Analysis on the formation of "high sucrose" characteristic in sugarcane genotypes with high sucrose and the role of genetic improvement in enhancing sucrose content based on sucrose accumulation amount (SAA)

Abstract

Currently, high-sucrose breeding in sugarcane is facing challenges. This study aims to characterize the formation of "high sucrose" characteristic in high-sucrose genotypes and the role of genetic improvement in enhancing sucrose content (SC), providing information for high-sucrose breeding. The SC data were obtained from the experiment encompassing 266 genotypes over three crop seasons. Based on the concept of sucrose accumulation amount (SAA), the total SAA over the entire growth period (A7) was divided into immature SAA (A1) and mature SAA (A6). Compared to low-sucrose genotypes, high-sucrose genotypes exhibited a significant increase in A1 (3.62 %, absolute value) and a significant decrease in A6 (1.55 %, absolute value). Since the increase was much larger than the decrease, the "high sucrose" characteristic was evident. Genetic improvement primarily enhanced A1, although it also led to a decrease in A6. Similarly, since the increase was greater than the decrease, SC improved. Further analysis revealed a relatively high negative genetic correlation was also observed between A1 and A6 (r = -0.66), which was further validated by SC from two environments over 11 years. The relationship between A1 and A6 plays a "pivotal" role. We hypothesize that there is an "inflection point" in the SAA curve over the full growth period, which triggers the relationship between A1 and A6. The A1 and A6 relationship might set a "ceiling" for the genetic improvement of SC, also providing an alternative perspective on the widely recognized slowdown in genetic gains in SC. Deeply understanding the characteristics of A1 and A6, especially their interrelationship, could be key to achieving further breakthroughs in high-sucrose breeding.