SummarySeed germination is a complex trait determined by both quantitative trait loci (QTLs) and environmental factors and also their interactions. In this study, we mapped one major QTL qSE3 for seed germination and seedling establishment under salinity stress in rice. To understand the molecular basis of this QTL, we isolated qSE3 by map‐based cloning and found that it encodes a K+ transporter gene, OsHAK21. The expression of qSE3 was significantly upregulated by salinity stress in germinating seeds. Physiological analysis suggested that qSE3 significantly increased K+ and Na+ uptake in germinating seeds under salinity stress, resulting in increased abscisic acid (ABA) biosynthesis and activated ABA signaling responses. Furthermore, qSE3 significantly decreased the H2O2 level in germinating seeds under salinity stress. All of these seed physiological changes modulated by qSE3 might contribute to seed germination and seedling establishment under salinity stress. Based on analysis of single‐nucleotide polymorphism data of rice accessions, we identified a HAP3 haplotype of qSE3 that was positively correlated with seed germination under salinity stress. This study provides important insights into the roles of qSE3 in seed germination and seedling establishment under salinity stress and facilitates the practical use of qSE3 in rice breeding.

Seed vigour is an imperative trait for the direct seeding of rice. Isopropylmalate synthase (IPMS) catalyses the committed step of leucine (Leu) biosynthesis, but its effect on seed vigour remains unclear. In this study, rice OsIPMS1 and OsIPMS2 was cloned, and the roles of OsIPMS1 in seed vigour were mainly investigated. OsIPMS1 and OsIPMS2 catalyse Leu biosynthesis, and Leu feedback inhibits their IPMS activities. Disruption of OsIPMS1 resulted in low seed vigour under various conditions, which might be tightly associated with the reduction of amino acids in germinating seeds. Eleven amino acids that associated with stress tolerance, GA biosynthesis and tricarboxylic acid (TCA) cycle were significantly reduced in osipms1 mutants compared with those in wide type (WT) during seed germination. Transcriptome analysis indicated that a total of 1209 differentially expressed genes (DEGs) were altered in osipms1a mutant compared with WT at the early germination stage, wherein most of the genes were involved in glycolysis/gluconeogenesis, protein processing, pyruvate, carbon, fructose and mannose metabolism. Further analysis confirmed that the regulation of OsIPMS1 in seed vigour involved in starch hydrolysis, glycolytic activity and energy levels in germinating seeds. The effects of seed priming were tightly associated with the mRNA levels of OsIPMS1 in priming seeds. The OsIPMS1 might be used as a biomarker to determine the best stop time-point of seed priming in rice. This study provides novel insights into the function of OsIPMS1 on seed vigour and should have practical applications in seed priming of rice.

Summary Seed vigour is an important trait for direct seeding in rice. In this study, indole‐3‐acetate beta‐glucosyltransferase OsIAGLU was cloned in rice, and its roles on seed vigour were mainly investigated. Disruption of OsIAGLU resulted in low seed vigour in rice. Quantitative RT‐PCR analysis showed that the expressions of OsIAGLU were relatively higher in the late developing and the early germinating seeds and were significantly induced by indole‐3‐acetic acid (IAA) and abscisic acid (ABA). Transcriptome analysis revealed that the IAA‐ and ABA‐related genes were involved in the OsIAGLU regulation of seed vigour in rice. The higher levels of free IAA and ABA were identified in germinating seeds of osiaglu mutants compared to wild‐type (WT) plants. When treated with exogenous IAA and ABA, the osiaglu mutants and WT plants showed sensitivity to ABA while not IAA, but the exogenous IAA amplified ABA‐induced reduction of seed vigour in rice. The continuously higher expressions of ABA‐INSENSITIVE 3 ( OsABI3 ) and OsABI5 occurred in germinating seeds of osiaglu mutants compared to WT plants. The regulation of seed vigour by OsIAGLU might be through modulating IAA and ABA levels to alert OsABIs expression in germinating seeds in rice. Based on analysis of single‐nucleotide polymorphism data of rice accessions, two haplotypes of OsIAGLU that positively correlated with seed vigour were identified in indica accessions. This study provides important insights into the roles of OsIAGLU on seed vigour and facilitates the practical use of OsIAGLU in rice breeding.

Seed germination and seedling establishment are critical phases in rice. In this study, 276 indica accessions were used to investigate the genetic control of seed germination and seedling growth under normal, drought and salt conditions by using the trait of germination percentage, germination index and seedling survival percentage. The significant natural variation of seed germination and seedling growth was observed among accessions at three conditions. Correlation analysis showed that the significant and positive relationship between drought and salt stress conditions was observed in seed germination while not in seedling growth. A total of 12, 14 and 9 simple sequence repeat (SSR) markers associated with three traits were identified under normal, drought and salt conditions respectively. Seven and two SSR loci were simultaneously identified at two and three conditions, respectively, five SSR loci each were specific for drought and salt stress condition. By comparing chromosomal positions of the markers here with previously studies, six SSR loci might represent novel. Several accessions with elite performance of seed germination and seedling growth under stress conditions were firstly identified, such as Gulfrose, Kaijiangliushizao, Yangxidao and Xincunheigu. Six cross combinations each for improving seed germination and seedling growth under stress conditions were predicted. The identified elite accessions and alleles might be applicable to improve rice seed germination and seedling growth by the marker-assisted selection approach.

Responses of nonhuman species to dying and dead conspecifics range from hard-wired, fixed-action patterns - as in social insects - to varied, flexible behaviors with cognitive and emotional correlates - as in some larger-brained mammals [1,2]. Comparative thanatology addresses issues that include empathy, compassion, and conceptual understanding of death across species [1-3]. Several aspects of how great apes react to illness, injury and death of others recall human behavior in comparable situations [1-5]. However, the extent to which more distantly related primates share these responses is largely unknown. Here, we describe behaviors shown toward a dying adult female in wild Sichuan snub-nosed monkeys (Rhinopithecus roxellana) [6] and argue that empathy and compassion surrounding death extend beyond humans and their closest evolutionary relatives.