Genome-wide identification of the CONSTANS-LIKE(COL)family and mechanism of fruit senescence regulation by PpCOL8 in sand pear(Pyrus pyrifolia)

Pyrus pyrifolia Nakai‘Whangkeumbae'is a sand pear fruit with excellent nutritional quality and taste.However,the industrial development of pear fruit is significantly limited by its short shelf life.Salicylic acid(SA),a well-known phytohormone,can delay fruit senescence and improve shelf life.However,the mechanism by which SA regulates CONSTANS-LIKE genes(COLs)during fruit senescence and the role of COL genes in mediating fruit senescence in sand pear are poorly understood.In this study,22 COL genes were identified in sand pear,including four COLs(Pp COL8,Pp COL9a,Pp COL9b,and Pp COL14)identified via transcriptome analysis and 18 COLs through genome-wide analysis.These COL genes were divided into three subgroups according to the structural domains of the COL protein.Pp COL8,with two B-box motifs and one CCT domain,belonged to the first subgroup.In contrast,the other three Pp COLs,Pp COL9a,Pp COL9b,and Pp COL14,with similar conserved protein domains and gene structures,were assigned to the third subgroup.The four COLs showed different expression patterns in pear tissues and were preferentially expressed at the early stage of fruit development.Moreover,the expression of Pp COL8 was inhibited by exogenous SA treatment,while SA up-regulated the expression of Pp COL9a and Pp COL9b.Interestingly,Pp COL8 interacts with Pp MADS,a MADS-box protein preferentially expressed in fruit,and SA up-regulated its expression.While the production of ethylene and the content of malondialdehyde(MDA)were increased in Pp COL8-overexpression sand pear fruit,the antioxidant enzyme(POD and SOD)activity and the expression of Pp POD1 and Pp SOD1 in the sand pear fruits were down-regulated,which showed that Pp COL8 promoted sand pear fruit senescence.In contrast,the corresponding changes were the opposite in Pp MADS-overexpression sand pear fruits,suggesting that Pp MADS delayed sand pear fruit senescence.The co-transformation of Pp COL8 and Pp MADS also delayed sand pear fruit senescence.The results of this study revealed that Pp COL8 can play a key role in pear fruit senescence by interacting with Pp MADS through the SA signaling pathway.

Identification of Self-Incompatibility Genotypes in Some Sand Pears (Pyrus pyrifolia Nakai) by PCR-RFLP Analysis

The identification of self-incompatibility genotype （S-genotype） will be useful for selection of pollinizers and design of crossing in cultivar improvement of sand pear. This paper reported the identification of self-incompatibility genotypes of seven Chinese and two Japanese sand pear cultivars using PCR-RFLP analysis and S-RNase sequencing. The Sgenotypes of these cultivars were determined as follows： Huali 1 S1S3, Shounan S1S3, Xizilti S1S4, Qingxiang S3S7, Sanhua S2S7, Huangmi （Imamuranatsu） S1S6, Huali 2 S3S4, Baozhuli S7S33, Cangxixueli S5S15. S-RNase alleles （S1 to S9） in sand pear could be identified effectively by PCR-RFLP analysis.

Relationship Between Anthocyanin Biosynthesis and Related Enzymes Activity in Pyrus pyrifolia Mantianhong and Its Bud Sports Aoguan

The aim of this article is to study the relationship between biosynthesis of anthocyanin and activities of phenylalanine ammonia lyase （PAL）, chalcone ismoerase （CHI） enzymes in Pyrus pyrifolia. Changes in the level of anthocyanin and the activities of enzymes of anthocyanin biosynthesis including PAL, CHI were studied in the pericarp of Pyrus pyrifolia Aoguan and Mantianhong during the period of pigment formation. Bagging treatment was also carried out to manipulate the synthesis of anthocyanin and the activities of related enzymes during the period of pigment formation. The results demonstrated that the level of anthocyanin of Aoguan was higher than that of Mantianhong. However, the content of anthocyanins has the similar changing trend in Aoguan and Mantianhong, highest anthocyanin concentrations of two varieties appeared in immature fruit and faded toward harvest. Meanwhile, similar changing trends of activities of PAL and CHI were also observed in both varieties. Aoguan has a lower activity of PAL than Mantianhong, whereas activity of CHI in Aoguan was higher than that in Mantianhong. Activity of PAL decreased during the period of pigment formation and was apparently not limiting to color development, whereas CHI activity increased at the same period and was closely related to the synthesis of anthocyanin. The results of bagging treatment showed that bagging treatment inhibited the activity of CHI, as well as the synthesis of anthocyanin, whereas debagging enhanced both the activity of CHI and synthesis of anthocyanin. The activity of CHI in debagging Aoguan pericarp was higher than the untreated Aoguan. However, effect of bagging treatment toward PAL activity was not obvious. Anthocyanin of bagging treated Aoguan decreased toward harvest. The content of anthocyanin of Pyruspyrifolia increased at the beginning of fruit coloration period and decreased toward fruit harvest. Activity of PAL was apparently not limiting to color development, whereas CHI activity was closely related to the synthesis of anthocyanin. Debagging enhanced both the activity of CHI and anthocyanin synthesis. Bagging treatment also proved that degradation of anthocyanin was not induced only by light. Light appeared to have two opposing effects in pears： it is required for anthocyanin synthesis and also for apparently increasing red color loss through increased degradation of anthocyanin.

