Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: February 12, 2003
Publication Date: March 1, 2003
Citation: JAN, C.C., VICK, B.A. A WHITE COTYLEDON MUTANT IN CULTIVATED SUNFLOWER WITH REDUCED CHLOROPHYLL SYNTHESIS. PROCEEDINGS SUNFLOWER RESEARCH WORKSHOP. 2003. www.sunflowernsa.com/research_statistics/research_workshop/documents/89.pdf Interpretive Summary: Chlorophyll is essential for plant growth and seed production of sunflower. Differences in sunflower leaf color due to chlorophyll content have been reported in the past by a number of different researchers. In an extreme case where seedlings that lacked chlorophyll died at an early stage, it was reported that the chlorophyll deficiency was controlled by a single recessive gene. In our ongoing studies on cytoplasmic male sterility, we recently observed two fertility restoration lines that produced some seedlings with white cotyledons. However, these mutant plants subsequently produced near normal true leaves and grew to maturity. This distinctive characteristic of white cotyledons and green true leaves has not been reported previously in sunflower. The objectives of this study were to characterize these white cotyledon (WC) mutants and to determine their inheritance. This cotyledon-specific total chlorophyll deficiency and the partial true-leaf chlorophyll deficiency of the two WC lines was controlled by a single recessive gene, and will offer an opportunity to study photosynthesis. The WC gene also provides an easily identified marker for mapping.
Technical Abstract: White cotyledon (WC) plants selected from two sources, PI413180/3*HA89/3/PI413180 /3*HA89//RHA801,F4 and PI413180/4*HA89//PI413180/RCMG1,F4 were designated WC1-F4 and WC2-F4, respectively. WC1-F4 and WC2-F4 were intercrossed and then crossed with HA89. F1 progeny of WC1-F4 x HA89, and WC2-F4 x HA89 were test-crossed with respective WC parents. The F1 plants of WC1-F4 x HA89, WC2-F4 x HA89, and the advanced WC parents, WC1-F6, and WC2-F6, were evaluated for WC characteristics and leaf chlorophyll. All F1 progenies of WC1-F4 x HA89 and WC2-F4 x HA89 were normal with green cotyledons and true leaves, indicating the WC gene(s) were recessive. Cotyledons of the intercrossed F1 progeny of WC1-F4 and WC2-F4 were all white, indicating the gene(s) controlling white cotyledons were at the same locus in both sources. Both the F2 progeny of WC1-F4 x HA89, and the test-cross progeny of WC2-F4 x (WC2-F4 x HA89) suggested single recessive gene control of WC. There is a clear difference between the WC parents and HA89 in chlorophyll content of cotyledons, with the WC parents having nearly zero chlorophyll. Cotyledons of the F1 hybrids of the crosses between the two WC parents also had near zero chlorophyll in cotyledons and a much increased chlorophyll content in the true leaves. The F1 hybrids of the two WC mutants x HA89 had chlorophyll contents equal to that of HA89, indicating complete dominance of the normal green cotyledon gene.