Invasive plant rhizome production and competitiveness vary based on neighbor identity

入侵植物根茎的生长和竞争力因相邻植物的不同而不同 物种内的遗传和表型变异对进化过程的影响已众所周知，但人们对种内变异如何影响群落水平过程还知之甚少。在人类对自然系统造成影响的大背景下，由于人类活动可能会产生巨大的选择压力，因此具有生态意义的种内变异可能会特别重要。在一项温室实验中，我们研究了一种分布广泛的入侵物种和农业杂草石茅(Sorghum halepense)在受到种间竞争、种内竞争和土壤肥力的影响时，其在生物量和根茎方面发生的种内变异和生态型变异。与我们的预期和此前的研究结果不同的是，我们并没有在这一早期生命阶段中发现石茅各生态型生物量的改变。然而，我们确实发现石茅的生物量会随着竞争植株种类和土壤施肥方式的不同而发生很显著的变化，同时不同株之间也存在很大差异。农业生态型的根茎较其它生态型大了11%，经施肥处理后的增大幅度更高至3倍；虽然施肥后的根茎生物量增加了~50%，但生态型之间却并无差异。有趣的是，当受到种内竞争时，与玉米(Zea mays)发生种间竞争时的情况相比，石茅的生物量和根茎生物量产出分别减少了32%和20%。我们的研究结果表明，针对相邻植株的种类而发生的物种特异性竞争响应以及根茎分配的改变，石茅在受竞争时可能会产生适应性响应，从而使分配情况发生改变。     

The AGCVIII kinase Dw2 modulates cell proliferation,endomembrane trafficking,and MLG/xylan cell wall localization in elongating stem internodes of Sorghum bicolor

Stems of bioenergy sorghum (Sorghum bicolor L. Moench.), a drought-tolerant C4 grass, contain up to 50 nodes and internodes of varying length that span 4–5 m and account for approximately 84% of harvested biomass. Stem internode growth impacts plant height and biomass accumulation and is regulated by brassinosteroid signaling, auxin transport, and gibberellin biosynthesis. In addition, an AGCVIII kinase (Dw2) regulates sorghum stem internode growth, but the underlying mechanism and signaling network are unknown. Here we provide evidence that mutation of Dw2 reduces cell proliferation in internode intercalary meristems, inhibits endocytosis, and alters the distribution of heteroxylan and mixed linkage glucan in cell walls. Phosphoproteomic analysis showed that Dw2 signaling influences the phosphorylation of proteins involved in lipid signaling (PLDδ), endomembrane trafficking, hormone, light, and receptor signaling, and photosynthesis. Together, our results show that Dw2 modulates endomembrane function and cell division during sorghum internode growth, providing insight into the regulation of monocot stem development.     

A low-copy-number Sorghum DNA sequence that detects hypervariable EcoRV fragments

A sorghum genomic DNA clone that hybridized on Southern blots in simple but different patterns to fragments produced by digestion of DNA from the parents of an F₂ mapping population was hybridized to EcoRV-digested DNA from 53 accessions. Forty-six different fragment patterns were observed, each comprised of from one to ten bands. Much less variability was detected in EcoRI than EcoRV digests of a selected subset of the accessions. Base-sequence analysis of the clone did not reveal a functional identity for the sequence and the clone does not contain repeated sequences often associated with hypervariable loci. Clones such as this will be especially useful in evaluating germplasm diversity and in identifying the potential parentage of hybrids.     

Multivariate analysis of sorghum volatiles for the fast screening of sugarcane aphid infestation

The sugarcane aphid, Melanaphis sacchari, has been a severe pest throughout the sorghum field in Texas, which can worse the sorghum yield economically. For this purpose of early detection, the mechanism of herbivore-induced plant volatiles (HIPVs) needs to be utilized in the detection method. In this study, the HayeSep Q adsorbent combined gas chromatography mass spectrometry (GC/MS) was tested to analyze the volatile organic compounds (VOCs) that sorghum can emit when they are in good shape as well as they are infested by the sugarcane aphids, and multivariate techniques were performed for the fast screening of the infestation. Several VOCs identified from Student’s t-test with p < 0.05 were finally chosen as variables for multivariate analysis, and both unsupervised learning of principal component analysis (PCA) and clustering analysis (CA) and supervised learning of linear discriminant analysis (LDA) were done, showing good performance on discrimination between healthy and infested sorghum.     

Comparative genetic mapping between duplicated segments on maize chromosomes 3 and 8 and homoeologous regions in sorghum and sugarcane

Comparative mapping within maize, sorghum and sugarcane has previously revealed the existence of syntenic regions between the crops. In the present study, mapping on the sorghum genome of a set of probes previously located on the maize and sugarcane maps allow a detailed analysis of the relationship between maize chromosomes 3 and 8 and sorghum and sugarcane homoeologous regions. Of 49 loci revealed by 46 (4 sugarcane and 42 maize) polymorphic probes in sorghum, 42 were linked and were assigned to linkage groups G (28), E (10) and I (4). On the basis of common probes, a complete co-linearity is observed between sorghum linkage group G and the two sugarcane linkage groups II and III. The comparison between the consensus sorghum/sugarcane map (G/II/III) and the maps of maize chromosomes 3 and 8 reveals a series of linkage blocks within which gene orders are conserved. These blocks are interspersed with non-homoeologous regions corresponding to the central part of the two maize chromosomes and have been reshuffled, resulting in several inversions in maize compared to sorghum and sugarcane. The results emphasize the fact that duplication will considerably complicate precise comparative mapping at the whole genome scale between maize and other Poaceae.     

Experiments on competitiveness of three endomycorrhizal fungi

Summary This paper examines competition between three VA endophytes places respectively as “inoculant” fungus in an inner compartment (300 ml) below the germinating seed, and as “indigenous” fungus in an outer compartment (900 ml). Previously prepared infested soil was used as source of the endophytes. Inner and outer compartment roots were harvested separately and percentage infection determined for each fungus, using diagnostic anatomical features of each fungus. Changes in colonisation patterns were followed up to 4 and 5 months. Treatments with non-infested soil in the outer compartment were used to compare infectivity and spread of the different endophytes. All three endophytes were able to invade soil already colonised by either of the other two, butGlomus fasciculatum (E₃) was more invasive thanGlomus tenue. This pattern appeared to be related to rates of spread of the fungi in the non-infested soil. The pattern was not affected by host, clover or sorghum, or by position, immediately below the seed or in the outer compartment. It seemed that the endophyte in the inner compartment had overriding and persistent effects on plant growth, unrelated to its dominance pattern or share of overall root infection at the later harvests.     

Effect of the seed coat on water uptake and electrolyt leakage of sorghum (Sorghum bicolor (L.) Moench) seeds

Four seed lots of sorghum cultivar IS 34213 were obtained which had been harvested early or at full maturity and then dried either swiftly in the sun or slowly in the shade. The earlier harvested seeds were lighter, smaller and of lower density. Earlier harvested seeds had pericarps which permitted faster water uptake and greater leakage of electrolytes. Water uptake and electrolyte leakage were positively correlated. The method of seed drying had no effect on water uptake or leakage. Greater leakage was associated with lower final germination. The results are interpreted in relation to germination testing.