Genetic Markers to Locate and Transfer Heterotic Chromosome Blocks for Increased Pearl Millet Yields
- Glenn W. Burton and
- B. K. Werner
The introgression of exotic germplasm by conventional breeding procedures to promote greater heterosis and yield within adapted hybrid cultivars often is a difficult and lengthy process. As part of long-term investigations, the objectives of this study were to evaluate and use nonlethal genetic markers to locate heterotic chromosome blocks (HCBs) in exotic pearl millet [Pennisetum glaucum (L.) R. Br.] lines, develop methods to use the markers to transfer in the future the selected HCBs to inbred T383, and to increase the yield of ‘Tifleaf 2’ (T85A ✕ T383). The nonlethal dominant R gene for red plant color was used to screen 129 pearl millet near-isogenic populations for high-yielding HCBs by measuring height and weight of at least 50 red and 50 green spaced plants in each population. In 27 populations, HCB heterosis [(green — red plant wt)/red plant wt) ✕ 100] ranged from 18 to 61% (P < 0.01). The nonlethal tr gene for the trichomeless condition was used to screen 91 pearl millet populations for HCB heterosis = [(Tr - tr plant wt)/tr plant wt) ✕ 100]. In 52 of these populations, HCB heterosis ranged from 17 to 44% (P < 0.01). The best HCBs are being transferred to inbred T383, the male parent of Tifleaf 2, using the genetic markers R and tr to follow the HCBs during the backcross transfer. The design calls for completing three to four backcross generations per year. When top-yielding HCBs identified by R and tr become a part of the gene complex of T383, T85A ✕ T383 HCB can be expected to outyield T85A ✕ T383. Plant height measurements were of no value in screening exotic lines for high yielding HCBs.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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