抗疫病加工型辣椒细胞质雄性不育恢复系的创制

为加快抗疫病加工型辣椒细胞质雄性不育(cytoplasmic male sterility,CMS)恢复系的创制,该试验以单生、长果自交系481 4 10为母本,以抗疫病的恢复系939 1和1021(1) 1为父本配制杂交组合,采用花药培养技术将抗疫病恢复系的Rf基因和抗疫病基因导入单生、长果自交系中,并利用分子标记辅助选择(molecular marker assisted selection, MAS)技术鉴定DH系(Double Haploid line)的Rf基因以及抗病性,进一步用室内苗期抗性鉴定的方法验证MAS筛选的含Rf DH系对疫病的抗性。结果表明：(1)花药培养的供体亲本(481 4 10×939 1)F₁诱导出22个胚状体,成苗后经倍性鉴定获得11个花培DH系;而由供体亲本［481 4 10×1021(1) 1］F₁获得 9个DH系。(2)分子标记CRF SCAR对花培DH系进行分子标记辅助选择验证结果表明,来自供体(481 4 10×939 1)F₁的DH系中有7个可扩增出870 bp的特异条带,占63.6%;而供体［481 4 10×1021(1) 1］F₁获得的DH系中则有8个能扩增出870 bp的特异条带,占88.9%。(3)分子标记FQ01/RQ01对DH系进行分子标记辅助选择筛选结果发现,来自供体(481 4 10×939 1)F₁的DH系有5个能扩增出717 bp的特异条带,占45.5%;而来自供体［481 4 10×1021(1) 1］F₁的DH系有4个可扩增出717 bp的特异条带,占44.4%。(4)MAS技术初步筛选到7个携带Rf的抗疫病DH系,分别命名为‘渝辣选3 2/3 3/3 5/7 1/7 5/7 6/7 9’;苗期抗性鉴定结果显示,7个DH系中5个DH系抗疫病,2个中抗疫病;农艺性状调查和测交实验表明,‘渝辣选3 2’和‘渝辣选7 1’是单生朝天椒、果实较长,味辣,均为CMS恢复系。该研究创制的2个DH系为利用辣椒CMS三系配套选育抗病新品种奠定了基础。     

Programmed nuclear destruction in yeast

Studies of the budding yeast Saccharomyces cerevisiae have provided many of the most important insights into the mechanisms of autophagy, which are common to all eukaryotes. However, investigation of yeast self-destruction pathways, including autophagy and programmed cell death, has been almost exclusively restricted to cells undergoing vegetative growth, leaving very little exploration of their functions during developmental transitions in the yeast life cycle. We have recently discovered that whole nuclei are subject to programmed destruction during yeast gametogenesis. Programmed nuclear destruction (PND) possesses characteristics of apoptosis in the form of DNA cleavage by endonuclease G, and involves bulk protein turnover through an unusual autophagic pathway involving lysis of the vacuole rather than delivery of components to it through macroautophagy. We thus illuminate an example of developmentally programmed cellular “self-eating” in yeast, which is associated with the rupture of a lytic organelle, reminiscent of programmed cell death mechanisms in plants and animals.     

Identification of the phosphoglycerate dehydrogenase isoform EDA9 as the essential gene for embryo and male gametophyte development in Arabidopsis

Three different pathways of serine (Ser) biosynthesis have been described in plants: the Glycolate pathway, which is part of the Photorespiratory pathway, and 2 non-Photorespiratory pathways, the Glycerate and the Phosphorylated pathways. The Phosphorylated Pathway of Ser Biosynthesis (PPSB) has been known to exist since the 1950s, but its biological relevance was not revealed until quite recently when the last enzyme of the pathway, the Phosphoserine Phosphatase, was functionally characterized. In the associated study¹, we characterized a family of genes coding for putatite phosphoglycerate dehydrogenases (PGDH, 3-PGDH, and EDA9), the first enzyme of the PPSB. A metabolomics study using overexpressing plants indicated that all PGDH family genes were able to regulate Ser homeostasis but only lacking of EDA9 expression caused drastic developmental defects. We provided genetic and molecular evidence for the essential role of EDA9 for embryo and pollen development. Here, some new insights into the physiological/molecular function of PPSB and Ser are presented and discussed.     

New insights into the functional roles of reactive oxygen species during embryo sac development and fertilization in Arabidopsis thaliana

Previously considered as toxic by-products of aerobic metabolism, reactive oxygen species (ROS) are emerging as essential signaling molecules in eukaryotes. Recent evidence showed that maintenance of ROS homeostasis during female gametophyte development is crucial for embryo sac patterning and fertilization. Although ROS are exclusively detected in the central cell of mature embryo sacs, the study of mutants deficient in ROS homeostasis suggests that controlled oxidative bursts might take place earlier during gametophyte development. Also, a ROS burst that depends on pollination takes place inside the embryo sac. This oxidative response might be required for pollen tube growth arrest and for sperm cell release. In this mini-review, we will focus on new insights into the role of ROS during female gametophyte development and fertilization. Special focus will be made on the mitochondrial Mn-Superoxide dismutase (MSD1), which has been recently reported to be essential for maintaining ROS homeostasis during embryo sac formation.     

