Genetic diversity and population structure analysis of Capsicum germplasm accessions

Genetic diversity plays an essential role in plant breeding and utilization.Pepper is an important vegetable and spice crop worldwide.The genetic diversity of 1 904 accessions of pepper conserved at the National Mid-term Genebank for Vegetables,Beijing,China was analyzed based on 29 simple sequence repeat(SSR)markers,which were evenly distributed over 12 pepper chromosomes.The pepper accessions were divided into two groups in a genetic structure analysis,and the two groups showed obvious differences in fruit type and geographical distribution.We finally selected 248 accessions capturing 75.6%of the SSR alleles as the core collection for further research.Insights into the genetic structure of pepper provide the basis for population-level gene mining and genetic improvement.

Genetic diversity of pepper(Capsicum spp.) germplasm resources in China reflects selection for cultivar types and spatial distribution

Pepper（Capsicum spp.） is an important vegetable crop in the world. Now the pepper in China contributes one-third of the world＇s peppers production. Genetic diversity of the pepper germplasm of China is expected interesting to know. To explore the structure of genetic diversity in Chinese pepper germplasm resources and possible relationship with cultivar types or geographic origin, we sampled and compared 372 Gen Bank pepper accessions（local cultivars and landraces） from 31 provinces, autonomous regions and municipalities of China and 31 additional accessions from other countries. These accessions were genotyped using 28 simple sequence repeat（SSR） markers spanning the entire pepper genome. We then investigated the genetic structure of the sampled collection using model-based analysis in STRUCTURE v2.3.4 and examined genetic relationships by the unweighted pair-group method of mathematical averages（UPGMA） in MEGA. In addition to geographic origin, we evaluated eight plant and fruit traits. In total, 363 alleles were amplified using the 28 SSR primers. Gene diversity, polymorphism information content and heterozygosity of the 28 SSR loci were estimated as 0.09–0.92, 0.08–0.92 and 0.01–0.34, respectively. The UPGMA cluster analysis clearly distinguished Capsicum annuum L. from other cultivated pepper species. Population structure analysis of the 368 C. annuum accessions uncovered three genetic groups which also corresponded to distinct cultivar types with respect to the plant and fruit descriptors. The genetic structure was also related to the geographic origin of the landraces. Overall results indicate that genetic diversity of Chinese pepper landraces were structured by migration of genotypes followed by human selection for cultivar types in agreement with consumption modes and adaptation to the highly diversified agro-climatic conditions.

中国杂交粳稻育种研究进展

近年来中国杂交水稻育种技术不断创新,高产优质杂交粳稻在新品种选育上取得了一定进展,但还存在一些问题和挑战。概述了中国杂交粳稻育种研究的现状,分析了杂交粳稻在育种及生产中所存在的主要问题,提出了杂交粳稻进一步发展的对策。

SSR分子标记法快速进行常规稻种子纯度检测的研究及应用

为了提高种子纯度鉴定效率,实现常规稻种子纯度的快速检测,本研究首先对几种简化DNA提取试剂和操作方法进行比较,结果表明以Buffer A、Buffer B作提取试剂,在提取过程中对种子充分研磨并进行95℃水浴,提取的DNA进行PCR,电泳条带均一且明亮,适用于SSR标记扩增。另外,利用多态性标记检测种子纯度时,通过5粒、10粒种子进行DNA混样,筛选能够扩增出差异条带的标记用于后续单株检测,筛选出的标记位点对待检种子的检测结果与前期标记筛选一致。因此,通过5粒、10粒种子的DNA混样初筛,而后对扩增出差异条带的混样内包含的单株进行鉴定能够准确定位到假种子,进而实现种子纯度的检测。这种方法在节约试剂、降低检测成本的同时,缩短了检测时间,大大提高了种子纯度检测效率。

利用互花米草和水稻杂交提高水稻耐盐性的研究

选取互花米草与水稻杂交加代后的6个稳定水稻品系分别与其水稻母本在淡水和4‰咸水处理下进行耐盐性试验。结果表明:海粳18号、海粳19、海粳23、海粳25、海粳31的咸水产量损失率显著低于其母本,海粳29的产量损失率低于其母本,但统计学上差异不显著;利用灰色关联度综合评价分析得出在咸水中种植的海粳19、海粳23、海粳25的综合生产性能表现好于其母本,表明利用互花米草与水稻杂交能够提高耐盐性。