Rice depends on its root system to perceive drought, a major environmental constraint that leads to severe yield losses worldwide. To dissect the underlying molecular basis, we conducted a comparative analysis of drought-sensitive (WAB) and drought-tolerant (IR65) rice genotypes that exhibited divergent drought tolerance at the seedling stage. After exposure to 15% PEG6000 (-0.4 MPa) for two days, the shoot and root architectural traits of IR65 were better than those of WAB seedlings. Measurements of physio-biochemical parameters (SOD, CAT, POD, APX, H2O2, and proline) suggest that IR65 seedling roots exhibit greater ROS scavenging and osmotic adjustment capacity than WAB, aligning with tolerance to PEG-induced water deficiency. Transcriptomic assessments of roots identified 802 commonly differentially expressed genes (DEGs) during the drought time course (12, 24, and 48 h) in WAB and IR65. They were clustered into eight groups based on their expression profiles and mainly enriched in phytohormone signaling, protein phosphorylation, and transcription factors. Using weighted gene co-expression network analysis (WGCNA), nine significant modules were identified based on n = 382 of the DEGs. A total of 12 DEGs up-regulated in IR65 were distributed in five modules, and five of them were selected for rapid functional validation through in vivo yeast expression. The results showed that transgenic yeasts were tolerant to simulated drought conditions (135 mM PEG3350), indicating that these genes would be potential targets for rice improvement in drought tolerance in the future.

Protein stability, which is precisely regulated by the ubiquitin-proteasome system (UPS), constitutes a fundamental mechanism in plant physiology under drought stress. While drought signaling cascades are well-studied, the specificity and molecular basis of the UPS-mediated protein degradation remain relatively fragmented. Plants harness ubiquitination-related components, especially E3 ubiquitin ligases, as they are central signal integrators to regulate drought stress responses. These E3 ligases directly modulate the abscisic acid (ABA) cascade pathway and orchestrate crosstalk with mitogen-activated protein kinase (MAPK) and jasmonic acid (JA) signaling, always acting downstream of ABA. Being an integral part of the UPS, the structural stability of the 26S proteasome significantly affects plant responses to dehydration conditions. Furthermore, SUMOylation serves as an additional regulatory layer in shaping plant drought tolerance. The current review summarizes the mechanisms of drought response regulation governed by the UPS and offers perspectives for breeding elite drought-tolerant crop varieties.

MADS-box transcription factors (MADS-box TFs) are central regulators integrating environmental cues with developmental and stress-adaptive mechanisms in plants. MADS-box TFs typically regulate target gene expression by binding to CArG-box [CC(A/T)GG] motifs, as well as through non-canonical mechanisms. One stress response modulated by MADS-box TFs is to drought. Here, a network of morphological modifications, physiological homeostasis, and transcriptome-wide reprogramming is altered by MADS-box TFs. MADS-box TFs balances organ development with stress acclimation and act as hubs to modulate hormone biosynthesis and signaling pathways regarding drought tolerance through manipulating gene expression. MADS-box TF activity is typically modified by post-translational events, particularly phosphorylation and dephosphorylation, to fine-tune plant adaptation to desiccation conditions. Evolutionarily, the functional conservation and divergence of MADS-box TFs dictate the progression of drought tolerance in plants. In addition, MADS-box TFs function in a spatiotemporally dynamic manner, critically modulating plant architecture formation and drought adaptation. In this review, we summarize the diverse regulatory networks orchestrated by MADS-box TFs that offer promising targets for designing crop plants with improved organ development and drought stress resilience.

The harmful effects of heat stress on agricultural production are becoming increasingly severe. Thaumatin-like proteins (TLPs) have been demonstrated to play crucial roles in regulating plant resistance to biotic and abiotic stresses. However, their involvement in plant thermotolerance is poorly understood. This study aims to investigate the major-effect gene in a key quantitative trait locus (QTL) associated with rice thermotolerance, namely Rtlp2, which encodes a rice TLP. The Rtlp2 protein was found to be localized in the endoplasmic reticulum (ER). Rice seedlings overexpressing the Rtlp2 gene showed significantly enhanced thermotolerance compared to the wild type, while rtlp2 mutant exhibited increased susceptibility to heat stress. After 48 h of heat stress treatment, rice plants overexpressing Rtlp2 exhibited reduced accumulation of hydrogen peroxide (H2O2) and cell death compared to the wild-type. Conversely, the mutant plants showed the opposite behavior. The results of gene expression level analyses revealed that Rtlp2 positively regulates rice thermotolerance through the modulation of rice heat shock transcription factors (HSFs) and heat shock proteins (HSPs) network. After undergoing natural heat stress in the field, the rice lines overexpressing Rtlp2 showed higher seed setting rate and yield per plant compared to the wild-type. In addition, Rtlp2 has also been found to positively regulate grain length and grain weight in rice. This study provides valuable resources for addressing the challenge of increasing environmental heat and promoting the breeding of heat-tolerant rice varieties.

