Construction of a high-density genetic map using specific-length amplified fragment markers and identification of QTLs for branching angle in poplar

Branching angle is a critical factor that determines the morphological establishment and is a typical quantitative trait controlled by multiple genes. In this study, we used SLAF-seq to construct a high-density genetic map, to investigate the genetic architecture of branching angle in poplar (Populus leucopyramidalis). A total of 240,672 SLAF tags were obtained, including 103,691 polymorphic SLAF tags. After filtering, 53,407 polymorphic markers were sorted into eight segregation types, and 11,162 of them were used to construct the genetic map. 8447 were on the female parent map, 8532 were on the male parent map, and 11,162 were on the integrated map. The marker coverage was 4820.84 and 5044.80 cM for the female and male maps, and 3142.61 cM for the integrated map. The average intervals between two adjacent mapped markers were 0.55, 0.59, and 0.28 cM for the three maps, respectively. Two quantitative trait loci (QTLs) were detected. Seven markers that exceeded the threshold in these two regions were considered as being associated with branching angle and the phenotypic variance explained by each of these marker was 10.64-11.66%. After functional annotation, we identified 15 candidate genes and analyzed the expression of candidate genes in narrow and wide crown progenies by qRT-PCR. These results show that the combination of QTL and SLAF-seq will contribute to future breeding plans in poplar breeding, especially in narrow crown poplar breeding.

Neonatal hearing screening in remote areas of China: a comparison between rural and urban populations

Objectives Universal neonatal hearing screening (UNHS) started late in some underdeveloped areas in China, with relatively scarce screening resources and a wide regional distribution. This study aimed to compare the screening performance between rural and urban populations, and to examine the characteristics and problems of UNHS in underdeveloped regions in China. Methods A two-step hearing screening program was used in neonates born in Liuzhou Maternal and Child Health Hospital and in patients who were born in other hospitals, but admitted to the neonatal intensive care unit. This program involved distortion product otoacoustic emission and automated auditory brainstem response. Characteristics of each newborn, as well as the screening outcomes and performance were compared between rural and urban populations. Results A total of 19,098 newborns were screened with a referral rate of 17.9% at the first step. Sixty-three (0.33%) newborns had hearing loss. The prevalence of permanent hearing loss was 2.25‰. The average screening age was significantly older in the rural population than in the urban population in the first ( P < 0.01) and second steps of screening ( P < 0.05). The rural population had a higher referral rate in both steps than the urban population ( P < 0.01). The follow-up rate was much lower in the rural population than in the urban population ( P < 0.05), but dramatically increased in 2014 compared with the previous 2 years. Conclusions A low follow-up rate is a critical issue when carrying out UNHS in developing countries, such as China, especially for rural populations. The government should establish more hearing referral centres to increase service coverage and supply financial assistance for low-income populations.