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Chen Q, Huang R, Xu Z, Zhang Y, Li L, Fu J, Wang G, Wang J, Du X, Gu R. Label-Free Comparative Proteomic Analysis Combined with Laser-Capture Microdissection Suggests Important Roles of Stress Responses in the Black Layer of Maize Kernels. Int J Mol Sci 2020; 21:ijms21041369. [PMID: 32085613 PMCID: PMC7072901 DOI: 10.3390/ijms21041369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 02/14/2020] [Accepted: 02/16/2020] [Indexed: 12/20/2022] Open
Abstract
The black layer (BL) is traditionally used as an indicator for kernel harvesting in maize, as it turns visibly dark when the kernel reaches physiological maturity. However, the molecular roles of BL in kernel development have not been fully elucidated. In this work, microscopy images showed that BL began to appear at a growth stage earlier than 10 days after pollination (DAP), and its color gradually deepened to become dark as the development period progressed. Scanning electron microscopy observations revealed that BL is a tissue structure composed of several layers of cells that are gradually squeezed and compressed during kernel development. Laser-capture microdissection (LCM) was used to sample BL and its neighboring inner tissue, basal endosperm transfer layer (BETL), and outer tissue, inner epidermis (IEP), from 20 DAP of kernels. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry profiling (MALDI-TOF MS profiling) detected 41, 104, and 120 proteins from LCM-sampled BL, BETL, and IEP, respectively. Gene ontology (GO) analysis indicated that the 41 BL proteins were primarily involved in the response to stress and stimuli. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis found that the BL proteins were enriched in several defense pathways, such as the ascorbate and aldarate metabolic pathways. Among the 41 BL proteins, six were BL-specific proteins that were only detected from BL. Annotations of five BL-specific proteins were related to stress responses. During kernel development, transcriptional expression of most BL proteins showed an increase, followed by a decrease, and reached a maximum zero to 20 DAP. These results suggest a role for BL in stress responses for protecting filial tissue against threats from maternal sides, which helps to elucidate the biological functions of BL.
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Affiliation(s)
- Quanquan Chen
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
| | - Ran Huang
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
| | - Zhenxiang Xu
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
| | - Yaxin Zhang
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
| | - Li Li
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
| | - Junjie Fu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (J.F.); (G.W.)
| | - Guoying Wang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China; (J.F.); (G.W.)
| | - Jianhua Wang
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
| | - Xuemei Du
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
- Correspondence: (X.D.); (R.G.)
| | - Riliang Gu
- Center for Seed Science and Technology, Beijing Innovation Center for Seed Technology (MOA), Key Laboratory of Crop Heterosis Utilization (MOE), College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; (Q.C.); (R.H.); (Z.X.); (Y.Z.); (L.L.); (J.W.)
- Correspondence: (X.D.); (R.G.)
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