Human serum albumin (HSA) is widely used in clinical and cell culture applications. Conventional production of HSA from human blood is limited by the availability of blood donation and the high risk of viral transmission from donors. Here, we report the production ofOryza sativarecombinant HSA (OsrHSA) from transgenic rice seeds. The level of OsrHSA reached 10.58% of the total soluble protein of the rice grain. Large-scale production of OsrHSA generated protein with a purity >99% and a productivity rate of 2.75 g/kg brown rice. Physical and biochemical characterization of OsrHSA revealed it to be equivalent to plasma-derived HSA (pHSA). The efficiency of OsrHSA in promoting cell growth and treating liver cirrhosis in rats was similar to that of pHSA. Furthermore, OsrHSA displays similar in vitro and in vivo immunogenicity as pHSA. Our results suggest that a rice seed bioreactor produces cost-effective recombinant HSA that is safe and can help to satisfy an increasing worldwide demand for human serum albumin.

Rice is sensitive to chilling stress, especially at the seedling stage. To elucidate the molecular genetic mechanisms of chilling tolerance in rice, comprehensive gene expressions of two rice genotypes (chilling-tolerant LTH and chilling-sensitive IR29) with contrasting responses to chilling stress were comparatively analyzed. Results revealed a differential constitutive gene expression prior to stress and distinct global transcription reprogramming between the two rice genotypes under time-series chilling stress and subsequent recovery conditions. A set of genes with higher basal expression were identified in chilling-tolerant LTH compared with chilling-sensitive IR29, indicating their possible role in intrinsic tolerance to chilling stress. Under chilling stress, the major effect on gene expression was up-regulation in the chilling- tolerant genotype and strong repression in chilling-sensitive genotype. Early responses to chilling stress in both genotypes featured commonly up-regulated genes related to transcription regulation and signal transduction, while functional categories for late phase chilling regulated genes were diverse with a wide range of functional adaptations to continuous stress. Following the cessation of chilling treatments, there was quick and efficient reversion of gene expression in the chilling-tolerant genotype, while the chilling-sensitive genotype displayed considerably slower recovering capacity at the transcriptional level. In addition, the detection of differentially-regulated TF genes and enriched cis-elements demonstrated that multiple regulatory pathways, including CBF and MYBS3 regulons, were involved in chilling stress tolerance. A number of the chilling-regulated genes identified in this study were co-localized onto previously fine-mapped cold-tolerance-related QTLs, providing candidates for gene cloning and elucidation of molecular mechanisms responsible for chilling tolerance in rice.

The circadian clock enables organisms to rapidly adapt to the ever‐changing environmental conditions that are caused by daily light/dark cycles. Circadian clock genes universally affect key agricultural traits, particularly flowering time. Here, we show thatOsPRR37, a circadian clock gene, delays rice flowering time in an expression level‐dependent manner. Using high‐throughput mRNA sequencing on anOsPRR37overexpressing transgenic line (OsPRR37‐OE5) and the recipient parent Guangluai4 that contains the loss‐of‐functionOsprr37, we identify 14,992 genes that display diurnal rhythms, which account for 52.9% of the transcriptome. OverexpressingOsPRR37weakens the transcriptomic rhythms and alters the phases of rhythmic genes. In total, 3,210 differentially expressed genes (DEGs) are identified, among which 1,863 rhythmic DEGs show a correlation between the change of absolute amplitudes and the mean expression levels. We further reveal that OsPRR37 functions as a transcriptional repressor to repress the expression levels and amplitudes of day‐phased clock genes. More importantly,OsPRR37confers expanded regulation on the evening‐phased rhythmic DEGs by repressing the morning‐phased rhythmic DEGs. Further study shows thatOsPRR37expands its regulation on flowering pathways by repressingEhd1. Thus, our results demonstrate an expanded regulation mechanism of the circadian clock on the diurnal rhythms of the transcriptome.

Background: Extensive studies on heterosis in plants using transcriptome analysis have identified differentially expressed genes (DEGs) in F₁ hybrids. However, it is not clear why yield in heterozygotes is superior to that of the homozygous parents or how DEGs are produced. Global allele-specific expression analysis in hybrid rice has the potential to answer these questions. Results: We report a genome-wide allele-specific expression analysis using RNA-sequencing technology of 3,637–3,824 genes from three rice F₁ hybrids. Of the expressed genes, 3.7% exhibited an unexpected type of monoallelic expression and 23.8% showed preferential allelic expression that was genotype-dependent in reciprocal crosses. Those genes exhibiting allele-specific expression comprised 42.4% of the genes differentially expressed between F₁ hybrids and their parents. Allele-specific expression accounted for 79.8% of the genes displaying more than a 10-fold expression level difference between an F₁ and its parents, and almost all (97.3%) of the genes expressed in F₁, but non-expressed in one parent. Significant allelic complementary effects were detected in the F₁ hybrids of rice. Conclusions: Analysis of the allelic expression profiles of genes at the critical stage for highest biomass production from the leaves of three different rice F₁ hybrids identified genotype-dependent allele-specific expression genes. A cis-regulatory mechanism was identified that contributes to allele-specific expression, leading to differential gene expression and allelic complementary effects in F₁ hybrids.

Artificial selection of high yield crops and better livestock is paramount importance in breeding programs. Selection of elite parents with preferred traits from a phalanx of inbred lines is extremely laborious, time-consuming and highly random. General combining ability (GCA) was proposed and has been widely used for the evaluation of parents in hybrid breeding for more than half a century. However, the genetic and molecular basis of GCA has been largely overlooked. Here, we present two pleotropic QTLs are accounting for GCA of days to heading (DTH), plant height (PH) and spikelet per panicle (SPP) using an F₂-based NCII design, the BC₃F₂ population as well as a set of nearly isogenic lines (NILs) with five testers. Both GCA1 and GCA2 were loss-of-function gene in low-GCA parent and gain-of-function gene in high-GCA parent, encoding the putative Pseudo-Response Regulators, OsPRR37 and Ghd7, respectively. Overexpression of GCA1 in low-GCA parent significantly increases GCA effects in three traits. Our results demonstrate that two GCA loci associate with OsPRR37 and Ghd7 and reveal that the genes responsible for important agronomic traits could simultaneously account for GCA effects.