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The defects in storage proteins secretion in the endosperm of transgenic rice seeds often leads to endoplasmic reticulum (ER) stress, which produces floury and shrunken seeds, but the mechanism of this response remains unclear. We used an iTRAQ-based proteomics analysis of ER-stressed rice seeds due to the endosperm-specific suppression of OsSar1 to identify changes in the protein levels in response to ER stress. ER stress changed the expression of 405 proteins in rice seed by >2.0- fold compared with the wild-type control. Of these proteins, 140 were upregulated and 265 were downregulated. The upregulated proteins were mainly involved in protein modification, transport and degradation, and the downregulated proteins were mainly involved in metabolism and stress/defense responses. A KOBAS analysis revealed that protein-processing in the ER and degradation-related proteasome were the predominant upregulated pathways in the rice endosperm in response to ER stress. Trans-Golgi protein transport was also involved in the ER stress response. Combined with bioinformatic and molecular biology analyses, our proteomic data will facilitate our understanding of the systemic responses to ER stress in rice seeds.

The cuticle is a hydrophobic lipid layer covering the epidermal cells of terrestrial plants. Although many genes involved in Arabidopsis cuticle development have been identified, the transcriptional regulation of these genes is largely unknown. Previously, we demonstrated that AtCFL1 negatively regulates cuticle development by interacting with the HD-ZIP IV transcription factor HDG1. Here, we report that two bHLH transcription factors, AtCFL1 associated protein 1 (CFLAP1) and CFLAP2, are also involved in AtCFL1-mediated regulation of cuticle development. CFLAP1 and CFLAP2 interact with AtCFL1 both in vitro and in vivo. Overexpression of either CFLAP1 or CFLAP2 led to expressional changes of genes involved in fatty acids, cutin and wax biosynthesis pathways and caused multiple cuticle defective phenotypes such as organ fusion, breakage of the cuticle layer and decreased epicuticular wax crystal loading. Functional inactivation of CFLAP1 and CFLAP2 by chimeric repression technology caused opposite phenotypes to the CFLAP1 overexpressor plants. Interestingly, we find that, similar to the transcription factor HDG1, the function of CFLAP1 in cuticle development is dependent on the presence of AtCFL1. Furthermore, both HDG1 and CFLAP1/2 interact with the same C-terminal C4 zinc finger domain of AtCFL1, a domain that is essential for AtCFL1 function. These results suggest that AtCFL1 may serve as a master regulator in the transcriptional regulation of cuticle development, and that CFLAP1 and CFLAP2 are involved in the AtCFL1-mediated regulation pathway, probably through competing with HDG1 to bind to AtCFL1.

Plant roots are in direct contact with the soil environment and thus particularly affected by unfavorable conditions. To withstand the surrounding environment, roots have developed anatomical and physiological adaptations. The development of Casparian strips (CSs) in the root endo-and exodermis is one such strategy. [1][2][3] In roots of most species, the sequence of development of the endo-and exodermis is roughly the same and involves two consecutive developmental stages: (1) formation of CSs in radial and transverse walls impregnating the primary cell wall pores with lipophilic and aromatic substances and (2) deposition of suberin lamellae to the inner surface of anticlinal and tangential cell walls. [4][5][6] A major function of the CS is to block the non-selective apoplastic bypass flow of water and ions into the stele.3 Therefore, the structure, 7-9 chemical nature, [10][11][12] and physiological function 13,14 of endo-and exdodermal CSs in roots have been the focus of many investigations. Although oxygen loss, drought and salinity can influence the development and chemical nature of CSs in different rice cultivars, [15][16][17][18][19] few investigations have considered the development and formation of endo-and exdodermal CSs in the roots of rice cultivars with different salt tolerance under normal growing conditions.In the present paper, light microscopy and Fourier transform infrared (FTIR) spectroscopy were used to examine the cytochemistry and root anatomy of isolated CSs. The aim was to compare anatomical development and chemical characteristics of the endoand exdodermal CSs of three rice (Oryza sativa L.) cultivars having different salt tolerance in north China: the salt-tolerant Liaohan 109 and two widely grown cultivars, Tianfeng 202 and Nipponbare.The development of casparian strips (cSs) on the endo-and exodermis and their chemical components in roots of three cultivars of rice (Oryza sativa) with different salt tolerance were compared using histochemistry and Fourier transform infrared (FTIr) spectroscopy. The development and deposition of suberin lamellae of cSs on the endo-and exodermis in the salt-tolerant cultivar Liaohan 109 was earlier than in the moderately tolerant cultivar Tianfeng 202 and the sensitive cultivar Nipponbare. The detection of chemical components indicated major contributions to the structure of the outer part from aliphatic suberin, lignin and cell wall proteins and carbohydrates to the rhizodermis, exodermis, sclerenchyma and one layer of cortical cells in series (OPr) and the endodermal casparian strip. Moreover, the amounts of these major chemical components in the outer part of the Liaohan 109 root were higher than in Tianfeng 202 and Nipponbare, but there was no distinct difference in endodermal cSs among the three rice cultivars. The results suggest that the exodermis of the salt-tolerant cultivar Liaohan 109 functions as a barrier for resisting salt stress. Development of Casparian strips and suberin lamellae on the endo-and exodermis. Casparian strips in the end...

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The industrialization of high-quality crops can help to increase the affordability of healthy diets for residents, and it is crucial to ensure food security and a better life. Quality traits are complex agronomic traits influenced by environment and regulated by multiple genes, whose basis is metabolism. Crops directly or indirectly provide energy and diversified nutrients for human beings through coordinated and orderly primary and/or secondary metabolism of photosynthates. Currently, several major genes responsible for nutrition, taste and other qualities have been cloned, and remarkable progress has been made in the analysis of metabolic pathways of vitamins and some special functional substances such as anthocyanins, and in the molecular design breeding of high-quality crops. However, our understanding of the regulatory mechanism of quality traits is limited, and the knowledge of environmental variation of quality traits is still lacking. Here, we summarized the present quality research on rice, wheat, corn and soybean at home and abroad, discussed the future development trend and bottleneck of quality research in China, and put forward some thoughts for crop quality research in China toward 2035.