Soil salinization is one of the most important abiotic stresses which can seriously affect the growth and development of rice, leading to the decrease in or even loss of a rice harvest. Increasing the rice yield of saline soil is a key issue for agricultural production. The utilization of heterosis could significantly increase crop biomass and yield, which might be an effective way to meet the demand for rice cultivation in saline soil. In this study, to elucidate the regulatory mechanisms of rice hybrids and their parents that respond to salt stress, we investigated the phenotypic characteristics, physiological and biochemical indexes, and expression level of salt-related genes at the seedling stage. In this study, two sets of materials, encapsulating the most significant differences between the rice hybrids and their parents, were screened using the salt damage index and a hybrid superiority analysis. Compared with their parents, the rice hybrids Guang-Ba-You-Hua-Zhan (BB1) and Y-Liang-You-900 (GD1) exhibited much better salt tolerance, including an increased fresh weight and higher survival rate, a better scavenging ability towards reactive oxygen species (ROS), better ionic homeostasis with lower content of Na+ in their Na+/K+ ratio, and a higher expression of salt-stress-responsive genes. These results indicated that rice hybrids developed complex regulatory mechanisms involving multiple pathways and genes to adapt to salt stress and provided a physiological basis for the utilization of heterosis for improving the yield of rice under salt stress.

The ATP-binding cassette (ABC) proteins are a diverse family of transmembrane transporter proteins widely identified in various organisms. The ABCG transporters belong to the G subfamily of the ABC transporter family. Rarely research on ABCG transporters involved in salt tolerance of rice was found. In this study, the evolutionary relationships, conserved motifs, intra- and inter-species homologous genes, and cis-acting elements of ABCG subfamily members were analyzed, and the expression changes of these genes under salt stress at 0 h, 3 h, and 24 h were detected. Based on these results, the candidate gene OsABCG7, which is induced by salt stress, was selected for further studies. Yeast experiments confirmed that the OsABCG7 gene might be involved in the regulation of salt tolerance. The abcg7 mutant showed a higher degree of leaf wilting and a lower survival rate, exhibiting a salt-sensitive phenotype. Systematic analysis of this family in rice helps design effective functional analysis strategies and provides data support for understanding the role of ABCG transporters under salt stress.

The consumption of high-quality rice is increasing. Low temperatures during grain filling may affect the starch synthesis of high-quality rice and thus affect the quality of the rice itself. In this study, two high-quality conventional rice cultivars and two high-quality hybrid rice cultivars were selected and sown at a low temperature and normal temperature in the field. The low temperature during grain filling increased the amylose content, final viscosity, setback, short amylopectin chain ratio, and degree of amylopectin branching in four high-quality rice cultivars; meanwhile, the amylopectin content, gelatinization temperature, proportion of medium-long chain amylopectin, and the short-range order of starch decreased. Compared with the normal temperature, the alterations in the physicochemical and structural qualities of high-quality conventional rice cultivars YZX and NX42 were less significant at lower temperatures. The starch quality of high-quality conventional rice was more stable than hybrid high-quality rice.

[目的]研究灌浆期不同时段高温对稻米淀粉组成、结构和理化特性的影响,揭示高温对稻米淀粉理化特性影响的时段效应,阐明高温、结构和功能之间的关系.[方法]以耐热水稻品种黄华占和热敏感的9311近等位基因系为实验材料,利用人工气候箱设置高温[38℃(昼)/30℃(夜)]和对照[28℃(昼)/22℃(夜)],研究灌浆前期(齐穗期后1-15 d)和后期(齐穗期后16 d至成熟)高温对稻米的加工品质、外观品质、淀粉组成、支链淀粉链长分布、粒度分布、胶稠度、黏度特性、糊化特性、结晶特性和颗粒形态的影响.[结果]灌浆期高温使糙米率、精米率、整精米率显著下降,使垩白粒率和垩白度显著升高,导致加工品质和外观品质变差.灌浆期高温使总淀粉含量、直链淀粉含量、短支链淀粉含量、大淀粉粒占比、直/支链淀粉比显著下降,而中等支链淀粉含量、小中淀粉粒占比、糊化温度和糊化焓显著上升,黏度特性显著改变,结晶类型不变但结晶度显著改变,淀粉颗粒表面出现小孔,表面变得凹凸不平,导致淀粉颗粒更加碎片化和蒸煮食味品质变劣.灌浆期不同时段高温对稻米品质的影响不同,灌浆前期高温对稻米淀粉的影响大于灌浆后期,耐热品种受影响小于热敏感品种.灌浆前期高温处理下供试材料具有较高的消减值和较低的崩解值,黏度特性变差;灌浆后期高温处理下供试材料具有较低的消减值和较高的崩解值,黏度特性变好.[结论]灌浆前期高温对淀粉理化特性的影响最大,进而导致稻米的加工品质、外观品质和蒸煮食味品质变劣,灌浆后期高温提升了黏度特性.

