Comparative Proteomic Analysis Reveals That the Heterosis of Two Maize Hybrids is Related to Enhancement of Stress Response and Photosynthesis Respectively

Abstract

Background Heterosis refers to superior traits exhibiting in a hybrid when compared with both parents. Generally, the hybridization between parents can change the expression pattern of some proteins such as non-additive proteins (NAPs) which might lead to heterosis. ‘Zhongdan808’ (ZD808) and ‘Zhongdan909’ (ZD909) are excellent maize hybrids in China, however, the heterosis mechanism of them are not clear. Proteomics has been wildly used in many filed, and comparative proteomic analysis of hybrid and its parents is helpful for understanding the mechanism of heterosis in the two maize hybrids.Results Over 2,000 protein groups were quantitatively identified from second seedling leaves of two hybrids and their parents by label-free quantification. Statistical analysis of total identified proteins, differentially accumulated proteins (DAPs) and NAPs of the two hybrids revealed that both of them were more similar to their female parents. In addition, most of DAPs were up-regulated and most of NAPs were high parent abundance or above-high parent abundance in ZD808, while in ZD909, most of DAPs were down-regulated and most of NAPs were low parent abundance or below-low parent abundance. Pathway enrichment analysis showed that more of stress response-related NAPs in ZD808 were high parent abundance or above-high parent abundance, and most of PS related NAPs in ZD909 were high parent abundance or above-high parent abundance. Finally, four stress response-related proteins and eight proteins related to PS were verified by PRM, ten of them had significant differences between hybrid and midparent value. Conclusions Even though every one of the two hybrids were more similar to its female parent at proteome level, the biological basis of heterosis is different in the two maize hybrids. In comparison with their parents, the excellent agronomic traits of hybrid ZD808 is mainly correlated with the high expression levels of some proteins related to stress responses and metabolic functions, while traits of ZD909 is mainly correlated with high expressed proteins related to photosynthesis. Our proteomics results support previous physiological and morphological research and have provided useful information in understanding the reason of valuable agronomic traits.

Plant height heterosis is quantitatively associated with expression levels of plastid ribosomal proteins

“…Carbon-fixation-related proteins had a mixed pattern of expression differences in the hybrid and overall were neither positively nor negatively correlated with plant height heterosis. Others report that hybrids are associated with either elevated levels of photosynthetic proteins (hybrid ZD909) or stress proteins (hybrid ZD808), but not both (33).…”

Plant trait heterosis is quantitatively associated with expression heterosis of the plastid ribosomal proteins

“…Carbon fixation-related proteins had a mixed pattern of expression differences in the hybrid, and overall were neither positively nor negatively correlated with plant height heterosis. Others report that hybrids are associated with either elevated levels of photosynthetic proteins (hybrid ZD909) or stress proteins (hybrid ZD808) but not both 26 .…”

Comparative proteomic analysis of hybrid maize MR2008 and its parental lines

“…(2018) with several proteomic studies on heterosis revealed that the fraction of non-additive proteins in the hybrid varied depending on the genotype, tissue and stage of development, and they consider that multiple molecular mechanisms could lead to an expression of differential protein profile, which in turn could be contributing to heterosis. A constant in these breeding is that F1 encodes a great variety of proteins with respect to the parental inbred lines (Wang et al ., 2020). Therefore, identifying the participation of proteins in metabolic pathways may be important to clarify the mechanisms of heterosis.…”