The Potential Function of SiLOX4 on Millet Discoloration during Storage in Foxtail Millet

Abstract

Millet color is an important index for consumers to assess foxtail millet quality. The yellow color of millet is mainly because of the accumulation of carotenoids, which are essential for human nutrition. However, the discoloration of millet during storage due to carotenoid degradation seriously reduces the nutritional and commercial value of millet products. The essential quality traits of millet discoloration during storage were analyzed using two foxtail millet varieties, namely 9806-1 and Baomihunzi. We observed that the millet discoloration was caused by carotenoid degradation during storage, and different genotypes exhibited different discoloration rates. The carotenoid reduction rate in 9806-1 (32.2%) was higher than that in Baomihunzi (10.5%). The positive correlation between carotenoid reduction and the expression of SiLOX protein indicated that SiLOX from foxtail millet played a major role in carotenoid reduction during storage. The expression profiles of the SiLOX gene family were analyzed at different grain maturing stages, from S1 to S3, in these two varieties to determine the key SiLOX genes responsive to millet discoloration in foxtail millet. The consecutively low expression of SiLOX2, SiLOX3, and SiLOX4 contributed to the low level of SiLOX protein in Baomihunzi. Furthermore, the undetectable expression of SiLOX4 in the later stage of maturation in Baomihunzi was associated with low discoloration, indicating that SiLOX4 might be a key gene in regulating the discoloration of millet. This study provided critical information on the mechanism of carotenoid degradation during millet storage and laid the foundation for further understanding of carotenoid metabolism in foxtail millet.

Germplasm Resources Exploration and Genetic Breeding of Crops

“…The Special Issue "Germplasm Resources Exploration and Genetic Breeding of Crops" was planned to cover all aspects of the characterization of crop genetic resources and their applications in breeding, as well as genetics research and molecular breeding, including gene/QTL detection or gene functional analysis in crops. In our Special Issue, we have united 16 papers addressing various aspects around the topic of plant genetic resources, including quantitative trait loci (QTL) mapping/gene discovery [2,3], genetic diversity/variation [4][5][6][7][8][9], breeding products [9][10][11][12][13], and genetic resource profiles for crops [14][15][16].…”

“…Ma et al [9] investigated the genetic basis of the foxtail millet (Setaria italica L.) discoloration rate caused by carotenoid degradation during storage and identified SiLOX4 as a potential key gene in regulating millet discoloration. This study provided critical information on the mechanism of carotenoid degradation during millet storage and laid the foundation for further understanding of carotenoid metabolism in millet.…”

QTL analysis of important agronomic traits and metabolites in foxtail millet (Setaria italica) by RIL population and widely targeted metabolome

“…Millet has the characteristics of wide adaptability and yield stability, and it adapt to high temperature and arid environment well ( Yuan et al., 2021 ; Han et al., 2022 ). In addition to its high nutritional value ( Li et al., 2018 ; Ma et al., 2022 ), millet is also an ideal model crop for studying grass crops due to its small genome and close relatedness to many important grass crops, such as switchgrass ( Panicum virgatum ), napiergrass( Pennisetum purpureum ), pearl millet ( Li et al., 2022 ; Xing et al., 2022 ). Therefore, the research on the formation of millet phenotype, genetic mechanism and molecular breeding is of great significance.…”