Simultaneous selection is effective in increasing betalain pigment concentration but not total dissolved solids in red beet

Abstract

Betalain pigments, composed of the red-violet betacyanins (BC) and the yellow betaxanthins (BX), provide an excellent natural alternative to synthetic red dyes. The objective of this investigation was to evaluate eight cycles of recurrent selection in two red beet (Beta vulgaris L.) populations selected for high total betalain pigment concentration and both high (HPHS) and low (HPLS) total dissolved solids (TDS). Remnant seed was planted in a randomized complete block design in replicated trials at two locations in 1994. Beet roots were sampled at harvest for concentrations of BC, BX, and TDS. Highly significant differences among cycles for BC, BX, BC:BX, total pigment, and TDS were observed. Average gains per cycle were 13.15 and 4.06 mg per 100 g fresh weight for BC and BX in HPHS, and 7.59 and 2.61 mg per 100 g fresh weight for BC and BX in HPLS, respectively. Total pigment increased about 200% in both populations. Selection for low TDS was ineffective, while only a mild response was detected from selection for high TDS. Since betalain pigments are formed following glycosylation of cyclodopa and betalamic acid, sugar molecules are associated with pigment biosynthesis. Simultaneous selection for high pigment and low TDS may therefore be metabolically incompatible. Our findings demonstrate betalain pigment concentration responds favorably to recurrent selection; however, a concomitant reduction in TDS is not a feasible selection goal.