通过分析我国1969—2019年间公开报道的125个小豆育成品种信息,发现我国小豆育种主体较少,且以主产区科研教学单位为主;育种目标多元,主要育种方式由系统选育向杂交育种转变,并据此将我国小豆品种改良划分为3个阶段.首次对豆类作物品种的新品种保护情况进行梳理,对申请新品种保护积极性不高和授权较慢的原因进行分析.结合小豆育种现状和产业发展趋势,建议加强小豆基础研究,发挥资源优势;重视产权保护,完善管理体系;深挖发展潜力,促进产业发展.

利用创5S为受体亲本的褐飞虱抗性改良中间材料7CS18[含Bph18(t)基因]和7CS10[含Bph20(t)、Bph21(t)基因]进行杂交,并在后代利用分子标记技术结合田间农艺性状筛选,获得了聚合Bph18(t)、Bph20(t)和Bph21(t))等3个纯合稻飞虱抗性基因的水稻两系不育系改良株系9S522.苗期抗性鉴定表明,创5S、7CS10和7CS18对褐飞虱抗性等级分别为"感""抗"和"中抗",改良株系9S522对褐飞虱抗性等级为"抗";改良株系9S522农艺性状与创5S基本保持一致.

水稻OsSGL(Oryza sativa stress tolerance and grain length)基因表达响应多种非生物逆境,参与调控水稻产量及耐旱性.该基因CDS全长768 bp,编码一个包含DUF1645(Domain of unknown function protein family 1645)结构域的功能蛋白.生物信息学分析预测显示该蛋白分子量为26.73 kD,理论等电点为9.35,为亲水性蛋白且没有跨膜区域,蛋白二级结构中α螺旋占15.69％,β转角占3.14％,延伸链占14.51％,无规则卷曲占66.67％.OsSGL基因CDS序列中稀有密码子的比例高达29.69％,且有多个串联稀有密码子.为进一步在生化水平研究OsSGL蛋白,本研究拟在原核表达系统中大量表达、纯化并鉴定His标签融合表达的Os-SGL蛋白.在不改变氨基酸序列的前提下,通过全基因合成技术,根据大肠杆菌密码子偏好性对OsSGL CDS序列进行优化、合成并连接到pET-32a表达载体中;然后将重组质粒pET-32a-OsSGL转化大肠杆菌,经体外表达条件优化大量合成融合His标签表达的OsSGL蛋白.结果显示,OsSGL基因在大肠杆菌中可实现诱导表达,融合蛋白分子质量约为45.7 kD.最优诱导表达温度、时间、IPTG浓度和摇床转速分别为16℃、16h、0.5 mmol/L和120 r/min.利用His抗体进行Western blotting进一步检测到纯化的His-OsSGL融合蛋白.OsSGL蛋白体外表达体系的建立有利于在生化水平上深入解析OsSGL参与的信号调控通路.

In order to compare the high temperature tolerance of six rice varieties, field experiments using interval sowing population were conducted to select sowing batches at high temperature and normal temperature during grain filling period. High filling temperature decreased significantly head milled rice rate, setback, amylose content and the proportion of the short chain of amylopectin, and increased obviously chalkiness, breakdown, gelatinization temperature, gelatinization enthalpy, and the proportion of the medium chain of amylopectin. Analysis of variance indicated significant differences with respect to physicochemical indexes of the starches from six rice varieties under high temperature during grain filling stage. In addition, five starch physicochemical indexes including apparent amylose content, setback, breakdown, chalkiness and gelatinization enthalpy showed more sensitivity to high temperature. These indexes could be considered as key indexes to evaluate the high temperature tolerance of these six rice varieties. The experimental results showed that the high temperature tolerance of the six varieties – Huanghuazhan, Y liangyou 957, Taiyou 390, Tianyouhuazhan, Zhongzao 39, Y liangyou NO 1 – ranged from strong to weak. The regression equation showed similar results and indicated that the high temperature tolerance of different varieties could be preliminarily evaluated using the key physicochemical indexes of starch.

