Integration of molecular breeding and multi-resistance screening for developing a promising restorer line Guihui5501 with heavy grain, good grain quality, and endurance to biotic and abiotic stresses.

Rice, a critical staple on a global scale, faces escalating challenges in yield preservation due to the rising prevalence of abiotic and biotic stressors, exacerbated by frequent climatic fluctuations in recent years. Moreover, the scorching climate prevalent in the rice-growing regions of South China poses obstacles to the cultivation of good-quality, heavy-grain varieties. Addressing this dilemma requires the development of resilient varieties capable of withstanding multiple stress factors. To achieve this objective, our study employed the broad-spectrum blast-resistant line Digu, the brown planthopper (BPH)-resistant line ASD7, and the heavy-grain backbone restorer lines Fuhui838 (FH838) and Shuhui527 (SH527) as parental materials for hybridization and multiple crossings. The incorporation of molecular markers facilitated the rapid pyramiding of six target genes (Pi5, Pita, Pid2, Pid3, Bph2, and Wxb ). Through a comprehensive evaluation encompassing blast resistance, BPH resistance, cold tolerance, grain appearance, and quality, alongside agronomic trait selection, a promising restorer line, Guihui5501 (GH5501), was successfully developed. It demonstrated broad-spectrum resistance to blast, exhibiting a resistance frequency of 77.33% against 75 artificially inoculated isolates, moderate resistance to BPH (3.78 grade), strong cold tolerance during the seedling stage (1.80 grade), and characteristics of heavy grains (1,000-grain weight reaching 35.64 g) with good grain quality. The primary rice quality parameters for GH5501, with the exception of alkali spreading value, either met or exceeded the second-grade national standard for premium edible rice varieties, signifying a significant advancement in the production of good-quality heavy-grain varieties in the southern rice-growing regions. Utilizing GH5501, a hybrid combination named Nayou5501, characterized by high yield, good quality, and resistance to multiple stresses, was bred and received approval as a rice variety in Guangxi in 2021. Furthermore, genomic analysis with gene chips revealed that GH5501 possessed an additional 20 exceptional alleles, such as NRT1.1B for efficient nitrogen utilization, SKC1 for salt tolerance, and STV11 for resistance to rice stripe virus. Consequently, the restorer line GH5501 could serve as a valuable resource for the subsequent breeding of high-yielding, good-quality, and stress-tolerant hybrid rice varieties.

Construction of High-Density Genetic Map and QTL Mapping for Grain Shape in the Rice RIL Population.

Grain shape is an important agronomic trait directly associated with yield in rice. In order to explore new genes related to rice grain shape, a high-density genetic map containing 2193 Bin markers (526957 SNP) was constructed by whole-genome resequencing of 208 recombinant inbred (RILs) derived from a cross between ZP37 and R8605, with a total genetic distance of 1542.27 cM. The average genetic distance between markers was 0.76 cM, and the physical distance was 201.29 kb. Quantitative trait locus (QTL) mapping was performed for six agronomic traits related to rice grain length, grain width, length-to-width ratio, thousand-grain weight, grain cross-sectional area, and grain perimeter under three different environments. A total of 39 QTLs were identified, with mapping intervals ranging from 8.1 kb to 1781.6 kb and an average physical distance of 517.5 kb. Among them, 15 QTLs were repeatedly detected in multiple environments. Analysis of the genetic effects of the identified QTLs revealed 14 stable genetic loci, including three loci that overlapped with previously reported gene positions, and the remaining 11 loci were newly identified loci associated with two or more environments or traits. Locus 1, Locus 3, Locus 10, and Locus 14 were novel loci exhibiting pleiotropic effects on at least three traits and were detected in multiple environments. Locus 14, with a contribution rate greater than 10%, influenced grain width, length-to-width ratio, and grain cross-sectional area. Furthermore, pyramiding effects analysis of three stable genetic loci showed that increasing the number of QTL could effectively improve the phenotypic value of grain shape. Collectively, our findings provided a theoretical basis and genetic resources for the cloning, functional analysis, and molecular breeding of genes related to rice grain shape.

Recent Advances in Molecular Mechanism and Breeding Utilization of Brown Planthopper Resistance Genes in Rice: An Integrated Review.

