Ethylene-responsive factors (ERFs), within a subgroup of the AP2/ERF transcription factor family, are involved in diverse plant reactions to biotic or abiotic stresses. Here, we report that overexpression of an ERF gene from Brassica rapa ssp. pekinensis (BrERF4) led to improved tolerance to salt and drought stresses in Arabidopsis. It also significantly affected the growth and development of transgenic plants. We detected that salt-induced expressions of a transcriptional repressor gene, AtERF4, and some Ser/Thr protein phosphatase2C genes, ABI1, ABI2 and AtPP2CA, were suppressed in BrERF4-overexpressing Arabidopsis plants. Furthermore, BrERF4 was induced by treatment with ethylene or methyljasmonate, but not by abscisic acid or NaCl in B. rapa. These results suggest that BrERF4 is activated through a network of different signaling pathways in response to salinity and drought.

Seed size is one of the most important traits determining the yield of cereal crops. Many studies have been performed to uncover the mechanism of seed development. However, much remains to be understood, especially at the molecular level, although several genes involved in seed size have been identified. Here, we show that rice Grain Width 2 (GW2), a RING-type E3 ubiquitin ligase, can control seed development by catalyzing the ubiquitination of expansin-like 1 (EXPLA1), a cell wall-loosening protein that increases cell growth. Microscopic examination revealed that a GW2 mutant had a chalky endosperm due to the presence of loosely packed, spherical starch granules, although the grain shape was normal. Yeast two-hybrid and in vitro pull-down assays showed a strong interaction between GW2 and EXPLA1. In vitro ubiquitination analysis demonstrated that EXPLA1 was ubiquitinated by GW2 at lysine 279 (K279). GW2 and EXPLA1 colocalized to the nucleus when expressed simultaneously. These results suggest that GW2 negatively regulates seed size by targeting EXPLA1 for degradation through its E3 ubiquitin ligase activity.

Renewable energy generation has attracted growing interest globally. The agro-photovoltaic (APV) system is a new alternative to conventional photovoltaic power plants, which can simultaneously generate renewable energy and increase agricultural productivity by the use of solar panels on the same farmland. The optimization of crop yields and assessment of their environmental sensitivity under the solar panels have not yet been evaluated with various crop species. This study aimed to evaluate the agronomic performances and crop yields under the APV system and the open field with crop species such as rice, onion, garlic, rye, soybean, adzuki bean, monocropping corn, and mixed planting of corn with soybean in South Korea. The results indicated that there was statistically no negative impact of the APV system on the forage yield of rye and corn over two years, suggesting that forage crops under the APV system were suitable to producing forage yield for livestock. In addition, the measured forage quality of rye was not significantly different between the open field and the APV system. However, rice yield was statistically reduced under the APV system. The yield of legume crops and vegetables in this study did not show consistent statistical results in two years. For further study, crop yield trials will still be required for rice, soybean, adzuki bean, onion, and garlic for multiple years under the APV system.