BGS 117, Chlorina seedling 2, fch2

Chlorina seedling 2 = f2 (13).
Light green 5 = lg5 (121).
Chlorina seedling f2 = clo-f2 (8).
Hordeum vulgare chlorophyllide α oxygenase = HvCAO (16).

Monofactorial recessive (3, 4, 13).
Located in chromosome 3HL (11, 13, 14, 15); fch2.c is about 7.7 cM distal from the cur2 (curly 2) locus (17); fch2.c is associated with SNP markers 1_0702 to 1_0694 (positions 239.73 to 248.51 cM) in 3H bin 15 in Bowman backcross-derived line BW358 (1), an fch2 mutant is in the 682.2 to 684.5 Mb region of 3HL (16).

The fch2.c seedlings have a pale yellow-green color, which persists until near maturity under greenhouse or field conditions. Development of homozygous plants is delayed, but the stunted plants survive to produce seed (3). A complete absence or greatly reduced levels of chlorophyll b were found in mutant plants (3, 4, 8). The respiratory and photosynthetic rates of detached leaves and intact plants are not significantly different from those of normal plants. However, the growth rate of mutant plants decreases after the endosperm is depleted (4). Plants of the Bowman backcross-derived line for fch2.c, BW358, showed a drastic response to environmental stress during the growing season. The heading date for BW358 plants was about 13 days later than Bowman. Plant height varied from near normal to a 20% reduction. Average kernel weights were reduced up to 40%. Grain yields of BW358 were 1/3 to 1/2 those of Bowman (2). An absence of chlorophyll b-binding proteins in the photosynthetic membranes is found in fch2 mutants (6, 7). Alleles at the fch2 locus were shown to have DNA sequence changes in the gene encoding chlorophyllide a oxygenase or interfere with regulators of enzyme production (8). The enzyme converts chlorophyllide a to chlorophyllide b and it is essential for Chl b biosynthesis (8).

A spontaneous mutant in progeny from the cross Moister (CIho 2799) X California Coast (CIho 6115) (3).

fch2.c (28-3398 Chlorina, GSHO 107) in Moister/California Coast (3, 10); fch2.y (lg5, GSHO 294) in CIho 6151 (12); clo-f2.2800, -f2.2807, -f2.3613 in Donaria (PI 209784), -f2.101, -f2.102, -f2.103, -f2.105, -f2.107, -f2.108, -f2.109 in Tron, -f2.122, -f2.123, -f2.133 in Bonus (NGB 14657, PI 189763) (9, 10). Additional mutants, presumably at the fch2 locus, were reported and mapped (16). All the clo-f2 mutant stocks are stored in the Biology Department, Lund University with Mats Hansson who is the coordinator for chlorophyll biosynthesis (5).

fch2.c (28-3398, GSHO 107) in Moister/California Coast; fch2.c in Bowman (PI 483237, NGB 22812)*7 (GSHO 1993, BW358, NGB 20597).

1. Druka, A., J. Franckowiak, U. Lundqvist, N. Bonar, J. Alexander, K. Houston, S. Radovic, F. Shahinnia, V. Vendramin, M. Morgante, N. Stein, and R. Waugh. 2011. Genetic dissection of barley morphology and development. Plant Physiol. 155:617-627.
2. Franckowiak, J.D. (Unpublished).
3. Highkin, H.R. 1950. Chlorophyll studies on barley mutants. Plant Physiol. 25:294-306.
4. Highkin, H.R., and A.W. Frenkel. 1962. Studies of growth and metabolism of a barley mutant lacking chlorophyll b. Plant Physiol. 37:814-820.
5. Lundqvist, U. (Unpublished).
6. Machold, O., A. Meister, H. Sagromsky, G. Høyer-Hansen, and D. von Wettstein. 1977. Composition of photosynthetic membranes of wild-type barley and chlorophyll b-less mutants. Photosynthetica 11:200-206.
7. Machold, O., D.J. Simpson, and B.L. Møller. 1979. Chlorophyll-proteins of thylakoids from wild and mutant barley (Hordeum vulgare L.). Carlsberg Res. Commun. 44:235-254.
8.. Mueller, A.H., C. Dockter, S.P. Gough, U. Lundqvist, D. von Wettstein, and M. Hansson. 2012. Characterization of mutations in barley fch2 encoding chlorophyllide a oxygenase. Plant Cell Physiol. 53:1232-1246.
9. Simpson, D.J., O. Machold, G. Høyer-Hansen, and D. von Wettstein. 1985. Chlorina mutants of barley (Hordeum vulgare L.). Carlsberg Res. Commun. 50:223-238.
10. Simpson, D.J., and D. von Wettstein. 1992. Coordinator's report: Nuclear genes affecting the chloroplast. Stock list of mutants kept at Carlsberg Laboratory. Barley Genet. Newsl. 21:102-108.
11. Singh, R.J., and T. Tsuchiya. 1974. Further information on telotrisomic analysis in barley. Barley Genet. Newsl. 4:66-69.
12. Takahashi, R., J. Hayashi, T. Konishi, and I. Moriya. 1975. Linkage analysis of barley mutants. Barley Genet. Newsl. 5:56-60.
13. Tsuchiya, T., and D.W. Robertson. 1971. Association of a chlorina mutant with chromosome 3. Barley Genet. Newsl. 1:64-65.
14. Tsuchiya, T., and R.J. Singh. 1982. Chromosome mapping in barley by means of telotrisomic analysis. Theor. Appl. Genet. 61:201-208.
15. Tsuchiya, T., R.J. Singh, A. Shahla, and A. Hang. 1984. Acrotrisomic analysis in linkage mapping in barley (Hordeum vulgare L.). Theor. Appl. Genet. 68:433-439.
16. Xu, D., D. Sun, Y. Diao, M. Liu, J. Gao, B. Wu, X. Yuan, P. Lu, Z. Zhang, J. Zhang, and G. Guo. 2018. Fast mapping of a chlorophyll b synthesis-deficiency gene in barley (Hordeum vulgare L.) via bulked-segregant analysis with reduced-representation sequencing. The Crop Journal (2018) https://doi.org/10.1016/j.cj.2018.07.002.
17. Yano, Y., K. Abe, and T. Konishi. 1991. Linkage analysis of the chlorina mutant gene (f2) in barley. Barley Genet. Newsl. 20:68-71.

T. Tsuchiya. 1972. Barley Genet. Newsl. 2:183.

J.D. Franckowiak. 1997. Barley Genet. Newsl. 26:151-152.
J.D. Franckowiak and U. Lundqvist. 2016. Barley Genet. Newsl. 46:63-64.