Genetic variations in ZmSAUR15 contribute to the formation of immature embryo‐derived embryonic calluses in maize

Abstract

The ability of immature maize (Zea mays) embryos to form embryonic calluses (ECs) is highly genotype dependent, which limits transgenic breeding development in maize. Here, we report the association mapbased cloning of ZmSAUR15 using an association panel (AP) consisting of 309 inbred lines with diverse formation abilities for ECs. We demonstrated that ZmSAUR15, which encodes a small auxin-upregulated RNA, acts as a negative effector in maize EC induction. Polymorphisms in the ZmSAUR15 promoter that influence the expression of ZmSAUR15 transcripts modulate the EC induction capacity in maize. ZmSAUR15 is involved in indole-3-acetic acid biosynthesis and cell division in immature embryo-derived callus. The ability of immature embryos to induce EC formation can be improved by the knockout of ZmSAUR15, which consequently increases the callus regeneration efficiency. Our study provides new insights into overcoming the genotypic limitations associated with EC formation and improving genetic transformation in maize.

Integrated Proteomic and Metabolomic Analyses Provide Insights Into Acquisition of Embryogenic Ability in Agapanthus praecox

“…Much progress has been made in the elucidation of the underlying mechanisms of SE ( Fehér, 2015 ; Horstman et al, 2017 ; Su et al, 2021 ). However, EC induction and plant regeneration are affected by many factors, including genotypes, explants, hormones, and concentrations of various substances in the induction medium ( Guo et al, 2020 ; Wang et al, 2020 , 2022 ). So far, the acquisition of EC has been shown as the critical process in plant SE ( Wang et al, 2022 ).…”

“…However, EC induction and plant regeneration are affected by many factors, including genotypes, explants, hormones, and concentrations of various substances in the induction medium ( Guo et al, 2020 ; Wang et al, 2020 , 2022 ). So far, the acquisition of EC has been shown as the critical process in plant SE ( Wang et al, 2022 ). However, it is difficult to identify the cells capable of embryogenesis with morphological data.…”

“…However, the acquisition of EC became a huge difficulty, which showed randomness and inefficiency ( Aguilar-Hernández and Loyola-Vargas, 2018 ). Many plants face a similar challenge, including even some important crops, such as O. sativa , Z. mays , G. hirsutum , and Triticum aestivum ( Yin et al, 2008 ; Yang et al, 2014 ; Guo et al, 2019 , 2020 ; Wang et al, 2022 ). Therefore, the transition from CA to EC is the key to SE.…”

“…The regulatory roles of chromatin accessibility, phytohormones, and stress-related events during SE in Arabidopsis thaliana have been well studied ( Su et al, 2009 ; Horstman et al, 2017 ; Wang et al, 2020 ). So far, few studies have revealed the mechanisms comprehensively, especially the induction of EC, due to the complexity and individuation of SE ( Wang et al, 2022 ). Proteins and metabolites are known as the active controllers of cellular physiology ( Wilinski et al, 2019 ; Castander-Olarieta et al, 2021 ).…”

Combined QTL Mapping across Multiple Environments and Co-Expression Network Analysis Identified Key Genes for Embryogenic Callus Induction from Immature Maize Embryos

“…Traditional genetic modification methods have a long cycle and are limited by natural variations [ 1 ], whereas transgenic breeding is able to break through these restrictions. In maize genetic transformation, the induction efficiency of embryogenic callus (EC) directly affects the transformation ratio of immature embryos [ 2 ]. Previous studies reported that EC induction from maize immature embryos was influenced by multiple factors, including genotypes, hormones, and compositions of induction media [ 3 , 4 , 5 ].…”