Prospectives of Albinism in Current Sugarcane Breeding Strategies.

The usefulness of breeding to improve sugarcane (a complex hybrid of Saccharum sp.) crop performance and productivity depends heavily on the continued availability of new and beneficial genes and on novel approaches to the reproductive and agronomic controls used to access their full potential. One such novel approach is the study of partial (variegation) or full albinism, an underexplored topic with implications both in variety development and crop production. In sugarcane and other domesticated cereal grasses, cell culture (e.g., anther, callus, and immature-embryo culture) has been employed in haploid and diploid embryogenesis in order to obtain genetically favorable parents, though rates of albinism in the regenerated plantlets are significant and it remains a major bottleneck. Progress has been made in identifying the underlying genetic nature of the problem, but sugarcane lags critically compared to other major crops like corn, oat, barley, and wheat. Agronomically, the physiology and implications of albinism occurring in sugarcane tillers remains nearly unstudied. How an albino tiller,a genuine photosynthate sink, will accumulate sugar and biomass and respond to light cues and senescence, as well as how the rest of the plant will respond to an albino tiller, is currently unknown. Healthy albino tillers on otherwise green or variegated sugarcane plants will be better able to answer these kinds of questions than with current methods.  The objective of this study was to utilize fully the unique opportunities available in screening for, identifying, describing, and genotyping naturally occurring variegated and albino sugarcane mutants obtained as part of the USDA-ARS Canal Point sugarcane variety production program. A continuous supply of new, not mutagenized varieties through breeding and access to historical clones may form a collection of notable and sufficient size to lay the groundwork, and provide plant materials for, further molecular and agronomic study. Early findings from two varieties with albino tillers demonstrate that these tillers can be grown without senescing and that they accumulate sugar despite being photosynthetically inactive. The ratios of weight (kg) and brix between normal (green) and albino tillers was 0.5:0.3, 16.4:11.2, and 0.6:0.2, 18.6:15.3, for the two varieties, respectively.