The vacuolar proton-pumping pyrophosphatase gene (VPP) is often used to enhance plant drought tolerance via genetic engineering.  In this study, the drought tolerance of four transgenic inbred maize lines overexpressing ZmVPP1 (PH4CV-T, PH6WC-T, Chang7-2-T, and Zheng58-T) and their transgenic hybrids was evaluated at various stages.  Under normal and drought conditions, the height and fresh weight were greater for the four transgenic inbred maize lines than for the wild-type (WT) controls at the germination and seedling stages.  Additionally, the transgenic plants exhibited enhanced photosynthetic efficiency at the seedling stage.  In irrigated and non-irrigated fields, the four transgenic lines grew normally, but with increased ear weight and yield compared with the WT plants.  Moreover, the ear weight and yield of the transgenic hybrids resulting from the PH4CV-T×PH6WC-W and Chang7-2-T×Zheng58-W crosses increased in the non-irrigated field.  Our results demonstrated that the growth and drought tolerance of four transgenic inbred maize lines with improved photosynthesis were enhanced by the overexpression of ZmVPP1.  Moreover, the Chang7-2 and PH4CV transgenic lines may be useful for future genetic improvements of maize hybrids to increase drought tolerance.

Light spectrum plays an important role in regulating the growth and development of in vitro cultured potato (Solanum tuberosum L.) plantlets.  The status of potato plantlets at the end of in vitro stage influences the minituber production after transplanting.  With 100 μmol m^–2 s^–1 total photosynthetic photon flux density (PPFD), a light spectrum study of 100% red light emitting diodes (LEDs) light spectrum (RR), 100% blue LEDs light spectrum (BB), 65% red+35% blue LEDs light spectrum (RB), and 45% red+35% blue+20% green LEDs light spectrum (RBG) providing illumination at the in vitro cultured stage of potato plantlets for 4 weeks using fluorescent lamp as control (CK) was performed to investigate the effects of LEDs light spectrum on the growth, leaf anatomy, and chloroplast ultrastructure of potato plantlets in vitro as well as the minituber yield after 2 months transplanting in the greenhouse.  Compared to CK, RB and RBG promoted the growth of potato plantlets in vitro with increased stem diameter, plantlet fresh weight, plantlet dry weight, and health index.  Furthermore, BB induced the greatest stem diameter as well as the highest health index in potato plantlets in vitro.  Root activity, soluble protein, and free amino acid were also significantly enhanced by BB, whereas carbohydrates were improved by RR.  In addition, thickness of leaf, palisade parenchyma and spongy parenchyma was significantly increased by BB and RBG.  Chloroplasts under BB and RBG showed well-developed grana thylakoid and stroma thylakoid.  Unexpectedly, distinct upper epidermis with greatest thickness was induced and palisade parenchyma and spongy parenchyma were arranged neatly in RR.  After transplanting in the greenhouse for 2 months, potato plantlets in vitro from BB, RB, and RBG produced high percentage of large size tuber.  BB improved fresh and dry weights of the biggest tuber but decreased tuber number per plantlet.  In addition, RBG increased tuber number as well as tuber fresh and dry weight slightly.  Our results suggested monochromatic blue LEDs as well as combined red, blue or/and green LEDs light spectrum were superior to fluorescent lamp spectrum in micro-propagation of potato plantlets.  Therefore, the application of RBG was suitable; BB and RB could be used as alternatives.

Non-homologous end-joining (NHEJ) is a predominant pathway for the repair of DNA double-strand breaks (DSB).  It inhibits the efficiency of homologous recombination (HR) by competing for DSB targets.  To improve the efficiency of HR, multiple CRISPR interference (CRISPRi) and Natronobacterium gregoryi Argonaute (NgAgo) interference (NgAgoi) systems have been designed for the knockdown of NHEJ key molecules, KU70, KU80, polynucleotide kinase/phosphatase (PNKP), DNA ligase IV (LIG4), and NHEJ1.  Suppression of KU70 and KU80 by CRISPRi dramatically promoted (P<0.05) the efficiency of HR to 1.85- and 1.58-fold, respectively, whereas knockdown of PNKP, LIG4, and NHEJ1 repair factors did not significantly increase (P>0.05) HR efficiency.  Interestingly, although the NgAgoi system significantly suppressed (P<0.05) KU70, KU80, PNKP, LIG4, and NHEJ1 expression, it did not improve (P>0.05) HR efficiency in primary fetal fibroblasts.  Our result showed that both NgAgo and catalytically inactive Cas9 (dCas9) could interfere with the expression of target genes, but the downstream factors appear to be more active following CRISPR-mediated interference than that of NgAgo. 

Understanding of moisture changes in fresh ear corn (Zea mays L.) during storage is imperative for maintaining fresh corn quality.  The changes of moisture distribution and migration in fresh ear corn during storage were investigated using low-field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).  Water loss was greater than water migration in fresh ear corn within the first hour of storage; thereafter, water loss was weaker than water migration.  With the extension of storage time, the signal intensity of MRI in different parts of sliced fresh corn with cob showed a downward trend, and the rate of signal intensity reduction was higher in the peripheral area than at the central part of sliced fresh corn with cob.  The relative proportion of bound water increased with a concomitant drop in that of free water, when the total water content reduced in fresh ear corn under storage.  In conclusion, NMR and MRI are useful and non-destructive tools for real-time monitoring of moisture distribution, migration, and loss in fresh ear corn during storage to assess its quality.  These results can be used for future design of the preserving and processing conditions for fresh ear corn.