Genetic Dissection of Major Rice QTLs for Strong Culms and Fine Mapping of qWS5 for Breeding Application in Transplanted System.

BACKGROUND: Rice is one of the major staples that feeds about one half of the global populations, and it is important to identify the genetic loci for the traits related to yield improvement. Lodging will cause severe yield loss when it happens, and stem diameter has been characterized as an important trait for lodging resistance. However, most QTLs for stem diameter have not been finely dissected due to their sensitivity to environmental fluctuation. RESULT: In this study, we performed QTL analysis for stem diameter using populations derived from Nipponbare (NIP) and strong culm variety YYP1, and confirmed the single and combined effect of three major QTLs by recombinant inbred lines (RILs). Based on the QTL location, we found that qWS5 is a novel QTL not well characterized before. To finely dissect the novel locus, several recombinant heterogeneous inbred families (HIFs) were selected from the RILs for linkage analysis and their derived nearly isogenic lines (NILs) were subjected to detailed trait investigation throughout different years. The HIF-NILs strategy confined the QTL to about 380 kb region supported by repeated genotype and phenotype data, and it lays the foundation for QTL cloning in the future. In addition, introgression of the QTL to an elite japonica variety SD785 was performed by successive backcrossing, and it confirmed the value of qWS5 in increasing stem diameter and other agronomic traits during rice breeding. CONCLUSIONS: We prove that qWS5 is a novel QTL with relatively stable effect for stem diameter and the QTL can be finely mapped to small region by the HIF-NILs strategy. The result will facilitate the improvement of rice lodging resistance by molecular marker assisted selection breeding.

Effect of Low Temperature on Insecticidal Protein Contents of Cotton (Gossypium herbaceum L.) in the Boll Shell and Its Physiological Mechanism.

Low temperature is the main factor for global natural disasters affecting the growth and distribution of plants, and cotton may be affected by low temperature and cold damage at all growth stages. In addition, the insecticidal resistance of cultivars has been reported to perform poorly or unstably due to adverse environments. The present study aimed to investigate the impact of low temperature on the levels of insecticidal protein in Bacillus thuringiensis (Bt) transgenic cotton plants during the peak boll stage. To achieve this, two Bt cotton cultivars, Sikang1 (SK1) and Sikang3 (SK3), were subjected to different temperature regimes and durations. The findings of the study demonstrated that the expression of insecticidal protein in the boll shell of Bt transgenic cotton plants was significantly inhibited under low-temperature stress. Specifically, in 2020, compared to the CK (27 °C), the insecticidal protein content in the boll shell of SK3 decreased by 28.19% after a 48 h of a 16 °C temperature. These results suggest that low-temperature stress can negatively impact the expression of insecticidal protein in Bt transgenic cotton, highlighting the need for appropriate measures to minimize its adverse effects on cotton production. In addition, the threshold temperature that leads to a significant decrease in the content of insecticidal proteins symbolizes an upward trend as the duration of stress prolongs. Decreased Bt protein content at low temperatures is associated with changes in the N metabolism. The present study revealed a significant positive correlation between the levels of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) activities, as well as in the soluble protein levels in the boll shell and the content of the Bt protein. On the other hand, a significant negative correlation was observed between the levels of free amino acids, peptidase, and protease activities, as well as of Bt protein content. These findings suggest that, in Bt cotton production, it is crucial to remain vigilant of prolonged low-temperature disasters, which last for over 12 h and drop below 17-20 °C during the peak boll stage. Such conditions may reduce insecticidal resistance, leading to substantial economic losses.

The second terminations of the suboccipital muscles: An assistant pivot for the To Be Named Ligament.

In the last two decades, many studies have focused on the muscles and dense connective tissues located in the suboccipital region. Our study investigated the existence of the second terminations originating from the suboccipital muscles, and the relationship between the variable types of the To Be Named Ligament (TBNL). Anatomical dissection was performed on 35 head-neck specimens. The existence of the second terminations of the suboccipital muscles was confirmed and various types of the TBNL were observed in this study. The second terminations originated from multiple suboccipital muscles including the rectus capitis posterior minor (RCPmi), rectus capitis posterior major (RCPma) and obliquus capitis inferior (OCI) muscles, merged and terminated at the TBNL. The overall incidence of the second terminations of the suboccipital muscles was 34.29% and it varied among the various suboccipital muscle origins. 28.57% of the second terminations originated from the RCPma; 11.43% was from the RCPmi and 8.57% was from the OCI. Furthermore, there was a significant relationship between the existence of second terminations and the particular type of the TBNL. 95% of the arcuate type of the TBNL was accompanied with the second terminations which attached to their turning part, whereas only 10% of all the radiate type of the TBNL was accompanied with the second terminations. This study for the first time described the second terminations originating from multiple suboccipital muscles and demonstrated the relationship with the various types of the TBNL. We speculated that the second terminations maintain the arcuate TBNL and transfer tensile forces to the Myodural Bridge (MDB), thereby modulating the physiological functions of the MDB.

Folic acid attenuates hyperhomocysteinemia-induced glomerular damage in rats.

The present study investigated whether lowering plasma homocysteine (Hcy) with folic acid (FA) could attenuate hyperhomocysteinemia (HHcy)-associated glomerular damage and possible mechanisms. The HHcy animal model was established by intragastric administration with l-methionine in rats. FA was also given intragastrically. Plasma Hcy and creatinine and urinary albumin were measured. Histological and ultrastructural changes were observed by light and electron microscopes. The expression of alpha-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA) and transforming growth factor-beta1 (TGF-ß1) in the kidney was examined by immunohistochemical staining and western blot analysis. The administration of l-methionine induced HHcy in rats. The HHcy rats developed glomerulosclerosis and fibrosis. Plasma creatinine concentration and urinary albumin excretion were also significantly increased in HHcy rats. Effacement and extensively fusion of podocyte foot process was observed in HHcy rats, which was associated with decreased expression of nephrin protein in renal cortex of HHcy rats. Supplementation with FA lowered plasma Hcy significantly. Plasma creatinine concentration and urinary albumin excretion were also significantly attenuated by FA. Morphologically, HHcy-associated glomerulosclerosis, fibrosis, podocyte foot process effacement and loss of podocyte nephrin, were significantly improved by FA. The expressions of α-SMA, PCNA and TGF-ß1 were increased in renal cortex of HHcy rats, and which were also partially reversed by FA. These data suggest that elevated plasma Hcy is an important pathogenic factor for glomerular damage. Lowering plasma Hcy by FA can inhibit TGF-ß1 expression and attenuate HHcy-induced glomerular damage.