Transcriptome Analysis Revealed the Regulation of Gibberellin and the Establishment of Photosynthetic System Promote Rapid Seed Germination and Early Growth of Seedling in Pearl Millet

Background：Seed germination is the most important stage for the formation of a new plant. This process starts when the dry seeds begin to absorb water and ends when the radicles sticks out. The germination rate of different plant seeds varies differently. Most energy plants that usually grow on marginal land, the rapid germination of seeds is more conducive to its superiority in competition with surrounding plants, which is also the guarantee of normal plant development and high yield. Pearl millet is an important cereal crop that shares widespread applications in the world. It has the advantages of fast growth, high yield, and low maintenance cost. It can also be used to extract bioethanol to solve the increasingly prominent energy problems. Previous germination experiments are the evidence of very fast seed germination rate of pearl millet, but the molecular mechanisms behind it is still unclear.Results: Through the germination test and the measurement of the germs and radicles length of the seedlings, we found that pearl millet seeds germinated very quickly after 24 hours of swelling of the dry seeds. By using transcriptome sequencing technology, we characterized the gene expression patterns of dry seeds, water imbibed seeds, germs and radicles of seedlings, and found the more DEGs in radicles than germs. Further analysis showed that different genome clusters function specifically at different tissues and time periods. WGCNA and KEGG enrichment analysis showed that that many genes that positively regulate plant growth and development are highly enriched and expressed, especially the gibberellin signaling pathway that can promote seed germination. We speculated that the activation of these key genes promotes the germination of pearl millet seeds and the growth of seedlings. To verify this inference, we measured the content of the main effect hormone gibberellin and found that the gibberellin content after seed imbibition rose sharply and remained at a high level.Conclusions：This study explored the expression patterns of genes involved in pearl millet growth from the germination of dry seeds to the early growth stages. Also identifies the key genes involved in the regulation of seed germination and seedling growth. The activation of key genes in these pathways may contribute to the rapid germination and growth of seeds and seedlings in pearl millet. These results provide new insights to solve the problem for the plants with slow seed germination and seedling growth.

External Quality Control: Official Results of Forage Seeds Quality

The objective of this work to evaluate the official results of seeds quality of ryegrass, black oat grass, sudangrass and pearl millet, originated from commercial establishments from the State of Santa Catarina. Lots of forage seeds sampled in the state of Santa Catarina in the year of 2013 to 2015, presented low physiologic and physic quality, being the main criteria of disapproval the physic purity and germination. The samples of forage seeds from C1 and C2 categories collected in Santa Catarina present superior quality in relation to the non-certified S1 and S2. The quality of ryegrass seeds (national) showed below the legal standards established, independent of the year, for the physic purity and germination criteria. Although, for the ryegrass lots (imported) there was none disapproval related to germination and physic purity being out of the tolerated limits.The germination and physic purity indexes, for sudangrass lots presented conformity index adequate to the tolerated limits allowed by legal standards. In the other hand, for the same species, the criteria for number of other cultivated species presented 100% of disapproval for the analyzed lots in the non-certified categories in 2013. Lots of pearl millet seeds, with exception of those from the C2 category sampled in 2014, presented in conformity to the legal standards required, being, in comparison with the other species, the one that showed lower non-conformity degree in the analyzed period.

New Vigor Methodology in Pearl Millet Seeds

The use of high quality seeds is of utmost importance and is intimately related to seed vigor. The objective of this study was to stablish a novel methodology for evaluating the vigor of pearl millet seeds. The experiment was performed at the Federal University of Pelotas, using 5 seed lots of pearl millet cv. BRS1501. The research was carried out in two stages: first, seed lots were characterized (physiological quality tests); second, the initial emergence and development of pearl millet seedlings was evaluated, testing four different substrates and five sowing depths in the emergence test. The experimental set up consisted of a completely randomized design with four replicates. Means were compared by the Scott-Knott test at the 5% probability level. The substrates sand and carbonized rice husk, at 1.0 cm depth, satisfactorily stratified seed lots. These methodologies correlated with the speed of emergency index and seedling emergency. Thus, the study identified an innovative method for testing vigor in pearl millet seeds.

Image analysis to evaluate the physiological potential and morphology of pearl millet seeds

The use of fast and precise procedures for seed analysis is an important factor for making decisions at different stages of seed production. The aim of this study was to evaluate the occurrence of internal damage and associate morphological traits of pearl millet seeds with their physiological potential, and evaluate seed vigor using the Seed Vigor Imaging System (SVIS®) compared to other traditional vigor tests. Eight seed lots of the pearl millet cultivar ADR 300 were analyzed for germination, vigor (first count, accelerated aging, cold test, and SVIS®), internal morphology (X-ray), and morphological parameters (perimeter, area, and roundness). The X-ray test is effective in evaluating the internal morphology of pearl millet seeds, allowing identification of mechanical damage and of deteriorated and malformed tissues, making it possible to establish a relationship between the damage observed and the negative effect on germination. SVIS® analyses on two-day-old seedlings are a reliable method for assessing seed vigor of pearl millet. Parameters of perimeter and area of the seeds are related to their physiological potential.

Forage yield of pearl millet (Pennisetum glaucum) underdifferent water quality and accessions

This study examined the effect of reused treated grey water on yield of 10 pearl millet accessions (Pennisetum glaucum) in An-Najah University, Tulkarm, Palestine. Ten pearl millet seeds were planted during May 2010 in each separate plastic containers (35 x 50 x 15 cm) filled with 45 kg sandy clay soil in four replication of a completely randomized design and irrigated with three types of water (Fresh water as control, raw grey water, treated grey water). Results clearly showed that there were no significant differences in the yield under different water treatments. Also no significant interaction was observed between water treatments and cultivars. However, accessions IP3616, IP22269, Sudan pop II, and Sudan pop I gave high total fresh weight fresh weight of straw while accessions IP3616 and IP22269 produced the highest fresh weight of straw. The accessions IP6104, IP6110, IP19612 and ICMV155 registered the highest plant height.