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1) Plant Breeding Dept., International Rice Research Institute, P.O. Box 933 Manila, Philippines, and
2) Agricultual Research Centre, Saka, Kufr-El Sheikh, Egypt
Inheritance of fertility restoration was studied in F\2\'s of ten
crosses of the Chinese male sterile lines, viz., Zhen Shan 97A (97A)- and
V20A with a set of complete restorers through chi-square analysis. The mode
of inheritance of fertility restoration appeared to vary with the restorers.
One to three genes appeared to control the restoration (Table 1). While
three restorers IR26, IR50 and Pusa 37-3 restored the fertility of V20A
monogenically, in case of Pusa 245-51-1 two genes interacting in a
complementary fashion (9F:7S) seemed to be involved. In crosses involving
different restorer lines three genes appeared to control the fertility
restoration. Appearance of partial fertile segregants in crosses with
complete restorers suggested the probable role of modifiers in fertility
restoration.
Soluble protein and esterase isoenzyme patterns in matured anthers and spikelets (at meiotic stage) of male sterile and maintainer lines were studied through isoelectric focussing technique. Soluble protein and esterase isoenzyme patterns of matured anthers of male steriles and maintainers differed qualitatively and quantitatively. Also, these biochemical parameters differed between matured anthers and spikelets. Nevertheless, comparison of soluble protein and esterase isoenzyme patterns of spikelets of male sterile and maintainer lines revealed no differences between them. Therefore, presence or absence of certain specific soluble protein and esterase isoenzyme bands might have a bearing on pollen abortion and consequent male sterility. Absence of differences between spikelets (at melotic stage) of male steriles and maintainers suggested that possibly the differences tended to appear late during the process of pollen development.
Amino acid analysis of matured anthers of male sterile, maintainer and restorer (IR36) lines revealed that proline content in anthers of maintainer/restorer lines was 3 to 6 times more than in the sterile anthers. On the other hand, we observed appreciable increase in the level of aspartic acid in the sterile anthers. No difference was, however, found between anthers of maintainer and restorer lines for any of the amino acids analyzed. This indicated that proline and aspartic acid in the sterile anthers may be in some way related to the phenomenon of male sterility. This relationship, however, needs further investigation.
Table 1. Genetics of fertility restoration of two Chinese cytoplsmic-genetic
male sterile lines.
=============================================================================
S. No. Crosses Number of Degree of restora- Genetic Level of
tion* ratio probabi-
============================= ratio lity
F2 plants Fully Partial Sterile
scored fertile fertile
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1. V20A x IR26 437 313 24 100 3:1 0.2-0.3
2. V20A x Pusa 37-3 505 332 39 134 3:1 0.05-0.1
3. V20A x IRSO 475 344 25 131 3:1 0.5-0.7
4. 97A x Pusa 245-51-1 200 88 22 90 9:7 0.7-0.9
5. 97A x IR19793-25-2-2-2 343 139 8 196 27:37 0.7-0.9
6. 97A x Mijingem 139 16 38 85 27:37 0.3-0.5
7. V20A x NDC 28 518 33 184 301 27:37 0.7-0.9
8. V20A x IET 4141 518 282 67 169 45:19 0.1-0.2
9. V20A x NDC 50 495 317 25 153 45:19 0.5-0.7
10. 97A x IR9761-19-1 200 123 5 72 45:19 0.05-0.1
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*Fully fertile and partial fertile classes were merged into one class to
enable X2 analysis.
