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Gene editing is a new genetic engineering technology that uses sequence-specific nucleases to insert, delete, or replace nucleic acid base(s) of the target gene, or introduce exogenous DNA sequences at a specific site in the genome of an organism to achieve the desired modification. Currently, the CRISPR/Cas system is the most widely used genome editing technology because it is relatively simple with high editing efficiency. In this review, we discuss the CRISPR/Cas system's application and its current limitations in rice breeding. Also, we elaborate on possible improved methods regarding its mechanism and development history. [ABSTRACT FROM AUTHOR]

Awn is one of important traits during rice domestication. To understand the development of rice awn and the roles it played in rice domestication, we preliminary mapped a major QTL An-3 for awn development using chromosome segment substitution line CSSL138 developed by introgressed genomic fragments of long-awned Guangxi common wild rice (GXCWR, Oryza rufipogon Griff.) into genetic background of short-awned indica cultivar 93-11. An-3 was then fine mapped to a 7-kb region of chromosome 8. An epidermal patterning factor-like protein gene was identified as the single candidate gene corresponding to this QTL. An-3 was showed to be an allele of RAE2 and GAD1, and negatively regulated 1000-grains weight, grain length, and length-width ratio. Comparing with the coding sequences of An-3 from CSSL138, a 2- and 4-bp frame-shift deletions in the second exon were identified in 93-11 and Nipponbare, respectively. Taken together, our results provide valuable natural variation in the alleles of An-3 between common wild rice and cultivated rice, which will be helpful in clarifying the mechanism of awn development and promoting the application of an-3 in genetic improvement of rice yield traits. [ABSTRACT FROM AUTHOR]

In pheochromocytomas, it is very difficult to predict malignant potential by conventional histology or immunohistochemical and molecular markers. We investigated the expression of human telomerase catalytic component (hTERT) mRNA, hTERT protein, Ki-67 antigen, and p27kip1 in pheochromocytomas (27 benign, 7 suspected malignant, and 7 malignant), and evaluated the possibility of expressions of these proteins, and hTERT mRNA serve as diagnostic markers for predicting the biological behavior of these tumors. All tumors showed the classical histology and typical immunohistochemical pattern. By in situ hybridization, hTERT mRNA was expressed in 5/7 malignant tumors (defined as the presence of metastasis and/or extensive local invasion) as compared with 3/27 benign tumors. We examined the hTERT by immunohistochemistry to confirm the mRNA. hTERT mRNA expression was correlated with hTERT protein expression. All benign tumors exhibited no immunopositivity or <1% of cells stained for Ki-67 antigen. Six out of seven malignant tumors have shown either hTERT mRNA expression or Ki-67 immunoreactivity While no statistical difference in p27kip1 expressions was observed among benign, malignant, and suspected malignant tumors, there was a statistical difference between the normal adrenal medulla samples and tumors ( p<0.001). Thus, hTERT mRNA detection by in situ hybridization, hTERT expression, and Ki-67 antigen expression are all useful tools for differentiating malignant from benign pheochromocytomas. [ABSTRACT FROM AUTHOR]