Maize ear growth is stimulated at the fourth day after pollination by cell wall remodeling and changes in lipid and hormone signaling

Abstract

BACKGROUND: Stimulating maize ear development is an effective way of improving yield. However, limited information is available regarding the regulation of sink strength change from weak to strong at the same position of maize plants. Here, a novel method for stimulating development combined with physiological assays and proteomics was applied to explore the regulation of ear strengthened development.RESULTS: By blocking pollination of the upper ear of maize hybrid Suyu 41, the adjacent lower ear was dramatically stimulated at 4 days after pollination (DAP). Tandem mass tag (TMT)-based proteomics identified 173 differentially expressed proteins (fold change >1.2 or <0.83, P < 0.05) from 7793 total proteins. Gene ontology annotations indicated that several pathways showed noticeable changes, with a preferential distribution to cell wall remodeling, hormone signals and lipid metabolism in the stimulated kernels. Cell wall remodeling was highly mediated by chitinase, exhydrolase II and xyloglucan enotransglucosylase/hydrolase, and accompanied by increased sucrose and glucose content. A series of lipoxygenase proteins were significantly upregulated, causing a significant alteration in lipid metabolism. Hormone signals were influenced by the expression of the proteins involved in indole-3-acetic acid (IAA) transport, zeatin (ZT) biosynthesis and abscisic acid (ABA) signal response, and increased IAA, ZT and ABA content.CONCLUSION: The critical time for understanding the mechanism by which ear growth is stimulated is 4 DAP. Comparative proteomics and physiological analysis revealed that lipid metabolism enhancement, cell wall remodeling and changes in hormone signaling (IAA, ZT and ABA) were all important in stimulating early ear development. Proper regulation of these pathways may improve ear development, resulting in increased maize yield.

Auxin and abscisic acid play important roles in promoting glucose metabolism of reactivated young kernels of maize (Zea mays L.)

“…Our previous study indicated that IAA, ABA, and cytokinin are mainly enriched at the 4 DAP in treatments that stimulate sink activities of early kernels (Du et al, 2022). We also found that IAA, cytokinin, and ABA metabolism were enriched mainly at the gene level (Figure S4) and few genes were enriched at the protein level (Figure S5).…”

“…At the time of husk emergence, two different pollination systems, herein named synchronouspollination (SP) and pollination-blocking and hand-pollination (PBH) were used. In a previous study, treatments-designated SP and PBH were referred to as NP and HP, respectively (Du et al, 2022). In the SP systems, the upper and lower ears were bagged before silk emergence, and when most of the silks emerged on both ears, they were F I G U R E 1 Overview of the ear pollination experimental design and sample collection.…”

“…The middle kernels of the lower ears between SP and PBH were designated as SPK and PBK. For reference, what is called SPK and PBK, respectively, were designated as NPK and HPK in our previous report (Du et al, 2022). Fresh upper and lower ears were randomly sampled at 8, 12, and 16 days after pollination (DAP) and used for growth measurements (Figure 1C).…”

“…Previous studies have provided many methods such as stem infusion of sucrose (Boyle et al, 1991), in vitro kernel culture (Nakamura, 1986), and partial pollination of ears (Feng et al, 2011;Shen et al, 2018Shen et al, , 2020a as methods to further increase the sink activity of kernels. Using experimental innovations in pollination-blocking and hand-pollination of maize ears, we previously achieved the goal of improving kernel sink activity from weak to strong in the same part of the ears, which provides new insights for improving the sink activity of early kernels (Du et al, 2022). In addition, the use of multi-omics analysis may reveal more interesting phenomena during sink activity regulation of early kernels (Guo et al, 2021;Prioul et al, 2008).…”

Quantitative proteomics analysis of tomato root cell wall proteins in response to salt stress

“…Although the characterization of plant cell wall proteins remains challenging and requires a combination of various analytical approaches, there have been rapid advances in cell wall protein research combined with proteomics approaches ( Komatsu and Yanagawa, 2013 ; Adelaide et al., 2018 ). To gain information about protein changes in cell walls, many types of stress-associated cell wall proteins have been identified in crops, and these researches have shown that cell wall proteins play an important role in stress signal transduction, cell defense and rescue, cell wall modification, etc ( Wolf, 2017 ; Du et al., 2022 ; Wolf, 2022 ). The top leaflets showed less stress signs by salinity have an increased expression of cell wall-related genes in tomato ( Hoffmann et al., 2021 ).…”