Over half of the world's population relies on rice as their staple food. The brown planthopper (Nilaparvata lugens Stål, BPH) is a significant insect pest that leads to global reductions in rice yields. Breeding rice varieties that are resistant to BPH has been acknowledged as the most cost-effective and efficient strategy to mitigate BPH infestation. Consequently, the exploration of BPH-resistant genes in rice and the development of resistant rice varieties have become focal points of interest and research for breeders. In this review, we summarized the latest advancements in the localization, cloning, molecular mechanisms, and breeding of BPH-resistant rice. Currently, a total of 70 BPH-resistant gene loci have been identified in rice, 64 out of 70 genes/QTLs were mapped on chromosomes 1, 2, 3, 4, 6, 8, 10, 11, and 12, respectively, with 17 of them successfully cloned. These genes primarily encode five types of proteins: lectin receptor kinase (LecRK), coiled-coil-nucleotide-binding-leucine-rich repeat (CC-NB-LRR), B3-DNA binding domain, leucine-rich repeat domain (LRD), and short consensus repeat (SCR). Through mediating plant hormone signaling, calcium ion signaling, protein kinase cascade activation of cell proliferation, transcription factors, and miRNA signaling pathways, these genes induce the deposition of callose and cell wall thickening in rice tissues, ultimately leading to the inhibition of BPH feeding and the formation of resistance mechanisms against BPH damage. Furthermore, we discussed the applications of these resistance genes in the genetic improvement and breeding of rice. Functional studies of these insect-resistant genes and the elucidation of their network mechanisms establish a strong theoretical foundation for investigating the interaction between rice and BPH. Furthermore, they provide ample genetic resources and technical support for achieving sustainable BPH control and developing innovative insect resistance strategies.

Bacterial leaf streak 1 encoding a mitogen-activated protein kinase confers resistance to bacterial leaf streak in rice.

Bacterial leaf streak (BLS) is a major bacterial disease of rice. Utilization of host genetic resistance has become one of the most important strategies for controlling BLS. However, only a few resistance genes have been characterized. Previously, a recessive BLS resistance gene bls1 was roughly mapped on chromosome 6. Here, we further delineated bls1 to a 21 kb region spanning four genes. Genetic analysis confirmed that the gene encoding a mitogen-activated protein kinase (OsMAPK6) is the target of the allelic genes BLS1 and bls1. Overexpression of BLS1 weakened resistance to the specific Xanthomonas oryzae pv. oryzicola (Xoc) strain JZ-8, while low expression of bls1 increased resistance. However, both overexpression of BLS1 and low expression of bls1 could increase no-race-specific broad-spectrum resistance. These results indicate that BLS1 and bls1 negatively regulate race-specific resistance to Xoc strain JZ-8 but positively and negatively control broad-spectrum resistance, respectively. Subcellular localization demonstrated that OsMAPK6 was localized in the nucleus. RGA4, which is known to mediate resistance to Xoc, is the potential target of OsMAPK6. Overexpression of BLS1 and low expression of bls1 showed increase in salicylic acid and induced expression of defense-related genes, simultaneously increasing broad-spectrum resistance. Moreover, low expression of bls1 showed increase an in jasmonic acid and abscisic acid, in company with an increase in resistance to Xoc strain JZ-8. Collectively, our study provides new insights into the understanding of BLS resistance and facilitates the development of rice host-resistant cultivars.

Preoperative transcatheter arterial chemotherapy may suppress oxidative stress in hepatocellular carcinoma cells and reduce the risk of short-term relapse.

In this study, we aim to investigate oxidative stress in hepatocellular carcinoma (HCC) tissues in patients receiving preoperative transcatheter arterial chemotherapy (TAC) and its association with prognosis. A total of 89 HCC patients enrolled in this study, 39 received preoperative TAC 1 week before surgery (pTAC group) and 50 did not (non-pTAC group). All patients underwent hepatectomy and postoperative TAC and were followed up to 400 weeks. Samples of liver tissue without HCC and hepatitis (n = 15) served as normal controls. Cellular levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), TP53, and p21waf1/cip1 were measured in both cancer and surrounding tissues using an immunohistochemistry assay. Taken together, our data suggested that preoperative TAC might postpone postoperative HCC relapse within 1 year via suppression of tumor cells by induction of high levels of oxidative stress.

