Evaluation of newly developed restorer gene pool inbreds for fertility restoring and maintaining behaviours in two diverse CMS sources of sunflower.

Abstract

Worldwide production of cultivated hybrid sunflower presently utilizes only the PET-1 source of cytoplasmic male sterility. The use of one sterile cytoplasm creates a high degree of genetic vulnerability. The present study was conducted to identify new fertility restorer for two diverse cytoplasmic male sterile sources i.e., PET-1 (COSF-6A, COSF-7A, CMS-38A, ARM-248A) and CMS PEF (FMS-852A). Five CMS lines were crossed with newly developed drought-tolerant 10 inbred lines in Line x Tester fashion and evaluation of test cross progenies was conducted. The presence or absence of pollen in F1s was recorded in the field whereas pollen fertility was confirmed in the laboratory by acetocarmine staining test. All the inbreds were categorized into complete, partial restorer and maintainer through cytological observation. Six inbreds viz.,RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP-233 behaved common restorer for all the CMS lines and restored the fertility, while RGP-222 and 298R inbreds maintained sterility. The second CMS line FMS-852A, was maintained by 4 inbreds indicating the involvement of different gene(s), while six inbreds RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP-233 were restored its fertility. None of the inbred was behaved as partial restorers for any of the CMS lines. The range of fertility restoration in different cross combinations was between 91.4 and 97.4 per cent. In the present study 80 per cent frequency of pollen fertility was reported for PET-1. However, only 60 per cent frequency of pollen fertility was observed for CMS F. From the study it was evident that among the two CMS sources, restorers for PET-1 and PEF are available. Efforts should be made to utilize of CMS PEF for production of more productive sunflower hybrids resistant to biotic and abiotic stresses.