Allelic Diversification of the Wx and ALK Loci in Indica Restorer Lines and Their Utilisation in Hybrid Rice Breeding in China over the Last 50 Years.

Hybrid rice technology has been used for more than 50 years, and eating and cooking quality (ECQ) has been a major focus throughout this period. Waxy (Wx) and alkaline denaturation (ALK) genes have received attention owing to their pivotal roles in determining rice characteristics. However, despite significant effort, the ECQ of restorer lines (RLs) has changed very little. By contrast, obvious changes have been seen in inbred rice varieties (IRVs), and the ECQ of IRVs is influenced by Wx, which reduces the proportion of Wxa and increases the proportion of Wxb, leading to a decrease in amylose content (AC) and an increase in ECQ. Meanwhile, ALK is not selected in the same way. We investigated Wx alleles and AC values of sterile lines of female parents with the main mating combinations in widely used areas. The results show that almost all sterile lines were Wxa-type with a high AC, which may explain the low ECQ of hybrid rice. Analysis of hybrid rice varieties and RLs in the last 5 years revealed serious homogenisation among hybrid rice varieties.

Transcription factor OsMADS25 improves rice tolerance to cold stress.

Cold stress is the limiting factor of rice growth and production, and it is important to clone cold stress tolerant genes and cultivate cold tolerance rice varieties. The MADS transcription factors play an important role in abiotic stress signaling in rice. This study showed that OsMADS25 was up-regulated by low temperature and abscisic acid (ABA), suggesting that OsMADS25 may be involved in ABA-dependent signaling. The OsMADS25 overexpression vector, pCambia1300-221-OsMADS25-Flag, was constructed and introduced into the rice variety Zhonghua 11 (ZH11) through Agrobacterium tumefacian-mediated genetic transformation. Two homozygous lines with high expression levels were selected for phenotypic identification. OsMADS25 overexpression lines show significantly improved cold stress tolerance and the sensitivity to ABA at the seedling stage of rice. Reactive oxygen species (ROS) was detected by diaminobenzidine (DAB) staining and nitroblue tetrazolium (NBT) staining. After treatment with cold stress, little ROS accumulation was observed in OsMADS25 overexpression lines compared to wild-type ZH11. In conclusion, OsMADS25 plays a role in scavenging reactive oxygen species (ROS) and could improve rice tolerance to cold stress involved in ABA-dependent pathway.

Molecular cloning and expression analysis of a new bilin lyase: the cpcT gene encoding a bilin lyase responsible for attachment of phycocyanobilin to Cys-153 on the ß-subunit of phycocyanin in Arthrospira platensis FACHB314.

To study the assembly of phycocyanin ß subunit, the gene cpcT was first cloned from Arthrospira platensis FACHB314. To explore the function of cpcT, the DNA of phycocyanin ß subunit and cpcT were transformed into Escherichia coli BL21 with the plasmid pET-hox1-pcyA, which contained the genes hemeoxygenase 1 (Hox1) and ferredoxin oxidoreductase (PcyA) needed to produce phycocyanobilin. The transformed strains showed specific phycocyanin fluorescence, and the fluorescence intensity was stronger than the strains with only phycocyanin ß subunit, indicating that CpcT can promote the assembly of phycocyanin to generate fluorescence. To study the possible binding sites of apo-phycocyanin and phycocyanobilin, the Cys-82 and Cys-153 of the ß subunit were individually mutated, giving two kinds of mutants. The results show that Cys-153 maybe the active site for ß subunit binding to phycocyanobilins, which is catalyzed by CpcT in A. platensis FACHB314.

Indication of the expression of transgene in rice plant based on hyperspectral remote sensing technique II--growth monitoring of samples in the contrast experiment.

Since the complication of monitoring and evaluating the problems about the transgenic expression and its impacts on the receptor in the transgenic crop breeding and other relevant evaluated works, the authors in the present work tried to assess the differences of spectral parameters of the transgenic rice in contrast with its parent group quantitatively and qualitatively, fulfilling the growth monitoring of the transgenic samples. The spectral parameters (spectral morphological characteristics and indices) chosen are highly related to internal or external stresses to the receipts, and thus could be applied as indicators of biophysical or biochemical processes changes of plant. By ASD portable field spectroradiometer with high-density probe, fine foliar spectra of 8 groups were obtained. By analyzing spectral angle and continuum removal, the spectral morphological differences and their locations of sample spectra were found which could be as auxiliary priori knowledge for quantitative analysis. By investigating spectral indices of the samples, the quantitative differences of spectra were revealed about foliar chlorophyll a+b and carotenoid content. In this study both the spectral differences between transgenic and parent groups and among transgenic groups were investigated. The results show that hyperspectral technique is promising and a helpful auxiliary tool in the study of monitoring the transgenic crop and other relevant researches. By this technique, quantitative and qualitative results of sample spectra could be provided as prior knowledge, as certain orientation, for laboratory professional advanced transgenic breeding study.

[Detection of the expression of transgene in rice plant based on hyperspectral remote sensing technique].

The present study aims to identify the expression of transgene in given rice plant samples in certain conditions. To avoid external noise caused by temperature change and water-loss, field spectrum was collected with ASD field spectrometer in natural state. The study calculated the mean spectrum of samples as main data set analyzed which were controlled by inner clustering coefficient to ensure data quality. By mean spectrum, the noise from random distinctions in few individual cultivators, which could not be expressed in the class stably, could be weakened even with filtering. With the help of parameters, such as red edge and green peak, this study gave qualitative spectral differences between transgenic samples and their parents. The results show that the transgenes in rice plant were expressed and influenced the samples. Moreover, it was found that the parameters of area are more suitable for describing the differences/changes of the samples, while PRI and SR-PRI are more sensitive to indicate them. Most of the above results could be found on the continuum-removal spectrum curve of samples. These conclusive results demonstrate that hyperspectral remote sensing technique has good prospects and application potential in transgene expression detection and monitoring, especially in plant breeding process.