HGT is widespread in insects and contributes to male courtship in lepidopterans

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Are extra‐pair males different from cuckolded males? A case study and a meta‐analytic examination

Traditional models for female extra‐pair matings assume that females benefit indirectly from extra‐pair mating behaviour. Under these so‐called adaptive models, extra‐pair males are hypothesized to have more compatible genotypes, larger body size, exaggerated ornaments or to be older than cuckolded males. Alternatively, (‘nonadaptive’) models that consider female extra‐pair matings to be a by‐product posit that female extra‐pair mating can be maintained even if there is no benefit to females. This could happen if, for example, males gained fitness benefits from extra‐pair mating, while female and male extra‐pair mating behaviours were genetically correlated. Extra‐pair males are also expected to be older and larger if this improves their ability to convince or coerce females to mate. We investigated whether a female's extra‐pair mates differed from her cuckolded mate in both genetic and phenotypic traits by analysing data from an insular house sparrow population. We found that extra‐pair males were older than cuckolded males, consistent with both models. However, in contrast to the expectations from from adaptive models, extra‐pair and cuckolded males were of similar genetic relatedness, and hence expected compatibility, with the female, and had comparable body size and secondary sexual traits. We also updated previous meta‐analyses examining differences between extra‐pair and cuckolded males. The meta‐analytic results matched results from our house sparrow case study. Although we cannot completely exclude indirect benefits for females, nonadaptive models may better explain female extra‐pair matings. These neglected alternative models deserve more research attention, and this should improve our understanding of the evolution of mating systems.     

Cyclin‐dependent kinase‐activating kinases CDKD;1 and CDKD;3 are essential for preserving mitotic activity in Arabidopsis thaliana

For the full activation of cyclin‐dependent kinases (CDKs), not only cyclin binding but also CDK phosphorylation is required. This activating phosphorylation is mediated by CDK‐activating kinases (CAKs). Arabidopsis has four genes showing similarity to vertebrate‐type CAKs, three CDKDs (CDKD;1‐CDKD;3) and one CDKF (CDKF;1). We previously found that the cdkf;1 mutant is defective in post‐embryonic development, even though the kinase activities of core CDKs remain unchanged relative to the wild type. This raised a question about the involvement of CDKDs in CDK activation in planta. Here we report that the cdkd;1 cdkd;3 double mutant showed gametophytic lethality. Most cdkd;1‐1 cdkd;3‐1 pollen grains were defective in pollen mitosis I and II, producing one‐cell or two‐cell pollen grains that lacked fertilization ability. We also found that the double knock‐out of CDKD;1 and CDKD;3 caused arrest and/or delay in the progression of female gametogenesis at multiple steps. Our genetic analyses revealed that the functions of CDKF;1 and CDKD;1 or CDKD;3 do not overlap, either during gametophyte and embryo development or in post‐embryonic development. Consistent with these analyses, CDKF;1 expression in the cdkd;1‐1 cdkd;3‐1 mutant could not rescue the gametophytic lethality. These results suggest that, in Arabidopsis, CDKD;1 and CDKD;3 function as CAKs controlling mitosis, whereas CDKF;1 plays a distinct role, mainly in post‐embryonic development. We propose that CDKD;1 and CDKD;3 phosphorylate and activate all core CDKs, CDKA, CDKB1 and CDKB2, thereby governing cell cycle progression throughout plant development.     

Y chromosome haplotype distribution of brown bears (Ursus arctos) in Northern Europe provides insight into population history and recovery

High‐resolution, male‐inherited Y‐chromosomal markers are a useful tool for population genetic analyses of wildlife species, but to date have only been applied in this context to relatively few species besides humans. Using nine Y‐chromosomal STRs and three Y‐chromosomal single nucleotide polymorphism markers (Y‐SNPs), we studied whether male gene flow was important for the recent recovery of the brown bear (Ursus arctos) in Northern Europe, where the species declined dramatically in numbers and geographical distribution during the last centuries but is expanding now. We found 36 haplotypes in 443 male extant brown bears from Sweden, Norway, Finland and northwestern Russia. In 14 individuals from southern Norway from 1780 to 1920, we found two Y chromosome haplotypes present in the extant population as well as four Y chromosome haplotypes not present among the modern samples. Our results suggested major differences in genetic connectivity, diversity and structure between the eastern and the western populations in Northern Europe. In the west, our results indicated that the recovered population originated from only four male lineages, displaying pronounced spatial structuring suggestive of large‐scale population size increase under limited male gene flow within the western subpopulation. In the east, we found a contrasting pattern, with high haplotype diversity and admixture. This first population genetic analysis of male brown bears shows conclusively that male gene flow was not the main force of population recovery.     

Comparative morphology study of the male genitalia in the tribe Astathini from China (Coleoptera: Cerambycidae)

The male genitalia of 13 species from four genera of Astathini were described and analyzed. The result showed that five genital characters, such as shape of the apex of 8th abdominal tergaum and sternum, ratio of the length of lateral lobes to tegmen, can be used to identify genera of Astathini; six characters, such as ratio of the length of lateral lobes to tegmen, ratio of the length of roof to lateral lobes, shape of the apex of ventral plate of median lobe, can be used to identify species in Bacchisa.