A novel method for screening sugarcane genotypes for maturity earliness through monitoring chloroplast development and starch accumulation

Abstract

Traditional methods for screening sugarcane (Saccharum hybrids) genotypes for maturity earliness, by monitoring sugar yield parameters, are tremendously laborious and time consuming. This study presents an alternative, easier and rapid method for grading early maturity in sugarcane genotypes on the basis of photosynthetic ability and efficiency of starch accumulation in mesophyll cells chloroplast of genotypes. The development of chloroplasts and rate of starch accumulation in a ring of mesophyll cells surrounding the leaf bundle sheath of seven weeks-oldin vitro-grown plantlets from micro sets of the early maturing (EM) var Q57 and the late maturing (LM) var Co1158, either under light or under dark, then illuminated for various periods, 0.0, 1.0, 4.0, 12.0 and 24.0 h, were investigated by electron microscopy. The mesophyll cells of the early maturing var Q57 showed a faster chloroplast development, more efficient starch accumulation, and delayed starch transportation to bundle sheath cells as compared to the late maturing var Co 1158. This approach provides a valuable tool for breeders, and could offers an easier and rapid novel method for screening and selection of sugarcane genotypes for maturity earliness at an early stage of growth.