New simple sequence repeat (SSR) markers were developed in the Japanese larch (Larix kaempferi) using unigene sequences for further genetic diversity studies and the genetic improvement of breeding programs. One thousand two handred and thirty five (1235) primer pairs were tested and 165 successfully identified in L. kaempferi. Out of the amplified candidate markers, 145 (90.6%) exhibited polymorphism among 24 individuals of L. kaempferi, with the number of alleles per locus (N_a), observed heterozygosity (H_o), expected heterozygosity (H_e) and polymorphic information content (PIC) averaging at 4.510, 0.487, 0.518 and 0.459, respectively. Cross-species amplification of randomly selection of 30 genic-SSRs among the 145 polymorphic ones showed that 80.0% of the SSRs could be amplified in Larix olgensis, 86.7% could be amplified in Larix principi-rupprechtii and 83.0% could be amplified in Larix gmelinii. High rates of cross-species amplification were observed. The genic-SSRs developed herein would be a valuable resource for genetic analysis of Larix kaempferi and related species, and also have the potential to facilitate the genetic improvement and breeding of larch.

Cunninghamia lanceolata is one of the most important tree species in China due to its significance both in economy and ecology. The aims of the present study were to construct a high-density genetic map and identify a quantitative trait locus (QTL) for C. lanceolata. In this study, an F1 population comprising 81 individuals was developed. Using specific length amplified fragment sequencing (SLAF-seq) technology, a total of 254,899 loci were found to be polymorphic. After linkage analysis, 2574 markers were used to construct genetic linkage maps. Specifically, 1632 markers were allocated to 11 linkage groups (LGs) for the female map, 1038 for the male map, and 2574 for the integrated map. The integrated map consisted of 4596 single-nucleotide polymorphisms (SNPs) loci, resulting in an average of 1.79 SNP loci per SLAF marker. The marker coverage was 1665.76 cM for the female map, 1436.39 cM for the male map, and 1748.40 cM for the integrated map. The average interval between two adjacent mapped markers was 1.03 cM, 1.40 cM, and 0.68 cM for the female map, male map, and integrated map, respectively. Using the integrated map, we performed interval mapping (logarithm of odds, LOD > 2.0) to detect traits of interest. We identified a total of 2, 1, 2, 5, 1, 2, 1, and 3 QTLs for diameter at breast height, heartwood diameter, heartwood proportion, heartwood a*, heartwood b*, heartwood L*, sapwood a*, and sapwood L*, respectively. The number of markers associated with each QTL ranged from 1 to 14, and each marker explained phenotypic variances ranging from 12.70% to 23.60%. Furthermore, a common QTL was identified for diameter at breast height and heartwood color a*, while another common QTL was observed for heartwood color L* and heartwood color a*. These findings suggest possible pleiotropic effects of the same genes on these traits. In conclusion, we successfully constructed high-density genetic maps for C. lanceolata using the SLAF-seq method with an F1 population. Notably, these linkage maps represent the most comprehensive and densest ones available to date for C. lanceolata and will facilitate future chromosome assignments for C. lanceolata whole-genome sequencing. These identified QTLs will serve as a valuable resource for conducting fine-scale QTL mapping and implementing marker-assisted selection in C. lanceolata, particularly for growth and wood-color traits.

01 The eco-toxicological effects of cadmium stress on five ornamental plants Zhouli Liu, Wei Chen, Xingyuan He, Shuai Yu, Weihang Ding 02 Study on the formation and release mechanisms of hydrogen sulfide in Longtan coal mine Jianjun Liu, Yuliang Wu, Kaixiang Fan 03 Coral bleaching in the North Reef of China’s Xisha Islands in 2014 Yuanchao Li, Xinqing Zheng, Shiquan Chen, Haiqun Xie 04 Soil chemical characteristics in a Cunninghamia lanceolata stand suffering from ice-snow damage Jie Li, Zhuomin Wang, Li Xue 05 Diversity of understory vegetation was under a Cunninghamia lanceolata stand suffering from ice-snow damage Zhiyang Lie, Weilong Huang, Tongtong Zhou, Li Xue 06 The effect of water, nitrogen and harvesting time on yield and biomass allocation of Helianthus tuberosus L. Kai Gao, Tiexia Zhu 07 The vertical variation of microbial communities in the sediment of sea cucumber pond Weiteng Mao, Pei Yu, Xinfang Lv, Yunchun Li 08 Indicating significances of alpine plant functional groups to environmental change Peixi Su, Rui Shi 09 Research on the daily CH4 fluxes of soil in summer mangrove community at Yingluogang of Guangxi, China Yong Jiang, Xingbin Chen, Shichu liang 10 Beach protection structures in middle and lower reaches of Yangtze River Junfeng Xu 11 Social responsibility management of large dam project with owner as core: an empirical case in China Jiwei Zhu, Zhao Zhai, Linan Zhou, Yun Le, Li Cao 12 The ecological function value assessment analysis of urban waterfront Jiwei Zhu, Ping Lu, Zhiqian Huang, Bei Zhou 13 Mechanism of diurnal osmotic potential changes and adjustment of three Caragana species in different habitats of the Inner Mongolia Plateau Zhirong Zheng, Shihai Lv, Chaoyang Feng 14 Biodiversity of phytoplankton and environmental influences analysis of Longfeng Wetland, China Nan Song, Yan Liu, Xinxin Lu, Yawen Fan 15 The effect of human activities on culturable soil microbes from Yaoquan Mountain in Wudalianchi, China Jianfei Guan, Jihua Wang, Xueping Zhang