Identification of key enzymes in lignocellulose biosynthesis from dynamic observations in maize stalks

Maize stalk lignin and cellulose contents are linked to lodging resistance,disease resistance,feed quality and ethanol conversion efficiency.After the six-leaf stage of maize(V6),these constituents are biosynthesized and accumulated under the control of related enzymes and genes.However,the key enzymes,critical MYB transcription factors,and their dynamic alterations pattern under natural field circumstances are still unknown.Hence,we selected five cultivars with significant differences in lignocellulose content and lodging resistance as testing materials,performed field experiments for two years,and investigated the dynamics of lignin and cellulose content,related enzyme concentrations,and gene expression levels in the 3^(rd) and 5^(th) internodes above the ground after V6.The results showed that lignin and cellulose content increased after V6,stabilizing during the silking stage.This study identified COMT(caffeic acid 3-Omethyltransferase),TAL(tyrosine ammonia-lyase)and PAL(phenylalanine ammonia-lyase)as the key enzymes of lignin biosynthesis,while ZmCOMT,ZmCesA10 and ZmCesA8 were identified as essential genes.ZmMYB8,ZmMYB31 and ZmMYB39 were involved in regulating the expression of genes related to lignin synthesis,with ZmMYB31 potentially acting as a key negative regulator,while ZmMYB39 and ZmMYB8 acting as positive regulators.The study also found that around 14 d after V6 was a critical stage for regulating lignocellulose synthesis in the 3^(rd) to 5^(th) basal internode.This provides a theoretical foundation for developing regulatory techniques and breeding new cultivars to enhance lodging and disease resistance as well as the utility of maize stalks.

Synergistic effects of planting density and nitrogen fertilization on chlorophyll degradation and leaf senescence after silking in maize

Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the activities of Chl a-degrading enzymes after silking,and the post-silking dry matter accumulation and grain yield under multiple planting densities and N fertilization rates.The dynamic change of GLA_(ear)after silking fitted to the logistic model,and the GLA_(ear) duration and the GLAearat 42 d after silking were affected mainly by the duration of the initial senescence period(T_(1))which was a key factor of the leaf senescence.The average chlorophyllase(CLH)activity was 8.3 times higher than pheophytinase activity and contributed most to the Chl content,indicating that CLH is a key enzyme for degrading Chl a in maize.Increasing density increased the CLH activity and decreased the Chl content,T1,GLAear,and GLA_(ear) duration.Under high density,appropriate N application reduced CLH activity,increased Chl content,prolonged T1,alleviated high-density-induced leaf senescence,and increased post-silking dry matter accumulation and grain yield.

Grain-filling characteristics and yield differences of maize cultivars with contrasting nitrogen efficiencies

To investigate the effect of nitrogen management on the grain-filling characteristics and yield formation of maize cultivars with contrasting nitrogen efficiencies,and to identify differences in grain-filling characteristics and yield of maize cultivars in response to nitrogen management,a two-year field experiment was conducted in southwest China in2015–2016.The grain-filling rate and duration of the N-inefficient cultivar XY 508 were higher than those of the N-efficient cultivar ZH 311.The 100-kernel weight of XY 508 was significantly higher than that of ZH 311.The kernel number per ear of ZH 311 was significantly higher than that of XY 508,making the population filling rate of ZH 311 significantly higher than that of XY 508.The higher population filling rate of the N-efficient maize cultivar led to a significant yield advantage over the N-inefficient maize cultivar.Nitrogen management effectively improved maize grain yield,but the response of maize cultivars with contrasting nitrogen efficiencies to nitrogen management was inconsistent.A basal fertilizer ratio 60.43%with a topdressing ratio 39.57%effectively increased grainfilling rate,delayed the time to maximum filling rate,prolonged the active filling period and effective grain-filling time,increased the 100-kernel weight,and maintained higher kernels per ear,thereby improving the population filling rate and maximizing the yield advantage of the N-efficient cultivar.A 100%basal fertilizer ratio not only increased the number of kernels per ear,but also maintained high grain filling characteristics to obtain a higher 100-kernel weight and increased the population filling rate,leading to a high grain yield in the N-inefficient cultivar.Thus,the 100%basal fertilizer ratio partially compensated for the deficient grain yield of the N-inefficient cultivar.

Research on the Effect of Planting Density on Rice Yield and Quality

Planting density is of great significance in adjusting the population structure of rice,increasing yield and reducing the cost. And suitable planting density can not only bring the yield potential of rice population into full play, obtain the maximum grain yield per unit area, but save labor, protect the environment and improve rice quality. This article summarizes the impact of planting density on rice growth, yield, the components as well as qualities at an attempt to provide theoretical guidance for high yield and quality cultivation of rice.

不完全型Wolfram综合征1型1例

患者,男,24岁,因双眼视力缓降10余年,于2023年5月11日就诊于山东中医药大学第一附属医院眼科。2013年患者(14岁)自觉双眼视力下降,就诊于外院,右眼裸眼视力(UCVA)0.25,最佳矫正视力(BCVA)0.8;左眼UCVA 0.25,BCVA 0.6。双眼眼压处于高线临界值。当时外院眼底照相示:双眼各象限视盘边沿均明显变窄,神经纤维层受损。初步诊断:青光眼待排。给予降眼压滴眼液,后续视力无明显改善。2018年患者(19岁)因口干、多饮、消瘦2个月余,就诊于外院,考虑为“1型糖尿病”所引起的“糖尿病酮症酸中毒”,后行胰岛素抗体检查,抗谷氨酸脱羧酶抗体(Glutamic acid decarboxylase antibody,GADA)阳性,更正诊断为“成人隐匿性自身免疫糖尿病”。2023年患者(24岁)及其父母行高通量基因检测,核基因分析结果:患者WFS1基因有2个杂合变异点c.2020G>A(p.Gly674Arg)和c.2654C>T(p.Pro885Leu);患者母亲c.2020G>A(p.Gly674Arg)杂合变异;患者父亲c.2654C>T(p.Pro885Leu)杂合变异。