ABSTRACT
Pyrus xerophila has strong resistance to drought, cold, salt, and rust. It is one of the main rootstock types of pear in Northwest China, with high production value. However, its habitat is seriously damaged. The prediction of the geographical distribution of P. xerophila under different climate scenarios will provide important scientific basis for rational development and utilization of resources and the protection of diversity. Based on MaxEnt model and ArcGIS spatial analysis, the potential spatial distribution pattern of P. xerophila in the current and future (2050, 2070) was constructed using comprehensive and accurate distribution records and high-resolution environmental data, and the relative importance of environmental factors was evaluated. The results showed that the suitable habitat area of P. xerophila was 3.32×105 km2, mainly located in eastern Qinghai, southern Gansu, southern Ningxia, central Shaanxi, southern Shanxi and western Henan. Mean UV-B of the month with lowest UV-B and altitude were identified as the critical factors shaping habitat availability for P. xerophila. Overall, with global warming, the potential habitat for P. xerophila might decrease in 2050 and 2070 under different CO2 climate scenarios. Real-time monitoring of P. xerophila populations should be enhanced.
Subject(s)
Pyrus , China , Climate , Climate Change , EcosystemABSTRACT
To resovle the problems of in-situ conservation and resource utilization of Pyrus caller-yana, maximum entropy model (MaxEnt) and geographic information system (GIS) were used to predict the global ecological suitable region of P. calleryana in different climate scenarios based on 236 distribution data and 19 ecological factors. The results showed that the ecological suitable regions of P. calleryana were mainly concentrated in North America, Asia and other regions, with a total area of 1.6×107 km2. In China, the regions with high ecological suitability were Hunan, Hubei, Anhui, Jiangxi, Jiangsu, Zhejiang and Fujian provinces. The main factors affecting the geographical distribution of P. calleryana were mean annual temperature and mean annual precipitation, followed by the seasonality of temperature. The model simulations indicated that P. calleryana would have different suitable habitat areas and marginally suitable habitat areas in different climate scenarios. In terms of the spatial distribution of the potential habitat area, both the distributional range and the center of distribution of suitable and marginally suitable habitat area would shift from east to west. The suitable habitat area in North America and marginally suitable habitat areas in Europe would increase rapidly.
Subject(s)
Climate Change , Pyrus/growth & development , Asia , China , Ecosystem , Europe , North AmericaABSTRACT
The wild Ussurian pear was the most important wild pear resource in northern China, belonging to the most hardiness species. Taking 48 accessions of wild Ussurian pear and 2 accessions of cultivated Ussurian pear as test materials, this paper studied the morphology of leaves, chlorophyll content, and photosynthetic characteristics. We compared the difference between the wild and cultivated Ussurian pear, analyzed the photosynthetic characteristics of wild Ussurian pear, clarified the interrelationships between the indices, and established significant linear equations of photosynthesis and water-related physiological indices. The results showed that the leaf morphological index, chlorophyll content and photosynthetic indices for cultivated Ussurian pear were significantly lower than their average values for wild Ussurian pear. The specific leaf area (SLA), leaf dry matter content ( LDMC) , and intercellular CO2 concentration had low coefficients of variation, and the other 8 indices had variation coefficient indices between 0.12-0.41. So, the level of diversity was high, indicating obvious difference in photosynthetic characteristic of wild pear resources in China. The photosynthetic indices were significantly correlated with chlorophyll composition (Chl a/b) and LDMC. The photosynthetic rate had significant exponential correlation with the intercellular CO2 concentration, transpiration rate, and stomatal conductance. The photosynthetic rate was mainly affected by stomatal limitation. The wild variety 'Jinzhoushanli' was selected as high photosynthetic genetic resource.
Subject(s)
Photosynthesis , Plant Leaves/physiology , Pyrus/physiology , China , Chlorophyll/analysis , Plant Leaves/anatomy & histology , WaterABSTRACT
Self-incompatibility (SI) is an important intraspecific reproductive barrier in flowering plants. To identify the S-alleles of Chinese pear species (Pyrus pyrifolia, P. bretschneideri, P. ussuriensis and P. sinkiangenis etc.), S-RNase-specific PCR amplification, sequence analyses and field pollination tests were performed using two cultivars 'Jingxiang' and 'Esu' of P. bretschneideri as materials. Two new S-RNase genes were identified from the two cultivars. They were 1,122 bp and 1,058 bp in length, and designated as S37-RNase (GenBank accession no. DQ839238) and S38-RNase (GenBank accession no. DQ839239). By comparison of their deduced amino acid sequences with those of S1-to S36-alleles of Oriental pear, it can be seen that both the two new S-alleles had their conserved regions C1 and C2, but their hypervariable regions (HV) were quite different from those of the others. S37 showed a higher similarity (96%) to S38 in the amino acid sequences deduced from them, whereas both of them displayed the highest similarity (98%) to S15 and the lowest (63%) to S32. The two S-alleles had introns of 786 bp and 723 bp, respectively, similar in size to that of S15 (777 bp). Finally, the S-genotypes of 'Jinxiang' and 'Esu' were unambiguously determined as S34S37 and S15S38, respectively.
