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Highlights • The 26S proteasome subunit RPT2a interacts with a SUMO ligase AtMMS21. • The mutants of AtMMS21 and RPT2a have similar root developmental defects. • RPT2a is covalently modified by SUMO3 potentially mediated via AtMMS21. • The protein level of RPT2a and activity of the 26S proteasome are decreased in the AtMMS21 mutant. Abstract The 26S proteasome is a multi-subunit protease controlling most of the cytosolic and nuclear protein turnover, regulating many cellular events in eukaryotes. However, functional modification on this complex remains unclear. Here, we showed a novel mechanism that a SUMO ligase AtMMS21 regulates activity of the 26S proteasome in root development of Arabidopsis. Our in vitro and in vivo data supported that AtMMS21 interacts with RPT2a, a subunit of the 26S proteasome. The mutants of AtMMS21 and RPT2a display similar developmental defect of roots, suggesting their association in this process. In addition, RPT2a is modified by SUMO3, potentially related to AtMMS21. During development, the activity of the 26S proteasome is lower in both mutants of AtMMS21 and RPT2a , compared with that of wild type. Furthermore, the protein level but not the RNA level of RPT2a is decreased in the absence of AtMMS21 , implying stability regulation of the proteasome complex through the AtMMS21-RPT2a interaction. Taken together, the current study would improve our understanding on the regulatory mechanism of the 26S proteasome via protein modification in root development. [ABSTRACT FROM AUTHOR]

The annual Zea mays ssp. mexicana L., a member of the teosinte group, is a close wild relative of maize and thus can be effectively used in maize improvement. In this study, an ICE- like gene, ZmmICE1 , was isolated from a cDNA library of RNA-Seq from cold-treated seedling tissues of Zea mays ssp. mexicana L. The deduced protein of ZmmICE1 contains a highly conserved basic helix-loop-helix (bHLH) domain and C-terminal region of ICE -like proteins. The ZmmICE1 protein localizes to the nucleus and shows sumoylation when expressed in an Escherichia coli reconstitution system. In addition, yeast one hybrid assays indicated that ZmmICE1 has transactivation activities. Moreover, ectopic expression of ZmmICE1 in the Arabidopsis ice1-2 mutant increased freezing tolerance. The ZmmICE1 overexpressed plants showed lower electrolyte leakage (EL), reduced contents of malondialdehyde (MDA). The expression of downstream cold related genes of Arabidopsis C-repeat-binding factors ( AtCBF1 , AtCBF2 and AtCBF3) , cold-responsive genes ( AtCOR15A and AtCOR47) , kinesin-1 member gene ( AtKIN1) and responsive to desiccation gene ( AtRD29A) was significantly induced when compared with wild type under low temperature treatment. Taken together, these results indicated that ZmmICE1 is the homolog of Arabidopsis inducer of CBF expression genes ( AtICE1/2) and plays an important role in the regulation of freezing stress response. [ABSTRACT FROM AUTHOR]

Worldwide significant amounts of food waste are generated daily causing serious environmental issues, occupying land and requiring expenditure of resources for its treatment. A smart method for handling this food waste problem is the development of novel processes targeting the conversion of this waste into value added products. Although valorization of food waste to biofuels, biochemicals and bio-polymers have been widely investigated, the utilization of food waste streams into biofertiliser has not been intensively reviewed. Conversion of food waste, especially agriculture residues into biofertiliser would reduce its environmental impact, improve nutrition levels of the soil, decrease requirements for synthetic chemical fertiliser and have a direct benefit on food production. This paper reviews recent progress in the field regarding the production of biofertiliser from food waste, using anaerobic digestion, aerobic composting, chemical hydrolysis, in situ degradation and direct burning methods. This review also highlights the latest field applications of biofertiliser derived from various food waste streams. It confirms that the technology for the conversion of food waste to biofertilisers is viable, but the production efficiency could be improved with better process control strategies, strict quality controls, development of a smart product distribution system and adoption of advanced technologies. Field tests have indicated that biofertilisers which are obtained in proper managed AD plants are safe and could partially replace the use of chemical fertilisers in field application. [ABSTRACT FROM AUTHOR]