连阴雨天气导致田间湿度增大，诱发田间霉菌的生长繁殖，并侵染农作物导致田间霉变的发生。在大豆生长后期，因连阴雨天气导致的田间霉变严重影响大豆的产量和品质。为探究田间霉变诱导大豆品质劣变的机制，本研究利用人工降雨室模拟连阴雨天气，诱发大豆籽粒田间霉变，结合转录组学和多种代谢检测平台，解析田间霉变胁迫下大豆品质劣变的生化机理。研究结果表明，田间霉变影响大豆的外观品质，霉变大豆籽粒皱缩、变形，并出现霉斑。田间霉变使大豆籽粒中蛋白质、多糖等储藏性物质的含量降低，导致籽粒百粒重显著下降。转录组分析发现，田间霉变使大豆籽粒中氨基酸代谢、糖酵解、三羧酸循环、脂肪酸β氧化等初生代谢过程加强。代谢组分析结果也表明，霉变大豆籽粒中多种氨基酸、糖类物质、有机酸的含量显著增加，而脂肪酸的含量则显著下降。与此同时，大豆异黄酮作为一类重要的抗逆活性物质，其生物合成在转录水平和代谢水平均受到田间霉变的诱导。田间霉变诱发大豆籽粒的防御机制，通过分解和消耗储藏性物质为防御体系的构建提供能量和底物，但储藏性物质的消耗导致了大豆品质劣变。本研究为深入了解大豆籽粒田间霉变的机制提供了重要的理论基础，同时也为抗田间霉变大豆品种的筛选指明方向。

Soybean is one of the major oil seed crops, which is usually intercropped with other crops to increase soybean production area and yield.  However, soybean is highly sensitive to shading.  It is unclear if soybean morphology responds to shading (i.e., shade tolerance or avoidance) and which features may be suitable as screening materials in relay strip intercropping.  Therefore, in this study, various agronomic characteristics of different soybean genotypes were analyzed under relay intercropping conditions.  The soybean materials used in this study exhibited genetic diversity, and the coefficient of variations of the agronomic parameters ranged from 13.84 to 72.08% during the shade period and from 6.44 to 52.49% during the maturity period.  The ratios of shading to full irradiance in stem mass fraction (SMF) were almost greater than 1, whereas opposite results were found in the leaves.  Compared with full irradiance, the average stem length (SL), leaf area ratio (LAR) and specific leaf area (SLA) for the two years (2013 and 2014) increased by 0.78, 0.47 and 0.65 under shady conditions, respectively.  However, the stem diameter (SD), total biomass (TB), leaf area (LA), number of nodes (NN) on the main stem, and number of branches (BN) all decreased.  During the shady period, the SL and SMF exhibited a significant negative correlation with yield, and the SD exhibited a significant positive correlation with yield.  The correlation between the soybean yield and agronomic parameters during the mature period, except for SL, the first pod height (FPH), 100-seed weight (100-SW), and reproductive growth period (RGP), were significant (P<0.01), especially for seed weight per branch (SWB), pods per plant (PP), BN, and vegetative growth period (VGP).  These results provide an insight into screening the shade tolerance of soybean varieties and can be useful in targeted breeding programs of relay intercropped soybeans.  

Phytophthora sojae Kanfman and Gerdemann (P. sojae) is one of the most prevalent pathogens and causes Phytophthora root rot, which limits soybean production worldwide. Development of resistant cultivars is a cost-effective approach to controlling this disease. In this study, 127 soybean germplasm were evaluated for their responses to Phytophthora sojae strain Pm28 using the hypocotyl inoculation technique, and 49 were found resistant to the strain. The hypocotyl of P1, P2, F1, and F2:3 of two crosses of Ludou 4 (resistant)×Youchu 4 (susceptible) and Cangdou 5 (resistant)×Williams (susceptible) were inoculated with Pm28, and were used to analyze the inheritance of resistance. The population derived from the cross of Ludou 4×Youchu 4 was used to map the resistance gene (designated as Rps9) to a linkage group. 932 pairs of SSR primers were used to detect polymorphism, and seven SSR markers were mapped near the resistance gene. The results showed that the resistance to Pm28 in Ludou 4 and Cangdou 5 was controlled by a single dominant gene Rps9, which was located on the molecular linkage group N between the SSR markers Satt631 (7.5 cM) and Sat_186 (4.3 cM).