Carbon dioxide responsiveness mitigates rice yield loss under high night temperature

Increasing night-time temperatures are a major threat to sustaining global rice (Oryza sativa L.) production. A simultaneous increase in [CO₂] will lead to an inevitable interaction between elevated [CO₂] (e[CO₂]) and high night temperature (HNT) under current and future climates. Here, we conducted field experiments to identify [CO₂] responsiveness from a diverse indica panel comprising 194 genotypes under different planting geometries in 2016. Twenty-three different genotypes were tested under different planting geometries and e[CO₂] using a free-air [CO₂] enrichment facility in 2017. The most promising genotypes and positive and negative controls were tested under HNT and e[CO₂] + HNT in 2018. [CO₂] responsiveness, measured as a composite response index on different yield components, grain yield, and photosynthesis, revealed a strong relationship (R² = 0.71) between low planting density and e[CO₂]. The most promising genotypes revealed significantly lower (P < 0.001) impact of HNT in high [CO₂] responsive (HCR) genotypes compared to the least [CO₂] responsive genotype. [CO₂] responsiveness was the major driver determining grain yield and related components in HCR genotypes with a negligible yield loss under HNT. A systematic investigation highlighted that active selection and breeding for [CO₂] responsiveness can lead to maintained carbon balance and compensate for HNT-induced yield losses in rice and potentially other C₃ crops under current and future warmer climates.

Active selection for carbon dioxide responsiveness in rice and other C₃ crops can mitigate yield loss induced by high night temperature.     

Superovulation and embryo recovery in rabbits (Oryctolagus cuniculus) using different doses of pregnant mare serum gonadotrophin (PMSG)

Present investigation was conducted to study the ovarian response and embryo recovery using different PMSG dose levels. Six rabbits each were assigned randomly to treatment 1 (PMSG 50 IU + hCG 100 IU), treatment 2 (PMSG 75 IU + hCG 100 IU) and the control group (no hormone administered). PMSG injection (im) was followed 68 hr later by natural mating to a fertile rabbit buck and human chorionic gonadotrophin (hCG) injection iv post coitum. Embryos were recovered 96 hr post coitum by a modified surgical method. Mean number of ovulations in the control group differed significantly from treatment 1 and 2, but no significant difference was observed between treatments 1 and 2. Mean embryo recovery percentage was lowest in treatment 2 and highest in the control group. The higher dose PMSG (treatment 2) was observed to be more disturbing in terms of recovery of embryos as well as their morphology.     

Abnormal segregation of prion protein octapeptide-repeat alleles in cattle

The study was conducted on full-families of Black-and-White cattle obtained as 25 AI sire families and 355 cows, as well as their progenies, mostly heifers at the age of 1-3 months. The sire group was composed by the casual qualification of 10 PRNP 6/6 and 15 PRNP 6/5 individuals on the basis of accessible young progenies. The randomly selected group of cows is characterised by a very high frequency of PRNP 6/6 (74.9%), followed by lower frequency of PRNP 6/5 (24.5%) and a very low frequency of PRNP 5/5 genotype (0.6%). The progenies represent all expected genotypes, such as: PRNP 6/6 (60.5%), PRNP 6/5 (35.8%) and PRNP 5/5 (3.7%), respectively. Taking into consideration the genotypes of parents and progenies, the segregation of PRNP 6 and PRNP 5 alleles was analysed. Results of the non-informative mating variant of male symbol PRNP 6/6 x female symbol PRNP 6/6 (n = 87) are affected by the PRNP 6/6 progeny genotype in all cases. Subsequently, the results of mating variants male symbol PRNP 6/6 x female symbol PRNP 6/5 (n = 29) and male symbol PRNP 6/5 female symbol PRNP 6/6 (n = 179) showed statistically non-significant differences in both above-mentioned alternations. The progeny group related from male symbol PRNP 6/5 x female symbol PRNP 6/5 parental mating obtained fully informative and most valuable results based on the presented research concept. In the common group of 58 calves, the genotype PRNP 6/6 is represented by 26 individuals (44.8%), PRNP 6/5 - by 19 individuals (32.8%) and PRNP 5/5 - by 13 individuals (22.4%). Therefore, the theoretical genotype rate (25% : 50% : 25%) is drastically deformed and the differentiation between the observed and expected numbers of animals is statistically highly significant (chi(2) = 12.72; 2 df.). These differences are affected by two times higher PRNP 6/6 homozygous (chi(2) = 9.12; 1 df.) and responsively by the low number of PRNP 6/5 heterozygous animals (chi(2) = 3.45; 1 df.). Further investigations are carried out to explain the genetic determination of abnormal PRNP octa-peptide repeat allele segregation, which suggests possible lethal cis-trans linkage effects.     

