Label-Free Comparative Proteomic Analysis Combined with Laser-Capture Microdissection Suggests Important Roles of Stress Responses in the Black Layer of Maize Kernels

Chen, Quanquan; Huang, Ran; Xu, Zhenxiang; Zhang, Yaxin; Li, Li; Fu, Junjie; Wang, Guoying; Wang, Jianhua; Du, Xuemei; Gu, Riliang

doi:10.3390/ijms21041369

Open AccessArticle

Label-Free Comparative Proteomic Analysis Combined with Laser-Capture Microdissection Suggests Important Roles of Stress Responses in the Black Layer of Maize Kernels

by

Quanquan Chen

^1,†

,

Ran Huang

^1,†,

Zhenxiang Xu

¹

,

Yaxin Zhang

¹,

Li Li

¹,

Junjie Fu

²

,

Guoying Wang

²,

Jianhua Wang

¹,

Xuemei Du

^1,*

and

Riliang Gu

^1,*

¹

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

²

Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China

^*

Authors to whom correspondence should be addressed.

^†

These authors contribute equally to this work.

Int. J. Mol. Sci. 2020, 21(4), 1369; https://doi.org/10.3390/ijms21041369

Submission received: 6 January 2020 / Revised: 14 February 2020 / Accepted: 16 February 2020 / Published: 18 February 2020

(This article belongs to the Special Issue Plant Proteomic Research 3.0)

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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.

Keywords: maize; black layer; seed development; proteomic analysis; stress response; MALDI-TOF MS

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MDPI and ACS Style

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, 1369. https://doi.org/10.3390/ijms21041369

AMA Style

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. International Journal of Molecular Sciences. 2020; 21(4):1369. https://doi.org/10.3390/ijms21041369

Chicago/Turabian Style

Chen, Quanquan, Ran Huang, Zhenxiang Xu, Yaxin Zhang, Li Li, Junjie Fu, Guoying Wang, Jianhua Wang, Xuemei Du, and Riliang Gu. 2020. "Label-Free Comparative Proteomic Analysis Combined with Laser-Capture Microdissection Suggests Important Roles of Stress Responses in the Black Layer of Maize Kernels" International Journal of Molecular Sciences 21, no. 4: 1369. https://doi.org/10.3390/ijms21041369

APA Style

Chen, Q., Huang, R., Xu, Z., Zhang, Y., Li, L., Fu, J., Wang, G., Wang, J., Du, X., & Gu, R. (2020). Label-Free Comparative Proteomic Analysis Combined with Laser-Capture Microdissection Suggests Important Roles of Stress Responses in the Black Layer of Maize Kernels. International Journal of Molecular Sciences, 21(4), 1369. https://doi.org/10.3390/ijms21041369

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Label-Free Comparative Proteomic Analysis Combined with Laser-Capture Microdissection Suggests Important Roles of Stress Responses in the Black Layer of Maize Kernels

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