Involvement of long non-coding RNAs in pear fruit senescence under high-and low-temperature conditions

Pear fruit senescence under high-and low-temperature conditions has been reported to be mediated by microRNAs.Long non-coding RNAs(lncRNAs),which can function as competing endogenous RNAs that interact with microRNAs,may also be involved in temperature-affected fruit senescence.Based on the transcriptome and microRNA sequencings,in this study,3330 lncRNAs were isolated from Pyrus pyrifolia fruit.Of these lncRNAs,2060 and 537 were responsive to high-and low-temperature conditions,respectively.Of these differentially expressed lncRNAs,82 and 24 correlated to the mRNAs involved in fruit senescence under high-and low-temperature conditions,respectively.Moreover,three lncRNAs were predicted to be competing endogenous RNAs(ceRNAs)that interact with the microRNAs involved in fruit senescence,while one and two ceRNAs were involved in fruit senescence under high-and low-temperature conditions,respectively.A dual-luciferase assay showed that the interaction of an lncRNA with a microRNA disrupts the action of the microRNA on the expression of its target mRNA(s).Furthermore,four alternative splicing-derived lncRNAs interacted with miR172i homologies(Novel_88 and Novel_69)to relieve the repressed expression of their target and produce an miR172i precursor.Correlation analysis of microRNA expression suggested that Novel_69 is likely involved in the cleavage of the pre-miR172i hairpin to generate mature miR172i.Taken together,lncRNAs are involved in pear fruit senescence under high-or low-temperature conditions through ceRNAs and the production of microRNA.

早熟砂梨苏翠1号在湖北省钟祥市的引种与栽培表现

早熟砂梨[Pyrus pyrifolia(Burm.F.)Nakai]新品种苏翠1号于2019年引入湖北省钟祥市梨产区进行引种栽培。结果表明,该品种在钟祥市表现为早果性好,成熟期早,果个大,石细胞少,风味甘甜,品质优,丰产、稳产,综合性状优良,是适合钟祥市梨产区发展的极早熟优良砂梨品种。

金碧梨果实膨大与新梢生长发育动态观测

以6年生的金碧梨(Pyrus pyrifolia Nakai Jinbi)为研究对象,定期测量其新梢的长度和果实纵径、横径,研究其新梢与果实生长发育动态。结果表明,在武汉地区,金碧梨新梢自3月下旬开始生长,到6月中旬停止生长,新梢长度从3.24 cm增长到68.98 cm,生长期为84 d,生长期间出现2次生长高峰,分别是4月13日和5月18日;金碧梨果实从4月初开始坐果,到8月下旬果实成熟停止生长,生长期153 d。果实纵横径生长呈S形曲线,发育过程中出现2次生长高峰,分别在4月中下旬和6月初。新梢生长与果实生长发育关系密切,4月13日新梢与果实生长养分竞争激烈,随后逐渐减弱,5月25日后新梢逐渐停止生长,果实迅速膨大并在6月8日达生长高峰。

南方四种砂梨果实营养及抗氧化活性成分比较分析

对南方地区的翠冠、翠玉、金水2号以及新水4个砂梨(Pyrus pyrifolia Nakai)品种的营养及抗氧化性能进行了测定和分析。结果表明,金水2号的维生素C含量最高,为(3.59±0.02)mg/100 g;新水的可溶性固形物含量最高,为12.32%±0.38%;翠冠的可滴定酸含量最低,为(0.60±0.07)g/kg;翠玉的总酚含量最低,为(0.035±0.003)mg GAE/g,果肉褐变耐受力最强。相关性分析结果显示,维生素C、可滴定酸是影响这4种砂梨果肉抗氧化能力的重要因子。总酚含量与果实可溶性固形物含量呈显著正相关,也是评价砂梨果实营养水平的重要因素。