A genetic diversity assessment of starch quality traits in rice landraces from the Taihu basin,China

There are nearly 1 000 rice landrace varieties in the Taihu basin, China. To assess the genetic diversity of the rice, 24 intragenic molecular markers（representing 17 starch synthesis-related genes） were investigated in 115 Taihu basin rice landraces and 87 improved cultivars simultaneously. The results show that the average genetic diversity and polymorphism information content values of the landraces were higher than those of improved cultivars. In total, 41 and 39 allele combinations（of the 17 genes） were derived from the landraces and improved cultivars, respectively; only two identical allele combinations were found bet ween the two rice variety sources. Cluster analysis, based on the molecular markers, revealed that the rice varieties could be subdivided into five groups and, within these, the japonica improved rice and japonica landrace rice varieties were in two separate groups. According to the quality reference criteria to classify the rice into grades, some of the landraces were found to perform we ll, in terms of starch quality. For example, according to NY /T595-2002 criteria from the Ministry of Agriculture of China, 25 and 33 landraces reached grade 1, in terms of their apparent amylose content and gel consistency. Th e varieties that had outstanding quality could be used as breeding materials for rice quality breeding programs in the future. Our study is useful for future applications, such as genetic diversity studies, the protection of rice variety and improvment of rice quality in breeding programs.

Plant food sources and stone tools' function at the site of Shunshanji based on starch grain analysis

The upper-middle Huai River valley(HRV) is located in the transition zone in the middle of eastern China. Previous studies have shown that the past populations in the upper HRV obtained plant food through gathering and cultivation of both rice and millet during the middle Neolithic. However, for the middle HRV it is not very clear what methods were used by humans to obtain plant food in that time. In this paper, starch grain analysis was carried out on 17 stone tools and 29 cauldron pottery sherds unearthed at Shunshanji(8.5–7.0 kyr BP), which is known as the earliest Neolithic site in the middle HRV excavated so far. Here, ancient starches from Coix lacryma-jobi, Triticeae, Oryza sativa, Trichosanthes kirilowii and one unidentified specie were recovered. This study contributes to the limited knowledge of food strategies as observed in the middle HRV. It demonstrates that both gathering and cultivation of rice took place during the middle-Neolithic. Among the identified species, Coix lacryma-jobi appears to have been the main plant food at Shunshanji. Moreover, it is clear that Oryza sativa was not consumed as much as other plant species according to the occurrence frequency of different starch grains. Starch grains were also found on the used surfaces of grinding stone implements as well as pestles, which means that these stone tools were used for food processing. In addition, axes from Shunshanji may also have been used for food processing as well as wood working because starches were also found on the edge of axes. Information about subsistence strategies and tool use at Shunshanji will also be helpful to understanding the utilization of plants and agricultural development in the middle HRV during the early-middle Neolithic period.

Early millet use in West Liaohe area during early-middle Holocene

It is generally recognized that millet agriculture originated in northern China. However, the domestication process of foxtail millet(Setaria italica) and broomcorn millet(Panicum miliaceum) is still poorly understood. Based on statistical and morphological analyses of ancient millet starch grains, a tangible hypothesis has been proposed for the long-term domestication of green foxtail millet(S. viridis). However, the hypothesis requires validation by evidence from more regions and more archaeological finds. The West Liaohe region is one of the earliest regions of millet cultivation. Here, we report ancient starch grains recovered from 12 stone grinding tools from eight sites of the Xiaohexi culture(before 8.5 ka BP), Xinglongwa culture(8.2–7.4 ka BP), Zhaobaogou culture(7.0–6.4 ka BP), and Hongshan culture(6.5–5.0 ka BP) in the West Liaohe region of China. Our results indicate that the proportion of millet starch grains with wrinkled surfaces and rough edges, which are diagnostic of wild millet grasses, decreased from 13.0% to 3.4% from the Xiaohexi culture to the Hongshan culture. Millet starch grains measuring >16.8 ?m, a size class recorded only in domesticated foxtail millet, increased from 55.0% to 62.1%. These millet data imply that the process of millet domestication in the West Liaohe region began in the Xiaohexi period and continued up to the Hongshan period.