had 92% with infringed antidromy. Such a high density of infringements is characteristic only for female plants (Sulima, 1970).

Based on Sulima's hypothesis it can be supposed that an increase of the number of dissymmetrical plants among haploids is caused by the fact that their panicles are practically completely sterile, but the ears are partially fertile. Through this the flow of metabolites in haploids blockades by means of antidromy infringements and reorientates mainly to the ears. In our work we received a confirmation of Sulima's hypothesis comparing numbers of asymmetrical plants in cycles of selection in the SP population. For the improvement of this population we use haploid recurrent selection (Chalyk and Rotarenco, MNL 1999). The results obtained on the diploid and haploid level are given in Table 2. An increase of the number of plants with an infringed antidromy in the cycle of selection takes place in both cases. Thus together with an increase of the ear's parameters (productivity) in our case, an increase in the number of asymmetrical plants takes place in the population.

Table 2. Part of asymmetrical - left (L) and right (D) plants in the cycles of selection on diploid (2n) and haploid (n) levels in SP population.
 
Cycles of selection
(2n)
(n) 
 
Asymmetrical plants,%
Of them 
Asymmetrical plants,%
Of them 
   
L, %
D, %
  
L, %
D, %
C0
16.2
43
57
36.2
53
47
C1
22.2
45
55
44.1
43
57
C2
32.9
30
70
36.0
37
63
C3
30.1
36
64
49.1
44
56

In the work by Maslobrod and others (2000, 2001) on tomatoes, it was shown that L-plants had a 15-20% higher yield than D-plants. In the work by Sulima (1970) D-plants of maize hybrids were more productive. In our investigation all the plants with an infringed antidromy were also divided into L and D-plants. It was determined that the number of D-plants with reference to L-plants, both on the diploid and haploid levels, increases in cycles of selection (Table 2). Thus the selection for yield leads to an increase in the number of D-plants with reference to L-plants. This indirectly confirms the fact that D-plants have a greater yield. Also a comparative analysis of quantitative traits (Table 3) has shown that D-plants on the diploid level essentially exceed L-plants for plant traits. On the haploid level, the differences in the traits studied are not essential. It is connected with the fact that haploids practically don't have correlations between traits of a plant and the ear (Rotarenco, MNL 2000).

Table 3. Parameters of quantitative plant's traits of L and D-plants in SP population on diploid (2n) and haploid (n) levels.
 
Traits
(2n)
(n)
 
L-plants
D-plants
L-plants
D-plants
Plant height, cm
181.7
197.6***
85.3
87.9
Height to the ear, cm
55
59.4**
18
17.7
Leaf length, cm
63.6
69***
34.4
35.6
Number of nodes
11.1
11.3*
8.1
8.5

*,**,*** Difference is significant at 5%, 1% and 0.1% level, respectively.

Some additional investigations should be carried out. However, the first experiments have already shown the certain connection between the antidromy infringement and maize productivity.
 
 

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