Breeding studies in potatoes containing high concentrations of anthocyanins

American Journal of Potato Research, Jul/Aug 2003 by Brown, C R, Wrolstad, R, Durst, R, Yang, C-P, Clevidence, B

Accepted for publication 7 May 2003.

ABSTRACT

Studies of the breeding behavior of clones containing high levels of anthocyanins were conducted. Red-fleshed clones appeared in proportions suggesting multigenic control of degree of pigmentation. Red-fleshed and purple-fleshed clones were always accompanied by red and purple skin, respectively. Red flesh ranged from partial pigmentation to complete pigmentation represented by pigment present in all tuber tissues. Percentage of completely red-fleshed progeny was 14.5% and 4.1% in red x red crosses vs red x white (or the reciprocal), respectively. Purple-fleshed progeny were obtained from red x white crosses where the white-fleshed parent harbored the P pigment gene in juxtaposition with the nulliplex recessive state of the I gene (i.e., iiii), which suppressed expression. Total anthocyanin ranged from 6.9 to 35 mg per 100 g fresh weight in the red-fleshed and 5.5 to 17.1 in the purple-fleshed clones. Red-fleshed clones contained predominantly acylated glycosides of pelargonidin while the purple-fleshed clones contained predominantly acylated glycosides of petunidin and peonidin. Oxygen Radical Absorbance Capacity and Ferrous Reducing Ability of Plasma revealed that the antioxidant levels in the red or purple-fleshed potatoes were two to three times higher than white-fleshed potato.

RESUMEN

Se llevaron a cabo estudios de mejoramiento sobre el comportamiento de clones de papa con niveles altos de antocianinas. Los clones de pulpa roja mostraron esta caracteristica en mayor proporcion, lo que sugiere un control multigenico del grado de pigmentacion. Los clones de pulpa roja y los de pulpa morada estuvieron siempre acompanados de piel roja y piel morada respectivamente. La pulpa roja vario desde una pigmentacion parcial a una pigmentacion completa, en el cual el pigmento se encontraba presente en todos los tejidos del tubercule. El porcentaje en una progenie de pulpa roja completa fue de 14.5% y 4.1% en los cruzamientos rojo x rojo vs. rojo x blanco (o reciproco) respectivamente. La progenie de pulpa morada se obtuvo de cruzamientos rojo x blanco, donde el progenitor de pulpa blanca albergaba el gen del pigmento morado P en yuxtaposicion con el estado recesivo nuliplex del gen inhibidor I, el cual suprimio la expresion. La antocianina total vario de 6.9 a 35mg por 100g de peso fresco en los clones de pulpa roja y de 5.5 a 17.1 mg en los de pulpa morada. Los clones de pulpa roja contenian predominantemente glicosidos acilados de pelargonidina, mientras que los clones morados contenian predominantemente glicosidos acilados de petunidina y pelargonidina. La Capacidad de Absorbencia del Radical Oxigeno y la Habilidad del Plasma para la Reduccion del Hierro revelaron que los niveles de antioxidante en papas de pulpa roja o morada fueron de dos a tres veces mayores que en las papas de pulpa blanca.

ADDITIONAL KEY WORDS: Antioxidants, pelargonidin, petunidin, peonidin, ORAC, FRAP.

INTRODUCTION

The natural variation of cultivated potato germplasm includes types that are red and purple pigmented due to the presence of flavonoids in the skin and/or flesh. Among the many flavonoids that may be found in potato tubers are the anthocyanins. A series of single genes control presence and absence of red and blue pigments. Although different genetic systems controlling pigment expression have been identified for diploid cultivated vs tetraploid cultivated potatoes, (Dodds and Long 1955, 1956; Lunden 1960), De Jong (1991) and Van Eck and coworkers (1994) have argued that the genes appear to be syntenic and should be regarded as belonging to one genome. The symbol D denotes a single gene controlling synthesis of red pigment, located on chromosome 2: the symbol P stands for a single gene on chromosome 11 controlling blue pigment synthesis, while I, of undetermined location, epistatically controls presence and absence of tuber skin and flesh pigmentation even when P and D are present. Gebhardt et al. (1989) reported a locus controlling purple skin color, Psc, on chromosome 4. The single gene Pf, linked to I, determines whether pigment is present beyond the periderm in the interior tissues of the tuber (DeJong 1987, 1991; Van Eck et al. 1994). The pigments have been determined to be varied types of acylated anthocyanidin glycosides (Harbourne 1960; Rodriguez-Saona et al. 1998). The gene Ac is imputed to control acylation of anthocyanins. Diploid cultivated potatoes display both acylated and non-acylated forms while only acylated anthocyanins are present in the tetraploid cultivars (Swaminathan and Howard 1953). Red- and purple-skinned potato varieties are not uncommon. Potatoes with varying distributions of anthocyanin in the flesh, appearing as rings and arcs and radiating stars are found in the native cultivars of the Andes and rarely among varieties in the rest of the world. Solidly colored red or purple tuber flesh is unusual throughout the world, but occurs as rare segregants in certain red- and purple-skinned breeding populations and a few pigmented flesh types are available commercially as specialty potatoes, e.g., cvs. Cranberry Red, All Blue.