Heat stress severely affects rice (Oryza sativa L.) growth, yield and milling quality. It is very important to breed heat-tolerant rice varieties to adapt to global warming year by year. However, heat tolerance is a very complex quantitative trait, and only a few related genes were cloned in the past few decades. Previously, we generated introgression lines with Teqing (Oryza sativa L. sspp. indica) as the background and Yuanjiang common wild rice (Oryza rufipogon Griff.) as the donor, and subsequently found that the line YIL106 carried three heat-sensitive QTLs. Here, we integrated microarray and QTL mapping methods to uncover candidate genes conferring heat-sensitivity at the seedling stage of YIL106.33 genes with response to abiotic stress were chosen for further investigation. After annotation analysis of the Rice Gene Ontology Database, three candidate heat stress responsive genes, LOC_OsOlg19020, LOC_OsOlg23630, and LOC_Os12g43440, were selected. Moreover, overexpression of LOC_Os12g43440 greatly increased rice heat tolerance at the seedling stage. This work uncovers a novel gene for heat tolerance with potential value in breeding. (C) 2020 Friends Science Publishers

This study investigated the effects of natural high temperature in the field during grain filling stage on the morphological structure and physicochemical properties of rice starch. High natural field temperature during rice grain filling stage resulted in poor processing and appearance quality, higher gelatinization properties including gelatinization temperature, gelatinization enthalpy, swelling power, and water solubility due to the reduction of amylose content. High temperature decreased the setback and trough viscosities, and increased breakdown, implying that the pasting properties were slightly better. High temperature did not change the starch crystalline type, while it significantly affected relative crystallinity, as well as pitting and unevenness on the surface of the starch granules with lower granule size. The above results imply that high temperature can degrade cooking and eating quality, and increase pasting properties of starch slightly.

简要回顾了水稻两用核不育系研究经历的探索阶段、生产初试阶段和大面积生产应用的历程,分析了当前育种和应用中存在着种质创新不够、实用型两用核不育系缺乏、种子生产决策不科学等主要问题,并提出了常规育种与分子育种紧密结合创新不育系种质资源、加快优质多抗不育系育种步伐、科学决策种子生产基地与时段以确保两系杂交稻健康持续发展的策略.

以水稻品种B5(含褐飞虱抗性基因Bph14、Bph15)为供体亲本,目前生产上大面积应用的两系不育系C815S为受体亲本,利用分子标记辅助选择技术,将2个褐飞虱抗性基因Bph14和Bph15导入C815S,获得3个同时携带2个抗性基因的纯合改良株系.苗期群体鉴定和大田成熟期鉴定表明,3个改良不育株系的褐飞虱抗性均为3级,表现为抗;而受体亲本C815S为9级,表现为感.农艺性状考察表明,改良不育株系基本保持了受体亲本的优良性状,部分穗部性状还显著优于C815S.因此,利用分子标记辅助选择技术聚合Bph14和Bph15基因改良不育系褐飞虱抗性效果明显.

为明确新选育的水稻两用核不育系的农艺性状和异交特性,本试验以目前生产上大面积应用的两用核不育系C815S为对照,对新育成的两用核不育系阳S和浩S的特征特性进行研究.结果表明,阳S分蘖力强、株型紧凑、植株较矮、花时集中、不育起点温度低,综合性状优良;浩S每穗总粒数多、颖间距大、开颖历期长、柱头外露率高、柱头活力强,异交特性好,具备高产制种的潜力;但浩S不育起点温度偏高,有必要进一步筛选低不育起点温度的核心单株,确保生产上制种安全.

选用水稻两系不育系创5S为改良对象,利用分子标记辅助选择技术将广谱抗稻瘟病基因Pi40和Pigm导入到创5S中.通过杂交和回交并结合农艺性状筛选,获得了分别携带Pigm基因(17S10、17S11和17S13)和Pi40基因(17S16、17S18、17S19)且农艺性状与轮回亲本创5S基本一致的改良不育系株系.抗性鉴定结果显示:不育系改良株系17S11、17S13、17S18的稻瘟病抗性已达抗病等级,17S10、17S16、17S19的稻瘟病抗性已达中等抗病.

To improve the blast resistance of C815S, a widely applicable two-line photo-thermal-sensitive male sterile in China, Gumei 4 contained rice blast risistance gene Pigm was used as gene donor to introduce Pigm into the genetic background of C815S by cross and then back cross breeding combined with molecular marker-assisted selection (MAS). Three improved sterile lines with Pigm homozygous genotype were developed through blast resistance identification and evaluation of comprehensive agronomic characters. 7CS01 showed 1st grade for blast, meant resistance; 7CS02 and 7CS03 showed 3rd grade for blast, meant middle resistance. Blast resistance comprehensive index of the improved sterile lines was raised by 58.05％ and average spike number raised by 26.45％, compared to C815S.

Rice blast is one of the most serious diseases in rice production.The harm of rice blast,infection process and genetic mechanism of resistance were described in this paper briefly.The research progress of localization and cloning of rice blast resistance gene,molecular marker assisted breeding were Summarized.Rice blast resistance breeding and its research direction were discussed.