[Relationship between combined multigene detection and response to chemotherapy and prognosis in epithelial ovarian carcinomas].

OBJECTIVE: To evaluate the relationship between combined multigene detection and response to chemotherapy and prognosis in epithelial ovarian carcinomas (EOCS). METHODS: A total of 80 ovarian tissue samples taken from the surgical specimens of patients with EOCS of our hospital in the last two decades who had received chemotherapy after surgery were paraffin-embedded. The samples were divided into 2 groups, good prognosis group (patients who survived more than 2 years, n = 46) and poor prognosis group (patients who survived less than 2 years, n = 34). The expression levels of ToPo-II, Ki-67, MGMT, PCNA, p27, p53, p16, P-gp, LRP, GST-pi, bcl-2, C-myc, Fas, bax, MSH2, MRP and BCRP were investigated by the combination of tissue arrays and immunohistochemical streptavidin-biotin peroxidase (SP) method in all samples. Data were analysed with SPSS 12.0 for windows. RESULTS: There were statistically significant differences in the positive expression levels of P-gp, BCRP, MGMT, MSH2, p27 and p16 (62%, 50% and 50% in poor prognosis group vs 33%, 28% and 28% respectively, P < 0.05) in the good prognosis group, suggesting that the positive expression levels of P-gp, BCRP, MGMT, MSH2, p27 and p16 were related to the response to chemotherapy and prognosis in EOCS. And the positive expression of P-gp, BCRP and MSH2 (43%, 54% and 43%) indicated poor prognosis, while the positive expression of MGMT, p27 and p16 (18%, 29% and 24%, P < 0.05) indicated good prognosis. Cox multigene expression analysis confirmed that the positive expression levels of MRP, C-myc, LRP, p16, p27, MGMT, ToPo-II, P-gp and GST-pi were related to the response to chemotherapy and prognosis in EOCS. And the positive expression of MRP, C-myc, LRP, ToPo-II, P-gp and GST-pi indicated poor prognosis, while the positive expression of MGMT, p27 and p16 indicated good prognosis. Combined multigene detections were conducted among P-gp, BCRP, MGMT, MSH2, p27 and p16, and there were statistically significant differences in the positive coexpression of P-gp plus MGMT in the two groups (P < 0.05); indicating that the combined multigene expression were related to the response to chemotherapy and prognosis in EOCS. The predictive value to response to chemotherapy and prognosis of the positive coexpression of P-gp plus MGMT was 70%. CONCLUSIONS: By univariate and multivariate analyses, the positive expression of P-gp, MGMT, p27 and p16 are related to the response to chemotherapy and prognosis in EOCS. The combined multigene expression of P-gp plus MGMT are related to the response to chemotherapy and prognosis and could predict prognosis more effectively.

Differential expression of human telomerase catalytic subunit mRNA by in situ hybridization in pheochromocytomas.

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.

Intestinal perforation after combined liver-kidney transplantation for a case of congenital polycystic disease.

AIM: To highlight the intestinal perforation (IP), an uncommon and catastrophic complication after combined liver-kidney transplantation. METHODS: Combined liver-kidney transplantation (LKTx) with left kidney excision and a cyst fenestration procedure on the right kidney were performed on a case of 46-year-old female with congenital polycystic disease (CPCD). RESULTS: Two sites of IP were noted 40-50 cm proximal to ileocecal area during emergent laparotomy 10 d postoperatively. Despite aggressive surgical and medical management, disease progressed toward a fatal outcome due to sepsis and multiple organ failure 11 d later. CONCLUSION: Long duration of operation without venovenous bypass, overdose of steroid together with postoperative volume excess may all contribute to the risk of idiopathic multiple IPs. Microbiology and pathology inspections suggested that the infected cyst of the fenestrated kidney might be one reason for the fatal intra-peritoneal infection. Thus for the CPCD patients who seem to be very susceptible to infectious complications, any sign of suspected renal-infection found before or during LKTx is indication for the excision of original kidney. And the intensity of immunosuppression therapy should be controlled cautiously.