Multiple factors interact in editing of PPR-E+-targeted sites in maize mitochondria and plastids.

RNA cytidine-to-uridine editing is essential for plant organellar gene expression. Pentatricopeptide repeat (PPR)-E+ proteins have been proposed to bind to target sites and recruit the cytidine deaminase AtDYW2, facilitated by AtNUWA. Here we analyze the function of ZmNUWA, ZmDYW2A, and ZmDYW2B and their relationships with other editing factors in maize. The zmdyw2a and zmdyw2b single mutants are normal, but the zmdyw2a::zmdyw2b and zmnuwa mutants are severely arrested in seed development. ZmNUWA, ZmDYW2A, and ZmDYW2B are dual localized in mitochondria and plastids. Loss of ZmNUWA decreases the editing at 99 mitochondrial sites and 8 plastid sites. Surprisingly, loss of ZmDYW2A:ZmDYW2B affects almost the same set of sites targeted by PPR-E+ proteins. ZmNUWA interacts with ZmDYW2A and ZmDYW2B, suggesting that ZmNUWA recruits ZmDYW2A/2B in the editing of PPR-E+-targeted sites in maize. Further protein interaction analyses show that ZmNUWA and ZmDYW2A/2B interact with ZmMORF1, ZmMORF8, ZmMORF2, and ZmMORF9 and that ZmOZ1 interacts with ZmORRM1, ZmDYW2A, ZmDYW2B, ZmMORF8, and ZmMORF9. These results suggest that the maize mitochondrial PPR-E+ editosome contains PPR-E+, ZmDYW2A/2B, ZmNUWA, and ZmMORF1/8, whereas the plastid PPR-E+ editosome is composed of PPR-E+, ZmDYW2A/2B, ZmNUWA, ZmMORF2/8/9, ZmORRM1, and ZmOZ1.

[Soil respiration rates and its affecting factors in winter wheat land in the Weihe Plain, Northwest China.] / æ¸­æ²³å¹³åŽŸå†œç”°å†¬å°éº¦åœŸå£¤å‘¼å¸åŠå ¶å½±å“å› ç´ .

Based on measurement on winter wheat soil respiration (SR), environmental and biotic factors from 2013 to 2014 in semi-humid and prone-to-drought area of Weihe Plain, this paper analyzed the characteristics of diurnal and seasonal variation of SR and influences of temperature (T), soil water content (W), gross primary productivity (GPP) and leaf area index (LAI). The results showed that the SR diurnal variation appeared as a single-peak curve ranging between 1.5 and 6.94 µmol CO2·m-2·s-1, with the peak presented during 12:00-14:00. Temperature was the driving factor for the SR diurnal variation, and land surface temperature (Ts) could explain 80.9% of the temporal variation for SR. The corresponding relationship between SR and temperature showed a clockwise nearly elliptic curve. From seedling stage to winter, the SR rate of wheat showed a descending trend, and stayed at a relatively low level until regreening stage. Then the rate of SR increased rapidly and reached peak in heading stage and filling stage, but there was a descending trend in mature stage. The SR values in growth period were between 0.65 and 4.85 µmol CO2·m-2·s-1. T, W, GPP and LAI were positively related to SR (P<0.01). Soil temperature and soil water content were the dominant factors affecting the SR seasonal variation, and they could explain 82.6% of its variation by a compound model SR=$e^{(a+bT_{5 cm}+cW_{10 cm}+dW_{10 cm}^2)}$, which was much better than monovariant model (below 65.7%). Based on the compound model results, the average rate of wheat SR during growth period in 2013-2014 was 1.67 µmol CO2·m-2·s-1.