Photosynthesis is the basis of crop growth and is sensitive to stress.  Smut (Sporisorium destruens) is the primary disease in the production of broomcorn millet (Panicum miliaceum L.).  This study evaluated the effects of infection with S. destruens on the photosynthesis of the resistant cultivar (BM) and susceptible cultivar (NF).  After inoculation, there was a decrease in the chlorophyll content, gas exchange parameters, and chlorophyll fluorescence of the two cultivars.  Observation of the ultrastructure of diseased leaves showed that the chloroplasts and mitochondria had abnormal morphology, and some vacuoles appeared.  RNA-seq was performed on the flag leaves after inoculation.  In addition to the resistant and susceptible cultivars, the diseased leaves developed from inflorescences were defined as S2.  The analysis showed that the pathways related to photosynthesis stimulated some differentially expressed genes (DEGs) after infection with S. destruens.  More DEGs were induced in the susceptible broomcorn millet NF than in the resistant broomcorn millet BM, and most of those genes were downregulated.  The number of DEGs induced by S2 was greater than that in susceptible cultivar NF, and most of them were upregulated.  These results indicate that infection with S. destruens affects the normal photosynthetic performance of broomcorn millet.  Understanding the mechanism between S. destruens, photosynthesis, and broomcorn millet is an effective measure to prevent the occurrence of smut and enhance its resistance. 

Heat stress is a major constraint to current and future maize production at the global scale.  Male and female reproductive organs both play major roles in increasing seed set under heat stress at flowering, but their relative contributions to seed set are unclear.  In this study, a 2-year field experiment including three sowing dates in each year and 20 inbred lines was conducted.  Seed set, kernel number per ear, and grain yield were all reduced by more than 80% in the third sowing dates compared to the first sowing dates.  Pollen viability, silk emergence ratio, and anthesis–silking interval were the key determinants of seed set under heat stress; and their correlation coefficients were 0.89^***, 0.65^***, and –0.72^***, respectively.  Vapor pressure deficit (VPD) and relative air humidity (RH) both had significant correlations with pollen viability and the silk emergence ratio.  High RH can alleviate the impacts of heat on maize seed set by maintaining high pollen viability and a high silk emergence ratio.  Under a warming climate from 2020 to 2050, VPD will decrease due to the increased RH.  Based on their pollen viability and silk emergence ratios, the 20 genotypes fell into four different groups.  The group with high pollen viability and a high silk emergence ratio performed better under heat stress, and their performance can be further improved by combining the improved flowering pattern traits. 

In the process of infecting plants, plant parasitic nematodes release a series of proteins that play an essential role in the successful infection and pathogenesis of plant cells and tissues through stylets or body walls.  In this study, based on transcriptome data, a chorismate mutase gene of Radopholus similis (RsCM) was identified and cloned, which is a single copy gene specifically expressed in the oesophageal gland and highly expressed in juveniles and females.  Transient expression of RsCM in tobacco leaves showed that it was localised in the cytoplasm and nucleus of tobacco leaf cells, which inhibited the pattern-triggered immunity (PTI) induced by flg22, including callose deposition and defence gene expression, and cell death induced by immune elicitors BAX, but could not inhibit cell death induced by immune elicitors Gpa2/RBP-1.  The RNA interference (RNAi) transgenic tomato of RsCM obviously inhibited the infection, pathogenicity, and reproduction of R. similis.  However, the resistance of the overexpression transgenic tomato of RsCM to R. similis infection was significantly reduced, and the expression levels of two salicylic acid (SA) pathway genes (PR1 and PR5) in roots infected by the nematode were significantly down-regulated, which indicated that RsCM might be involved in the inhibition of SA pathway.  The results of this study demonstrate that RsCM suppresses the host immune system and might be a new target for the control of R. similis, which also provides new data for the function and mechanism of CM genes of migratory parasitic plant nematodes.

To evaluate the impact of climate change on maize production, it is critical to accurately measure the radiation use efficiency (RUE) for maize. In this study, we focused on three maize cultivars in Jilin Province, China: Zhengdan 958 (ZD958), Xianyu 335 (XY335), and Liangyu 99 (LY99).  Under the optimal growing conditions for high density (9 plants m^-2), we investigated the maize RUE during the vegetative and reproductive phases, and the entire growth period.  The results showed that the canopy light interception for maize peaked during anthesis.  After anthesis, maize plant biomass continued to accumulate.  Based on the absorbed photosynthetically active radiation (APAR), we calculated maize RUE.  During the entire growth period, maize RUE averaged 5.71 g MJ^-1 APAR among the three cultivars, with a high-to-low order of ZD958 (5.85 g MJ^-1 APAR)>XY335 (5.64 g MJ^-1 APAR)>LY99 (5.07 g MJ^-1 APAR).  Within the vegetative and reproductive growth periods, maize RUE averaged 6.85 and 5.64 g MJ^-1 APAR, respectively.  When utilizing maize models, such as APSIM, that depend on radiation use efficiency (RUE) to predict aboveground biomass accumulation, we observed that the current RUE value of 3.6 g MJ^-1 APAR is considerably lower than the measured value obtained under high-density optimal growing conditions.  Consequently, to derive the optimal potential yield for maize in such planting conditions, we recommend adjusting the RUE to a range of 5.07-5.85 g MJ^-1 APAR.