Almond population genomics and non-additive GWAS reveal new insights into almond dissemination history and candidate genes for nut traits and blooming time

Domestication drastically changed crop genomes,fixing alleles of interest and creating different genetic populations.Genome-wide association studies(GWASs)are a powerful tool to detect these alleles of interest(and so QTLs).In this study,we explored the genetic structure as well as additive and non-additive genotype-phenotype associations in a collection of 243 almond accessions.Our genetic structure analysis strongly supported the subdivision of the accessions into five ancestral groups,all formed by accessions with a common origin.One of these groups was formed exclusively by Spanish accessions,while the rest were mainly formed by accessions from China,Italy,France,and the USA.These results agree with archaeological and historical evidence that separate modern almond dissemination into four phases:Asiatic,Mediterranean,Californian,and southern hemisphere.In total,we found 13 independent QTLs for nut weight,crack-out percentage,double kernels percentage,and blooming time.Of the 13 QTLs found,only one had an additive effect.Through candidate gene analysis,we proposed Prudul26A013473 as a candidate gene responsible for the main QTL found in crack-out percentage,Prudul26A012082 and Prudul26A017782 as candidate genes for the QTLs found in double kernels percentage,and Prudul26A000954 as a candidate gene for the QTL found in blooming time.Our study enhances our knowledge of almond dissemination history and will have a great impact on almond breeding.

基于SNP和InDel标记的巴西木薯遗传多样性与群体遗传结构分析

为了对巴西木薯种质资源进行遗传多样性、亲缘关系和群体遗传结构分析,本研究利用了7946个SNPs和1997个InDels分子标记,通过ADMIXTURE软件进行群体结构分析、GCTA软件进行主成分分析。结果显示,巴西木薯被划分为9个亚群。这与利用PHYLIP进行的聚类分析结果大概一致,其中亚群1、亚群2、亚群4、亚群6和亚群8能较好地分别聚在一起,而其他亚群中的样品大致能聚在一起,且样品间有一定的交叉。巴西木薯种质资源遗传多样性指数(0.274)高于中国、尼日利亚等,其中巴西木薯亚群5具有相对较高的遗传多样性水平(0.29)。巴西木薯各亚群的群体遗传分化程度较低(群体分化指数在0.03~0.15之间),但高于中国木薯种质资源的群体分化指数。各木薯材料间的遗传距离变幅为0.084~0.297,平均遗传距离为0.228。本研究结果可为后续关联分析发掘优良等位基因及引种提供依据。

Production of Dietetic Jam of Umbu-Caja (<i>Spondias</i>sp.): Physical, Physicochemical and Sensorial Evaluations

The umbucajazeira is specie native to the Brazilian Northeast semiarid areas, which is economically explored based on the fruit. The fruit has a high agroindustrial potential, mainly for jam production. The aim of this study was to evaluate through sensorial analysis, two formulations of umbu-caja jams: a dietetic one with xylitol, used as an option for substitution of the sugars, and a conventional one. The proportion of 50:50:0.5 (pulp/sugar/pectin or pulp/xylitol/pectin) was used for jam processing. The mixture was concentrated up to reach 65°Brix. The jams were evaluated by 50 non-trained tasters, through a hedonic scale of nine points, whereas the following attributes were used: appearance, color, flavor, aroma and texture. The results of the physical and physicochemical analysis showed that the characteristics of jams prepared with sucrose are close to the ones made with xylitol, except for the total sugars and the energetic value. The jams had pH values ranging between 2.37 and 2.92;titratable acidity varying between 0.56 and 0.78 g citric acid/100 g pulp;soluble solids ranging between 60.92°and 65.08°Brix, respectively. A tendency for yellow color was noticed by the color analysis. Jam diet had the highest scores for appearance (7.4 - 7.7). No significant differences (p > 0.05) were obtained to flavor and texture. The fruit of the umbucajazeira showed to be adequate for jam manufature since they had good sensorial acceptance. The use of xylitol was satisfactory for obtaining a product with jam characteristics similar to the conventional jam, but with lower energetic value.

