Modulation of cell cycle progression and chromatin dynamic as tolerance mechanisms to salinity and drought stress in maize.

Salinity and drought are the major abiotic stresses that disturb several aspects of maize plants growth at the cellular level, one of these aspects is cell cycle machinery. In our study, we dissected the molecular alterations and downstream effectors of salinity and drought stress on cell cycle regulation and chromatin remodeling. Effects of salinity and drought stress were determined on maize seedlings using 200 mM NaCl (induced salinity stress), and 250 mM mannitol (induced drought stress) treatments, then cell cycle progression and chromatin remodeling dynamics were investigated. Seedlings displayed severe growth defects, including inhibition of root growth. Interestingly, stress treatments induced cell cycle arrest in S-phase with extensive depletion of cyclins B1 and A1. Further investigation of gene expression profiles of cell cycle regulators showed the downregulation of the CDKA, CDKB, CYCA, and CYCB. These results reveal the direct link between salinity and drought stress and cell cycle deregulation leading to a low cell proliferation rate. Moreover, abiotic stress alters chromatin remodeling dynamic in a way that directs the cell cycle arrest. We observed low DNA methylation patterns accompanied by dynamic histone modifications that favor chromatin decondensation. Also, the high expression of DNA topoisomerase 2, 6 family was detected as consequence of DNA damage. In conclusion, in response to salinity and drought stress, maize seedlings exhibit modulation of cell cycle progression, resulting in the cell cycle arrest through chromatin remodeling.

Evaluation of growth and nutritional value of Brassica microgreens grown under red, blue and green LEDs combinations.

Microgreens are rich functional crops with valuable nutritional elements that have health benefits when used as food supplements. Growth characterization, nutritional composition profile of 21 varieties representing five species of the Brassica genus as microgreens were assessed under light-emitting diodes (LEDs) conditions. Microgreens were grown under four different LEDs ratios (%); red:blue 80:20 and 20:80 (R80 :B20 and R20 :B80 ), or red:green:blue 70:10:20 and 20:10:70 (R70 :G10 :B20 and R20 :G10 :B70 ). Results indicated that supplemental lighting with green LEDs (R70 :G10 :B20 ) enhanced vegetative growth and morphology, while blue LEDs (R20 :B80 ) increased the mineral and vitamin contents. Interestingly, by linking the nutritional content with the growth yield to define the optimal LEDs setup, we found that the best lighting to promote the microgreen growth was the green LEDs combination (R70 :G10 :B20 ). Remarkably, under the green LEDs combination (R70 :G10 :B20 ) conditions, the microgreens of Kohlrabi purple, Cabbage red, Broccoli, Kale Tucsan, Komatsuna red, Tatsoi and Cabbage green, which can benefit human health in conditions with limited food, had the highest growth and nutritional content.