Structure and mechanistic insights into novel iron-mediated moonlighting functions of human J-protein cochaperone, Dph4

J-proteins are obligate cochaperones of Hsp70s and stimulate their ATPase activity via the J-domain. Although the functions of J-proteins have been well understood in the context of Hsp70s, their additional co-evolved "physiological functions" are still elusive. We report here the solution structure and mechanism of novel iron-mediated functional roles of human Dph4, a type III J-protein playing a vital role in diphthamide biosynthesis and normal development. The NMR structure of Dph4 reveals two domains: a conserved J-domain and a CSL-domain connected via a flexible linker-helix. The linker-helix modulates the conformational flexibility between the two domains, regulating thereby the protein function. Dph4 exhibits a unique ability to bind iron in tetrahedral coordination geometry through cysteines of its CSL-domain. The oxidized Fe-Dph4 shows characteristic UV-visible and electron paramagnetic resonance spectral properties similar to rubredoxins. Iron-bound Dph4 (Fe-Dph4) also undergoes oligomerization, thus potentially functioning as a transient "iron storage protein," thereby regulating the intracellular iron homeostasis. Remarkably, Fe-Dph4 exhibits vital redox and electron carrier activity, which is critical for important metabolic reactions, including diphthamide biosynthesis. Further, we observed that Fe-Dph4 is conformationally better poised to perform Hsp70-dependent functions, thus underlining the significance of iron binding in Dph4. Yeast Jjj3, a functional ortholog of human Dph4 also shows a similar iron-binding property, indicating the conserved nature of iron sequestration across species. Taken together, our findings provide invaluable evidence in favor of additional co-evolved specialized functions of J-proteins, previously not well appreciated.     

Molecular cloning and characterization of genes encoding FK506-binding proteins (FKBPs) in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

The family of FK506-binding proteins (FKBPs) consists of several members, which show peptidyl prolyl cis–trans isomerase (PPIase) activity. PPIases facilitate the conversion of peptidyl prolyl bonds from cis to trans conformation, a rate-limiting step in protein folding. In the present study, we carried out cloning of cDNAs encoding three different wheat FKBPs viz., TaFKBP20-1, TaFKBP16-1 and TaFKBP15-1. In silico analysis suggested their likely localization to nucleus, cytosol and endoplasmic reticulum, respectively. Biochemical analyses demonstrated that none of the three purified FKBP proteins possesses detectable PPIase activity. Several putative interacting partners of TaFKBP20-1, TaFKBP16-1 and TaFKBP15-1were identified using online software tools. The results of this study provide further evidence that PPIase activity in plant FKBPs is not conserved, and these proteins may be playing important roles in the cell through interaction with target proteins.     

Host-induced silencing of the Colletotrichum gloeosporioides conidial morphology 1 gene (CgCOM1) confers resistance against Anthracnose disease in chilli and tomato

Plant Molecular Biology - Host mediated silencing of COM1 gene of Colletotrichum gloeosporioides disables appressorial differentiation and effectively prevents the development of Anthracnose...