Regulatory circuits involving bud dormancy factor PpeDAM6

DORMANCY-ASSOCIATED MADS-BOX(DAM)genes have recently emerged as key potential regulators of the dormancy cycle and climate adaptation in perennial species.Particularly,PpeDAM6 has been proposed to act as a major repressor of bud dormancy release and bud break in peach(Prunus persica).PpeDAM6 expression is downregulated concomitantly with the perception of a given genotype-dependent accumulation of winter chilling time,and the coincident enrichment in H3K27me3 chromatin modification at a specific genomic region.We have identified three peach BASIC PENTACYSTEINE PROTEINs(PpeBPCs)interacting with two GA-repeat motifs present in this H3K27me3-enriched region.Moreover,PpeBPC1 represses PpeDAM6 promoter activity by transient expression experiments.On the other hand,the heterologous overexpression of PpeDAM6 in European plum(Prunus domestica)alters plant vegetative growth,resulting in dwarf plants tending toward shoot meristem collapse.These alterations in vegetative growth of transgenic lines associate with impaired hormone homeostasis due to the modulation of genes involved in jasmonic acid,cytokinin,abscisic acid,and gibberellin pathways,and the downregulation of shoot meristem factors,specifically in transgenic leaf and apical tissues.The expression of many of these genes is also modified in flower buds of peach concomitantly with PpeDAM6 downregulation,which suggests a role of hormone homeostasis mechanisms in PpeDAM6-dependent maintenance of floral bud dormancy and growth repression.

Nitrate Transport, Sensing, and Responses in Plants

Nitrogen （N） is an essential macronutrient that affects plant growth and development. N is an important component of chlorophyll, amino acids, nucleic acids, and secondary metabolites. Nitrate is one of the most abundant N sources in the soil. Because nitrate and other N nutrients are often limiting, plants have developed sophisticated mechanisms to ensure adequate supply of nutrients in a variable environment. Nitrate is absorbed in the root and mobilized to other organs by nitrate transporters. Nitrate sensing activates signaling pathways that impinge upon molecular, metabolic, physiological, and developmental responses locally and at the whole plant level. With the advent of genomics technologies and genetic tools, important advances in our understanding of nitrate and other N nutrient responses have been achieved in the past decade. Furthermore, techniques that take advantage of natural polymor- phisms present in divergent individuals from a single species have been essential in uncovering new components. However, there are still gaps in our understanding of how nitrate signaling affects biolog- ical processes in plants. Moreover, we still lack an integrated view of how all the regulatory factors iden- tified interact or crosstalk to orchestrate the myriad N responses plants typically exhibit. In this review, we provide an updated overview of mechanisms by which nitrate is sensed and transported throughout the plant. We discuss signaling components and how nitrate sensing crosstalks with hormonal pathways for developmental responses locally and globally in the plant. Understanding how nitrate impacts on plant metabolism, physiology, and growth and development in plants is key to improving crops for sustainable agriculture.

Selection of Bacillus thuringiensis strains in citrus and their pathogenicity to Diaphorina citri (Hemiptera: Liviidae) nymphs

Bacillus thuringiensis(Bt)toxins are effective in controlling insect pests either through the spraying of products or when expressed in transgenic crops.The discovery of endophytic Bt strains opened new perspectives for studies aimed at the control of sap‐sucking insects,such as the Asian citrus psyllid Diaphorina citri Kuwayama(Hemiptera:Liviidae),a vector of“Candidatus Liberibacter spp.,”associated with citrus huanglongbing(HLB).In this study,translocation of endophytic Bt strains in citrus seedlings inoculated with Bt suspension delivered by soil‐drench,and their systemic pathogenicity to D.citri nymphs were investigated.The pathogenicity of three wild‐type Bt strains against D.citri third‐instar nymphs was demonstrated.Among the 10 recombinant strains tested(each of them harboring a single cry or cyt gene),3 can be highlighted,causing 42%–77%and 66%–90%nymphal mortality at 2 and 5 d after inoculation,respectively.The isolation of Bt cells from young citrus shoots and dead nymphs,and PCR performed with specific primers,confirmed the involvement of the Bt strains in the psyllid mortality.This is the first report showing the translocation of Bt strains from citrus seedling roots to shoots and their potential to control D.citri nymphs that fed on these soil‐drench inoculated seedlings.The Bt strains that caused the highest mortality rates have the potential to be used as bioinsecticides to control D.citri and the identified genes can be used for the production of transgenic Bt citrus.