Receptor-like kinases (RLKs) are essential for plant abiotic stress responses.  Methylglyoxal (MG) is a cellular metabolite that is often considered to be a stress signal molecule.  However, limited information is available about the relationship between RLKs and MG.  Here, we addressed the function of a receptor-like kinase, OsASLRK, in the MG response and content in rice.  A typical MG-responsive element (AAAAAAAA) exists in the promoter region of the OsASLRK gene.  RT-qPCR analysis indicated that the transcript level of OsASLRK was significantly increased by exogenous MG in a time- and dosage-dependent fashion.  GUS staining also confirmed that the expression of OsASLRK in rice root was enhanced by exogenous MG treatment.  Genetic analysis suggested that the Osaslrk mutant displays increased sensitivity to MG and it showed higher endogenous MG content under exogenous MG treatments, while OsASLRK-overexpressing rice plants showed the opposite phenotypes.  Diaminobenzidine (DAB) staining, scavenging enzyme activities and GSH content assays indicate that OsASLRK regulates MG sensitivity and content via the elevation of antioxidative enzyme activities and alleviation of membrane damage.  Therefore, our results provide new evidence illustrating the roles that receptor-like kinase OsASLRK plays in MG regulation in rice.

The mutant efficiency and hatching ratio are two key factors that significantly affect the construction of genome-modified mutant insects.  In the construction of CRISPR/Cas9-mediated dsLmRNase2^–/–mutant locusts, we found that the tanned eggs which experienced a 20-min contact with the oocyst exhibited a higher success rate compared to fresh newly-laid eggs that were less tanned.  However, the heritable efficiency of the dsLmRNase2 deletion to the next generation G₁ progeny was similar between adults derived from the tanned or less tanned engineered eggs.  Further, the similar effective mutant ratios in the normally developed eggs and G₀ adults of tanned and less tanned eggs also indicated that tanning did not reduce the absolute mutation efficiency induced by CRISPR/Cas9.  Moreover, we found that the syncytial division period, which was longer than the time for tanning, conferred a window period for microinjection treatment with efficient mutation in both tanned and less tanned eggs.  We further found that tanned eggs exhibited a higher hatching rate due to a reduced infection rate following microinjection.  Both the anti-pressure and ultrastructure analyses indicated that the tanned eggs contained compressed eggshells to withstand increased external pressure.  In summary, tanned eggs possess stronger defense responses and higher efficiency of genome editing, providing an improved model for developing Cas9-mediated gene editing procedures in locusts.

For evaluating the effects of UV-B treatment on lignification and quality of bamboo (Phyllostachys prominens) shoots during postharvest, fresh bamboo shoots without sheaths were irradiated with UV-B at a dose of 8.0 kJ m^–2 and then stored at (6±1)°C along with 85–90% relative humidity (RH) for 15 d.  The results showed that UV-B treatment apparently slowed down the increase rates of flesh firmness, weight loss, and contents of cellulose and lignin.  It also decreased the activities of 4-coumarate CoA ligase (4CL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and phenylalanine ammonia-lyase (PAL) and the expression of their encoding genes during cold storage.  It was suggested that these effects of UV-B treatment on decreases in these enzymatic activities and the expression of encoding genes might collectively regulate lignin synthesis and accumulation in the flesh of bamboo shoots and consequently benefit in maintaining the edible quality of bamboo shoots during cold storage.

 

The kiwifruit trees (Actinidia deliciosa cv. Bruno) were sprayed with 5 mmol L^–1 oxalic acid (OA) or water (as control) at 130, 137 or 144 d after full-blossom, and then the fruit were harvested at commercial maturity and stored at room temperature (20±1)°C for 13 d.  The effect of pre-harvest spraying of OA on postharvest quality of kiwifruit was evaluated during storage.  The OA spraying slowed the increase in soluble solids content (SSC) and decrease in titratable acid (TA), as well as increased contents of ascorbic acid (AsA) and total-AsA accompanied with higher AsA/DHA ratio in kiwifruit during storage.  Moreover, the OA spraying significantly reduced the contents of acetaldehyde and ethanol in kiwifruit, along with significant decrease in activities of enzymes involved in ethanol fermentation metabolism during the later period of storage, which was beneficial to control off-flavor associated with over accumulation of ethanol during postharvest.  It was suggested that pre-harvest spraying of OA might maintain the postharvest quality of kiwifruit in relation to delay in fruit ripening, AsA maintenance and regulation of ethanol fermentation.

Five lactating Holstein cows in a 5×5 Latin square experiment were fed five high-concentrate total mixed rations (TMRs) to investigate the effects of step-wise improvement of forage combination on ruminal and milk fatty acid profiles.  The ratio of concentrate to forage was fixed as 61:39, and the step-wise improvement of forage combination was applied as: TMR1, a ration containing corn stover; TMR2, a ration containing corn stover and ensiled corn stover; TMR3, a ration containing ensiled corn stover and Chinese wild ryegrass hay (Leymus chinensis); TMR4, a ration containing the ryegrass hay and whole corn silage; TMR5, a ration containing the ryegrass hay, whole corn silage and alfalfa hay.  The TMRs were offered to the cows twice daily at 0700 and 1900 h.  The entire experiment was completed in five periods, and each period lasted for 18 days.  Diurnal samples of rumen fluids were collected at 0100, 0700, 1300 and 1900 h (day 16); 0300, 0900, 1500 and 2100 h (day 17); and 0500, 1100, 1700 and 2300 h (day 18).  The step-wise improvement of forage combination increased energy and crude protein contents and decreased fibre content.  As a result, the step-wise improvement of forage combination increased dry matter intake and milk yield (P<0.05).  The step-wise improvement increased dietary content of linolenic acid (C18:3n-3), but did not alter dietary proportions of palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1cis-9), linoleic acid (C18:2n-6) and arachidic acid (C20:0).  In response to the forage combination, ruminal concentration of C16:0, C18:2n-6 and C18:3n-3 linearly increased against their dietary intakes (P<0.10).  The step-wise improvement increased milk contents of C10:0, C12:0, C14:0, C16:0, C18:2n-6 and C18:3n-3 (P<0.10) and decreased milk contents of C18:0 and C18:1cis-9 (P<0.05).  Milk yields of C16:0, C18:1cis-9, C18:2n-6 and C18:3n-3 were linearly increased by the increase of these fatty acids in the rumen (R²≥0.79, P<0.05), and milk yields of C18:2n-6 and C18:3n-3 were also positively correlated with dietary intake of these fatty acids (R²≥0.85, P<0.05).  The step-wise improvement increased the transfer efficiencies from feed to milk for C18:2n-6 from 11.8 to 14.2% and for C18:3n-3 from 19.1 to 22.3%.  In a brief, along with the step-wise improvement of forage combination, more dietary linoleic and linolenic acids might escape microbial hydrogenation in the rumen and consequently accumulated in milk fat though these fatty acids were present in low concentrations in ruminal fluids.  The step-wise improvement of forage combinations could be recommended as a dietary strategy to increase the transfer efficiency of linoleic and linolenic acids from feed to milk.